Rad io- Electronics5

BUILD A SENSITIVE WIDE -BAND VTVM

Radi

Small -BoatRadioTune -Up Time

APRIL 1959

EIectronicIND

Reduce Noise in TV Antennas

Build a Free -Power Transistor Radio

The Old Fran

Model 310 a complete miniatureV -O -M with single switch selectionand the ranges and accuracy of unitsseveral times its size. Used withModel 10 clamp -on ammete pluggedin it becomes one of the world's mostversatile pieces of test ecn. ipment-even measuring current flow withoutstripping wires.

1ft

.The New Frontiers

Model 630 -PL V -0-M with such ad-vanced features as an unbreakableclear plastic front for wide range,shadowless, instant vision, polarityreversing switch, single king sizeknob for selecting both range andcircuit, continuous resistance read-ings from 0.1 ohm to 100 megohms.

Triplett ElectricalInstrument CompanyBluffton, Ohio

are in science, design, production

The new frontiers are being exploited by companieswhich like Triplett have worked the frontier of elec-tronics for over 55 years.

Working the frontier means being on the spotwith the equipment to develop and maintain thisnew made world. Triplett has a history of over 50years of being first with the best in panel instru-ments and test equipment at a practical cost.Triplett is still working on the frontier of electronicswith such innovations as these:

kJver i) years experience in instrument

Model 690-A, a new Transistor Testerwith more Triplett "plus" in accuracyand simplicity, for testing leakage andgain of all low and medium power PNPand NPN transistors. Small, rugged,battery -operated, it measures DC Betafrom 5 to infinity. Affords exact tests forshorts, checks forward & reverse leakageof diodes. Features single switch selec-tion of transistor types, positive "off" toprevent accidental battery drain, separate"calibrate" and "gain" buttons eliminateerrors, transistor socket and externalleads for any basing arrargement.

New Unimeters-a great stepforward in increasing meter n-ventory flexibility while cuttinginventory cost. These Select -Your -Range unimeters consist ofonly two basic meter movements,which can be combined with anyone of a number of separate dial -component units for a wide varietyof meter ranges. Movementsquickly and simply slide onto dial -components and lock together-no soldering, no wiring. ExclusiveTriplett Bar -Ring construction forself -shielding, greater accuracyand sensitivity.

Throughout the world Triplett first . . to last

Learn Radio -TelevisionServicing or Communicationsby Practicing at Home

in Spare TimeN.R.I. SENDS kits with which you prac-tice building circuits common to Radioand TV sets. You LEARN -BY -DOINGto locate Radio -TV troubles. As part ofN.R.I. Servicing Course, you build VacuumTube Voltmeter and AC -DC receiver. UseVTVM to conduct experiments,earn extra money fixingsets in spare time

Fast Growing Field Offers YouGood Pay, Success, Bright Future

More than 150 million homeRADIO -TV BROADCASTING (see above,: otTers and auto Radios, 40 millionimportant positions as Operators and Technicians. TV sets. Color TV promisesRADIO -TV SERVICING Technicians (see below, added opportunities. For theneeded in every community. Their services are trained man, there are good jobs, bright fu -respected, their skill appreciated. tures in Radio -TV Servicing or Broadcasting.

t't% Training PLUS opportunity is the idealcombination for success. So plan now to getinto Radio -TV. The technical man is lookedup to. He does important work, gets goodpay for it. Radio -Television offers that kindof work. NRI can supply training quickly,without expense of going away to school.Keep your job while training. You learnat home in your spare time. NRI is theOLDEST and LARGEST home study Radio -TV school. Its methods have proved success-ful for more than 40 years.

N.R.I. TRAINED THESE MEN FOR SUCCESS

"I was repairing Radiosby 10th lesson. Nowhave good TV job."M. R. LINDEMUTH,Fort Wayne, Ind.

had a successfulRadio repair shop. NowI'm Engineer forWHPE." V.W.WORK- ,

MAN, High Point, N.C.

AJ. E. SMITH

Founder

"Doing spare time re-pairs on Radio and TV.Soon servicing fulltime." CLYDE HIG-GINS, Waltham, Mass.

"There are a number ofNRI graduates here. I

can thank NRI for thisjob." JACK WAG-

, NER, Lexington, N. C

VETERANS Approved Under G.I. Bills

Bigger than ever and still grow- Added Income Soon - $10, $15ing fast. That's why Radio -TVhas special appeal to ambitious a Week in Spare Timemen not satisfied with their Soon after enrolling, many NRI studentsjob and earnings. More than start to earn $10, $15 a week in spare time4,000 Radio and TV stations. fixing sets. Some pay for their training and

enjoy extra luxuries this way. Some makeenough to start their own Radio -TV shops.NRI training is practical-gets quick results.Easy to understand, well illustrated lessonsteach you basic principles. And you LEARN -BY -DOING by practicing with kits of equip-ment which "bring to life" things you study.

Find Out What NRI OffersNRI has trained thousands for successfulcareers in Radio -TV. Study fast or slow-asyou like. Diploma when you. graduate. Mailcoupon now. Paste it on a postcard or mail inenvelope. ACTUAL LESSON FREE. Also 64page catalog that shows opportunities, showsequipment you get. Cost of NRI courses low.Easy terms. NATIONAL RADIO INSTITUTE,Dept. 9DF, Washington 16. D. C.

National Radio InstituteDept. 9DF, Washington 16, D. C.

Mail me Sample Lesson and 64 -Page CatalogFREE. (No salesman will call. Please write plainly.)

Name_ _Age_ - -

Address_

City Zone_ _State.ACCREDITED MEMBER, NATIONAL HOME STUDY COUNCIL

1.

APRIL, 1959 3

APRIL, 1959

Radio -ElectronicsFormerly RADIO CRAFT Incorporating SHORT WAVE CRAFT TELEVISION NEWS RADIO 8 TELEVISION

EDITORIAL31 Electronics vs War-Hugo Gernsback

TEST INSTRUMENTS

ON THE COVER

(More on page 59)

32 Sensitive Wind -Band Ac Vtvm-Phillip D. Blais36 Using Scope Probes-R. M. Centerville Marine radio service special-

ist Maurice Holland tunes up39 Simple Capacitor Checking Method-George P. Pearce a small -boat radio prepara-

tory to the 1959 sailingseason.

RADIO41 ABC's of Mobile Radio, Part III-Leo G. Sands Color original by Jacques

44 Echo Sounder for Small -Boat Owners-Elbert RobbersonSaphier

48 Radio Telegraphy in 1866-Darrell L. Geiger49 Experimenter's Carrier -Power Receiver-Dr. William H. Grace

WHAT'S NEW51 Pictorial Reports of New Developments

TELEVISION52 Hush the Noise in Antennas and Lead-ins-

Engineering Staff. Scala Radio Co.54 TV's Tricky R -C Circuits-Cyrus Glickstein57 TV Service Clinic-Conducted by Robert G. Middleton59 Color -Projection Systems60 Small Claims Court in Session-H. A. Highstone

AUDIO -HIGH FIDELITY 61 The Record Skips-Charles W. Farrington

76 Ultra -Steered -Stereo Projector-Mohammed Ulysses Fips82 All About the Reflex Enclosure, Part II-P. G. A. H. Voigt95 New Discs and Tapes, Stereo and Mono-Reviewed by

Chester Santon

ELECTRONICS98 Cold-Cathode-Revolutionary New Heaterless Tube-Eric Leslie

v" 99 Electronics Guides Your Car-Vladimir K. Zworykin andLeslie E. Flory

134 Books 125 Noteworthy Circuits129 Business and People 116 On the Market108, 133 Corrections 127 Patents24 Correspondence 110 Technicians' News

132 Literature 123 Technotes106 New Tubes and Semiconductors 121 Try This One

6 News Briefs 1:31 50 Years Ago

RADIO -ELECTRONICS is indexed in Applied Science & Technology Index (Formerly Industrial Arts Index)

Hugo GernsbackEditor and Publisher

M. Harvey GernsbackEditorial Director

Fred ShunamanManaging Editor

Robert F ScottW2PWG, Technical Editor

Larry StecklerAssociate Editor

I. QueenEditorial Associate

Robert G. Middleton............Television Consultant

Elizabeth StalcupProduction Manager

Cathy Coccozza..........Advertising Production

Wm. Lyon McLaughlin....TeCh. Illustration Director

Sol EhrlichArt Director.

Fred NeinastStaff Artist

Lee Robinson..... . ..... .General Manager

John J. LamsonSales Manager

G. Aliquo........_....Circulation Manager

Adam J. Smith....Director, Newsstand Sales

Robert FallathPromotion Manager

Average Paid CirculationOver 199,000

RADIO -ELECTRONICS, April, 1950, Vol. XXX. No. 4. Published monthly at mt. Morels, III., by Cernsback Publications, Inc. Second -Cie, mail privileges authorizedat Mt. Morris, Ill. Copyright 1959 by Cernsback Publications, Inc. All rights reserved under Universal, International and Pan-American Copyright Conventions.SUBSCRIPTION RATES: U.S., U.S. possessions and Canada, $4.00 for one year; $7.00 for two years; $10.00 for three years; single copies 35c, Pan-American countries $5.00for one year; $9.00 for two years; $13.00 for three years. All other countries $5.50 a year;$10.00 for two years; $14.50 for three years.SUBSCRIPTIONS: Address correspondence to Radio -Electronics, Subscription Dept., 154 West 14th St., New York 11, N.Y. When requesting a change of address, please fur-nish an address label from a recent issue. Allow one month for change of address.GERNSBACK PUBLICATIONS, INC. Executive, Editorial and Advertising Offices, 154 West 1401 St., New York 11, N.Y. Telephone Algonquin 5-7755. Hugo Gernsback,Chairman of the Board; M. Harvey Gernsback. President; G. Aliquo, Secretary.BRANCH ADVERTISING OFFICES and FOREIGN AGENTS listed on page 139.POSTMASTER: If undeliverable, send Form 3579 to: RADIO -ELECTRONICS, 154 West 14th St., New York 11, N.Y. Trademark registered U. S. Pat. Office.

4 RADIO -ELECTRONICS

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LIFETIME SECURITY CAN BE YOURS!You are needed in the Television, Radio, and Electronics industry !Trained technicians are in growing demand at excellent pay- inALL PHASES, including Servicing, Manufacturing, Broadcasting andCommunications, Automation, Radar, Government Missile Projects.NATIONAL SCHOOLS SHOP -METHOD HOMETRAINING, with newly added lessonsand equipment, trains you in yourspare time at home, for these unlim-ited opportunities, including manytechnical jobs leading to supervisorypositions.YOU LEARN BY BUILDING EQUIPMENT WITHKITS AND PARTS WE SEND YOU. YourNational Schools course includesthorough Practical training-YOULEARN BY DOING! We send youcomplete standard equipment of pro-fessional quality for building variousexperimental and test units. You ad-vance step by step, perform more than100 experiments, and you build acomplete TV set from the ground up,that is yours to keep! A big, new TVpicture tube is included at no extracharge.EARN AS YOU LEARN. We'll show youhow to earn extra money right fromthe start. Many of our students payfor their course-and more-whilestudying. So can you!

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If you wish to take your training in our ResidentSchool at Los Angeles, the world's TV capital,start NOW in our big, modern Shops, Labs andRadioTV Studios. Here you work with latestElectronic equipment - - professionally installed

- finest, most complete facilities offered byany school. Expert, friendly instructors. Personalattention. Graduate Employment Service. Helpin finding home near school and part timejob while you learn. Check box in coupon forfull information.

APRIL, 1959

H

LESSONS AND INSTRUCTION MATERIAL AREUP-TO-DATE, PRACTICAL, INTERESTING.Every National Schools Shop -Methodlesson is made easy to understand bynumerous illustrations and diagrams.All instruction material has been de-veloped and tested in our own Resi-dent School Shops, Laboratories andStudios.SEND FOR INFORMATION TODAY ... it canmean the difference between SUCCESSand failure for you! Send for yourFREE BOOK "Your Future inTelevision -Radio -Electronics" andFREE Sample Lesson. Do it TODAY,while you are thinking about yourfuture. It doesn't cost you anythingto investigate!

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SHOP -METHOD HOME TRAININGCOVERS ALL PHASES OF INDUSTRY1. Television, including Color TV2. Radio AM & FM3. Electronics for Guided Missiles4. Sound Recording and Hi -Fidelity5. FCC License6. Automation and Computers7. Radar & Micro -Waves8. Broadcasting and

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NATIONAL*riiNicA SCHOOLSWORLD-WIDE TRAINING SINCE 1905

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II mow NEWS BRIEFS

aso aim fb- um TV PROGRAM LICENSING bill* has beenintroduced in the New York StateLegislature by Assemblyman A. BruceManley. It is intended to give theState's highest educational authoritiescensorship power over television of thetype that they now have over motionpictures. if passed, many TV programswill have to get a license from theBoard of Regents at a cost of $50 orless for each half hour. Public-service,sporting events and news programswould be exempted from the licensingrequirement.

Mr. Manley has stated that TV showshad been offering "a disproportionateamount of crime, sex, horror, terror,brutality and violence," harming themorals of young people and promotingjuvenile delinquency.ULTRA - VIOLET MICROSCOPE bringsheretofore invisible things to light.Based on the ultrascope, an ultra-violet converter tube, the new devicemakes it possible for scientists to studyliving cancer cells. Previously, thesewere transparent under an ordinarymicroscope and had to be killed andstained before viewing. Announced byRCA, the ultra -violet microscope is amodified optical microscope. A standardmicroscope body is used, but, the lensesare made of quartz (ordinary glass

VIEWING SCREEN

ELECTRON OPTICS

ULTRA -VIOLETSENSITIVEFACEPLATE

POWERSUPPLY r

A C LINE

absorbs ultra -violet light). The ultra -scope tube fits over the top of themicroscope and is connected to its 12,-500 -volt power supply (see diagram).An ultra -violet light source projectslight through the specimen and themicroscope's objective lens. This beamthen hits the ultrascope's face plate,which is ultra -violet -sensitive. Theimage converter tube changes the in-visible ultra -violet light into a visiblegreen -tinted picture on the tube'sfluorescent viewing screen.MAPPING THE WASTELANDS becomespossible at a fraction of the time andcost formerly necessary with the helpof a new Doppler radar device. Mappingof desert or waste areas has beenespecially difficult because of their lackof landmarks. The air surveyor wasforced to use navigational systems thatrequired expensive manned ground sta-tions. The new system, called Radon,is completely self-contained and oper-ates by direct measurement of the di-rection and distance traveled. It isproduced by General Precision Labora-tory Inc., Pleasantville, N. Y.

The system has been used by the AeroService Co., Philadelphia, Pa., to makean aerial survey of 40,000 miles of thecentral Sahara Desert in southernLibya. The exploration target was oil.

--.. EYEPIECEVISIBLE LIGHTHOUSING

ELECTRONS

ULTRASCOPE

BARRELADAPTER

- OPTICALMICROSCOPE

) ____OBJECTIVE

,---S

SPECIMEN__,....-

- ULTRA -VIOLET

MIRROR rNARROW PASS ULTRA -VIOLETFILTERS SOURCE

A similar guided survey will cover partof the Spanish Sahara in southwesternMorocco.

Radan uses the same principle aspolice highway radars. If a radar beamis reflected from a car moving towardthe instrument, the length of the re-flected waves will be shorter than ifthe car were stationary, since thecar moves a slight distance toward theradar between each wave. The fasterthe car comes, the greater this Dopplereffect. In the Radan system, four beamsare radiated diagonally downward to-ward the terrain. They are so patternedthat they reach the ground at the ex-tremities of an X-shaped figure, withthe airplane directly above the centerof the X.

To measure forward speed, the frontand rear pair of beams are compared;for side drift, the two diagonal pairsare compared. Results are fed into acomputer which indicates the differencebetween the actual and desired courseon a dial, permitting the pilot to flya true course. For mapping a largearea, a number of range lines areplotted and the plane made to fly eachof them successively, photographing theterrain beneath with its mappingcameras.LIVE ACTION and miniature backgroundsets (1/6 scale), still photographs ormotion pictures are blended into asingle TV scene through a device called

ideoScene. It enables live televisionto use a variety of scenes in a limitedarea, eliminating the need for bulkysets. In the CBS Television Network'sVideoScene technique the master camerahas two pickup tubes. One photographsthe actor against a special reflective pat-tern background made by MinnesotaMining and Manufacturing Co. The sec-ond tube, sensitive to the highly reflec-tive indigo background, silhouettes theactor and blacks out the backgroundscene in the area he occupies. The back-ground camera photographing the mini-ature set feeds its picture into a keyingamplifier, where the background pic-ture is combined with the picture of theactor as a single scene.

The "live" camera and the back-ground camera are linked through aservo system which synchronizes theirmovements so the background and actorare always perfectly matched. As themaster camera pans, tilts or zoomswhile photographing the actor, thebackground camera follows.

In its present form, VideoScene isdesigned for black and white but canbe adapted for color television.


SOMETHING

* HAS BEEN ADDED TO THE

DEVRY TECH TRAINING PROGRAM

Prepare in Spare Time At Home for a

JOB THAT PADSREAL MONEYitt TELEVISION -RADIO -ELECTRONICS

Many DeVry-trained men who now hold good jobs paying real money were once lookingfor opportunity, yet wondering if they needed advanced schooling, special experience, orhigher math. They clipped a DeVry Tech coupon, mailed it in-and were pleasantly SUR-PRISED! Now they work in one of today's fastest -growing fields-TELEVISION-RADIO-ELECTRONICS. Many have their own profitable service shops. DeVry Tech's "Learn -by -Seeing,""Learn -by -Reading," "Learn -by -Doing" training made the difference! You, too, may train athome the DeVry Tech way with wonderful, helpful movies, clear texts and valuable homelaboratory equipment-or in our well-equipped Chicago or Toronto Training Centers.Now something NEW* has been added to help you learn more by "doing." You can chooseto build and keep your own top quality 6 -speaker STEREOPHONIC SOUND SYSTEM that willprovide thrilling enjoyment for years to come. Plans are furnished so that you can alsobuild your own speaker cabinets-or we can tell you where to buy them. DeVry Tech'sspecially designed Stereo System includes:

Turntable with Stereo cartridge Stereo Amplifier Stereo Pre -Amplifier 2 Cross -Over Networks Six Speakers: two 12 -in., two 8 -in., two 3 -in.

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MANY OPTIONS!NOW ... DeVry Tech men can take their choice of anyor all of the quality equipment shown above: The StereoSystem . . . the Scope and Meter . . . a 21 -inch TV Set(not pictured) . . . or ALL THREE. But no matter whichway you do it, you get practical home training at itsbest . . . the kind you need to get started in thefast-moving Electronics field. Send coupon for details.

When you build your own equipment, youlearn about the working parts. You canrepair, adjust, maintain. You learn bydoing-the DeVry Tech way. You put basicprinciples into "on-the-job" practice.

EMPLOYMENTSERVICE

DeVry Tech offers real,down-to-earth employ-ment service to help youtoward a ood job after

9"One of North America's graduation - even pro -Foremost Electronics

vides help in gynesutr. own servicing bum -

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47 Accredited Member ofNational Home Study Council

DEVRY TECHNICAL INSTITUTE4141 BELMONT CHICAGO 41, ILL. Formerly DeFOREST'S TRAINING, Inc.

EarningsEledronIcs

and YOU.

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MAIL TODAY FOR FREE FACTSDeVry Technical Institute4141 Belmont Ave., Chicago 41, III., Dept. RE -4-PPlease give me your two FREE booklets, "Pocket Guide toReal Earnings" and "Electronics and You," and tell me howto prepare to enter one or more branches of Electronics.

NAME

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CITY ZONE STATEI Check here if subject to military training.I DeVry Tech's Canadian Training Center is located atII 2053

626 Roselawn Avenue, Toronto 12, Ontario

AGEPLEASE PRINT

APRIL, 1959 7

The Greater VibratorRadiart Vibrators are unaffected by bounce, jounce, heat, cold,moisture. There's a replacement type for every 6- and 12 -voltapplication. Ask your Radiart Distributor for a free RadiartVibrator Replacement Guide or write The Radiart Corporation,2900 Columbia Avenue, Indianapolis 5, Indiana.

RADIARTVibrators

NEWS BRIEFS (Continued)

DR. W. R. G. BAKER, director of the EIAEngineering Department, announcedthe formation of the National Stereo-phonic Radio Committee. Set up to studymethods of broadcasting stereophonicsound by AM, FM and TV stations, thecommittee is composed of technical ex-perts in the field. Six panels within thecommittee will review the technicalfactors involved. Dr. Baker said allknown technical proposals for suchsystems would be studied and urgedthose who have such proposals to sub-mit them to the committee, through theEIA Engineering Department's asso-

Calendar of Events

Symposium on Millimeter Waves, Mar.31-Apr. 2, Engineering Society Build-ing, New York, N. Y.Pittsburgh Hi-Fi Music Show, Apr. 3-5, Penn -Sheraton Motel.British Radio and Electronic Compo-nent Show, Apr. 6-5, Grosvenor Houseand Park Lane House, London, England.Buffalo (N. Y.) Hi-Fi Music Show, Apr.10-12, Hotel Stetler.Conference on Industrial Instrumenta-tion and Control, Apr. 14-15, IllinoisInstitute of Technology, Chicago, Ill.Southwestern IRE Conference & Elec-tronics Show, Apr. 16-18, Dallas (Tex.)Memorial Auditorium and Baker Hotel.Conference on Analog & Digital Re-cording & Controlling Instrumentation,Apr. 20-21, Bellevue -Stratford Hotel,Philadelphia, Pa.British Industrial Photographic & TVExhibition, Apr. 20-24, London, Eng-land.Annual Technical Conference on TV &Transistors, Apr. 21-22, Cincinnati,Ohio.National Aeronautical Electronics Con-ference, May 4-6, Biltmore Hotel. Day-ton, Ohio.Society of Motion Picture and Tele-vision Engineers Convention, May 4-8,Fontainebleau Hotel, Miami, Fla.URSI Spring Meeting, May 5-7. Wash-ington, D. C.1959 Electronic Components Confer-ference, May 6-8, Ben Franklin Hotel,Philadelphia, Pa.7th Regional IRE Technical Conferenceand Trade Show, May 6-8, Universityof New Mexico, Albuquerque, N. M.Joint Conference on Automatic Tech-niques, May 11-13, Pick -Congress Ho-tel, Chicago, Ill.1959 Electronic Parts DistributorsShow, May 18-W, Conrad Hilton Hotel,Chicago, Ill. For manufacturers, repre-sentatives and distributors only. RA-mo-EtEcTuoNics will exhibit in Room504 and GERNSBACK LIBRARY in Booth107.5th National Symposium on Instru-mental Methods of Analysis, May 18-20, Shamrock -Hilton, Houston, Tex.International Convention on Transis-tors, May 21-27, Earl's Court, London,England.National Telemetering Conference,May 25-27, Brown Palace and Cosmo-politan Hotel, Denver, Colo.

date director, Virgil M. Graham, 11 W.42 St., New York 36, N. Y. The com-mittee's formation was suggested lastNovember by Dr. Baker.

OPEN LETTER TO THE FCC suggestsfive changes in rule making to "insurea complete and equitable utilization of

RADIO -ELECTRONICS

Do you WISH youwere EMPLOYED ><- F.C.C. LICENSEin ELECTRONICS? x QUICKLY

F.C.C. LICENSE -THE KEY TO BETTER JOBS

An F.C.C. commercial (not amateur) license is your ticketto higher pay and more interesting employment. This licenseis Federal Government evidence of your qualifications inelectronics. Employers are eager to hire licensed technicians.

WHICH LICENSE FOR WHICH JOB?The THIRD CLASS radiotelephone license is of value

primarily in that it qualifies you to take the second classexamination. The scope of authority covered by a third classlicense is extremely limited.

The SECOND CLASS radiotelephone license qualifiesyou to install, maintain and operate most all radiotelephoneequipment except commercial broadcast station equipment.

The FIRST CLASS radio telephone license qualifies youto install, maintain and operate every type of radiotelephoneequipment (except amateur) including all radio and tele-vision stations in the United States, its territories and pos-sessions. This is the highest class of radiotelephone licenseavailable.

GRANTHAM TRAINING PREPARES YOU

The Grantham course covers the required subjectmatter completely. Even though it is planned prima-rily to lead directly to a first class FCC license, it doesthis by TEACHING you electronics. Some of thesubjects covered in detail are: Basic Electricity forBeginners, Basic Mathematics, Ohm's and Kirchhoff'sLaws, Alternating Current, Frequency and Wave-length, Inductance, Capacitance, Impedance, Reso-nance, Vacuum Tubes, Transistors, Basic Principlesof Amplification, Classes of Amplifiers, Oscillators.Power Supplies, AM Transmitters and Receivers. FMTransmitters and Receivers, Antennas and Trans-mission Lines, Measuring Instruments, FCC Rulesand Regulations, and extensive theory and mathe-matical calculations associated with all the abovesubjects explained simply and in detail.

OUR GUARANTEEIf you should fail the F. C. C. exam after finishing our

course, we guarantee to give additional training at NOADDITIONAL COST. Read details in our free booklet.

Grantham

/ Hollywood Division

Washington Division

Seattle Division

VA

GetYour First Class Commercial

CORRESPONDENCE OR RESIDENCE CLASSESGrantham School of Electronics specializes in F.C.C. license

preparation. Correspondence training is conducted from Washington,Hollywood, and Seattle; also, resident DAY and EVENING classesare held in all three cities. Either way, by correspondence or in resi-dent classes, we train you quickly and well.

This bookletFREE!

This free booklet givesdetails of our trainingand explains what anF. C. C. license can dofor your future.

HERE'S PROOF...that Grantham students prepare for F.C.C. examinations in aminimum of time. Here is a list of a few of our recent graduates,the class of license they got, and how long it took them :

License Weeks

Roy E. Alexander, Pikeville, Kentucky 1st 12

Robert J. Conley, 129 W. 46th St., New York 36, N. Y 1st 14

W. R. Smith, 1335 E. 8th St., Long Beach, Calif. 1st 12

Howard E. Martz, 301 S. Penn. St., Fairmount, Ind. 1st 24

John W. Dempsey, Box 55, Rising Sun, Md. 1st 12

Donald H. Ford, Hyannis RD, Barnstable, Mass. 1st 12

Richard 1. Falk, 2303 Holman St., Bremerton, Wash. 1st 22

Denson D. McNully, 1117 N. Houston St., Amarillo, Texas 1st 9

lames D. Hough, 400 S. Church St., East Troy, Wisc. 1st 12

Odie B. Perry, Jr., Rt. #3, Zebulon, N. C. 1st 12

Milton C. Gee, Rt. #1, Washington, N.J.1st 11

School of Electronics1505 N. Western Ave.Hollywood 27, Calif.

(Phone: HO 7.7727)

821 -19th Street, N.WWashington 6, 0.0

(Phone: ST 3-3614)/

408 Marion StreetSeattle 4, Wash. /

(Phone.' MA 2-7227)

MAIL COUPON TO SCHOOL NEAREST YOU

r(Mail in envelope or paste on postal card)

To: GRANTHAM SCHOOL OF ELECTRONICS821 -19th. NW 130.5 N. Western -108 Mario,,Washington Hollywood Seattle

Gentlemen:Please send me your free booklet telling how I can get my com-

mercial F.C.C. license quickly. I understand there is no obligationand no salesman will call.

Name Age

Address

1

City State! am interested in: El Home Study, 0 Resident Classes 94 1/ J

APRIL, 1 9 5 9 9

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the 88-108-mc band assigned to FM."These changes, detailed in the letter byCharles W. Kline, president of FM Un-limited Inc., are:

1. 105.1-107.9 mc be designatedfor use by class -A stations onlywith a maximum power of 3 kwand maximum height of 300 feet,instead of 1 kw at 250 feet.

2. 91.5-104.9 mc be designated foruse by class -B stations only.

3. 88.1-91.3 mc be designated foruse by class -N (noncommercial)stations - educational, religious,municipal, etc. All 10 -watt"campus" stations be assigned to88.1 mc only.

4. Stations licensed to metropoli-tan -suburban and communityareas be designated as class -Astations and be required to pro-vide maximum service for theareas to which they are assigned.

5. Class -B stations in Zone 1 bepermitted the equivalent of 20kw at 1,000 feet, instead of20 kw at 500 feet.

Justification for the preceding sug-gestions is included in the letter alongwith a list showing what the new chan-nel allocations would look like if thesuggested changes are adopted. An in-teresting point is the following para-graph-one of the reasons behindsuggested change 1.

"As FM allocations now stand, class -A channels are situated between or ad-jacent to metropolitan class -B channels.However, according to present rules,there must be an 800-kc separation be-tween two class -B stations serving thesame area. Nevertheless, applicationsare beginning to be granted for class -Astations serving suburban sections ofmetropolitan areas-only 400 kc awayfrom existing class -B stations. Thesesuburban class -A stations not only in-terfere with the primary coverage ofthe adjoining class B's but are them-selves prevented from rendering maxi-mum service to their communities be-cause they are 'hemmed in' by the sameclass -B stations whose coverage theyare interfering with."TWO ON A CHANNEL is the basic prin-ciple behind TASI ( Time AssignmentSpeech Interpolation). Bell TelephoneLabs say that using this system theycan increase the capacity of a 36 -channel submarine telephone cable tohandle 72 talkers.

In a normal two-way phone conversa-tion, each person, on the average, speaksonly half the time and, even while heis speaking, there are gaps and pausesin his speech. So if the two directionsof transmission are separated, eachpath is idle more than half the time.If two conversations were interlacedto take advantage of these gaps, youcould get twice as many conversationsper channel.

In practice, more than two channelsare needed for the system to work-two talkers would frequently speak atthe same time. In a submarine tele-phone cable, say one with 36 channels,


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APRIL, 1959 11

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an averaging effect occurs and at anyone instant there is a greater prob-ability of enough free time to accom-modate the larger number of conversa-tions.

TASI is essentially a group of high-speed switches and an electronic com-puter. When there are more talkersthan channels, the equipment connectsactive talkers by disconnecting talkerswho are inactive at that moment. Inturn, the disconnected talker is assignedanother momentarily inactive channelwhen he starts to speak again. A talkeris disconnected only when he is silent.

When a talker starts speaking, hisvoice triggers a speech detector. Thedetector is scanned by a control circuitsimilar to a modern digital computer.The control circuit sends a coded toneburst consisting of four audio toneswhich precede the voice over the avail-able channel. After the 10 -millisecondtone burst, the control circuit connectsthe talker to the same channel. Thecoded tones operate switches whichconnect the talker to the proper lineat the receiving end.THOUSANDS OF MESSAGES handled forpersonnel at isolated Arctic and SouthPacific posts earned Julius M. J. Madey,18, of Clark, N. J., General Electric's1958 Edison Radio Amateur Award forpublic service. One of a family of fourlicensed radio amateurs, Madey spendsan average of 90 hours a week at hisstation K2KGJ in his home.

Madey transmitted more thanmessages in the past year, maintainingalmost continuous contact with the far-flung outposts from mid -afternoon to

8 am. Several times, he has handledofficial Navy and Coast Guard mes-sages for those services.

Active in local Civil Defense andother community activities, his workhas been featured in several magazinesand newspapers. He won studentscience -fair honors several years agofor inventing an ultrasonic drill. Henow plans building a system for creat-ing man-made "whistlers," the eeriehigh -frequency sounds in space whichare attracting scientific attention.MECHANIZED MAIL PROCESSING fromstart to finish is the unusual feature

(Continued on Page 18)


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APRIL, 1959 13

THE

ARCTIC EYE

THAT NEVER

SLEEPS

WORLD CENTER OF COMMUNICATIONS RESEARCH AND DEVELOPMENT

This plastic radome houses a radar antenna constantly scanning the skies to detect the presence of aircraft.A line of these radars provides early warning of any threatening approach to the North American continent.

The Distant Early Warning Line is now on perpetual guard duty. Spanning theArctic from Baffin Island to Alaska, this great system was conceived at the LincolnLaboratory of M.I.T. and produced under the leadership of Western Electric.

But first the DEW Line had to be engineered into a workable system. This wasdone at Bell Telephone Laboratories.

The obstacles were formidable. Conventional means of communication-telephonepoles, cables and even line -of -sight microwave radio-weren't feasible. A complicatedsystem had to be made to operate reliably in a climate so cold that outdoor maintenanceis impracticable farther than a few hundred feet from heated habitation.

Whenever possible, Bell Laboratories engineers utilized well -proven art. But as itbecame necessary, they innovated. For example, they designed and directed the devel-opment of a new and superior radar which automatically scans the skies, pinpoints aplane and alerts the operator.

To reach around the horizon from one radar station to another, they applied on amassive scale a development which they pioneered-transmission by tropospheric scatter.Result: at a DEW Line Station you can dial directly a station more than a thousand milesaway and converse as clearly as with your home telephone.

Bell Laboratories' contribution to the DEW Line demonstrates again how telephonescience works for the defense of America.

BELL TELEPHONE LABORATORIES 22i


If you have some knowledgeof Radio or Television orElectronics now and want toBECOME A PROFESSIONAL

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Over 40 years ago, J. E. Smith, founder of theNational Radio Institute, pioneered in teachingRadio by the home study method. Today, this mag-nificent building is completely devoted to NRI'sRadio -TV Electronics training. Here up-to-date lab-oratory and research facilities are constantly testingnew developments and improved methods of train-ing men for Radio -TV Electronics careers.

All -Practice MethodN RI's Professional TV ServicingTraining is practical, complete.You make tests and experimentsto help thoroughly understandTV problems. You get equipmentto build a 5" Oscilloscope, a 17"picture tube and all componentsfor building a TV receiver. Com-prehensive Color TV manualsalso included. You learn how ex-perts diagnose TV defects, getknowledge of professional tech-niques. Mail the coupon forfree catalog now. NATIONALRADIO INSTITUTE,Washing-ton 16, D. C.

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APRIL, 1959 15


aarTNEON

RAYTHEON MANUFACTURING COMPANY

DISTRIBUTOR PRODUCTS DIVISION

55 CHAPEL STREET NEWTON 58 MASSACHUSETTS BIGELOW 4-7500

Dear Frank:

How can I prove Raytheon Tubes are superior to all others?A good question and I'm going to try and give you an honestanswer!

First, we believe that what we put in Raytheon TV andRadio Tubes . . . and the way we make them . . . are thereal reasons why they are best. Pictures of quality control,manufacturing processes, might help convince you, but wouldthey actually prove the end result is a quality product?

You still wouldn't be sure that the Raytheon replacementTube you put in your customer's set was as good as or betterthan the original and would outlast it in saving you allthose no-charge repeat calls.

To be sure, Frank, we could give you a long list of howwe make all our own tube parts --use imported getters,special grids, ceramic insulated multiple fold heaters, andmany, many others --but do you really care about thesethings?

You know, of course, that Raytheon is the world's largestexclusive manufacturer of Electronic Components. RaytheonTubes and Components which go into 21 of our nation'smissiles have to be better than normal. They don't just haveto be good!

Honestly, Frank, maybe we can't prove superiority . .

but you can! You and thousands of men like yourself areproving it every day. I would suggest that as long as thereis a doubt in your mind, why don't you find out foryourself by using Raytheon Tubes as others have done? Idon't know of any other way.

Thanks for your letter . . . let's hear from you againreal soon. I know you're going to be convinced.

Sincerely,

RAYTHEON MANUFACTURING COMPANY

ke-y

P.S. I'll be talking to you again next month.

APRIL, 1959 17

a quarter -century of PRECISION * know-howis now yours in

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MODEL B-10 MODEL S-55Battery Eliminator Kit Wideband 5" Oscilloscope

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Kit Net Price: $41.85 Kit Net Price: $87.50LFactory Wired: $49.50AL.Factory Wired: $139.50

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MODEL T-60MODEL C-20 Tube Checker KitRes -Cap -Ratio Bridge Kit full free -point lever 10 mmfd to 2000 mfd selector system

1/2 ohm to 200 megs built-in roll chartKit Net Price: $20.95 Kit Net Price: $38.75Factory Wired: $31.50 Factory Wired: $54.50

1

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MODEL T-65MODEL G-30 Transistor and Crystal DiodeRF Signal Generator Kit Tester Kit 160 Kc to 240 Mc in 8 bands testsIceq,galn, leakage, etc. 120 Mc fundamental output tests both p -n -p and n -p -n typesKit Net Price: $28.50 Kit Net Price: $39.95

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MODEL M-40 MODEL V-70High Sensitivity 11-0.M Kit Vacuum Tube Voltmeter Kit 20,000 ohms/volt DC wide -range 10,000 ohms/volt AC peak -to -peak

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1

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MODEL S-50 MODEL Z-805" Cathode Ray Oscilloscope Kit RF-AF Signal Tracer Kit push-pull vertical and high gain RF and AF amplifier

horizontal amplifiers visual and audible IndicatorKit Net Price: $49.50 Kit Net Price: $29.50Factory Wired: $84.50*-AL Factory Wired: $42.50.

70-31

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*A DIVISION OF PRECIJCION APPARATUS COMPANY, INC.

NEWS BRIEFS (Continued from page 12)

of the Post Office's first fully mech-anized mail processing plant and postoffice to be built at Providence, R. I. Asin many modern mechanized systemselectronic equipment plays an importantrole. Operations of this plant will besupervised from an elevated controlcenter that will have visual and elec-tronic views of all activities. Cancelledletters will be sorted by operatorsseated at keyboards which controlother machines that will sort thousandsof letters hourly. The postal stationwill be built and equipped by InterlexSystems Inc., a subsidiary of ITT.Scheduled completion date is September,1960.

TALKBACK TV lets the student watchinga remote TV receiver ask and answerquestions, and hear questions andanswers from students in other class-rooms. Currently used in Cortland,N. Y., the system was reviewed in apaper by R. C. Norton and J. B. David-son of the New York Telephone Co., atthe recent general meeting of the AIEEin New York.

Regular telephone circuits providethe talkback over a single pair ofwires between each classroom and thestudio. Two small loudspeakers areplaced in each room and one on theteacher's desk. Using, reversible ampli-fiers, these speakers serve as both mikeand receiver.

ONE NEW TV STATION and the returnof an old-timer reinforce the nation'snetworks.KOKH-TV, Oklahoma City, Okla 25WHCT, Hartford, Conn 18

WHCT came back on the air afteran absence of a little over a month.

One station closed down:KXLJ-TV, Helena, Mont 12

KIDO-TV, Boise, channel 7, becameKTVB in January, and WKTV, Utica,N. Y., switched from channel 13 tochannel 2.

Leslie F. Garrett, of Derry, N. H.,reminded us of our oversight in omittingWHDH-TV, Boston, Mass., channel 5,from our January master list and alsocalled to our attention that WAST,Albany-Schenectady-Troy, channel 13,was shown incorrectly as WTAS. Wethank him for his interest.

The US total is now 549, of which463 are vhf and 86 uhf. KOKH-TV iseducational, therefore the non-com-mercial total is 37.ELECTRONICS COURSE via radio, spon-sored by the First Army, celebrated itsfirst anniversary with the New Year.Outstanding specialists have given lec-tures over the First Army MARS SSBTechnical Net each Wednesday night.Ham members of MARS follow up thelectures with calls, contributing to a"forum by radio."

Although theoretically limited to a1,000 -mile radius of New York, thenet has received letters from as far asthe Azores, 2,500 miles distant.

The MARS technical sessions areconducted each Wednesday at 9 pm on4030-kc upper sideband. END


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APRIL, 1959 21

41P

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Contains information and specifi-cations on all University public ad-dress speakers...directional, radial,wide-angle, paging and talk -back,submergence -proof, high fidelityweatherproof, super -power, explo-sion -proof, portable soundcasting.etc. Also, high fidelity cone speak-ers, enclosures and speaker systemssuited for commercial installations.


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APRIL, 959

VIBRATORS CONTROLS

23

Tung -Sol audio tubesnow twin -packedin matched pairs

by the manufacturer

5881 For service inamplifiers of up to 50watts.

6550 For service inamplifiers and commer-cial audio equipment ofup to 100 watts.

Now you can come as close tofaultless sound reproduction

as the design and circuitry ofyour hi-fi equipment will permit.Tung -Sol 5881 and 6550 beam -power amplifier tubes are factory -matched to very tight perform-ance limits and twin -packed tohelp you achieve lowest distor-tion levels at all volume levels.

Use of Tung -Sol 5881 and 6550tubes has long been associatedwith amplifiers of the very finestdesign. These tubes have alwaysbeen produced to closest possibletolerances with cathode currentranges held to an absolute mini-mum.

Now, in twin -packed pairs, theyassure the hi-fi enthusiast andthe commercial sound engineerof replacement tubes that willprovide new standards of per-formance-a feature of specialimportance with the newest am-plifiers and loudspeakers, particu-larly binaural sound equipment.See your parts supplier.

Tung -Sol Electric Inc., Newark4, New Jersey.

TUNG-SOL

Correspondence

ValINTERFERENCE -PRONE SETS

Dear Editor:The letter "TVI and the Law" in your

September 1958, issue omits a ratherimportant consideration. The writer,Mr. Dagion, fails to mention that inter-ference as it finally shows up on thepicture tube or in the loudspeaker isdue to, not caused by, two differentthings.

First, there is the fact that some ma-chines actually emit spurious radiation.This sort of thing is controlled by rulesof the FCC which require proper shield-ing to eliminate illegal emission. Recentrulings have required manufacturers tohold down local oscillator emission byshielding or filtering in radio and TVsets and other devices which may emitradiation. Most manufacturers are gladto go along with this sort of treatmentbecause they have to keep peace withtheir customers.

But the most frequent problem is lackof discrimination in the receiving equip-ment-both TV and radio. In an effortto get a sharper picture, more brilliantsound-and perhaps most important, tocut production costs-manufacturersuse broad -band circuits which will notdiscriminate between the desired signaland the unwanted one beyond a givenpoint. "Funnel" type front ends whichseemingly reach out for unwanted in-terference have been a considerableproblem to those owning industrial,commercial or amateur gear when thefault lies with the design techniquesof the manufacturer of the receivingequipment.

This has been recognized by mostleading TV manufacturers, who supply,through their distributors, filters toeliminate this trouble, usually at nocost to the service technician or cus-tomer. Such filters are not installed atthe time of manufacture since the per-centage of these interference cases isso low that it would become an unnec-essary production expense if incorpo-rated in all sets. It has become standardprocedure to supply filters only whenrequired.

The primary misunderstanding isblaming the equipment producing theinterference rather than the nonselec-tive receiving equipment. In practicallyevery case, owners of electronic equip-ment are most anxious to clean theirown houses and avoid offending the pub-lic but are unable to do the whole jobbecause of design deficiencies in receiv-ing equipment.

After dealing with this difficulty agood many times, I am convinced that

the dealer who sells the receiver owesthe purchaser an explanation of theproblem. Though some may not beaware of this situation, most dealersare and they are doing a distinct dis-service to the electronics business andthe service profession by not explainingit to the customers who are troubled.There is no excuse for trying to placethe blame on an equipment user whenit belongs on the set manufacturer.

BOB FORMANForman Co., Monmouth, Ill.

(The problem of TV and radio inter-ference will be treated in detail in aforthcoming issue.-Editor)

ANOTHER SA5-MREPLACEMENT

Dear Editor:The SA5-M used by Ted Ladd in a

light meter (page 123, December, 1958)and Rufus P. Turner in a light -poweredfrequency standard (page 58, February1959) has been dropped from ourstandard products line. However, thiscell can be replaced by a newer typeunit that operates at a higher efficiency.It is the type S -1020B (unmounted) orthe SD -1020B (mounted). Two of thesecells connected in parallel replace theSA5-M. HARRY NASHChief Application EngineerInternational Rectifier Corp.

REFLEX CORRECTIONDear Editor:

Something unfortunate seems to havehappened at a vital spot to my article("All About the Reflex Enclosure,"Part I, February, 1959).

The diagram on page 39 with itsthree sine curves each a quarter cyclelater than the previous one is correct.The error is in the explanation on page40, column one.

The wording refers to port airvelocity and states: "It also increasesbetween E and G." That is wrong. Thetwo sentences there should read: "Itincreases between D and F. The airmoving through the port (Fig. I -2-c)moves forward between E and G."

As additional explanation I wouldsay that port air velocity increases (ina forward direction) during the wholetime of forward acceleration-from Dto F and not E to G. Maximum velocityis therefore reached at F, 90° laterthan maximum acceleration. The airparticle displacement at the port passesthrough its mid -point at F and reachesmaximum forward displacement at G.It is thus at its maximum 180° aftermaximum rearward motion of the cone(E). By then the cone is fully forward


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Compact, proportioned for book-shelf or table top, JBL Bel-Aires-a pair with components in mirrorimage arrangement-will give youthe clean, exquisitely detailedstereo reproduction that can onlybe achieved with transducers of thehighest precision.

Now JBL enclosuresare matched for ster-eo. If you own a JBLC34, C35, C37, C39,or co) you can adda matching enclosurewith speaker unitsarranged in a pat-tern that is a mirrorimage of your pres-ent system.

The JBL Ranger -Paragonis the ultimate stereospeaker system. Devel-oped as a master moni-tor for use in perfectingstereo recording tech-niques, the Paragon addsto twin folded horns andprofessional driver unitsa radial refraction panelwhich integrates the twosound sources anddisperses true stereothroughout the room.

The JBL Ranger-Metregon incorporatesthe virtues of radial refraction in anenclosure of acceptable size for theaverage living room. No hole in themiddle, no split soloists, but soundreproduction spatially proportional toits original source. The Metregon ac-cepts seven different speaker systemcombinations: can be upgradedprogressively.

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again and so the port air displacementsynchronizes with the motion of thefront of the cone. Relative to the in-ward cone motion which compressedthe air cushion in the first place, portmotion is reversed in phase.

In connection with Fig. 1-3, it shouldbe made cleat that the left side illus-trates "what one might expect" (andactually happens at very low fre-quencies), but does NOT happen whenreflexing. The right side of that figureillustrates conditions when reflexing.Toronto, Canada P. G. A. H. VOIGT

KNOCKS PRINTED CIRCUITSDear Editor:

I think it is about time we got areport out concerning the printed cir-cuits radio and television manufacturershave been using.

We get about two printed -circuitsets to every wired set. The trouble isusually twice as difficult to trace. Partsreplacement is also twice as difficultbecause of the heat -sensitive copperfoil and multiple -terminal components.We usually run into twice as manytough dogs and find twice the numberof failures per year on printed circuitsets than on wired sets. The failuresresult from leakage between foil wiringor component breakdown due to thecompactness of portables and lack ofsufficient ventilation. Usually twice thetime is spent in troubleshooting printedcircuits. Therefore, printed circuits area loss to technicians. I still preferwired sets. I have asked the opinion ofmany of the technicians in my area-they agree. BRIAN CHINNew York, N. Y.

RUMBLE'S RUMBLEDear Editor:

In the Try This One column in theJanuary, 1959, issue (page 136), Mr.C. E. Cohn recommends disconnectingthe plate -load resistor of the first audiostage from B plus and connecting it tothe plate of the output tube as a methodof applying inverse feedback. However,the item failed to point out that youonly get inverse feedback if there arean even number of stages in the ampli-fier. If there are an odd number ofstages, positive feedback occurs and theamplifier oscillates. ROBERT RUMBLESan Luis Obispo, Calif.

SWEET MUSICDear Editor:

I feel like someone who has beengiven a map with indications for find-ing buried treasure. For composers,your "Micromusic" (editorial in theMarch 1959 issue) is the open sesameto a cave of infinite sound and I, forone, am infinitely grateful.

Your artide also calls to mind thesewarning words of Einstein's: "Ouractual situation cannot be comparedwith anything in the past. We mustradically change our ways of thinking,our method of action."

My thanks for "Micromusic."New York, N. Y. EDGARD VARESE

END


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APRIL, 1959 27

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NEW STEREOPHONIC EQUIPMENT11F85: Stereo Dual Preamplifier is a complete stereo con-trol system in "low silhouette" design adaptable to anytype of installation. Selects, preamplifies, controls anystereo source-tape, discs, broadcasts. Superb variablecrossover, feedback tone controls driven by feedbackamplifier pairs in each channel. Distortion borders onunmeasurable even at high output levels. Separate lo -level input in each channel for mag. phono, tape head,mike. Separate hi -level inputs for AM & FM tuners & FMMultiplex. One each auxiliary A & B input in each channel.Independent level, bass & treble controls in each channelmay be operated together with built-in clutch. Switched.in loudness compensator. Function Selector permits hear-ing each stereo channel individually, and reversing them;also use of unit for stereo or monophonic play. Full -waverectifier tube power supply. 5-12AX7/ECC83, 1-6X4. Workswith any high -quality stereo power amplifier such asEICO HF86, or any 2 high -quality mono power amplifierssuch as EICO HF14, HF22, HF30, HF35, HF50, HF60."Extreme flexibility . . . a bargain" - HI -Fl REVIEW.Kit $39.95. Wired $64.95. Includes cover.HF86: Stereo Dual Power Amplifier for use with HF85above or any good self -powered stereo preamp. IdenticalWilliamson -type push-pull EL84 power amplifiers, con-servatively rated at 14W, may be operated in parallel todeliver 28W for non -stereo use. Either input can be madecommon for both amplifiers by Service Selector switch.Voltage amplifier & split -load phase inverter circuitryfeature EICO-developed 12DW7 audio tube for significantlybetter performance. Kit $43.95. Wired $74.95.IfF111: Stereo Dual Amplifier -Preamplifier selects, ampli.ties & controls any stereo source - tape, discs, broadCasts-& feeds it thru self-contained dual 14W amplifiersto a pair of speakers. Monophonically: 28 watts for yourSpeakers; complete stereo preamp. Ganged level controls,separate focus (balance) control, independent full -rangebass & treble controls for each channel. Identical William.son -type, push-pull EL84 power amplifiers, excellent out-put transformers. "Service Selector" switch permits onepreamp-control section to drive the internal power ampli-fiers while other preamp-control section is left free todrive your existing external amplifier. "Excellent" -SATURDAY REVIEW; HI-FI MUSIC AT HOME. "Outstand-ing quality ... extremely versatile" - RADIO & TV NEWSLAB -TESTED. Kit $69.95. Wired $109.95. Includes cover.MONO PREAMPLIFIERS (stack 2 for Stereo) HF-65: superbnew design, Inputs for tape head, microphone, mag-phono cartridge & hi -level sources. IM distortion 0.04%0 2V out. Attractive "low silhouette" design. HF65AKit $29.95. Wired $44.95. HF65 (with power supply) Kit$33.95. Wired $49.95.

MONO POWER AMPLIFIERS(use 2 for STEREO)

HF60 (60W), HF50 (50W), HF35 (35W), HF30 (30W), HF22(22W), HF14 (14W): from Kit $23.50. Wired $41.50.

MONO INTEGRATED AMPLIFIERS(use 2 for STEREO)

HF52 (50W), HF32 (30W), HF20 (20W), HF12 (12W): fromKit $34.95. Wired $57.95.

SPEAKER SYSTEMS (use 2 for STEREO)HFS2: Natural bass 30-200 cps via slot -loaded 12 -ft. splitconical bass horn. Middles & lower highs: front radiationfrom 81/2" edge -damped cone. Distortionless spike -shapedsuper -tweeter radiates omni-directionallv. Flat 45-20,000cps, useful 30-40,000 cps. 16 ohms. HWD 36", 151/4",111/2". "Eminently musical"-Holt, HIGH FIDELITY. "Finefor stereo"-MODERN HI -Fl. Completely factory -built:Mahogany or Walnut, $139.95; Blonde, $144.95.HFS1: Bookshelf Speaker System, complete with factory.built cabinet. Jensen 8" woofer, matching Jensen com-pression -driver exponential horn tweeter. Smooth cleanbass; crisp extended highs. 70-12,000 cps range.Capacity 25 w. 8 ohms. HWD: 11" x 23" x 9". Wiringtime 15 min. Price $39.95.FM TUNER HFT90: Surpasses wired tuners up to 3X itscost. For the first time, makes practical even for thenovice the building of an FM tuner kit equal to really goodfactory -wired units. No alignment instruments needed.Pre -wired, pre -aligned temperature -compensated "frontend" is drift -free - eliminates need for AFC. Precision"eye-tronic" DM -70 traveling tuning indicator, suppliedpre -wired, contracts at exact center of each FM channel.Pre -aligned IF coils. Sensitivity 6X that of other kittuners: 1.5 uv for 20 db quieting, 2.5 uv for 30 db quiet-ing, full limiting from 25 uv. IF bandwidth 260 kc at 6db points. Frequency response uniform 20-20,000 cps=L- 1 db. Cathode -follower & Multiplex outputs. Flywheeltuning, automatic gain control, stabilized low limitingthreshold for excellent performance from weaker signals,broad -band ratio detector for improved capture ratio &easier tuning, full -wave rectifier & heavy filtering, verylow distortion. "One of the best buys you can get inhigh fidelity kits"-AUDIOCRAFT Kit Report. Kit $39.95*.Wired $65.95*. Cover $3.95. *Less Cover, F.E.T. incl.NEW AM TUNER HFT94: Matches HFT90. Selects "hi-fi"wide (20c - 9kc 0 -3 db) or weak -station narrow(20c - 5kc @ -3 db) bandpass. Tuned RF stage for highselectivity & sensitivity; precision "eye-tronic" tuning.Built-in ferrite loop, prealigned RF & IF coils. Sensitivity3 uv @ 30% mod. for 1.0 V out, 20 db S/N. Very lownoise & distortion. High -Q 10 kc whistle filter.Kit $39.95. Wired $69.95, incl. Cover & F.E.T.

BEFORE YOU BUY, COMPARE:

You may examine the complete EICO line atany of 1900 neighborhood EICO distributorscoast to coast. Compare critically with equip-ment several times the EICO cost-then youjudge. You'll see why the experts recommendEICO, kit or wired, as your best buy.EICO. 33-00 NORTHERN BLVD.. L.I.C. I. N.Y.Fill out coupon on other side for FREE CATALOG

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Radio -Electronics

ELECTRONICS vs WAR. . . Why the Billions of Defense Dollars? . .

THE following letter by the mother of a young son isone of many similar ones which have reached usperiodically throughout the years. It deserves everyreader's thoughtful attention, as it correctly mirrors

the sentiments of a large cross-section of our population inthese most unusual times in our history. The letter is slightlycondensed from the original.

In an old (September, 1955) issue of your magazine thatmy young son brought home recently, I was interested insome statistics given in the editorial "The Giant Electron-ics Industry." To quote: "By far the largest customer ofthe industry is the United States Government. Defensepurchases of electronic equipment last year are estimatedat $2,300,000,000, ... and may go up to over $4,000,000,000a year by 1964."In my opinion it bodes no good for the future when greatnations and blocs of nations concentrate so much of theireconomy & know-how in technology & science on purely de-structive mechanisms of rapidly increasing power. It isobvious that this stupid (in my opinion) waste of humaningenuity is extremely corrupting in several ways. Forexample, the world's human energy is channeled destruc-tively instead of constructively, natural entropy is need-lessly increased by the addition of human entropy, youngpeople sense unknowingly the terrible possibilities of mod-ern technological warfare-hence the rise in juvenile de-linquency-& a disproportionate part of national incomesgoes into what the nations call defense. It is true thatdefense mechanisms are needed but not to such an un-balanced degree. Otherwise, if our grave problems shouldbe settled by arbitration or other civilized methods insteadof war, I simply cannot see how economies that lean heav-ily on war mechanisms will be able to adjust to a construc-tive economy without very considerable hardship.Whole populations today are living under the black andreal shadow of huge scale slaughter; therefore pleasetell us about the need for far greater applications oftechnology & science for constructive purposes.Baldwin Path, MRS. P. CAMMERHuntington, N.Y.

The ideas expressed so well by our correspondent areunfortunately not new. They have occurred to every think-ing individual since our aborigine days, millenia ago. War,unhappily, has been with us always, and "war" will be withus until the end of the world, in one form or another.

The nations recognizing this must build up their defenses,and this admittedly brings considerable waste in its wake.This is true of most large-scale human endeavors.

If the people of a community are threatened by period-ically recurring floods, they sooner or later must build adam or levee to keep the waters from flooding their homes.If they skimp in labor, money-and good engineering-their work may go for naught, as the Johnstown flooddemonstrated. Hence, it is better for safety's sake to spendmore rather than less. Incidentally, while building manydams, we learn in time how to build them better, and oftenmore economically.

When a nation bolsters its defenses, the human energyexpended is not necessarily all channeled destructively. To

Hugo Gernsback, Editor

the contrary, the nation builds up its economy, enriches itsengineering in the country's industrial plant, gives vastemployment and, through hundreds of byproducts of everyimaginable kind, enhances its standard of living.

Even war machines become peace messengers. Our largefour -motor civilian airplanes are, in reality, bombers ina new dress. Our new passenger jet planes were born as warplanes. They were brought to their present perfection solelybecause of our defense efforts. Is this not in a way a con-structive result?

The greatest difficulty most people have today is theirinability to distinguish between human -made war and ourconstant war against non -human enemies.

We are always at war with famine, cold, heat, floods,'tempests, epidemics, insect pests and microbe invasions, bethey colds, measles or tuberculosis. We fight a continuingwar against cancer and heart disease, and countless otherminor wars. Our war with accidents of every kind willnever be won as long as the world lasts. Nearly 10 milliona year, almost 100,000 deaths in the U.S. alone-the best wecan hope for is to reduce this frightful toll.

Add up the cost of all these wars, which is far greater inlost lives and treasure in a single decade than any periodicman-made war you can name. The money we pour into thedefense against these non -man-made wars is fantastic, yetwe know we dare not stop lest we revert to the dark ageswhen man died before he was 40, mostly due to ravages ofunconquered diseases.

As to the billions of dollars we pour into the defenseagainst man-made war during peace, it is in the end a cheapinsurance against such a war. The more formidable ourdefense, the less the chances of war, be it man-made ornature. Take one instance, smallpox, which accounted formillions of deaths and disfigurement of hundreds of millionsbefore vaccination was introduced.

Now let us turn to the comparatively few billions of dollarsexpended yearly in electronics. It was World War I whichgave us radio and radio communication as we have it today.War or defense always speeds up technological inventions,whether we like it or not, and we all hate war. World WarII gave us radar and countless other inventions includingthe atomic bomb, which, when used as atomic power, in thenear future, will be a far more important instrument forpeace than anything man ever knew.

The electronic defense billions we expend now and later,we repeat, bring in their wake not only war inventions butcountless others as byproducts which we would not haveotherwise. These discoveries, inventions, devices and methodshelp us in the fighting of our other wars, too, as, forinstance, in the electronic battle against diseases. SinceWorld War II, electronbiology and electronics in medicine,among others, have become big branches in the art ofmedicine and disease prevention.

Americans should realize that the terminology war shouldno longer apply solely to man-made war. We have neverbeen at peace since man arrived on this planet and we prob-ably never shall be. As long as humanity endures, there willalways be an eternal war for man's survival. -H.G.

APRIL, 1959 31

TEST INSTRUMENTS

Laboratory accuracy in a hoate-built unit lets you measure acvoltages between .0001 and 10 volts with an error of less than 2%over a bandwidth of 9 cycles to 8.5 mc

SENSITIVE

By PHILLIP D. BLAISAC VOLTAGE measurements are

probably the most importantmethod of evaluating circuitperformance. Most vtvm's can-

not be used because of insufficientsensitivity and bandwidth. Crystal rec-tifier probes and preamplifiers are com-monly used in attempts to increase therange vtvm's. Calibrationof such accessories is very difficult, andstability is poor. The ac vtvm describedis of laboratory quality, and its accu-racy is surpassed by only a few veryexpensive commercial units.

The requirements for a laboratoryvoltmeter are many. High input imped-ance, reliability, etc. are all familiarto the technician. Statistics can bestrepresent these qualities:Ranges (full scale) .005, .01, .05, 0.1,

0.5, 1, 5, 10Bandwidth 9 cycles -8.5 mc±-.5%

20 cycles -3.5 mc±-4%25 cycles -2.5 mc-±-2%

Input impedance 10 megohms, 25 µµfNoise level Equiv. to 20-AvinputNegative feedback 30 dbLine -voltage error Less than 2%

90-125 voltsThe serious experimenter will imme-

diately see the advantages of this volt-meter and its possibilities in his work-shop. Design of preamplifiers, poweramplifiers and other test equipmentis possible with such an instrument.

Basic circuit design

A block diagram of the ac vtvm isshown in Fig. 1. A cathode follower in

CATHINPUT FOLL ATTENUATOR

the input provides a high input and alow output impedance for the attenu-ator, which is composed of low -valueprecision resistors. At all frequenciesthe attenuator is compensated againsterrors due to stray capacitance, bysmall trimmer capacitors. No atten-uator compensation is needed on the

-volt range because there is noadditional series resistor between VI'scathode and V2's grid. Thus the currentdue to V2's input capacitance does notaffect the attenuation. At high fre-quencies, it does shunt the attenuatoras a whole and produce an error. Thiserror is very small, because of the lowoutput impedance of the cathode fol-lower, and is negligible up to 10 mc.

The 5- and 10 -volt ranges are notcompensated because the input react-ance to V2 is much larger than the 1.5ohms presented by the attenuator. Onthese two ranges the attenuator's out-put impedance is approximately 1.5and 0.75 ohm while the input reactanceto V2 is approximately 800 ohms at10 mc. Thus, over 99% of the currentin Vl's cathode passes through R12and R13, producing an error of lessthan 1%.

The attenuator is followed by a high -gain video amplifier to boost smallvoltages. The output of the video ampli-fier is rectified by a full -wave dioderectifier and applied to a 0 -1 -ma milli-ammeter.

Nonlinear elements, such as vacuumtubes, in a circuit always produce dis-tortion and variations in gain with

VIDEORECTAMPL

POWERSUPPLY

METER

Fig. 1-Block diagramof the ac RM.

Mchanges in applied voltage, temperature,etc. Gain variations are intolerable involtmeters, and some way to controlthis source of error is needed. Themost practical way to stabilize gain isthrough the use of negative feedback.In this voltmeter 30 db of negativecurrent feedback is applied around fourstages, in the video amplifier,responsible for many of the desirablecharacteristics. The meter is includedin the feedback circuit for good scalelinearity.

The power supply is electronicallyregulated to reduce further the effectsof line -voltage variations. A dc heatersupply reduces hum and noise in thefirst amplifier stages.

Cathode follower and attenuatorA voltmeter's accuracy is often

limited by attenuator accuracy. Theimpedance of an attenuator should beas low as possible to minimize theeffects of stray capacitance. Largevalues of resistance show frequencyeffects which yield an effective acresistance considerably lower than thedc value. An ordinary 1/2 -watt 1-meg-ohm carbon resistor has an effectiveresistance of only 570,000 ohms at 10me. Precision carbon resistors sufferleast from this effect and are used inthis voltmeter's attenuator. See Fig. 2.

Resistors R12 and R13 in the atten-uator are 0.75 ohm and are not com-mercially available precision units. Useparallel combinations such as 1 and 3to obtain 0.75 ohms, or fabricate fromresistance wire. If resistance wire isused, keep the inductance at a minimumby keeping the area enclosed by theloop of wire to a minimum. At 5 mc,an inductance of only .02 Alt has areactance of 0.75 ohm and contributesan error of 41%. A short hairpin -shaped loop is satisfactory.

Capacitors C3 through C10 in corn -


TEST INSTRUMENTS

6J4CATH FOLL

172VR4820 X

INPUT RI 470n..

?C11.01qIJ2

6O

R2

R3120K5%

C2 140450V

1,5

10MEG

R22 1ST VIDEO AMPL6AC7(4)

2ND VIDEO AMPL 3RD VIDEO AMPL 4711 VIDEO AMPL 1N34 -A(2)

VI

C16T.01450 V

RI4-21470 KEACH

C3

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RI, 61-470 ohmsR2-10 megohms, 1%R3 -I20,000 ohms, 5%R4-820,000 ohmsR5-120 ohmsR6-750 ohms, 1%R7-600 ohms, 1% (300 and 300 in series)R8-75 ohms, 1%R9-60 ohms, 1% (50 and 10 in series)R10-7.5 ohms, I% (30 and 10 in parallel)R11-6 ohms, I% (5 and I in series)RI2, 13-075 ohm, 1% (3 and 1 in parallel)RI4, 15, 16, 17, 18, 19, 20, 21, 23, 29, 33, 34, 35, 40, 41,

42-470,000 ohmsR22-8,200 ohms, 2 wattsR24, 45-10 ohmsR25, 30, 36, 43-68,000 ohmsR26, 56-1,200 ohmsR27-330 ohmsR28, 32, 39-10,000 ohms, I wattR3I-1,000 ohmsR37-1,800 ohmsR38-680 ohmsR44, 48, 55-15,000 ohms, I wattR46-33,000 ohms, 5%R47 -pot, 103 ohms, carbonR49 -pot, 50 ohms, 4 watts, wirewoundR50-22 ohms, 2 wattsR51, 52-22 ohmsR53-25 000 ohms, 10 watts, wirewoundR54 -103,C00 ohms, I watt

CII

3-30µµf21,

3-12µµfC13

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470K

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R32 10K/IW 1339

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R29 C25+47014

100pf350 VR 3068K

150 V

R34

V4

R 35

470 ,100pf350V

1014/IW + R44C3850

R37 C31 1450V

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24V/IA

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2112111MiltPILOT LIGHT

R502202W

CH6H/150MA

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SEL RECT BRIDGE 28 V/IAAC ® R60 7,2,4

30 150

AC

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R57 -pot, 10,000 ohms, 2 wattsR59-27,000 ohms, 2 wattsR59 -pot, 3 ohms, 4 watts, wirewoundR60-15 ohms, 5 watts, wirewoundAll resistors V2 -watt 10% unless notedCl, 16, 18, 44-.01 id disc ceramicC2-40 pf, 450 volts, electrolyticC3, 4, 5, 6 7, 8, 9, 10-5 pf, 50 volts, electrolyticCII, 14, 15-3-30 Atgf, miniature disc trimmerC12, 13-3-12 µµf, miniature disc trimmerCI7-125 pf, 450 volts, electrolyticC19-500 pf, 25 volts, electrolyticC20, 45, 46-1,000 pf, 25 volts, electrolyticC21, 25, 29-100 µf, 350 volts, electrolyticC22, 26, 30-30 pf, 450 volts, electrolyticC23-70 AO, micaC24, 28-.02 pi, disc ceramicC27-.005 pf, paperC3I-150 p1d, micaC32-500 µ/./f, micaC33-.05 ,uf, paperC34-80 pf, 350 volts, electrolyticC35, 36-0.5 pf, miniature paperC37-500 pf, 6 volts, electrolyticC38-50 pf, 450 volts, electrolyticC39 -a-9-180 AO, trimmer (see text)C39 -b-200 yid, mica (see text)C40-50 pf, 6 volts. electrolyticC4I-a, -b-25 pf, 450 volts, electrolyticC42-0.1 pi, paper

Fig. 2 -It takes nine tubes and two crystal diodes to give

WW

the

C 39-a

C39 -b

200µµt

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C43-40 4, 350 volts, electrolyticAIi capacitors 600 volts unless notedCH -6 henrys, 150 maDI, 2 -1N34 -AF-1.25 AJ1, 2 -terminal -binding -post assembly (National

FWH or equivalent)M-0-1 maRECT-full-wave bridge, selenium, 28 volts output,

1 amp or higherSI-spst toggle52 -5 -gang 5 -pole 8 -position steatite rotaryTI -power transformer: primary, 117 volts: second-

ary, 800 volts ct, 200 ma; 5 volts, 3 amps; 6.3v -Its, 5 amps; (Thordarson 24R07 or equivalent)

72 -filament transformer: primary 117 volts: second-ary, 6.3 volts, 2 amps (Stancor P6466 or equiva-lent)

T3 -filament transformer: primary, 117 volts: sec-ondary, 24 volts ct, I ampere (Triad F -40X orequivalent)

V1 -6J4V2, 3, 4, 5-6AC7V6-5Y3-GTV7 -6Y6 -GV8 -65J7V9 -0A2Pilot lamp, No. 47ChassisMiscellaneous hardware

4

ac vtvm its accuracy.

bination with resistors R14 throughR21 reduce transients in the input cir-cuit when changing ranges, and reducewaiting time. Trimmer capacitors C11through C15 are adjusted during cali-bration to compensate for stray capac-itance in the attenuator. The attenuatoris constructed on a five -gang eight -position steatite switch, and details areshown in the photo. Unused sectionsare disabled by removing the rotor.

A two -pole eight -position rotary couldhave been used, but it would not allowfor easy attenuator construction. Allcomponents are mounted on the switch.

A 6J4 triode is the input cathodefollower, because of its unusually hightransconductance-12,000 µmhos. Thespecial circuit used to obtain the gridbias on the 6J4 reduces the noisefigure' and illustrates the many specialprecautions used to obtain the low

noise figure. Heater current requiredby the 6J4 is less than that for a 6AC7,and the 6J4 heater is shunted by R5to allow series connection of the tubes'heaters. The grid circuit has a smallresistor near the tube socket to preventparasitic oscillations when the input isshort-circuited.

Video amplifierThe video amplifier consists of four

APRIL, 1959 33

TEST INSTRUMENTS

ATTENUATION =

C2

R2INPUT RI CI OUTPUT

LOW HIGHFREQ FREQRI R2 CI

RI CI C2

RI CI = R2 C2

Fig. 3-How to determine componentvalues for a frequency -compensated

attenuator.

6AC7 stages. The 6AC7's are usedbecause of their high transconductanceand low noise figure. The first two6AC7's have a de heater supply. Thecathodes of the second, third and fourthvideo amplifiers are grounded directlyto reduce hum and noise. This alsoremoves any complex impedances inthe cathode circuits, which tend to pro-duce degeneration at low frequencies.

A collective back -bias arrangementprovides the required negative gridvoltage.' Each grid is returned to acommon negative voltage source pro-vided by the center tap of the platepower transformer winding. This volt-age is proportional to the total current,and in this way a collective self -biassource is maintained. This design isresponsible for the complete absenceof hum in the video amplifier.

The screen grids of the 6AC7's aresupplied through large screen drop-ping resistors from the voltage -reg-ulated supply to reduce changes intransconductance due to changes inline voltage. Very large screen bypasscapacitors keep degeneration and phaseshift small at low frequencies. Thecost of electrolytic capacitors is smalland "bargain" units may be used here.If their quality is questionable, bypasseach one with a .01-µf ceramic unit toeliminate high -frequency inductanceeffects. These capacitors, not shown inFig. 2, were used in the finished vtvm.They are visible in the bottom view ofthe video amplifier. They are coded

C19

R22

C21 -o

C43 -a

R25R23C21

C18

R24C25 -o

R30C25

C28C29-0

C39-0

R47

C39 -b

V4

C35,C34

DI

02

C38

C33 C34 -a R42I R5V25 R44 036Fr5

with the number of the bypassed elec-trolytic and the suffix "a".

The coupling between stages involvesR -C networks called Bode networks' tocontrol phase shift and attenuation,for stability with negative feedback.These networks are the result of manytrials and calculations, and should notbe varied. The balance between fre-quency response and phase shift isdelicate when applying 30 db of nega-tive feedback around four stages witha bandwidth of 10 me, and the designis vindicated by the final result.

The final 6AC7 stage has a highplate load resistance -15,000 ohms. Itis shunted by the relatively low imped-ance of the meter circuit. The meter -circuit current is thus equal to the actube current, which is equal to thetransconductance multiplied by the acgrid voltage. The current is rectifiedby the two germanium rectifiers andapplied to the meter circuit as pulsatingdc, filtered by C37. The two half -wavesof current are then recombined bycapacitors C35 and C36, and appliedto R45. The negative -feedback voltageis taken from R45. Being familiar withnegative feedback, we realize that thistends to keep the voltage across R45constant. This voltage is merely ameasure of the current through themeter circuit, and thus the feedback isactually negative current feedback.The tendency to maintain constant cur-rent through the meter circuit by nega-tive current feedback results in a verylinear scale regardless of changes inthe rectifier's forward characteristicswith applied voltage. Feedback isadjusted with R47, and the voltmetergain is adjusted during calibration byR47. C39 corrects the negative feed-back at higher frequencies to improvefrequency response.

Capacitor C39 consists of a 9 -180 -Aid trimmer in parallel with a 200 -µId mica. However, in my unit thetrimmer is adjusted for maximumcapacitance and the total value of thecombination is 380 µµf. Due to differ -

A look under thevideo amplifier

chassis.

The attenuator isin a chassis of its

own.

ences in construction and tubes, adifferent value may be required. Theoutside limits to the value you mayneed in the meter you build are 40 µµfand .0015 µf. For best results try a170-780-µµf trimmer as a start. Thechances are the value you need will bewithin its range.

The first 6AC7 stage has a smallgrid -isolating resistor R61 to preventparasitic oscillations at high fre-quencies.

The power supply is straightforwardin design and construction and will notbe discussed in detail. A separate chas-sis is used for the power supply toisolate unwanted signals and to facil-itate adjustment and repair. I used apower transformer from an old Atwater -Kent and two 6.3 -volt heater trans-formers. However, you can use thearrangement shown in the schematicfor greater convenience.Construction hints

Construction is not critical or trickyand the layout may be modified forspecial requirements. The layout shownin the photos is recommended for gen-eral use. Input capacitance can be re-duced slightly by placing V1 closer tothe input terminals, and is recom-mended. A separate, totally enclosedchassis for the attenuator and cathodefollower is a necessity to reduce humpickup in the high input impedance.Placement of circuit components is notcritical, although normal precautionsshould be taken.

The attenuator resistors are the onlyprecision components required; allother components are normal 10%tolerance. Some attenuator resistorvalues are not stock items, but maybe made up as combinations of stockvalues. Use a heat sink when solder-ing precision resistors to prevent apermanent change in resistance dueto heating. Broad limits are possibleon all electrolytic capacitors and near-est available values may be used.

The custom appearance of the indi-

R14RI5R16RI7R18R19 C7

C8C9RIORII


TEST INSTRUMENTS

eating meter is obtained by using astandard 41/2 -inch Triplett 0-1 milli -ammeter. The unwanted lettering isremoved from the meter scale by gentlyrubbing with a small cloth dampenedwith acetone.

Two sets of scale numerals shouldbe applied to match the attenuatorranges. Appearance may be furtherenhanced by drilling two small holesthrough the back of the meter and in-serting two small pilot lights. Theseholes must be drilled with a hand drill,being extremely careful not to damagethe delicate meter movement. Orientthe meter so drill chips fall away fromthe suspended coil and pivots.

Use decals to label the front of theinstrument and give a professionalappearance. The clear birch wood cabi-net is assembled with screws and glue.Give the sanded surface several coatsof clear lacquer, until it is glossy. Thefinished instrument is very attractive,and professional in appearance andperformance.

Adjustments and calibrationNow that the instrument is com-

pleted, it must be adjusted to makemeasurements. After a 30 -minute warm-up, adjust:

1. The voltage -regulated supply. SetR57 for 300 volts at the cathode of the6Y6 -G.

2. Heater voltage. Trim R59 to get18.9 volts dc at C45 and C46.

3. Grid bias in video amplifier. RotateR49 until -2 volts is obtained acrossC40.

This completes the adjustments, andall voltage measurements are withrespect to chassis ground. It may benecesary to repeat these twice.

Calibration is more difficult, and in-genuity is required if laboratory stand-ards are not available. Get a 60 -cyclesource that is within the voltmeter'srange and the most accurate meteravailable. With the appropriate meterscale and range setting adjust R47until the voltmeter reads the same as

The finishedchassis has aprofessional

look.

Under thepower -supply

chassis.

the calibrating voltmeter used as the"standard."

The attenuator trimmer capacitorsrequire a frequency source above 3 mewith a variable output. The requiredsteps are:

1. Set the voltmeter range switch to.005 volt. Adjust the output of a signalgenerator, set between 3 and 10 mc andconnected to the voltmeter, so the volt-meter reads full scale.

2. Without changing the signal gen-erator's output, set the voltmeter rangeto .01, and adjust trimmer capacitorC11 until the output meter reads halfscale (.005).

3. Adjust the signal generator's out-put until the voltmeter reads full scale:Now set the voltmeter range switch to.05, and adjust C12 until voltmeterreads .01 volt.

4. Adjust the output of the signalgenerator until the voltmeter againreads full scale. Set the meter to 0.1,and adjust C13 until voltmeter readshalf scale.

5. Increase signal generator outputfor full-scale reading. Change voltmeterrange switch to 0.5, and adjust C14 tot'read 0.1 on voltmeter.

6. Finally, increase signal generatoragain to give full-scale deflection, andchange the voltmeter range switch to1 volt. Adjust C15 for half -scale read-ing.

This completes the attenuator ad-justments, and the attenuator shouldbe independent of frequency.

High -frequency calibration is thefinal adjustment necessary before use.Set the signal generator at 7 mc andthe output at 1 volt. The output maybe measured at this level and fre-quency by using a simple diode recti-fier probe and an ordinary de vtvm.The 1 -volt output is applied to theinput of the voltmeter, and C39 adjustedto give a full-scale reading on the 1 -volt range. The voltmeter is then placedin the cabinet, and is ready for use.

Occasionally, due to a 6AC7 with anunusually high transconductance, the

6.3 VTRANS

FOR V7V8

RECT

R59

FUSEHOLDER

CH

R50

6.3 VTRANSFORV4 &V5

R55

R58

R54

C42

R60

video amplifier's gain requires morethan 30 db of negative feedback forcorrect calibration, and any attemptsto reduce the gain, by adjusting R47for correct calibration, may result inviolent circuit oscillation. Poorly placedcomponents can also cause oscillation.The stability margin for this voltmeteris only 6 db and is ideal for flat re-sponse. Changing circuitry is not ad-vised as a solution, and the best methodto correct this trouble is to increase thebias on the 6AC7 tubes by adjustingR49 until oscillation ceases. In thismanner, the total gain may be adjustedfor 30 db of feedback.

Input attenuators and probesThe reader may wonder why the top

range of this ac vtvm is only 10 volts.Why not higher? The reason is simple.It is better to add attenuation by anexternal attenuator or by a probe, andachieve an even higher input impedance.A 100 x attenuator could have beenplaced in the grid circuit of the inputcathode follower to get ranges 100 timesthose on the present range switch, butthe input capacitance would still beapproximately 20 µAL However, with anexternal probe attenuator, the inputcapacitance can be made as small as 2or 3 lig.

Probes and external attenuators aremore versatile, and are necessary athigh frequencies to prevent standingwaves in the leads. Attenuators andprobes may be designed and constructedas in Fig. 3.

For frequency -independent attenu-ation, R1C1 = R2C2. The designermust include the input capacitance andresistance of the voltmeter as beingin parallel with R1 and Cl. Also, inthe case of probes, the capacitance ofthe cable must be added to Ci. END

References1International Resistance Co., Bulletin B-1.2 Langford -Smith, Radiotron Designers Hand-

book, pages 789-90.3 Langford -Smith, Radiotron Designers Hand-

book, page 597.Bode, H. W., "Network Analysis and Feed-

back Amplifier Design," D. Van Nostrand.

APRIL, 1959 35

TEST INSTRUMENTS

using SCOPE PROBESLike a diode tube, a singleprobe won't handle all jobs.Knowing where and whento use what probe speedsservicing

By ROBERT G. MIDDLETONRADIO -ELECTRONICS TELEVISION CONSULTANT

WIT HOUT question, the oscilloscope is among themost essential instruments used in TV trouble-shooting. Most technicians have little difficulty inoperating their scopes with direct test leads, but

scope probes often lead to questions.Field experience proves that some technicians are con-

fused when it comes to which probe to use in a specific ap-plication. This article will clarify that question. In general,scope probes extend the applications of a service scopeinto high -frequency, high -impedance and high -voltage cir-cuits. Without suitable probes, scope applications are seri-ously limited.

The better grades of probes are adjustable, so their char-acteristics can be matched to various scopes. Thus, betterlow -capacitance probes have service adjustments for both

A typical scope demodulator probe.

probe resistance and capacitance, and the capacitance -di-vider probe for probe capacitance. Accordingly, theseprobes can be adjusted for accurate operation with anymodern scope.

A demodulator probe does not require a service adjust-ment, since no attenuation factor is involved and the proberesponds upon the basis of the peak -to -peak voltage of theapplied signal. The total output from a demodulator probeis applied directly to the scope input terminals.

HIGH -VOLTAGE CAPACITANCE -DIVIDER PROBES(Also

A probe that extends the permissibleinput voltage rating of a scope to 10,000peak volts is the high -voltage capaci-tance -divider type. Without such aprobe, a service scope typically with-stands only 600 peak volts before wave-form distortion starts. Excessively highinput voltages will damage a scope'sinput circuit unless a suitable probe isused.

A high -voltage probe of this type isusually designed for 100 -to -1 attenua-tion. Thus, if a 10,000 -volt waveform isapplied to the probe, the scope receives1/100 of this voltage, or 100 volts,which is well within the capability ofthe vertical amplifier for undistortedreproduction. The probe can be used to

IX2-A .INPUT TO

SCOPE

TRIMMER 100Auf MAX

termed High -Voltage 100 -to -1 Divider Probe)advantage at the plate of the horizontaloutput tube to check the peak -to -peakvoltage of the flyback waveform and tocompare its shape with the service dataspecifications for the receiver.

When measuring peak -to -peak volt-ages, the operator adds two zeros tothe scope calibrating factor when theprobe is used and no recalibration isrequired. It is clear that use of decimalattenuation factors in such probesgreatly speeds up practical applica-tions. Of course, the probe must be usedwith an up-to-date scope which has astep attenuator calibrated in intervals

.44 10 ( x 1, X10, X100, etc.).A 100 -to -1 capacitance divider probe

can be used also to check the waveform

CircuitThis is a high -voltage ac probe, designed tooperate at input voltages up to 10,000 peakvolts. The IX2-A tube serves as a small high -voltage capacitor. The trimmer is used tocalibrate the probe for 100 -to -I attenuation.

and peak -to -peak voltage at the cathodeof a damper tube, across the horizontal -deflection coils and similar high -voltagepoints.

There is one limitation in the use ofa capacitance -divider probe which mustbe recognized-the probe is not suitablefor checking 60 -cycle sweep circuits.At 60 cycles, the resistive componentof the scope input circuit becomes ap-preciable with respect to the reactanceof the probe and, since the capacitance -divider probe is uncompensated, its usemust be restricted to horizontal -fre-quency circuits. However, this is nota matter for practical concern, since a10 -to -1 probe will handle the operatingvoltages of vertical -frequency circuits.

ApplicationsProbe can be used to check waveforms andpeak -to -peak voltages at the plate of thehorizontal output tube, cathode of dampertube and across horizontal deflection coils.Should be used in horizontal -frequency circuitsonly. Distorts 60 -cycle (vertical) waveforms.

LOW -CAPACITANCE PROBES(Also termed High -Impedance or 10 -to -I Attenuating Probe)

A low -capacitance probe effectivelyincreases the input impedance of thescope input circuit. This lets you testhigh -impedance circuits without undueloading and the resulting waveformdistortion incurred when direct testleads are used in this type circuit. Forexample, many synchronizing circuits,

such as the popular Synchroguide phasedetector, have high internal impedancesand using a low -capacitance probe letsyou adjust such circuits more accu-rately than otherwise possible.

Low -capacitance probes are usuallyadjusted to provide an impedance step-up of 10 times. Concurrent with this

provision for high input impedance isa loss of signal, also of 10 times. Inother words, signal strength is tradedfor stepped -up input impedance. How-ever, the bargain is a good one, as theavailable signal is usually much greaterthan required for full -screen deflec-tion, while a higher input impedance is


often required for an undistorted wave-form display.

The attenuation factor of 10 is chosenso the scope's basic calibration factor isretained, whether or not the low -capacitance probe is used. If the low -capacitance probe is connected to thescope's input, the operator merely addsone zero to his calibration factor and

TRIMMER 15p.I.f MAX> -

COAX

INPUTR r0 MEG

MINIATURE

TRIM ER 15µµf MAX

5.IMEG

INPUT

TRIMMER 15140 MAX

SPECIAL LOW CAPACITANCE COAX

5.IMEG

INPUT

MINIATURE

COAX

TO SCOPE

MINIATURE

TO SCOPE

TRIMMER 15 f MAX

RIINPUT 5.1 MEG

357 K

TO SCOPE

11111111111.1.11111111111tr..111111:11111:111:1;g1111111i,,.:1 11

AX

TO SCOPE

NOTE: Low -capacitance probes can be used properly only if the scope hasa step attenuator which has the same input resistance and capacitance on eachstep. Most modern service scopes have satisfactorily constant input impedanceon the XI, X10, X100 and XI,000 steps.

peak -to -peak waveform voltages can bemeasured without recalibrating thescope's vertical amplifier.

A low -capacitance probe is also valu-able for checking signal levels througha video amplifier, as it keeps you fromloading the peaking coils excessively.Tests can be made at either the plateor the grid of a video amplifier tube.

CircuitsWhen C is set at 1/9 the input capacitanceof the cable and scope, and R is set at9 times the scope's input resistance, the probehas 10 -to -I characteristics-the input resist-ance becomes 10 times higher and the inputcapacitance 10 times lower than when a ments with a calibrated scope. The 10. o-1

direct cable is used to the scope's input probe imposes a 90% loss on the signal ap-plied to the scope.

This arrangement is similar to the foregoing,except that a fixed resistor is used in series,

and the potentiometer is placed in shunt.Better compensation (better square -wave re-sponse is obtained with this arrangement) atthe expense of slightly greater complexity.

TEST INSTRUMENTS

When testing at the picture tube, themost accurate waveform reproductionis obtained by unplugging the picture -tube socket and inserting the probe tipinto the video -signal socket terminal(grid or cathode). The input capacitanceof the probe substitutes for the input -capacitance of the CRT, and nearlynormal load conditions are realized.

Applications

terminals.

Value of RI principally determines the probe'sinput resistance. A 5-megohm metallized -filmresistor is suitable for probe construction.Potentiometer R2 is adjusted to provide 10:1signal attenuation at low frequencies and Cto provide 10:1 attenuation at high frequen-cies. The scope input capacitance is reducedto 1/10 by use of the probe, but input resist-ance is multiplied by a factor less than 10.

Because the input capacitance of a scopemay be about 20 µpi, while the input capaci-tance of the cable may be about 100 ilia, itis clearly advantageous for the scope user toemploy low -capacitance coaxial cable with theprobe.

Because the probe has 10 times higher inputimpedance than -a direct cable, it is sometimescalled a '"high -impedance" probe. The 10 -to -1factor is not always provided, but is preferredto facilitate peak -to -peak voltage measure -

Low -capacitance coaxial cable may be diffi-cult to obtain, but may be constructed bystripping the central conductor out of a lengthof RG-59/U cable and threading a No. 36copper wire through instead. This arrange-ment drops the cable input capacitance toabout 1/8 its nominal value. Attenuation factoris still 10:1, but the input capacitance is verymuch less.

A low -capacitance probe is sometimes simpli- To illustrate the low -frequency consideration,fied by using fixed values for both RI and R2. good low -frequency compensation is obtainedThis arrangement makes it possible to obtain when R2 equals 357,000 ohms, provided thehigh -frequency compensation, but low-fre- scope's input resistance is I megohm. How-quency compensation is correct only with ever, this is not always the case-a scope maythe scope for which the probe was designed. have as little as 500,000 ohms input resistance

or as much as 3 megohms.

Maximum simplification of the low -capacitance Compensation error which results when thisprobe is shown here. Fixed values of resistance type of probe is used with various scopes canand capacitance are used, and proper corn- be made less serious by using a small valuepensation at low and high frequencies can be of resistance for R, and a high cable capaci-obtained only for one particular scope. tance. This is a "brute -force"' arrangement

in which compensation is approximated at asacrifice of input impedance advantage.

VARIOUS DEMODULATOR PROBES(Also called Defector, Crystal, High -Frequency, RF or Travelling Detector Probel

The photo shows a typical demodu-lator probe. This type of probe lets youuse a scope in higher -frequency circuitsthan otherwise possible. Popular usesfor the demodulator probe are signaltracing in if amplifiers, display of sin-gle -stage if response, display of videoamplifier response curves and displayof bandpass amplifier response in colortelevision receivers.

There is a practical limitation in theapplication of a demodulator probe. Re-member that waveforms of more than50 volts peak to peak tend to produce

pattern distortion, while outputs in ex-cess of 100 volts peak to peak can im-pair the sensitivity of the crystal di-ode or burn it out completely.

A demodulator probe used with ascope must have several special fea-tures. Unlike a probe designed for avtvm, a scope demodulator probe mustrectify the rf component of the wave-form and it must pass the modulationenvelope of the signal to the scope'svertical amplifier. Accordingly, a scopedemodulator probe must have optimumfilter characteristics to meet the service

applications for which it is intended.The probe shown on page 36 has a

voltage -doubler configuration in thecrystal -diode network to provide maxi-mum sensitivity. With such a probe,you can trace if signals back to thetuner output, provided a reasonablesignal input is applied to the receiver'santenna input terminals. When astrong TV station signal is not avail-able, the output of a sweep generatoris useful for signal tracing.

The demodulating capability of suchprobes is somewhat limited, due to the

APRIL, 1959 37

TEST INSTRUMENTS

appreciable input capacitance of serv-ice scopes, and this point should beclearly recognized so the receiver isnot unjustly blamed for limitations ofprobe response. The demodulating ca-pability of the probe permits good re-production of a vertical sync pulse,but only partial reproduction of a hori-zontal sync pulse. Hence, signal -tracingprocedures should always be followedwith the scope deflection rate set to 60cycles (or 30 cycles), and the observa-tions based upon the observed displayof vertical sync pulses.

To display a bandpass amplifier re-sponse curve, the fundamental require-ment is that the probe be capable ofdisplaying a 60 -cycle square -wave en-

IN34-A> N c)

INPUT COAX

2741.1 220K

INPUT = COAXTO SCOPE

0

TO SCOPE

0

IN34-A

C

270p.µfINPUT

0

/31.:111.1t1111111111111111111111111111111111111111111111111111111111

220KlOOK

IN34-A

2744 IN34-A

INPUT

COAX

COAX

105 10K

0

TO SCOPE

TO SCOPE

0111111111111111111111t1111111111111t,11111111111111111111111111111111111111111.

now IN34-A(2) COAX

INPUT2NIE

T2m 4TO SCOPE

IN34-A

270µµf

INPUT

22K

3300I20µH

10p.p.f

TO SCOPE

11111111111111111111111111111111111111111111111111111111111111111111111T1111,1111. I

SPECIALLOW -CAPACITANCECOAX

250µH

SWEEP 8MARKERGEN SCOPE

BANDPASSAMPL VERT

I

DEMODNPUT

PROBE

Fig. 1-Test setup for checking band-pass amplifier response in a color TV

receiver.

velope without distortion. The probe iscapable of this response, and hence thetest setup shown in Fig. 1 provides anaccurate check of bandpass amplifier

CircuitsSimplest form of demodulator probe, madeup of a germanium diode in series with theshielded input cable. The input cable servesas a charging capacitor. A series -detectorarrangement, providing half -wave rectification.

A general-purpose demodulator probe. Thedetector is arranged in shunt, with a 270-µµfcharging capacitor. The shielded input cableis isolated from the high -frequency circuit inthe probe by a 220,000 -ohm resistor. Half -wave rectification is provided.

This arrangement for a demodulator probe isthe same as the preceding version, except thatthe diode is shunted by a 100,000 -ohm re-sistor. When a diode with a high front -to -back ratio is used, the shunt improves theprobe's demodulating capability.

Fig. 2-Typical bandpass amplifier re-sponse curve obtained with the test set-

up in Fig. 1.response in a color TV receiver, withthe result shown in Fig. 2.

ApplicationsArrangement is simple and economical, buthas limited demodulating capability-hori-zontal sync pulse is greatly attenuated anddistorted, although vertical sync pulse is de-modulated without severe distortion. Inputcable is not isolated from the probe networkand operates as a resonant stub at varioushigh frequencies, which makes the probe ap-pear insensitive at certain radio frequencies.

This type is not resonant at radio frequenciesand provides uniform sensitivity. Sensitivity is

less than that of doubler types, but its cutofffrequency is considerably higher than that ofa doubler probe. The series charging capaci-tor permits using it in signal circuits wheresome 60 -cycle hum voltage may be present.Vertical sync pulses are demodulated reason-ably well, but horizontal sync pulses aregreatly attenuated and distorted.

Demodulating capability cannot be extendedindefinitely by lowering the value of RI, be-cause a limitation is imposed by the time con-stant of R2 and cable capacitance. It is notpractical to reduce the value of R2 appreci-ably because cable capacitance then imposesan excessive capacitive shunt across the diodeand reduces the detector efficiency.

11111111111111111111',1..:IiIIII.1

Demodulator -probe arrangement using a se-

ries detector, with a 10,000 -ohm shunt on bothsides of the diode and no cable isolation.Sensitivity is moderate, and demodulatingcapability is considerably greater than for theforegoing types of demodulator probes. De-modulates horizontal sync pulse satisfactorily.

Chief disadvantage of this probe arrange-ment is lack of rf isolation between the cableand the probe network. Therefore, the probe'ssensitivity will appear quite good at someradio frequencies, but poor at others. The

series input capacitor provides good rejectionof 60 -cycle hum voltages.

This arrangement is used in a voltage -doubler Demodulating capability is not greater thandemodulator probe, sometimes called a peak- that of conventional half -wave types and

to -peak high -frequency probe. The probe net- horizontal sync pulses are greatly attenuatedwork provides full -wave rectification and cor- and distorted. Vertical sync pulses are rea-

respondingly greater sensitivity, compared sonably well demodulated. The frequency cut -with a half -wave probe. off is only about half as high (about 100 mc)

as that of typical half -wave probes.

Wide -band demodulator probe, with high-fre- To obtain the 4-mc bandwidth of output signalquency compensation for reproducing enve- from the probe, the scope's input capacitancelope frequencies up to 4 mc. The input cable must be maintained very low (not over 10

to the scope is of special low -capacitance con- µµf). This necessitates bypassing the step at-struction having an outer diameter of 1/2 tenuator and applying the cable output direct -inch and a No. 40 central conductor. ly to the grid of the cathode-folllower input

stage. The probe's sensitivity is much less thanthat of the narrow -band probes shown above.

NOTE: The input resistance of all service demodulator probes is relatively low and the input capacitanceis appreciable. For this reason, the probe fends to load signal circuits in which it may be applied, and theuser must be aware of this limitation to avoid the possibilty of drawing false conclusions in some testsituations. END


TEST INSTRUMENTS

-J.SIMPLE CAPACITORCHECKING 1111

METHOD

Simple circuit plus multimetermake accurate test instrument

By GEORGE P. PEARCE

FOR several years I have been test-ing capacitors by measuring thecurrent flow through them whenconnected in a 120 -volt 60 -cycle

line and calculating the capacitance bythe standard formula. I never liked theidea although it gave very good results.The trouble was that while testing Iwas pestered with the disturbingthought of what would happen to thedelicate and expensive 50-Aa meter inmy multitester if the capacitor undertest should puncture or short-a flip,a puff of smoke and no meter. I finallydecided to build a capacitor checker fortesting a wide range of capacitances,one that could not possibly damage myexpensive meter even if a capacitorshould short while I read the meter.

The circuit is shown in the schematicdiagram. The potentiometer permitsobtaining the exact voltage required forany test on capacitors from .00025-10 µf. My junkbox supplied all theitems needed to assemble the checker,except the steel cabinet which I bought.The transformer has a 270 -volt sec-ondary with taps at 120, 30, 8 and 1.5volts. I happened to have a burnt -outpower transformer so I pulled it apart,cleaned the steel laminations, woundthe coil for the above voltages and re-assembled it. The amount of secondarycurrent required is very small so fine

VOLTAGESELECTOR

5K NEON LAMP TOVOLTMETER

PUSHBUTTON

DPST SWITCH

wire can be used. I had some No. 33enameled copper wire on hand and usedthis for the secondary winding.

(A tube tester transformer has allthe voltages but 270. Readers wishingto wind their own transformers wouldbe well advised to pick up one in goodcondition-from the junkbox, prefer-ably-with a secondary of roughly therequired voltage. The filament wind-ings and half the secondary can thenbe removed and the other taps obtainedby winding some of the secondary wireback on again. The center tap willthen become the common lead, with270 volts on one side and the tappedwinding from 1.5 to 120 volts on theother. The number of turns needed pervolt can be learned by counting theturns on a filament winding and divid-ing the figure by the voltage of thewind ing.-Editor)

To obtain the testing range I usedfive voltage scales on my multitester :

IINAC.4-0

.5APWR TRANS

I/25W NEON 270V

120V

30VTO VOLTMETER

8V

TO_CAPACITOR

Front -panel view showing all controls.

250, 100, 25, 5 and 1. I wound thetransformer for a higher voltage ineach range so that even during thelowest house voltage I would be ableto get what was necessary. This iswhere the potentiometer is so valuable.All that has to be done is to set theselector switch to the nearest highervoltage. Then, with the potentiometer,reduce and adjust the voltage to themeter to the exact amount needed fora given range.

Operating the checkerSuppose the transformer is set to

deliver exactly 250 volts to the multi -tester. If, say, a .001-g capacitor isplaced in series in one of the leads tothe meter, the reading will no longerbe 250 volts but something less. It isbest to read this deflection on the uni-form scale which has the most divi-sions. On my meter there is a scaledivided into 50 spaces that I always

I-power transformer with Tapped secondary (see

text); I -5 -position selector switch; I-pushbuttonswitch, normally closed; 1.5 -amp fuse and holder;I -5,000 -ohm I -watt potentiometer; I -220,000 -ohmresistor; 1 -1/25 -watt neon lamp and holder; 2-alligator clips; I-cabinet.

Schematic of the capacitor checker.

APRIL, 195939

TEST INSTRUMENTS

220 K

PUSHBUTTONSWITCH

5K

TOCAPACITOR

TO VOLTMETERNEON LAMP

VOLTAGESE LECTOR

Layout of capacitor checker parts.

use when checking capacitors. On thisscale, with 250 volts potential, I geta deflection of 4 divisions when testinga .001-µf capacitor, about 0.7 divisionfor a .00025-pf capacitor and 46 divi-sions for a .03-pf unit.

By providing a table based on theseand other readings the value of anycapacitor from about .00025 to .05 pfcan be determined immediately in the250 -volt range. If the capacitor to betested is larger than .03 pf, say .07 if,then it cannot be tested at 250 voltsbecause the needle deflection would betoo small to give an accurate reading.

This difficulty can be easily overcomesimply by taking the next lower voltagefrom the transformer (in my case, the120 -volt tap) and then carefully adjust-ing the potentiometer to give full-scaledeflection. Readings on this scale canbe taken on capacitors ranging fromabout .001 to 0.1 pf, on the 25 -volt scalefrom .005 to 0.2 µf, on the 5 -volt scalefrom .03 to 1.2 pf and on the 1 -voltscale from 0.5 to 10 pf. It does not mat-ter what the scale ranges are on yourmultitester or even a simple high -resistance ac voltmeter, you can makeyour calibration to suit.

When the capacitor to be tested isplaced between the alligator clips (seediagram), it is shorted and the meterreads the transformer voltage. Pushingthe test button removes the short andplaces the capacitor in series with thecircuit so you can take the capacitorreading. Release the button and checkto see that the voltage has not changedwhile testing. You now have a simplemethod of getting an exact voltageacross the terminals of the capacitorunder test and reading the meter deflec-tion. You know that any other capac-itor that gives the same deflection underthe same voltage will have to have thesame capacitive reactance (and capac-itance). Thus you can equate the scaledivisions with microfarads. This isyour test scale.

It is possible to calculate the exactreading for every capacitor within the

POWERTRANS

range of the multitester, but it is alot of trouble. It is easier to just pickup a couple of dozen good fixed capac-itors from .00025 to about 10 pi and,one by one, get the readings at thevarious voltages. Then make a tablesimilar to that shown. When testing acapacitor, should the needle just barelydip, you will have to turn to a lowervoltage. If the needle swings too nearzero, you will have to use a highervoltage. The alligator clips are very

TYPICAL CAPACITOR RATINGS(50 -division scale -numbers indicate

divisions from full scale)

Capacitor Meter Scale -Volts Ac(0) 250 100 25 5 1

.00025 0.7

.001 4.0 1.5

.002 10.0 4.0

.005 20.0 8.5 1.5

.01 34.0 18.5 4.0

.015 41.0 28.0 7.0

.03 46.0 39.0 14.0 2.0

.05 48.0 45.5 23.0 4.00.10 48.0 33.0 8.00.20 44.0 16.50.50 36.0 8.51.0 44.0 10.51.2 45.0 11.02.0 22.04.0 36.06.0 42.08.0 46.0

10.0 47.6

handy for they bite onto almost anykind of capacitor connection. If acapacitor should suddenly short, noharm will come to the meter -it willsimply swing to full deflection andstay there.

Because the test voltage at times isas high as 250 it is advisable to openthe line switch when clipping to acapacitor. When checking a pile ofcapacitors, one is apt to become con-fused and either snap the switch twiceor not at all so to be absolutely safe Iincluded the little 1/25 -watt neon lampin the primary circuit so it would glowwhenever the primary circuit was en-ergized. END

NEXTmlMONTH

Golden Ears or Bats' Ears?Is the widely touted frequency response ofmodern high-fidelity audio equipment necessary-or useful? This and some other fetishes ofhi-fi are discussed -and demolished -by GeorgeFletcher Cooper.

Water Is the TriggerA 1 -transistor alarm thatsenses rain and actuatesa relay to shut windowsand doors, or warns sleep-ers of rain. It can alsobe adjusted to act as ahumidity alarm or relay.

Tube Changers and "tube changers"Depending on whether the service technicianknows what he is doing or not, tube changing canbe the quickest and best service technique or itcan be worthless. The Old -Timer distinguishes be-tween tube changers and Tube Changers.


RADIO

ABC's of MOBILE RADIO

Part III-Circuitry andspecial features of mobileradio equipment

By LEO G. SANDS

ALLmakes of mobile equipment areessentially similar: the trans-mitters must conform to thesame FCC technical standards

and the receivers must have competitivecharacteristics. They do differ in cir-cuitry, special features and styling.

Mobile equipmentA mobile unit is a radio station on

board a vehicle or one carried by aperson. A typical mobile unit consistsof a transmitter and receiver with theirpower supply, an antenna system, handmicrophone or handset, speaker, controlhead and interunit cabling. The trans-mitter, receiver and power supply areusually housed in a single sheet -metalcase, forming a package often called a"communications unit," which is mount-ed in the trunk or under the dash of apassenger automobile (or in a box orother protective enclosure when in-stalled on a truck).

Some manufacturers have weather-proof cases for radio units that will beexposed to the elements. Sometimes theradio is installed without an externalprotective enclosure when used indoors.The control head, speaker and micro-phone are installed near the driver.Mobile communications units installedunder the dash of a vehicle are gen-erally provided with a built-in speaker,and the controls are mounted on thefront panel.

The transmitter, receiver and powersupply may be on individual chassisstrips fastened together or combinedon a single chassis. Sometimes, there ismore than one receiver strip and, insome sets, space for selective -callingdecoders or auxiliary audio amplifiersis provided. In some early sets, thetransmitter and receiver were packagedas separate units.

MIKEEXC TERVOLTAGE

.01

XTALTRIMMER

82 µµt

I2AT7OSC-MOD

22µ0

o XTAL

5-25/5µFf

1/2 I2AT71ST AF AMPL .001

CARBONMIKE

2M11

8+

2MH

6AL5LIMITER

25

New 450 -470 -me mobileradio developed by Ben-nett Laboratories is an

AM unit.

100µµf RF TO(----)"C/UADRUPLER

I5K

2MH18p.µf

.0047 10K

100K .02

470K .01

1/2I2AT7 56K2ND AFAMPL

47K

50K is

DEVIATIONCONTROL

Fig. 1-Unique phase modulator used in theBendix Dyna--Com 1V14A for the 25-54-mc band.

Mobile units are also available forthe 1.6-8.0-mc portion of the radiospectrum. Operation at these relativelylow frequencies is restricted to certainindustries and governmental agencieswhich have special need for longer -range communication than is normallyavailable in the vhf and uhf bands.

These medium -frequency mobile unitsare AM whereas most vhf and uhfequipment are FM. AM vhf sets, com-patible with aviation radio systems,are used on land vehicles in airportutility applications and are operated

B+

22011

in the 118 -134 -me aeronautical band.Some low -power -industrial (LPI) unitsfor the 25-54- and 152 -162 -me bandsare also AM. Also using AM is a new450-470-mc mobile unit recently devel-oped by Bennett Laboratories.

Ordinarily, the mobile transmitterand receiver are operated sequentially.The receiver is left on so a signal canbe intercepted. A squelch circuit silencesthe speaker except when a strongenough signal to override backgroundnoise triggers the squelch circuit andactivates the receiver's audio amplifier.

APRIL, 1959 41

RADIO

The receiver is disabled and thetransmitter turned on with the press-to -talk button on the handset or palmmicrophone. This also switches theantenna from the receiver to the trans-mitter. When the press -to -talk buttonis released, the transmitter is turnedoff and the receiver turned on.

Rated power output of mobile trans-mitters ranges from 0.1 to more than100 watts. Most mobile units operateinterchangeably from either a 6- or12 -volt battery, although there is atrend toward eliminating the require-ment for 6 -volt operation since moderncars have 12 -volt batteries. Mobile unitsfor on trains are generally designedfor direct operation from 64 volts dcthough some operate from 117 volts acfurnished by a dc -to -ac rotary orvibrator type converter.

25-54-mc equipmentBecause of its long-range capabil-

ities, the 25-54-mc band is popular andused by nearly all who are eligible forlicensing in this band. Ignition noiseand skip interference, however, aremore of a problem than at higherfrequencies.

Most mobile radio manufacturersbuild units for this band. Bendix Radio,for one, makes both wide -band andnarrow -band mobile sets in 30- and60 -watt models. They can be operatedfrom either 6- or 12 -volt batteries with-out modification and are available withvibrator or transistor power supplies.

The Bendix Dyna-Com 1V14A is anarrow -band model for operation onany frequency in the 25-54-mc range.Output power is 30 watts. Frequencystability of --1--.003( is obtained withouta crystal oven while ±.0006% stabilityis realized when a temperature -con-trolled crystal oven is used. Crystalfrequency is multiplied 16 times by aquadrupler and two doubler stages. Asingle 6146 is used as the final rfamplifier. In the 60 -watt model, a pairof 6146's is used.

Bendix uses the unique phase mod-ulator shown in Fig. 1. A 12AT7 dual -triode serves as the crystal oscillator-modulator. The audio modulating signalis fed to the grid of one of the triodes,causing both phase and amplitude mod-ulation. The following class -C stageserase the amplitude modulation, yield-ing an FM signal at the transmitter'soutput.

The signal from the microphone isamplified by one section of a dual -triodewhose output is fed to the second audioamplifier stage through a dual -diodelimiter. The limiter, which uses biaseddiodes, prevents overdriving the secondaudio stage, effectively eliminatingovermodulation. A 50,000 -ohm poten-tiometer at the input of the secondaudio stage may be adjusted to setmaximum frequency deviation to anypoint between 0 and -.±:15 kc.

The receiver employs a uniquedouble -conversion superheterodyne cir-cuit. However, three, not two inter-mediate frequencies are used. The out-

put of the mixer is at 5.8 mc. The mainif amplifier and first and second limitersare tuned to 262.5 kc. The secondlimiter, however, also acts as a fre-quency doubler. Its plate circuit, tunedto 525 kc, feeds a third limiter which inturn feeds the discriminator, also tunedto 525 kc. The frequency -doubling actionalso doubles frequency deviation at thediscriminator's input.

To provide ± 7.5-kc if bandpass andmore than 100-db attenuation of signals±17 kc off frequency center, two 5.8-mcfilter networks are used between thefirst and second mixers, and four 262.5-kc bandpass filters in the main ifamplifier of narrow -band models. Ninetriodes and only one pentode are em-ployed as amplifiers in the if section.However, pentodes are used in thethree limiter stages. Most of the triodeif amplifiers are used in a grounded -grid arrangement and are followed bya cathode follower. Thus, the if trans-formers are connected between twocathodes rather than between plate andgrid as they would be in a conventionalpentode if strip.

The Bendix Dyna-Com low -band setshave three separate chassis. One con-tains the transmitter, another the re-ceiver. The power supply, receiver audiooutput stage and transmitter speechamplifier-limiter are on the third. Allthree are in a single metal enclosure.

152-162-mc unitsMuch of the available so-called 152-

162 -me band equipment is also operablein the 144-148-mc Amateur band aswell as the 162-174-mc Governmentband.

This is true of General Electric'sProgress Line. This equipment may bepackaged in various combinations indifferent size cases, as is true with25-54-mc G -E units, to meet individualrequirements.

G -E model 4ET21 transmitters arerated at 50 watts output when operatedbetween 144-162 mc, and 40 watts from162-174 mc. The crystal frequency ismultiplied 24 times and frequencydeviation can be adjusted from 0 to-± 15 kc for wide- or narrow -bandoperation. Deviation is automaticallyregulated to prevent overmodulation.Two -channel operation may be obtainedby adding a second crystal oscillator.Four frequency -multiplier stages areused, compared to three in G -E equiv-alent low -band (25-54-mc) equipment.Otherwise the circuitry is similar.

In G -E model 4ER25 receivers, as inlow -band G -E units, multiple -tuned cir-cuits are used ahead of the rf amplifierand between various stages. Separatecrystals are used for the first andsecond converters (mixers). The firstif amplifier section is tuned to 8.7 mcand the second section to 290 kc. Similarcircuitry is used in G -E low -bandreceivers. The if filters may be re-placed when converting from wide -band to narrow -band operation.

Two limiter stages precede a Foster -Seely type discriminator which drives

RECTIFIEDNOISE SIG

.01

12AX7SQUELCH AF AMPL

15560

100 K 22 K

+ 7.

IFROM DISCRIM

AUDIO SIG

.01

.001

220 K

I MEG

TO AUDIOOUTPUTSTAGE \

.0039

8+

Fig. 2-Simplified diagram of thesquelch circuit found in G -E model

4ER25 receivers.

both the audio amplifier and the squelchcircuit. In the squelch circuit, shownin simplified form in Fig. 2, the higher -frequency components of the noisevoltage at the discriminator's outputwhen no signal is being received areamplified and fed to a noise rectifier.The de output of the noise rectifier,which is a voltage doubler, is fed tothe squelch tube. The grid of the squelchtube is driven to cathode potential,causing plate current to flow anddeveloping a large drop across theplate resistor. This biases the firstaudio amplifier to cutoff, disabling itand electronically muting the speaker.

When a strong enough signal is re-ceived, the high -frequency noise compo-nents are eliminated from the discrim-inator output by the limiter stages.The squelch tube no longer disables theaudio amplifier, because of the absenceof noise, the received audio signal isamplified and heard through the loud-speaker. Squelch threshold is set by anexternal variable control.

The choice of 6- and 12 -volt powersupplies which use vibrators or acombination of a vibrator and a dyna-motor depends upon transmitter re-quirements. There are also transistorpower supplies. Smaller than theirelectromechanical equivalents, they haveno moving parts.

For the 450-470-mc bandSeveral makers are turning out uhf

mobile units for the 450-470-mc band.Transmitter power is less significant atultrahigh and microwave frequenciesand range is limited more by obstruc-tions in the signal path than by lack ofpower. To get a significant extension inrange by raising transmitter powerwould require a drastic increase, beyondthe capabilities of existing mobileequipment.

When operating on the same fre-quency, the man with the higher -powered rig has the advantage that hissignal can sometimes capture receiverswithin range, blanking out a signalfrom a lower -powered transmitter.This capture effect occurs in FM sys-tems. The stronger signal saturatesthe limiter of a receiver, making itinsensitive to a weaker signal on thesame frequency. The stronger signal


RADIO

18.7-19.6 MC

RF SIGFROM OSC

IAUDIO IN

6BH6PHASE MOD

B+

RI

DEVIATIONCONTROL

18.7-I9.6MC

TDIIITLERGRID

BIAS

Fig. 3-This phase modulator is in theKaar Expeditor, 450-470-mc transmit-

ter. It is shown in simplified form.

does not necessarily come from themost powerful transmitter but couldcome from a lower -powered transmittera short distance away.

While many uhf mobile transmitterson the market can be loaded to as muchas 50 watts input to the final, KaarEngineering Corp. deliberately designedits TR500 and TR501 Expeditor mobileunits for lower power. The transmittersof these 450-470-mc mobile units areloaded to 12 watts input to the final onfrequencies where more than 10 wattsis permitted and to 10 watts for use inthe Citizens band.

Actual field tests revealed that underconditions when a 50 -watt -input unitprovided 12 -mile range, a 10 -watt setreached out to 10 miles.

Since a 10 -watt set would provideadequate range in urban applications,Kaar designed a compact uhf mobileunit which consumes very little batterypower. When transmitting, only 8.5amperes is required (with 12.6 voltsdc input) compared to 20 or moreamperes for higher -powered sets.

The transmitter, receiver and tran-sistor power supply are housed in asingle case. The model TR500 is in-tended for mounting under the dashor for use as a base station. It has abuilt-in speaker, and the operatingcontrols are on the front panel. TheTR501, intended for trunk installation,has an external control head, externalspeaker and remoting cables.

The transmitter section employs ninetubes. A new type, the 6939, is used inthe tripler and power amplifier stages.It costs considerably less than tubesused in these stages in earlier equip-ment. Tests also indicate that it has agreater life expectancy.

While many vhf transmitters employconventional coils and capacitors in therf tank circuits, resonant lines orcavities are used in uhf transmitters,lines tunable by trimmer capacitors areused in the plate circuit of the triplerand both the grid and plate circuits ofthe power amplifier of this equipment.

Frequency stability is ±.0025% instandard models and, when a tempera-ture -controlled crystal oven is used,

stability is increased to ±.001%. Thecrystal frequency is multiplied 24 times.

Fig. 3 is a simplified schematic ofthe phase modulator. The audio signalfrom the speech amplifier is fed througha speech clipper to the grid of the6BH6 phase modulator. This causesthe rf signal being fed to the firstdoubler to lead and lag in step withthe modulation. This changes the phaseof the rf signal reaching the firstdoubler, giving the effect of frequencymodulation. Potentiometer R1 can beset to produce frequency deviation from0 to a maximum of -±-15 kc.

Overmodulation is prevented by aspeech clipper inserted between thespeech amplifier and the phase mod-ulator. Fig. 4 shows the speech amplifierand clipper sections of the transmitter.The components have been selected tofavor amplification of speech between

6BH6SPEECH AMPL

TODYNAMICMIKE

1K 470Ntf220 0

220 e.f

150K 220K

1:05

10

Fig. 4-Speech amplifier and

0+

ciated oscillator feed local -oscillatorsignal to the third mixer.

An adjustable L -C filter assemblybetween the third mixer and the 1,500-kc if amplifier; normally supplied withthe equipment, provides adequate selec-tivity for operating on a 100-kc channel -spacing basis (100 db down at -± 100kc). Another filter may be installed atany time to provide adequate selectivityfor 50-kc channel spacing (100 db downat ±50 kc).

The squelch circuit is of the signal-to-noise ratio type, activating the firstaudio amplifier when background noiseis quieted by the presence of a signal.An afc circuit automatically adjuststhe first and second mixer local -oscil-lator frequencies to the incoming signal.The afc correction ratio is 5 to 1 over afrequency range of ±20 kc; a switchis provided for disabling afc if desired.

E+

12AX7CLIPPER

I K

B+

*OK

I MEGTO PHASEMOD

DEVIATIONCONTROL

phase modulator circuitry of the Kaar TR500.

300 and 3,000 cycles. The clipper is atwo -stage cathode -coupled amplifierwhich saturates when overdriven, limit-ing the amplitude of the audio signalsreaching the modulator.

The receiver has 18 tubes. It employstriple conversion using 50 mc, 10 mc,and 1,500 kc as intermediate fre-quencies. Two rf stages, employingcoaxial lines, precede the first mixer,which delivers a 50-mc signal to an ifamplifier which feeds the second mixer.One if stage at 10 mc feeds the thirdmixer whose 1,500 kc output is ampli-fied by two more if stages. Two limiterstages precede the phase detector whichfeeds audio to a two -stage audio ampli-fier.

A single crystal provides local -oscillator signal for both the first andsecond mixers. The crystal signal isfed through two tripler stages to thefirst mixer and directly to the secondmixer. A separate crystal and asso-

1500 KC SIG rFROM 2ND LIM I

1500 KCIF TRANS

L

The afc control voltage is obtainedfrom the cathode of one of the diodesof the unique phase detector (dis-criminator) shown in Fig. 5. Thisdetector is sensitive to changes in phaseof the incoming if signal yielding theaudio component which is fed to theaudio amplifier.

The Kaar Expeditor is furnished witheither a transistor power supply for12 -volt de operation only or a universalvibrator type supply for 12 -volt dc or117 -volt ac operation. The latter unitpermits using the same set as either amobile unit or as a base station.

So far we have examined severaltypes of mobile equipment. Units for25-54-, 152-162- and 450-470-mc bandshave been described. Next month wecontinue with details on portable equip-ment, railroad radio, and AM operationin the 118-134-mc band. A few wordson antennas and a forecast of thingsto come end the series. TO BE CONTINUED

6AL5PHASE DET

220K

220K

B+ .= AFC TO SQUELCHNOISE AMPL

Fig. 5-Phase detector in the receiver section of the Kaar TR500.

47K 220K

MEG TO AUDIOAMPL

VOLUME CONT

APRIL, 1959 43

RADIO

You can determine the distance to the oceanfloor with an echo sounder. But can you

tell someone how it works and'you fix one that comes

ECHO SOUNDERS for SMAlt:into your shop?

W."

Soliar portable echo sounder with single -hole transducer.

Rend is recorder. Right: Ju ble type transducer. Leicable. "stuffing tube" seals transducer cable passing through hull.

Ross .port -man sounder consists of indicator, po» Cr unit andtrio ri!ever.

44

BOAT

OWNERS

By ELBERT ROBBERSON

41111.4

)4111111*

4111110-4

PuSIRRIo

}..atte

WHEN a person gets out in aboat, the land may fade inthe distance and seem veryremote. Actually, it is never

very far away-straight down. Know-ing just how far away this closest landlies has always been one of the nav-igator's prime concerns. And nowa-days, the term "navigator" meansabout 30 million Americans. Use yourelectronic skill to help these boatmenkeep track of the bottom, and you'llbe aiding public convenience and safety,and very likely helping yourself finan-cially.

The first commercial echo sounderswere several -hundred -pound brutes scat-tered in pieces throughout a ship, fromthe bridge deck to the keel. To carryone, a vessel had to be a thousand-tonner, with an owner having moneyto match. Today, a good sounder canbe bought with lunch money and carriedaway under an arm. No toys, either,are these. They will spot the bottomas effectively as the big babies, andeven find fish.

The science of echo sounding beganwith percussion devices, set in the hullof a ship, that periodically sent out awalloping burst of sound. An operatorequipped with a microphone, headsetand stop watch measured the intervalbetween the main bang and the echofrom the bottom. Sound has an averagevelocity in salt water of 4,800 fps(feet per second). If the bottom lay2,400 feet below, the sound would re-turn in 1 second.

In shallow water, it would take afast man with a stop watch to measurethis interval, so various clockworkmechanisms were devised. One had adepth -graduated dial which startedrevolving when the sound was sent out.The returning echo stopped the dial,and the distance to the bottom couldbe read off. Primitive though it mayseem, this basic scheme is so effectivethat some variation of it is employedin most echo sounders used today.

The timer indicatorThe heart of most modern echo

RADIO -ELECTRONICS

RADIO

Ross Labs transistor sounder uses permanentlyinstalled or portable transducer.

ELAC (Electroacoustic) echo soundershowing recorded trace of bottom.

..40.0,040ises4404400"410"00"ftereNsiorftio"ftirovar14.0".10.4.0sounders is a constant -speed ac motor,which drives a rotating arm carrying aneon bulb at its end. The circle de-scribed by the neon lamp on this armconstitutes the time base, and foot orfathom (6 -foot) calibrations are super-scribed on a transparent cover.

The rotating arm also is fitted witha contactor or magnetic keying arrange-ment which initiates the sound pulse attime zero. A returning echo causes theneon bulb to flash, and the distance tothe bottom is read off the scale. Byrunning the arm at different speeds,the maximum range of the indicator ismade to be any desired value fromunder a hundred feet to many thou-sands.

Motor speed and accuracy dependupon a carefully regulated powersupply, which converts dc power fromthe boat's batteries to ac. Two kinds ofpower supply are used: the vibratortype, which chops battery current intosquare waves that are stepped up tothe motor voltage by a transformer,and the more recent transistor oscillatoror chopper, which does the same thingelectronically.

Instead of indicating depths with aflashing light, some instruments arebuilt to record the contour of thebottom on a specially prepared sheet ofgraph paper. In place of the revolvingarm an electrical stylus on a motor -driven belt writes vertically on theslowly moving sheet of paper. At thereturn of each echo, the stylus burnsa mark, which is interpreted in termsof depth from calibrations printed onthe paper. The result is a profile mapof the bottom over which the boat hassailed. By comparing this with astandard navigational chart, under-water landmarks may be spotted, orschools of fish.

One instrument, manufactured byBludworth Marine, has an all -electronictiming and indicating system. A multi -vibrator flip-flop and integrating cir-cuit allows current flow to build upthrough a conventional meter 12 timesa second. The sound signal is sent outin synchronization. If no echo is re-

turned within the 1/12 second, themeter will reach full scale. However,when an echo is received, the integrat-ing circuit is cut off, allowing only aproportionate amount of the full-scalecurrent to flow. Therefore, the angleof needle deflection indicates the depth,up to 200 feet.

The most elaborate instruments, usedon large fishing vessels or ocean-goingships, use electronic timing circuits,with depths indicated as a trace on acathode-ray tube.

TransducersThe next distinguishing feature of

an echo sounder is the transducer sys-tem which sends the pulse of sounddownward into the water and receivesthe echo. Some instruments have twotransducers-one for each function-while others have one that serves bothfor sending and receiving.

Magnetostriction transducers use astack of nickel laminations, excited bycurrent through a coil. An oscillatorydischarge of current through the coilcauses the nickel to expand and con-tract, or "ring," and the resultingsound is transmitted from the trans-ducer face to the water. Oscillating fre-quencies are in or near the ultrasonicrange, from 14 to about 50 kc.

Piezoelectric transducers use Ro-chelle salt crystals or ceramic wafers.An oscillatory pulse of voltage appliedto the crystal electrodes causes physicaloscillation, which is transmitted throughthe transducer face to the water. Fre-quencies used with piezoelectric trans-ducers extend all the way up to 500 kc.Low frequencies have the longest range,while high frequencies detect smallerobjects and have better resolution.

For insulation and cooling, and toseal out moisture, transducer housingsare filled with a special oil which alsoacts as an efficient conductor of sound.Most housings are designed to be fittedonto the surface of the keel or theboat's hull, while others are intendedto be recessed to present a smoothouter surface to the flow of water.Sometimes transducers are installed

inside the hull, in a specially con-structed water -filled well. This form ofinstallation eliminates holes in the hulland is a convenient method to use forinstallations made while the boat is inthe water.

Driver-oscillatorTo excite the transducer a powerful

pulse of current or voltage whichoscillates at the transducer's resonantfrequency must be generated. Thesimplest drivers use a gaseous dis-charge tube or thyratron, fired by thekeying circuit in the timer-indicator,to discharge a capacitor into a mag-netostrictive transducer. Circuit timeconstants are chosen to create anoscillatory current discharge at thedesired frequency.

Another system uses a coil in par-allel with a piezoelectric transducer inthe cathode circuit of a thyratron.When the keyer drives the thyratroninto conduction, a capacitor dischargeis impressed upon this cathode "ring-ing circuit," creating the oscillatorypulse.

Still another method is to use aconventional oscillator circuit, such asthe Colpitts or Hartley. Its output isimpressed upon the transducer whenthe tube is keyed by the timer.

Video amplifierThe type of circuit used to amplify

returning echoes depends upon thefrequency of oscillation. At frequenciesjust above the audible range, a conven-tional R -C -coupled amplifier, using upto five tubes, with coupling componentschosen to accentuate the "highs," willturn the trick. Higher -frequency ampli-fiers very closely resemble radio re-ceiver if amplifiers, and have three orfour transformer- or impedance -coupledstages.

Put it all togetherYou can see how the different parts

of an echo sounder work together bytracing through the schematic of theRoss echo sounder (Fig. 1). Thevibrator and vacuum -tube rectifier

APRIL, 1959 45

RADIO

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power supply and the heater lineupfollow conventional mobile equipmentdesign. Power consumption is approx-imately 40 watts, with inputs of 6, 12or 32 volts dc.

The synchronous ac timing motor(box labeled INDICATOR) is run fromthe secondary of the vibrator trans-former, the speed being kept within±5% by the vibrator. Connected to themotor shaft are the keying contractorand the neon -bulb echo indicator.

Once every revolution of the motor

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arm, the keying contactor closesmomentarily. This grounds the networkthrough which a highly negative block-ing bias from rectifier V7 is appliedto the grid of oscillator Vl. When thecontact opens, the blocking bias is notreapplied for a total time of 1 milli-second, because of the grid network'stime constant (R2, Cl, C2). Duringthe time that the bias is removed, V1oscillates at 110 kc, its power outputappearing at the plate.

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former T1 to the ceramic transducerunit, which oscillates in resonance,sending the pulse down through thewater. Another secondary also sends asmall amount of energy to the receiver.

While most receivers consist of aresistance, transformer- or impedance -coupled amplifier, this unit is a super-heterodyne, closely resembling a low -frequency radio receiver. With a local -oscillator frequency of 285 kc, thesignal is converted to 175 kc in V3,and amplified. The if amplifier ends up


RANGE 42.5NORTH OFC.L. TRENCH

C.L. TRENCH

RIVER BOTTOM

SHOAL TO BEREMOVED

15 75

-1 RANGE 42.5'SOUTH OFC.L. TRENCH

55-

61,

70 -

Chart of a pipe -laying operation as tracedby a recording echo sounder.

with a diode detector that applies anegative voltage to V5's grid.

The output tube plate is groundedand its cathode connected to the -375 -volt line through a 40,000 -ohm resistor.The tube is used as a variable resist-ance. To see how it acts to trigger theneon indicating lamp, see Fig. 2, asimplified diagram of the circuit.

V5 forms part of a voltage dividerthat applies current to the neon lamp.When V5' conducts, as during normaloperation (no pulse), it acts as a lowresistance and does not let enough cur-rent flow through R15 to fire the neonlamp. When the 1 -millisecond trans-mitted pulse from V1 reaches V5'sgrid, the tube is cut off and becomes avery high resistance. Now current flowsthrough the tube is at a minimum andenough current flows through R15 toflash the lamp. This is at the zero depthpoint. When the pulse ends, V5 con-ducts once again.

The entire circuit has quick recoveryso that, immediately after the pulse istransmitted, the system is ready forthe reception of echoes. Echoes strikingthe transducer are coupled into thereceiver by Tl, and amplified.

After the neon lamp flashes at thezero depth point, it continues aroundthe indicating scale. When the echo ispicked up and fed through the receiver,V5 is cut off once again and the neonlamp flashes-this time indicating thedistance to the bottom.

Any echo which falls outside theenvelope of the transmitted pulse shows

DREDGE D

TRENCH

LOCATION OF- NATURAL GAS

PIPE LINES TOBE INSTALLE DIN TRENCH

REQUIREDDEPTH OFTRENCH

Fig. 2-Partial simplified schematicshows neon triggering circuit.

as a flash of light, so depths from about1 foot down are registered.

InstallationIndicators should be located where

they can be easily viewed by the manat the helm. Instruments using flashing

Oscilloscope indi-cator made byEdo.

RADIO

lights should be placed in an areawhere direct sunlight will not fall onthe dial, if possible. An external powersupply can be mounted in a lockerbelow or in the engine compartment.Keep equipment as far from the com-pass as conditions permit, and makesure at the time of installation thatputting the equipment in place doesnot swing the compass off.

Transducers are most easily installedwhen the boat is hauled out or laid upfor off-season storage. For this reason,it is a good idea to sell the owner onthe idea of an installation in the winter,so the underwater parts can be in-stalled during layup. Some agenciessell the transducer in the winter, theremainder being purchased later. Thishas the further advantage to the cus-tomer of spreading out payments, andit also provides winter work for tech-nicians.

Transducer installation ranges frommounting a clip on the hull, for portableor "flashlight" types, to boring one ormore holes in the bottom, and fittingand sealing on fairing blocks forstreamlining.

Techniques have even been workedout for installing the transducer onthe bottom of the boat while it is in thewater. This involves boring a hole inthe bottom and sending a "leader" floatthrough the hole and up to the surfaceof the water outside. Then the trans-ducer cable is attached to the leader,and the unit is pulled down outside thehull. Next, the mounting bolt is pulledup into the hole, and the fastening nutsare installed. A little water comes intothe boat in the process, but hardlyenough to get your feet wet, and cer-tainly not enough to be dangerous.

The transducer should be mountedso the sending face points exactlystraight down. A position amidships isgenerally best, since the forward partof many fast boats is often out of thewater, or at least picking up quantitiesof air which boil along the bottom fora considerable distance and would blockoff transmission and reception of sig-nals. In the stern, engine and propeller

APRIL. 1959 47

RADIO

vibration and noise create interferencethat might obliterate the sounding sig-nals. Another consideration is to makesure that the transducer is not locatedwhere it might be damaged by thecradle when the boat is being hauled.The face of the transducer should notbe painted.

Wiring should conform to manufac-turer's instructions. Also, it is a goodidea to get acquainted with the recom-mendations of the National Fire Pro-tection Association. Standards for smallcraft are set forth in their publicationNo. 302, available for 50 cents fromtheir office at 60 Batterymarch St.,Boston 10, Mass. Be particularly care-ful that battery connections are notreversed from the specifications.

ServiceAs in other mobile electronic equip-

ment, vibrators and tubes should bechecked in case of trouble-and remem-ber the neon bulb. Also, the motorshould be inspected and lubricatedperiodically and slip rings, brushes andcontactors must be kept scrupulouslyclean. Intermittent or jumpy indica-tions are usually caused by a dirtycontactor or slip rings. An oscilloscopeis very handy for servicing by signaltracing, but in its absence trouble canbe corrected by the well known proce-dure of cleaning and tightening con-nections, checking voltages and resist-ances, and exercising a little commonsense.

One of the peculiarities of marineelectronic equipment is that it suffersmore from lying idle than from beingused. Gear which is operated dailykeeps dry. The controls and othervulnerable points are kept clear ofcorrosion. Capacitors stay formed andthe owner becomes familiar with properoperation. Always stress the point thatthe equipment is aboard to be used, andactually benefits thereby. If the owneroperates the equipment every time heis aboard his boat, service will probablyamount to nothing more than a routineyearly check up. END

(14'1' ,3

"Ok! Ok! Don't burn it to a crisp thistime!"

RADIO TELEGRAPHY in 1866Like Columbus, Marconi wasn't first

By DARRELL L. GEIGER

YEARSbefore Marconi was even born,

a now forgotten Washington, D. C.,dentist, Mahlon Loomis, was communi-cating by wireless telegraphy for dis-tances of at least 14 miles. Thus, wire-less communication, far from being new,is nearly as old as most other practicaluses of electricity. The electric lampwas not invented until 1878, long afterLoomis' successful experiments.

Dr. Loomis called his system "aerialtelegraphy," and his first public demon-stration was made in 1866 between twopeaks of the Blue Ridge mountains ofVirginia. A kite was sent up from eachsite, each with a small piece of finecopper -wire gauze attached to its under-side. Metallic kite strings, 600 feetlong, the ground ends submerged inwater, conducted the signals to earth.Galvanometers were used to indicatesignal reception.

In his later patent application hestates that he dispenses with all "arti-ficial" batteries, using the "natural" or

- /4.VI

Dr. Mahlon Loomis.

Wall Street crash and later by theChicago Fire.' Dr. Loomis died shortlyafter, without realizing his ambitions.

Loomis was led to his experiments bynoting that in wire telegraphy, theearth (charged, it was then supposed,with negative electricity) could be madeto serve as one conductor. Why then

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...A. -J.2\:.

"free" electricity of the atmosphere forpower "Upon these mountain tops Ierect suitable towers and apparatus toattract the electricity-or in otherwords to disturb the electrical equi-librum-and thus obtain a current ofelectricity, or shocks, or pulsationswhich traverse or disturb the positiveelectrical body above and between thetwo given points. . . ."

Loomis states that reception wasperfect during the cloudy part of theday, "as exact and distinct as any thatever traveled over metallic conductors."The distance was 14 to 18 miles. In 1896,thirty years later, Marconi had suc-ceeded in signaling barely more than 1mile. Loomis was granted patent No.129,971, entitled "Improvement in Tele-graphing," on his invention in 1872, twoyears before Marconi was born!

After receiving his patent Loomis,as had Morse before him, appealed toCongress for funds. But Congress didnot have the imagination to cope withan idea this revolutionary. Funds wererefused and two companies formed toback him were wiped out, first by a

Sketch of Loomis'transmitting andreceiving setup.(Reproductionfrom Loomis'sketch, 1865.Original drawingnow in archivesof Library of Con-gress, Washing-ton, D. C.)

could not the upper atmosphere, alsoabundant with electricity, be used asthe other conductor, thus doing awaywith all wires?

By making contact with the atmos-pheric stratum of electricity throughtowers built on high mountains, Loomisvisualized world-wide communication.The atmospheric electricity, which heconsidered as positively charged, wouldwith the negative electricity of theground furnish all needed power.

Should Loomis rather than Marconibe acclaimed the inventor of radio?Probably not. For one thing he did notknow that his method of communicationwas by radio waves. Loomis' patentspecifications show that he himself con-sidered his method to be similar to thatused with wire telegraphy. But asprimitive as his ideas seem to us now,they were advanced for their time. HadLoomis lived, who knows how he wouldhave influenced the early developmentof radio? END

1 Mary Texanna Loomis, Radio Theory and Oper-ating, Loomis Publishing Co., Washington, D. C.,1925.


RADIO

Want something for nothing ?Try a free -power one -tran-sistor radio receiver thatdoesn't need a battery

By DR. WILLIAM H. GRACE

IF you live within 10 miles or so ofa broadcasting transmitter, this cir-cuit is a way to get something fornothing. The field created by the

nearby transmitter can supply thepower you need to operate a 1 -tran-sistor receiver. Circuits of this typehave appeared before (see "TransistorRadio Uses No Power Supply," RADIO -ELECTRONICS, April, 1955, and "FreePower Receiver," RADIO -ELECTRONICS,April, 1957). But the one describedhere has a few unusual features.

Some models consist of two receiversincluding separate antennas. In thisunit (see Fig. 1) only one antenna isneeded and the detector, amplifier andpower supply are connected by onlyone lead to the rf or tuned section.No ground return is used as it is notneeded. At first glance the circuit mayappear unworkable, but it does work,and very efficiently at that.

Check for powerBefore building any free -power re-

ceiver you should determine if yourlocation, plus a suitable antenna sys-tem, will deliver enough power to oper-ate the amplifier. There are at leasttwo ways to do this. Dr. H. E. Holl-mann, in his April, 1957, article "FreePower Receivers," suggests a formulafor the purpose. It is a simple, work-able method by which the transmitter'spower, the effective length of thereceiving antenna and the distance ofthe receiver from the transmitter arecorrelated mathematically to give thepower available in microwatts.

There is one important factor Dr.Hollmann did not include in his for-mula that affects the strength of a

EXPERIMENTER'S

CARRIER -

POWER

EC ER

receiver's signal, and that is the heightof the receiving antenna. In practice,antenna height contributes as much asits effective length to signal strength,so place the receiving antenna as highas you can possibly get it.

The second way to determine theamount of available power is empir-

SEE TEXTANTCOIL

2N1062N1072NI30

( SEE NOTE)

CK705 \AMPL33 T IN34

\DET .1-1

66 T

C I -b

365mf

TRANSISTOR BASING

2N35,2N106 2N107

DI

PWCTRRE

D2

B Eo 0 o

2C4SEE TEXT

C3

250µµ1-.001

HI -2 PHONES

2NI30C B E0 0 o

\BASE RED DOT

CONNECTEDTO CASE

NOTE. 2N35 CAN BE USED IF DI, D2POLARITY IS REVERSED. IT ISAN NPN UNIT.

CI -2 -gang variable capacitor, 365 AO each sectionC2-0.1 to I µfC3-250 AO to .001 µfC4-(see text)

2-1N34, CK705L-antenna coil, 99 turns No. 22 or 24 dcc on 2 -inch

diameter form, tapped at 33 turnsV -2N35, 2N106, 2N107, 2N130High -impedance headphonesMiscellaneous hardware

Fig. 1-Circuit of the batteryless re-ceiver.

ical-erect the longest and highestsingle -wire antenna possible in yourlocation and connect it to the simplecrystal set shown in Fig. 2. The tunerand the two diodes are connected withclip leads as these components will beused in the receiver. Place a microam-meter across the diodes and, if you get areading of 500 iza or better, you shouldhave enough power for a batterylesstransistor radio. If you get a readingbetween 1 and 2 ma, you have enoughdc to operate an efficient speaker. Ofcourse, a good ground such as a water -pipe will contribute to the power re-ceived. Sometimes multiple ground con-nections to separate grounds produceeven greater current.

In making your tests, be certain youhave tuned in your strongest stationbecause this is the frequency you willuse later. In short, if you live withinreasonable distance of a strong trans-mitting station, have an antenna atleast 100 or 150 feet long and 35 to 45feet high, you should have no powershortage. I have seen antenna systemsonly 75 feet in length at an aver-age height of 35 feet that were capableof delivering better than 1 ma whenlocated in a favorable spot and I haveobtained nearly 3 ma, 17 miles northof a New York City station, at nightduring the winter season.

The receiver circuitWhile the few components required

are familiar to all radio men and needno description, the unconventional cir-cuit does require some discussion. Itsoperation is similar to that of thedouble -diode arrangement in the power -checking circuit of Fig. 2 with detector

APRIL, 1959 49

RADIO

L

CI

D2 t2 V

One possible parts layout for thecarrier -power receiver.

diode DI working in conjunction withthe emitter to the base element of thetransistor. Diode D2 is set up so therectified carrier dc is supplied to thecollector in the proper direction. Whilethe circuit appears freakish upon casualinspection, its operation is entirely con-ventional.

It may interest readers to know thatin the power -checking circuit, one ofthe diodes may be replaced with an rfchoke with equal efficiency. This lattertype of one -wire feed was used quiteoften in the circuitry of wavemeters inthe days of spark and is employed todayin the Miller hi-fi crystal tuner.

Of the several types of diodes tested,the 1N34 and CK705 were found suit-able, with perhaps a shade in favor ofCK705's. Various types of junctiontransistors were tried and some per-formed better than others. Among thosewhich seemed to produce the loudestand clearest signals were the Raytheon2N106, 2N130, G -E 2N107 andSylvania 2N35. The last is a n -p -ntype and, if used, the polarity of bothdiodes must be reversed. The circuitworks just as well with either type oftransistor if proper current directionis insured. The value of the base capac-itor is not critical and values from 0.1to 1 pf were suitable. A base -biasresistor did not add to the circuit'sefficiency. Try several diodes and tran-sistors, using the ones that performbest in your final circuit. Many inex-pensive types are suitable.

Almost any type of coil may be usedin the antenna circuit. A single -layercoil of 99 turns of No. 22 or 24 dccwire, tapped at the 33d turn allowed foradjusting the total inductance used, soI could adjust for the most favorableratio of L to C in the series -tuned cir-cuit. For best power response Cl shouldbe the largest value that will let thecircuit be resonant at a given fre-quency in respect to the value of L-more current is passed when the ratioof C to L is large. Naturally, a series -tuned tank is not the most selectivetype of tuning element, but selectivity

is not too important with this receiver.Because both the signal frequency andthe power or carrier frequency are thesame. A station has to be on frequencyfor the power circuit to function, hencethe amplifier works only when there issufficient power to activate it. Further-more, it is unlikely that any builderlives at a location where more thantwo or three local transmitting stationsfurnish enough power for signal over-lapping. So selectivity is sacrificed forsimplicity.

Some operating notesReceiver operation is exactly the

same as that of a simple crystal set-the one dial is moved to the point ofgreatest volume. With certain tran-sistors, a heterodynelike whistle may beheard just to the higher -frequency sideof the station resonant point on thedial. The whistle is caused by feedback,but does not interfere with receptionif the dial is turned a slight bit towardthe lower -frequency side. By adjusting

SEE TEXTANTCOIL

33 T

66 T

I -b

365µµf

0-1 MA

IN54,CK705

RFC

2.5MH

MAY REPLACE D2SEE TEXT

CI -2 -gang variable capacitor, 365 AO each sectionDI, 2-1N34, CK705L-antenna coil, 99 turns No. 22 or 24 dcc on 2 -inch

diameter form, tapped at 33 turnsM-meter, I maRFC -2.5 mh (optional, see text)Miscellaneous hardware

Fig. 2-To check available power usethis setup.

The author got enough output fromhis set to drive a speaker.

C4, a small tuning capacitor or medium-sized trimmer, the whistle can be elim-inated. The point of clearest receptionis easily noted, and once adjusted neednot be changed.

Another interesting point noted wasthat it does not seem to make much, ifany, difference how long a conductoris used to connect the tuning circuit tothe rest of the set. One experiment wasmade with the tuner proper left in oneroom while the rest of the unit wasplaced 40 feet away in another partof the house. There was no reduction involume.

If the receiver is operating correctly,its output is in the order of four toeight times that of a plain crystal set.Exact measurements cannot be givenbecause the volume always depends onthe actual power delivered by the an-tenna. In some places the volume levelis surprisingly strong-enough to drivea sensitive PM or an old magnetic typespeaker, should one be at hand. Signalsfrom a pair of headphones should beaudible 10 or 15 feet away. The whistleeffect will be absent and the qualityragged if power is borderline. A longerantenna will usually end this problem.

The percentage of modulation of thetransmitter can also affect receptionon a receiver of this type if the modula-tion is less than 100%, the quality ofthe receiver's output will be far betterthan otherwise. There must always bemore carrier power to the collectorthan voice signal.

The experimental receiver describedabove uses the same station to furnishboth the signal and power but some-what more advanced circuitry leads toa batteryless receiver which uses thecarrier frequency of a very strongtransmitting station to amplify thesignals from a low-level or weakerstation on another frequency. The re-ceiver described here serves as aninteresting introduction to the con-struction of more complicated receiversusing the free -power principle. And weall like to get something for nothing.

END


what'snew

EASE OF SERVICING is emphasized in thisnew 17 -inch TV which doubles as a portable andtable model. Housed completely in plastic, thechassis is exposed by removing eight screws (threeon each side, two on the top) and sliding the cabi-net off. The chassis may be completely removedby unscrewing two more screws, providing accessto the filter capacitors. Made by Sylvania, thismodel is called the Dualette.

MODULES FOR THE KIT BUILDERhave now appeared. This Kuight chassis (model 83Y 737 clock radio) uses two of them in its circuitry.The module terminals are pushed into predrilledholes in the printed -circuit board and soldered bythe constructor on the under side. All the smallfixed resistors and capacitors in the set are in themodules. The schematic supplied to the do-it-yourselffer is standard, with indications showing themodule terminals.

MAGNETIC DISC RECORDER combines discand tape techniques; records and plays back 70 secondsof material on each side of a 7 -inch disc at 331A, rpm.Recording grooves are premolded into the blank discwhich is said to have a life expectancy equal to or greaterthan tape. Recorded material on the discs may be easilyerased. The magnetic head (inset) consists of twoC -shaped pole pieces which protrude through the narrowslot (arrow). The recorder in the photo was designed byRCA for broadcasting use; plug-in pickups convert it forplaying of standard records or transcriptions. Anotherversion is designed for computer use. No unit for use inthe home has as yet been developed.

UNIQUE ANTENNA DESIGN using 33 end -fire arrays inparallel is a scale model of a 40 -foot telemetry antenna whichwill soon be built for operation at about 200 me by GB ElectronicsCorp., subsidiary of General Bronze Corp., Garden City, N. Y. Theantenna has a gain of 30 db, and is the equivalent of a 60 -ft. parab-oloid. Other versions of this design, called SVE (for "swept vol-ume efficiency"), replace parabolas in radar and scatter installations.Made of lightweight aluminum, they are far lighter and easier toship, install and maintain than conventional parabolic units.

TEL

110°

120*

50° 130°

400

30°

20°

10°

140°

MO°

160*

in*80°

0 OW -DIPOLE GAIN

HORIZONTAL RESPONSE OF SINGLE YAGI

Fig. 1-Polar diagram for a single 10-element Yagi.

N

008.0IPOLE GAIN

HORIZONTAL RESPONSE OF 4 -BAY HORIZONTAL STACK

Fig. 2-Horizontal polar diagram fora 4 -bay horizontally stacked array.

20°

130*

40°

50°

160°

70°

80°

the noise

in antennas

and lead-insNoise can be generated right in theantenna or lead-in-or in the con-nections. In fringe areas this addednoise may make the difference be-tween a usable picture and a snow-storm,

Fig. 3-These illustrations show hownoise from above or below can be re-jected by vertical stacking: a-verticalpattern of single 10 -element Yagiz b-vertical pattern of two 10 -element

Yagis.

VERTICAL RESPONSE OF SINGLE YAG1a

70°

50

EC° 0° 000110°

1300

140°

150'

1600

170°

80°

VERTICAL RESPONSE OF 2-8AY VERTICAL SACK

By The Engineering Staff,Scala Radio Co.

WE measure signal strength inmicrovolts. If the numberof microvolts is above a cer-tain minimum value, we

sometimes consider an antenna instal-lation to be satisfactory.

Such a simple measurement can bemisleading. What we really need toknow is how much the signal is abovethe noise level. For example, 500 /ivon a field -strength meter is usuallyconsidered good. But such a 500 -Ay sig-nal can be completely unsatisfactory ina very noisy area. On the other hand,a signal of only 150 ilv can be verygood if noise is low.

How antennas generate noiseNoise can be, and often is, generated

right in the antenna and lead-in system.Metallic antennas corrode when ex-posed to the weather. Oxidation onmetal surfaces adds resistance to thesystem and decreases antenna efficiency.

Oxidation is chiefly responsible forthe noise that develops as the antennaages. Here is what can happen: Thelead-in terminals usually consist ofzinc- or cadmium -plated steel bolts.They pass through holes punched ordrilled through the aluminum antennafeed element.

Lead-ins and connecting lugs areusually made of copper. These metalsfall at opposite ends of the galvanic


table. Moisture causes them to form abattery, oxidizing and corroding themetal.

Vibration varies the pressures on theoxidized surfaces. This makes thema changing resistance in series with thetransmission line. It changes the ter-minal impedance and causes the sig-nal at the receiver to vary.

Corrosion progresses more rapidly astime passes. Evenually, a point isreached where there is no effective con-nection between transmission line andantenna.

The same situation occurs at pointswhere antenna elements are spliced.Hence, we can reduce the inroads ofcorrosion by protecting connectionsfrom the weather. They should becovered with a good high -frequencyinsulating tape. You can also protecta joint with silicone jelly-Dow Corn-ing No. 5, or some equivalent product.

Corrosion problems are reduced byreplacing the cadmium- or zinc -platedscrews with stainless -steel or Monelscrews of the same size. Noise volt-ages generated by other joints, such asthe connection of the matching sectionto the driven elements, can also be pro-tected by tapes and plastics. The sameprecaution applies to joints at centerfolds, which are provided for easy as-sembly and shipping.

Polar diagram helps fight noiseWe can reduce noise further by

proper use of the antenna's radiationpattern (see "Dipoles and Yagis,"November, 1958).

For example, Fig. 1 is the polar dia-gram for a single 10 -element Yagi (fora forward gain of 8 db over a dipole).Note that the sensitivity lessens con-siderably at the sides and rear.

In addition to a gain of 8 db, we havepickup rejection exceeding 12 db fromthe sides and rear of the array. Thesmaller lobe at the right would notbe present in free space. However, itshould be considered in most installa-tions, because of the disturbance ofthe antenna field by the supportingtower.

This means that much less noise ispicked up from the sides and rear. Ifnoise comes from the sides, it can be

Installation atEagle Mountain,Calif. The left bayis cut to channel7, right bay to

channel 9.

Courtesy JerroldElectronics Corp.

reduced even further by horizontalstacking. Fig. 2 shows this. Note theincreased rejection of pickup from thesides. We can increase this rejectionstill further, if we wish, by additionalhorizontal stacking.

If there is a noise source below (orabove) the antenna array, we can helpsolve this problem by vertical stacking,as shown in Fig. 3. Two prominent butminor vertical lobes to the left andright of the single Yagi (Fig. 3-a)(caused by side radiation of the drivenelement) can be reduced considerablyby using two vertically stacked anten-nas (Fig. 3-b). We can stack more thantwo arrays, to reduce these lobes stillfurther.

Stacking in both horizontal and ver-tical planes reduces noise from bothplanes. For example, in the Barstow,Calif., community system, the antennasare located on a tower on a hillside.The city of Barstow is immediately be-low. A main highway is on the right.After experimenting with variousmethods of stacking, four Yagis wereused for each channel, stacked bothhorizontally and vertically.

A community system in Guyman,Okla., on the other hand, had littletrouble from the sides. Most of thenoise was coming from below the an-tenna site. Hence, eight Yagis werestacked vertically for the troublesomechannel.

The photo shows the Eagle Moun-tain installation, located approximately

"I'm afraid that I'llhave to take it intothe .hop!"

TELEVISION

175 miles from Los Angeles TV trans-mitters. After careful probing to locatea constant signal level and maximumrejection of man-made noise from thetown 2,000 feet below, it was decided touse eight 10 -element Yagis for eachchannel. They were stacked two hori-zontally and four vertically.

Co -channel interferenceCo -channel interference is caused by

two TV stations operating on the samechannel. This is often a problem incommunity systems. In fringe areas,signals are received over long distances,because the antenna site is usually on avery high mountain or tower.

We recognize co -channel interferenceas a venetian -blind or windshield -wiperpattern in the picture. The windshield -wiper pattern results from interferingsync. and blanking pulses. Sometimes,sound is distorted by co -channel inter-ference.

The usual method of locating thesource of interference is to study a mapof the area. However, because of re-flections, conclusions drawn from a mapmay be incorrect. Direction of the in-terference can be determined by rotat-ing the antenna carefully, until maxi-mum unwanted signal is noted. Then,measure the angle between the wantedand unwanted signals. This angle, plusthe signal strength of the interference,gives the installation man the dataneeded to determine the required di-rectivity of the array.

A single -channel Yagi has 30° to 60°beam width to the half -power point.Horizontal stacking of the two Yagisreduces this figure to half, approxi-mately. If four Yagis are used, thefigure is further reduced.

Thus, the greater the number of an-tennas stacked in a horizontal plane,the greater is the directivity obtained.

Remember, vertical stacking affectsonly the vertical lobe. Horizontal stack-ing effects only the horizontal lobe.Hence, if you need directivity in bothplanes, stack antennas both verticallyand horizontally.

Following our discussion of noise re-jection, the next article will cover locat-ing the best antenna sites, shatteredwavefronts, impedance matching, an-tenna spacing and phasing for maxi-mum gain. END

APRIL, 1959 53

TELEVISION

Those odd -looking R -C net-

works in the TV set's hori-

zontal circuits aren't so

hard to understand

e R -C CIRCUITSBy CYRUS GLICKSTEIN*

EVERY so often, in servicing somesection of a TV receiver, I've comeacross a complex R -C circuitwhich made me scratch my head.

Complex (series -parallel) R -C circuitsdon't act like series R -C circuits. Theydon't even act like each other. Eachbasic type of complex R -C circuit actsin a different way.

The circuit in Fig. 1 is part of thephase -detector system of horizontalafc (automatic frequency control) foundin many TV sets. Afc keeps the hori-zontal oscillator at the correct fre-quency by changing out -of -phase syncpulses to a dc correction voltage whenthe oscillator starts to slip out of sync.Afc circuits must prevent noise pulsesfrom developing any control voltage inthe system, since that would cause aloss of sync. The systems must also pre-vent hunting.

Afc huntingToo much correction voltage devel-

oped at the instant the oscillator goesoff frequency causes hunting (movingrapidly above and below correct fre-quency). To prevent hunting, over -correction of the horizontal oscillatormust be avoided by building up thecorrection voltage gradually.

The general operation of horizontalafc circuits has been described manytimes. However, almost no informationhas previously appeared on exactly howanti -hunt action takes place. A largecorrection voltage is developed instan-taneously when circuit conditionschange, but the afc circuit is designedto allow only a small part of this tobe applied to the horizontal oscillatorat the first instant. As the horizontaloscillator starts to come back to fre-quency, less correction voltage is devel-oped. A point is finally reached wherejust enough correction voltage is gener-ated to keep the oscillator at the cor-rect frequency under the new circuitconditions. This full correction voltageis applied to the horizontal oscillator'sgrid.

Hunting is prevented by the smalltime lag between the instantaneousgeneration of the input correction volt -

*Author of Repairing Television Receivers(John F. Rider Publisher, Inc.).

age (across R3 or R4 in series withR2 in Fig. 1) and the comparativelyslow increase of de correction voltageapplied to the grid (across C2). If thefull correction voltage were appliedimmediately to the grid, the horizontaloscillator would shift frequency in theopposite direction, generating a correc-tion voltage of opposite polarity tocause another frequency shift in theoriginal direction, and so on. The oscil-lator would hunt above and below thecorrect frequency.

Therefore, the portion of the phase -detector circuit in Fig. 1 consisting ofR1, Cl, C2, R2 and R3-R4, has threefunctions:

1. It integrates out -of -phase syncpulses so that only the average correc-tion voltage is applied to the horizontaloscillator to bring it back to the correctfrequency.

2. It reduces the effect of noise pulsesand minimizes development of a controlvoltage by these pulses.

3. It prevents hunting.The R -C circuit has a long time con-

stant and the correction voltage is takenoff C2. It can therefore be consideredan integrating circuit. The de correctionvoltage is applied to one grid of thehorizontal oscillator. Positive correctionvoltages decrease the oscillator's fre-quency and negative pulses increase thefrequency.

A specific example will clarify thisaction. Assume the plate voltage of thehorizontal oscillator drops. When thisoccurs, the oscillator shifts to a lowerfrequency. The horizontal sawtooth, fedto the phase -detector diodes (V2), is

SYNC AMPL

VI

.001

13+

now out of phase with the incomingsync pulses. Negative pulses are devel-oped across R2 as a result. These pulsesare applied to the parallel combinationR1, Cl in series with C2 (see Fig. 1).During the initial charge period, seriescapacitors Cl and C2 act as a voltagedivider.

The capacitors charge through R3 orR4. This time, they charge through R3.The time it takes for them to chargedepends on the circuit's time constant.At the first instant, the capacitorsshort out R2. As more sync pulses comein they start to charge. The pulse volt-age divides across them in inverse ratioto their capacitance. That is, since C2 is10 times as large as Cl, C2 has approxi-mately 1/10 as much voltage or 1/11 ofthe applied voltage. The capacitorscharge through R3 but dischargeslightly through R2 and R1 betweenpulses.

As C2 charges, the oscillator starts toreturn toward its original frequencydue to the negative correction voltageon its grid. The sync pulses applied toR1, R2, Cl and C2 become smaller sincethe frequency is a little less off. Assmaller sync pulses are applied to Cland C2, the capacitors try to charge toa smaller voltage. They still continueto charge, since an integrating circuit isunable to charge instantly to the appliedvoltage because of its long time con-stant.

As C2 continues to charge, the oscil-lator's frequency continues to changetoward the original frequency. The out -of -phase sync pulses become smaller.C2 continues to charge more slowly as

FROM HORIZ OUTPUT CRT

V3 HORIZ CSC(MVO)

Fig. 1-Phase-detector R -C circuit. Arrows show chargepath for C2 when negative incoming pulses are developed.


TELEVISION

it is now closer to the maximum appliedvoltage. Also as C2 continues to charge,Cl reaches a maximum value and thendischarges, allowing C2 to charge fully.(This action is typical in this type ofcomplex R -C circuit and will be dis-cussed in greater detail later.)

Phase and frequency

A point is reached where equilibriumis established with C2 charged to themaximum amplitude of the sync pulsesand there is just enough correction volt-age at the oscillator's grid to give thecorrect oscillator frequency. The phaseof the picture is slightly different butthe frequency is correct.

The difference in phase causes aslight sideways displacement of the pic-ture. This displacement is unavoidableand necessary to keep generating a cor-rection voltage as long as the oscilla-tor's plate voltage remains low (Fig. 2).The same kind of corrective action oc-curs for any change in operating condi-tions of the horizontal oscillator cir-cuit.

Action of this circuit becomes clearby comparing it with several basic cir-cuits. If two capacitors are connected inseries across a battery, both charge in-stantly (Fig. 3). If a resistor is placedin series with the capacitors (Fig. 4),the action is a combination of a seriesR -C circuit and the instantaneous actiondescribed above. When the switch isclosed, the capacitors start to charge.The voltage across each capacitor riseswhile the voltage across the resistorfalls. Through the charge period, thevoltage across Cl plus the voltageacross C2 plus the voltage across RIadds up to the battery voltage. Whenthey are fully charged, the smaller ca-pacitor has the larger voltage across it.Voltages across the capacitors equal thesource voltage and there is no voltageacross the resistor.

In Fig. 5-a, a parallel R -C networkis in series with a capacitor. When theswitch is closed, the battery voltagedivides across the two capacitors. Inthis first instant R1 has no effect on theaction, but immediately thereafter Clstarts to discharge through R1 at a rate

POS SYNC PULSE

NEG SYNC PULSE

SAWTOOTH

POS SYNC PULSE

NEG SYNC PULSE

f.

SAWTOOTH

determined by the network's time con-stant. At the same time C2 continues tocharge through R1 until it charges tothe source voltage while C1 dischargesto zero (Fig. 5-b). Curves showing thevoltage change across each capacitorappear in Figs. 5-c and 5-d.

The basic R -C circuit correspondingto the one in thephase -detector circuitis shown in Fig. 6. It acts like a com-bination of the two preceding circuits,but not exactly like either.

When the switch is first closed, Cland C2 short out R1 and R2, placing thewhole battery voltage across R3. As thecapacitors charge, the voltage across R2rises. The voltage across R2 equals thevoltage across Cl plus the voltageacross C2. In the same way the voltageacross RI rises. Throughout the firstpart of the charge period, voltagesacross the capacitors are in inverseproportion to their capacitance. Also,during this period, voltage across R3decreases across R2 increases.

At the instant the increasing currentthrough R1 equals the decreasing cur-rent through C2, Cl stops charging andstarts to discharge through Rl. Thisoccurs because the total current keepsdropping as C2 continues to charge (C1is fully charged). Therefore, the voltageacross R1 must drop as the currentdrops. Cl cannot keep its full chargeand starts to discharge through Rl. C2charges while Cl discharges. The volt-age across R2 keeps increasing, the volt-age across R3 keeps decreasing. Thevoltage across R1 decreases as Cl dis-charges. As the voltage across R3started at battery potential and wentdown while the voltage across R2started at zero and went up, a point isreached where the voltages across theresistors are proportional to their re-sistance. At this instant C2 (charged tothe voltage across R2) stops charging.Cl is discharged and there is no voltageacross Rl. A steady current flowsthrough R2 and R3, and they act as avoltage divider.

In the circuit of Fig. 1, positive ornegative pulses of decreasing amplitudeare the source of voltage, rather than abattery. However, circuit action is es-sentially the same.

Fig. 2-a - Sawtooth voltagein phase with sync pulses;b-out of phase sawtoothvoltage results in negativecorrection voltage.

CI1

C2t

Fig. 3-Two capacitors in series with abattery act as a voltage divider.

120 V

CI T.05

C2± .1

141 >100K

Fig. 4-Series resistor slows down thecharge action of the capacitors.

1.11120V

aVOLTAGE

CI (+111.1

1200

80V

40V

CI =t RI 21

40.1

V

el .gT80V

TIMEC

X.1NSTANT SWITCH IS CLOSED

-4-

120Vy IT

ill S25

VOLTAGE

C2

120 V

40V

0

6

AweX --11.

dTIME

Fig. 5-Action of a parallel R -C networkin series with a second capacitor.

Fig. 6-Basic circuit corresponds to por-tion of Fig. 1 phase detector. Arrowsshow current paths during initial charg-ing period.

CONTROL TUBE7vk VI .051

.002 \HORIZ

10-180ppf

LOCK -IN/.-RANGE 8206

C11.2 C2"'.02 R3

T'RI I R2

404Wt.6.2K - 220 K

15014

50 K

HOWHOLD

68 K

120 K2.7 MEG

180 pp f

HCRI OSC

V2

1001

HORIZ 120 KLOCK

470 pp

8.214

L.

60oTO HORIZ

1HORIZ FREQ75K GRID

OUTPUT

40-370pp fHORIZ DRIVE

14+

Fig. 7-Pulse-width afcsystem, showing anti -hunt circuit (Cl-R1).

APRIL, 1959 55

TELEVISION

(ORIGINALLY120V)

CI

.1

+20 V

is re-established even though the changein operating conditions continues. Asbefore, there is a slight phase displace-

20 ment of the picture to maintain theC25 correction voltage.

INSTANTANEOUS ACTION

a

(ORIGINALLY I t120V)

CI 20V.1 20V C2

+T .5

SLOWER ACTION -DETERMINEDBY CRT'S TIME CONSTANT

Fig. 8-Circuit action when a chargedcapacitor is placed across an unchargedone.

The integrating action of this circuittends to make it less sensitive to noisepulses. Fast, random pulses have littleeffect in building up a charge on C2. R1has a double function in the anti -huntportion of the circuit (R1-C1). Firstit lets Cl discharge toward the end ofthe correction period, allowing C2 tobuild up to the full amplitude of thesource pulses. Second, it provides a depath from the horizontal oscillator'sgrid to ground through R2.

In this circuit, if C2's capacitance de-creases or Cl's increases, correctionvoltages may build up too fast andcause hunting.

Pulse -width circuit

Another common afc circuit is thepulse -width circuit (see Fig. 7). R1 -Cl in Vl's cathode circuit acts as theanti -hunt network. In this system, acomposite signal appears at Vl's gridat the end of every line. This signal con-sists of a trapezoidal (modified saw -tooth) signal with a sync pulse ridingon top. If the oscillator's frequencychanges, the sync pulse is displaced onthe composite signal, making the topeither narrower or wider. This makesthe control tube, normally cut off be-tween pulses, conduct for a longer orshorter interval when the signal comesin. This, in turn, develops a smaller orlarger average cathode voltage. Part ofthe positive cathode voltage is tappedoff by R2 and applied to V2's grid. Thistapped positive voltage bucks the nega-tive voltage at the oscillator's grid.This bucking voltage determines thepoint at which the oscillator fires, there-by controlling oscillator frequency.C1-R1 in Vl's cathode circuit pre-

vents hunting by not allowing full cor-rection voltage to be applied to the os-cillator's grid at the instant there is achange of frequency. As in the phase-detector system C1-R1 act so that thecorrection voltage at the grid builds upgradually. The circuit permits an equi-librium point to be reached after sev-eral cycles, when a slightly displacedsync pulse provides the required amountof corrective voltage for the oscillator'sgrid. The correct horizontal frequency

The exact action to the C1-R1 anti -hunt network can be understood by no-ting the action in the simplified circuitsof Fig. 8.

When a charged capacitor is placedacross an uncharged one (Fig. 8-a), itdischarges into the uncharged one andthe voltages across the two becomeequal. If both capacitors have the samecapacitance, the charged one loses halfits charge before the voltages becomeequal. If one capacitor is larger, C2 inFig. 8-a, it requires more electrons tocharge to same voltage as Cl. So Clwill discharge more than half its elec-trons before the voltages across the twocapacitors become equal.

Since Q = CE, E = Q/C. If two ca-pacitors of unequal C are to have thesame E, the smaller capacitor must havea smaller Q (quantity of electrons). Cloriginally had 120 volts. Cl is 0.1 laand C2, 0.5 if. To find the new voltageacross both capacitors remember thatC2, the uncharged capacitor, is fivetimes as large as Cl. Therefore it musthave five times as much charge for thecapacitors to have the same voltageacross them. When C2 is placed acrossCl, Cl discharges to 1/6 of its originalcharge or 20 volts. Five parts of theoriginal charge go to C2, one part re-mains in Cl. There are now 20 voltsacross both capacitors.

Add a resistor to Fig. 8-a as shownin Fig. 8-b. The charged capacitor isagain allowed to discharge into un-charged C2. The only effect of the re-sistor is to slow down the action.

Anti -hunt system

Fig. 9 shows the exact action of thepulse -width anti -hunt circuit. When theswitch is closed (Fig. 9-a), C2 instantlycharges to the battery voltage. Clcharges more slowly through R1 andcan charge to battery voltage only ifthe switch is kept closed for a periodof about 5 RC. (A capacitor charges to63% of the battery voltage in 1 RC andto 100% in about 5 RC, in a series R -Ccircuit.) If the switch is kept closedfor only a fraction of this time, C2charges to the full battery voltage butCl charges to only a small fraction ofthis voltage. When the switch is opened,C2 discharges into Cl through R1 (Fig.9-b). C2 also discharges through R2.However, R2 is a high -resistance pathcompared to Cl-R1. Most of the chargein C2 is discharged into Cl. Also, sinceCl is large compared to C2, C2 losesmost of its electrons and its voltage indischarging into Cl. C2 gains a smallvoltage. At the instant the voltagesacross the capacitors becomes equal,they both discharge through R2 (Fig.9-c).

The effect of placing C1-R1 acrossC2, while opening and closing theswitch, is to make C2 lose part of its

CI .1

C2 .01 R2

RI 5K

500K

1.:3K

500K

Fig. 9-Equivalent circuit illustratesaction of a series anti -hunt network(Cl-R1).

voltage each time the switch is opened.Without Cl-R1, C2 would immediatelycharge to the battery voltage and keepthis voltage at practically the samevalue during the intervals when theswitch is open. With C1-R1 in the cir-cuit C2 discharges into Cl at the instantthe switch is opened, but, as the switchis repeatedly closed and opened, theaverage voltage across the capacitorsbuilds up the battery voltage.

Hunting in the afc circuit of Fig. 7may be caused by anti -hunt capacitorCl opening or decreasing in value. Theanti -hunt circuit would naturally bechecked first for defects. However,other possibilities are: cathode capaci-tor C2 increasing, R2 increasing or R3decreasing in value.

The basic principle s used in analyzingthe anti -hunt circuits can be applied tomany other complex R -C circuits in TVreceivers. END

Transistor Lecture SeriesBeginning April 1 and continuing

for the next five Wednesday even-ings, the Boston Section of the In-stitute of Radio Engineers will spon-sor a series of practical, workshoptype transistor conferences. Eachwill be given by an expert in thefield of transistors. The whole ven-ture is supported by six leadingtransistor manufacturers.

The six -session series will be heldat Boston's John Hancock Hall, be-ginning at 7:30 pm. Cost of the wholecourse is $7 to IRE members andstudents, $10 to others. For furtherinformation, write to the BostonSection, IRE, 73 Tremont St., Boston8, Mass.


TELEVISION

pROBLEMS of ringing in the rasteror in the picture often are per-plexing at the service bench.Hence, we are giving this sub-

ject a once-over-lightly this month.First, we have to distinguish clearly

between raster ringing and picture ring-ing. Raster ringing (Fig. 1) is apparenteven when there is no picture. It showsup as a series of vertical gray bars atthe left side of the screen.

There are two sources of these barsin a raster:

1. The ringing voltage can be pickedup by the video input lead to thecathode-ray tube.

2. The ringing voltage can be gen-erated by transient oscillations inthe yoke circuit.

It is easy to distinguish between thesetypes of ringing. If you shunt a 0.1-µfcapacitor from the video signal lead tochassis, the first type disappears, butthe second type does not.

If you find that the bars disappearwhen the shunt capacitor is connectedin circuit, the remedy is to dress thevideo signal lead out of any field that

Fig. 1-Vertical bars caused by transientringing in horizontal yoke circuit.

(Foldover was a separate trouble.)might cause such bars. Ringing fieldsare strongest near the high -voltagecage.

On the other hand, if you find thatthe bars remain with the shunt capac-itor connected, the yoke circuit needsattention. As shown in Fig. 2, a fixedcapacitor or sometimes a resistor andcapacitor are needed across the "high"side of the horizontal yoke winding.

Values required vary considerably,but 56 Nif is typical for C. Sometimesthe value is rather critical. R is rela-tively low, and the best value can befound only by experiment.

Note that Fig. 1 also shows a verticalfoldover. The receiver had a weakvertical output tube, which was re-placed to correct this raster trouble.

If you inspect the ringing bars care-fully, you can distinguish between thetwo types of displays just described.When the ringing voltage is picked upby the video signal lead, the rasterlines remain straight but they changein intensity to give the appearance ofa bar.

On the other hand, when the barsare caused by transient ringing in theyoke circuit, the raster lines becomecurved or kinked, as shown in Fig. 3.

Ringing in the picture only is causedby sharp peaks in the response curve-

a" "V" Serv-ioe.4-A11111k - ,41111L-

--...

=_m.

.11111F 71111111111 27

conducted by

ROBERT G. MIDDLETONRADIO -ELECTRONICS TELEVISION CONSULTANT

either in the if or video amplifier. Theproper procedure is to use a good sweepand marker generator, with a scope, toalign the circuits for flat-topped re-sponse.

Distorted soundI have an Admiral 2024FFB with

distorted sound. It has a backgroundhiss which follows the sound, especiallyon loud peaks. Sometimes a cracklingnoise comes through. Any suggestions?-A. A., Chicago, Ill.

The trailing hiss in the audio ischaracteristic of regeneration. The bestapproach will be to sweep the 4.5 -meintercarrier circuits from the soundtakeoff point to the FM detector circuit.Regeneration will show up as a sharplypeaked response curve. By checkingthe circuit components systematically,

Fig. 2-Transient ringing can be cor-rected or minimized by shunting thehorizontal yoke winding with a capacitor

or capacitor and resistor in series.

you will be able to see from the scopepattern which fault has been corrected.

Conversion problemCan !Ina provide a diagram and list

of parts to change from a 16- to a 21 -inch picture tube in a Video ProductsK33130 receiver?-J. I., Fort Lee., N. J.

We have found in the past that thistype of conversion is difficult, but it isa job which can be done if cost is notthe primary factor. I would suggestthat you consider reworking the chassisin accordance with the circuit and partslist for the RCA 21-T-6115, as pub-lished in standard service data.

Fuse -blowing 6D96I would like some information about

fuse blowing and shorts in the 6DQ6in an RCA 21D8588. (I replaced it with

1

RASTERLINES

a 6BQ6.) Also, how can focus be ad-justed for a sharp and clear picture?-A. V. P., Troy, N. Y.

It would be advisable to check thevoltages at the 6DQ6 socket. Drive orscreen voltages may be too high. Thisreceiver uses an electrostatically fo-cused picture tube. The focus electroderequires different voltages for picturetubes with varying manufacturing tol-erances. Try adjusting this voltage fromzero to full B -plus, to find the bestfocus.

Drifting vertical holdThe vertical hold drifts in a Motorola

TS45 as the set warms up. A heat lamptest shows that the chassis is heat -sensitive. However, I cannot pinpointthis to a definite component. I will ap-preciate any help.-J. I. L., NiagaraFalls, N. Y.

You have made a good start with theheat lamp. The next step is to heatindividual components in the generaltrouble area to see which one is heat -sensitive. Use a soldering gun, andhold it close to each suspected com-ponent in turn. You will soon be ableto run down the faulty part.

Problem in a color setI hope you can help solve a problem

which has stumped local techs, includ-ing the factory service people. A CTC5color set has off -tolerance vertical lin-earity. The horizontal linearity also isnot too good. Scanning lines arebunched at the top, then spread forabout 3 inches, after which the rasterappears normal. To avoid a long listof tests and replacements, many partswere replaced in the sweep circuits,the PW board changed, and the chassistested in another cabinet to check theyoke and picture tube. This is not abreakdown, as it was delivered this

/RINGING KINKS

Fig. 3-A ringing yoke circuit shows upas kinks in the scanning lines.

APRIL, 1959 57

TELEVISION

way. Hope you can help.-R. D. P.,Marrero, La.

I have seen this type of difficulty inanother make of color set, as deliveredfrom the plant. This might be a leadwhich would apply. The trouble wascaused by filtering and decouplingcapacitances which were on the lowside. As a result, peak current drainswere affecting the operation of thevertical section noticeably. With capac-itances on the high side in the power -supply circuits, better regulation isobtained, as shown by scope tests.

Too much widthCould you give me a lead on how to

reduce the width on a Philo) 22C4014,code 131?-F. L. T., Fortville, Ind.

The simplest method is to slide asleeve of aluminum foil under the yoke.This has very little effect on height,but reduces the width of the picture.

No color syncll'e ho r ; it our shop a CBS Columbia

color receiver, model 205C1, whichgives good black -and -white reception.On color reception, however, the colorsare in red, green and blue horizontalbars across the screen. Can you give

seen similar cases in which loss of ca-pacitance in decoupling electrolyticscaused just this trouble. This is a goodjob for a scope. The vertical bar ismost likely caused by spurious ac volt-ages entering at one of the picture -tubeelectrodes. The scope will show wheth-er the dc supplies to the picture -tubeelectrodes are clean or not. Then, it is asimple matter to follow back throughthe faulty supply circuit, to find a faul-ty decoupling capacitor. There is alesser possibility that the sawtooth cur-rent waveform through the horizontalyoke windings is distorted, but your re-port does not seem to indicate scanningdistortion.

Horizontal nonlinearityWe have an Olympic 21KB24 in the

shop with considerable nonlinearity.The sweep is compressed on the leftand expanded on the right. Since thereis no linearity coil in the circuit, wewould like to get data on adding one toovercome this difficulty. - J. B., NewYork, N. Y.

Since the original circuit does notprovide for a linearity coil, it is quitepossible to get satisfactory linearity ifthe circuit components are within tol-

0-1LA.1

a -

cccc O 7-0

RED

GREEN

BLUE

WHITE BLACK

any clues as to where the trouble couldbe?-H. S., Leesburg, Ind.

This is loss of color sync. It wouldbe advisable to try new tubes in thecolor sync section first. Then try adjust-ing the color afc balance control forzero volts to ground, with burst pres-ent. ( See Figs. 4 and 5). If this doesnot snap the color into sync, the possi-bility of color sync circuit trouble mustbe investigated.

Bright, blurred vertical barA G -E 21C115 is giving us some

difficulty. The raster has a wide verti-cal bar which is both bright and blurred.The picture can be seen at the left- andright-hand sides, but appears at lowbrightness. The vertical hold controlhas been replaced. A suspected electro-lytic checked out OK on an ohmmetertest. We would appreciate any assist-ance.-F. L. A., Los Angeles, Calif.

You are probably on the right trackin checking out the electrolytics. I have

VTVM

Fig. 4-Loss of colorsync causes color pic-ture to split up intohorizontal strips of red,green and blue. Colorbar generator patternmakes fault obvious.

It

li

1(

REACTANCE

PHASE DET(2)

COLORAFC

1

Fig. 5-To adjust color afc balance con-trol, tune in a color signal. Connect avtvm where indicated. Adjust control

for zero volts.

erance. Instead of changing the origi-nal design, it would be advisable tolocate the faulty component. First checkthe sweep -circuit capacitors for correctvalues. If this does not turn up thefault, check the horizontal oscillatorplate voltage. This should be close to240 volts. Low plate voltage will causea nonlinear sweep.

Faulty test instruments?We , f een tly added a popular sweep

and marker generator and a scope toour shop equipment. Failing to gettrue displays of curves, we returnedthe generator to the factory for acheckup, but we are having difficultyand are taking alignment jobs to an-other shop. Do you consider the populartype of alignment equipment adequate?-W. S., Saco, Me.

Our experience has been that inad-equate sweep and marker generatorsdisappeared from the market a numberof years ago. The equipment you men-tion should perform satisfactorily.Difficulties in making sweep -alignmenttests are to be expected, until theoperator has gained considerable ex-perience. Control settings are morenumerous than in simpler instruments,and one incorrect setting can throw thepattern completely off. After the oper-ator learns the ropes, such incorrectoperation is immediately recognized.Since you have access to a shop whichis doing sweep -alignment work, it mightbe possible to check your instrumentsagainst theirs on a chassis, and observethe control settings used by theiroperator.

Power -line interferenceI would like to eliminate interference

that seems to be coming from the powerlines. Three or four of my customers indifferent parts of town are having thesame trouble. It seems to be a 120 -cycleinterference, producing two dark barsabout 2 inches wide horizontally acrossthe screen. There is a loud buzz. Some-times the picture rolls and tears. Thelocal channel is unaffected.-J. K.,Toledo, Ohio

This report is indicative of diathermyinterference. It is quite possibly beingradiated from power lines about town.The interference is not noticeable onyour local channel because the highsignal strength gives a high age volt-age and suppresses the effect of theinterference voltage. The only possi-bility of eliminating the interferenceat the receiver is to use a directionalantenna. A better plan is to run downthe source of the interference andeliminate it. If you can establish thatthe interference is being radiated frompower lines, I am sure that your localutility company will offer you all pos-sible assistance in locating the sourceand eliminating the cause.Split picture

An Admiral 20A1 has an intermit-tent split picture. The horizontal lockcontrol does not correct the split pic-ture, but will cause a high-pitched


TELEVISION

squeal with a bright vertical line atright screen. The trouble occurs oncommercials or from outside interfer-ence. If the receiver is turned off, it willstart up again OK.-J. 0., Copiague,N. Y.

This is a squegging condition which isalmost certainly caused by poor de -coupling between circuits which includethe horizontal output system. This isa sneaky type of trouble, because usualde voltage checks do not turn it up.It can be easily found with a scope,which will show abnormally high acvoltages on de supply buses. Checkbypass and decoupling capacitors.

16-2 I -inch conversionI would like some advice on convert-

ing a Hyde Park 16CD from a 16DP4picture tube to a 21EP4.-B. P., NewYork, N. Y.

Some of these receivers used a 60°yoke on the 16DP4 glass tube. If thisreceiver has a 60° yoke, the 21EP4 canbe used with minor electrical changes.Width may be insufficient. If so, it canbe increased by any of the usual meth-ods, such as shunting a 20-30-µµf 6,000 -volt capacitor from the 6BG6-G plate tochassis. If the receiver does not havea 69' yoke, it will need to be supplied.

Horizontal jitterI em writing for your opinion on

hori:ontal jitter in a Regal 101. The

jitter does not affect the entire pictureat one time, but occurs at all points atirregular intervals. Only sections of thepicture jitter, and the raster is un-affected. All tubes and the horizontaloscillator coil have been replaced.C.tpacitors and resistors in the Synchro-lock section check out OK. I will appre-ciate any help you may offer.-J. C. K.,Manchester, N. H.

There is not a great deal to go onhere, but this report could describe theeffect of a small arc somewhere in theflyback or high -voltage circuits. Thisshould be investigated. Frequent inter-mittent breakdown in an electrolyticcapacitor could also be responsible. Thereport does not indicate that this pos-sibility has been eliminated.

Convert to intercarrier soundI have the problem of converting a

DuMont RA112 to intercarrier sound.Can. you help me?-J. S., Bronx, N. Y.

Disconnect the existing sound -takeofflead. Remove the second sound trap,located at the picture detector input.Take intercarrier (4.5-mc) sound fromthe plate of the second video amplifier.This can be done by using a 1-µlifcapacitor at this point. The sound ifsystem must be converted to 4.5 mc.I would suggest using a circuit similarto the Trav-Ler 517-82. The sound ifis driven from the 1-Ag couplingcapacitor. END

COVER FEATURE

RADIO IN YOUR BOATNow is the time to install new

marine radiotelephones or reinstallthe old ones on cabin type boats. Onopen outboards, the new type "out-board radiotelephone," which is de-signed for easy installation and re-moval, should be given its "start ofthe season" tune-up, since every ra-diotelephone should be tuned tomatch a specific boat's antenna andground system. The Kaar TR249shown on the cover fits onto a per-manently installed mounting platefrom which it can be quickly slippedoff and made more accessible fortune-up before being placed intoservice for the 1959 boating season.Tune-up includes frequency check,trimming and tube testing. Be surealso to read the interesting articleabout echo sounders in this issue.The color transparency was taken byJacques Saphier of Paramus, N. J.at Freeport on Long Island andshows Maurice Holland, veteran ma-rine radio service specialist doingthe tune-up with Lee Sands watch-ing.

COLOR -PROJECTION SYSTEMScolor TV projectors, both de-

veloped in Europe, have been demon-strated in the US by two pharmaceuticalfirms, which will use them for closed-circuit medical demonstrations andseminars. Both color systems set newrecords for brightness and screen size.

The Swiss -developed Eidophor sys-tem, long in preparation (RADIO -ELEC-TRONICS, October, 1946; October, 1952)was unveiled by Ciba Pharmaceutical

Products Inc. Unlike conventional TVprojection systems, it does not dependon a cathode-ray tube as the lightsource and therefore has vastly in-creased brightness: it can project abright color picture on a 12 x 16 -foottheatre screen.

Eidophor (a Greek word meaning"image bearer") works in this way:An electron beam bombards, and mod-ifies, the surface of 'a film of oil on aconcave mirror. Light from a xenonarc lamp passing through the resulting"wrinkles" in the oil film is projectedthrough a special grating onto thescreen. The field -sequential color sys-

Smith, Kline &French use threeprojector 'barrels'for their colorprojection system.

Eidophor systemdoes not use acathode-ray tubeas the lightsource.

tern is used. The Eidophor projector(left) is 5I/2 feet high, weighs 800pounds.

The other new color TV unit is the1,500 -pound Norelco projector built byPhilips of Eindhoven, Netherlands, andintroduced in this country by Smith,Kline & French Laboratories, Phila-delphia.

It uses the more conventional Schmidtoptical system, with three separateprojector "barrels"-one for each color.It projects a color TV picture of goodbrightness on a 9 x 12 -foot screen. Thestandard NTSC (broadcast) color sys-tem is used. END

APRIL, 1959 59

TELEVISION

Stall Glusin Se5sion....

Q -Please tell the court in your ownwords, Mr. Slowblow, your reasons

for refusing to pay the plaintiff $6allegedly due for one home -service call.

A.-Well, this man was out to myhouse about two weeks before and wassupposed to have fixed my TV, but hedidn't. In fact it played worse thanit did before, and I told him so. Rightaway I said this call should be free.

Q.-How did he respond?A.-Well, he fumbled around in a

book and finally came up claiming hisrecords showed it had been five monthssince he had been there, and whyhadn't I phoned him before if I wasdissatisfied ?

Q.-Why hadn't you?A.-I meant to, but just never got

around to it.Q.-Go on.A.-That seemed to make him mad.

Right away he began picking on mykids, asking would I please stop themfrom jumping on his tube caddy, hecalled it. Next he snatched some toolsaway from Junior, who was only look-ing at them. It he hadn't been so rough,he wouldn't have startled little Clevisand made him break the guy's mirror,like he did.

Q.-You said the plaintiff grew pro-gressively belligerent?

A.-Yes. When I told him I knewthere was nothing wrong with my TVexcept a small tube, he stopped doinganything for about a minute; just satthere glaring into the back of thecabinet, muttering. Sounded like hewas kind of swearing under his breath.He didn't even answer when I explainedhow I'd adjusted all the knobs andcontrols on the back so he wouldn'thave to waste any time fooling withthem.

Q.-It was at this juncture that theplaintiff took exception to your dog?

A.-Well, he seemed to be deadscared of Queenie, although I told himshe never bites. She just growls andsnarls and lunges like that wheneverstrangers are around. She acts likeshe was ready to eat you up, butactually there ain't a mean hair in allher 95 pounds.

Q.-You have charged that the plain-tiff appeared to be making alibis. Howwas that?

A.-He was trying to alibi, all right.You see, the trouble with my TV was

Dort

By H. A. HIGHSTONE

a short in the condenser or else a shortin a small tube. Also it wasn't throw-ing a very good picture; kind of smeary,which was the main trouble. This shortwould make the screen go squigglyabout every three or four hours, andsometimes it would go four or five dayswithout shorting. That was when thisman tried to tell me that intermittents,he said they were, generally had to betaken into the shop for repairs. Rightthen I said nobody was going to takemy TV to no shop. You know how itis; let one of these racketeers get holdof your set and he loads it up withdefective parts that break down againright away and bingo, he's got you onthe hook again.

Q.-By this time you say the plaintiffbecame so surly that your childrenbegan crying. Tell the Court whathappened.

A.-Not all the kids; just little Aspic.All she wanted was to have him waitand leave the set on channel 4 until theBugs Bunny cartoon was over, but thisman kept switching around from chan-nel to channel. Finally he batted littleAspic's hand away from the selectorknob so hard she started crying. She'sa very sensitive child, you know; herteacher says she's definitely "unusual."

All this got Queenie worked up ofcourse. I kept telling this man shedidn't mean a thing by snarling andshowing her teeth but he grabbed abig soldering iron out of his kit andacted like he was all set to knock herbrains out. The only way I got him todrop the iron was by dragging Queenieout and locking her in the kitchen.

Q.-Everything went from bad toworse quite rapidly thereafter?

A.-It sure did. I have a very goodbook, "How To Fix Your Own TV,"which tells everything. It starts inwith aerials, all about the differencebetween Comicals and Yogis and Ele-phant Ears, and ends up explainingexactly how to adjust your own irontrap. Very thorough. I could see thisman was getting nowhere fixing myTV-I don't think he knows his business-so I tried to help him by showinghim page 17, where it says when a setgoes squiggly, the thing to do is sticka screwdriver in the horizontal some-thing -or -other.

These TV guys are all alike. Theminute they find out you know some -

Case 441: Fly-back TV Servicevs. Slowblow,Praying Judg-ment in the Sumof $6

thing about your set, they get mean.Like that other TV gyp downtownwhere I took my tubes to be tested.Sold me four new ones and the setdidn't work a bit better, actuallyworked worse. Then got very meanand said absolutely no dice when I triedto insist on getting my money back.

Q.-Please confine your remarks tothe current case, Mr. Slowblow. Willyou proceed?

A.-The way it wound up was by thisFlyback TV guy insisting he had totake the set into his shop if he wasgoing to correct this intermittent, andalso to find out why the picture was sosmeary. When I said uh-uh, nobodywas taking my TV into no shop justbecause the condenser was shorted, hehad the nerve to try to collect $6 fora service call. Now he sues me for it!

Q.-You said earlier you subsequent-ly called a second TV repairman whosucceeded in correcting the trouble inyour home?

A.-Yes. And that goes to show howlittle this Flyback guy knows abouthis business. This second man wasmean too; didn't like Queenie and gothuffy when Aspic broke the lid on histube tester, but he fixed my set allright, after I all of a sudden remem-bered and told him how I had triedswapping tubes around in differentsockets, hoping that could cure thetrouble. It was something about a 6CB6and a 6AU6 changed around whichmade the picture smeary and here thisFlyback guy . . . Hey, what's he doing,jumping over that rail at me? Ow!Help! Murder! Get him offa me!Police! Judge! . . . END


AUDIO-HIGH FIDELITY

It's seldom the record that causes the skip-ping-groove jumping is nearly always thefault of the player. Here's a simple, proc-ess -of -elimination treatment for recordplaying's worst nuisance

SKIPSthe record

By CHARLES W. FARRINGTON

SELDOM considered as a subjectfor service, the skipping and stick-ing of records is already a hotproblem from the industry down

to the customer, and it's getting hotter.Those responsible for and those

affected by the problem bat the ball ofblame back and forth without producingany remedy. Included are record buyersand dealers, player dealers, distributorsand manufacturers.

The ability of the service technician,combined with his unbiased understand-ing of the situation, can provide theonly tangible relief presently availableto the frustrated victim of it all-thecustomer. The remedy can be effectivelyapplied only with clear comprehensionof the facts which pose the problem.

Ignored and unrecognized, a commonlaw of standards actually exists forrecords and playback equipment: Vir-tually all 33- and 45 -rpm records can betraced without trouble by the majorityof players.

The fact that one allergic recordplayer is unable to trace a particularpressing can never condemn that press-ing as "defective" so long as a majorityof representative players can trace it.One exception is the vastly superiorrecord, of wide dynamic range, coura-geously marketed by a few manufac-turers; these can be traced only bycomponents of high compliance.

The standard level of record manu-facture is necessarily held to a com-patibility with the class of parts usedin $19.95 super hi fi. To be marketable,any record run must meet these un-natural but exacting playback require-ments. As a result, records have a strictuniformity, limiting to be sure, butnevertheless adhering to high toleranceswhich are sadly missing in playbackapparatus. Therefore, players whichare unable to trace all ordinary recordsare subjects for service.

An awareness of such facts permitsa straightforward approach to the cureof skipping. One other help is an under-standing of the human attitudes in-volved.

For instance, the record dealer usu-ally placates the customer with anaffable exchange. This avoids argument

and explanation, but omits the genuinehelp of locating the real cause oftrouble. Player dealers receive fewercomplaints, and usually parry thosethey do with condemnation of records.A little investigation and enlightenedservicing could be profitable!

Until some miracle happens to pullinto sync the makers of players andthe makers of records, here is easy firstaid. Service technicians and set ownerswith superior do-it-yourself ability canbe sure of results by following a simpleformula.

Although many factors contribute toimproper groove tracing, checking allof them is seldom required except toinsure optimum preservation and per-formance of records; skipping usuallyis cured early in the process.

Testing the equipmentThe control in these tests is the cur-

rent production standard already de-scribed-Any record which can beplayed by a majority of equipment isnormal.

Test the record first, on equipmentin which:

1. The needle is perfect; either newor checked by microscope.

2. Cartridge compliance is consider-ably superior to that in the one thatskipped.

3. The arm is friction -free, nonreso-nant and nonautomatic (even to tripswitch).

4. Stylus pressure is well within therange recommended by the cartridgemanufacturer.

Examine under magnification the dullmarks left on the record at skip pointsif tracing is still imperfect (except forthe slight clicks to be expected at pointswhere the previous stylus skipped). Ifjagged or lateral, usually caused bymishandling, accidental needle drop orjarring the turntable, an identical rec-ord can be tried on the original player.If there's no skip, check and remedyeither handling and care of records orsusceptibility of the turntable to anykind of jarring.

Examine the needle with a micro-scope of at least 100 x power (Fig. 1).Any worn needle should be quickly re -

Fig. 1-Microphotograph of a wornneedle tip (top) compared with a goodone. Worn needles should be replaced

immediately.

placed, but the idea that worn needlesare a primary cause of skipping issubject to question. Some cases of skip-ping which are stopped by replacing theneedle may have had other contributingfactors. To check on this probability,the tests can be continued with the wornneedle. If some other remedy proveseffective, its benefit plus needle re-newal will provide a double gain towardrecord preservation.

Reject compromise needles. Quicksurgery is the remedy for a hot appen-dix, and for any compromise needle-cut it out! Replace with a microgroovepoint. If 78's are used, change thecartridge or give the customer twoneedles.

After each of the remaining tests,try the record again. If it can be tracedwithout skips, further procedure isoptional.

Level the turntable with a circularspirit level.

Measure stylus pressure, accurately,(Continued on page 74)

APRIL, 1959 61

do somany people buyATHKITS?

every year more peoplebuy Heathkits than any other

Electronic Instrumentsin kit form!

62

Here are a fewreasons why...EASY TO BUILDHeathkits are engineered for easy kit construc-tion. You need no electronic or kit building ex-perience whatsoever to successfully completeyour own kit. Use of printed circuit boards andpre -wired, pre -aligned assemblies cut construc-tion time. Manuals are carefully prepared, em-ploying step-by-step instructions written insimple, non -technical language. Large pictorialdiagrams and photographs show you exactlywhere each part goes.

LASTING QUALITYOnly top quality components go into Heathkits,assuring you of a finished product that is unsur-passed in performance, dependability and endur-ance. Rigid quality control standards are main-tained at the Heath factory to see that eachcomponent lives up to its advertised specifica-tions. Heathkits are conservatively rated. No per-formance claims are made that are not thoroughlyproven and tested under the most stringent labo-ratory conditions.

ADVANCED ENGINEERINGProgress in electronics engineering never standsstill at Heath. The latest developments in circuitdesign and components are exploited by Heathengineers, offering you superior performance -atlower costs. New advances in all fields of elec-tronics are carefully watched by Heath engineersto keep abreast of the rapidly growing industry.The modern, up-to-date styling of Heathkitsmake them a handsome addition to your homeor workshop.

WORLD-WIDE REPUTATIONA pioneer in do-it-yourself electronics, HeathCompany, over more than a decade, has estab-lished public confidence in its products both inthe United States and abroad. Today, as theworld's largest manufacturer of electronic kits,Heath stands as the leader in its field.

GREATER SAVINGSDo-it-yourself Heathkits save you up to 1/2 thecost of equivalent ready-made equipment. Directfactory -to -you selling, eliminating middle -manprofit, plus the tremendous Heath purchasingpower mean even further savings to you. And theconvenient Heath Time Payment Plan allows youto use and enjoy your Heathkit NOW, while youpay for it in easy Installments.

HEATH COMPANYBenton Harbor 20, Michigan

u), a subsidiary of DayProm, Inc.

RADIO -ELECTRONICS

TRANSISTOR PORTABLE RADIO KITFun for the whole family, this easy -to -build 6 -transistorportable radio is ready to go wherever you go. The modernmolded plastic case with pull-out carrying handle and fullyenclosed back add beauty and convenience to this splendidkit. Six name -brand (Texas Instrument) transistors are usedfor good sensitivity and selectivity. The 4" x 6" PM speakerwith heavy magnet provides "big set" tone quality. Use ofthis large speaker and roomy chassis make it unnecessary tocrowd components adding greatly to the ease of construc-tion. Transformers are prealigned making the radio readyfor use as soon as kit is assembled. A built-in rod -type an-tenna assures good reception in all locations. Six standardflashlight batteries are used for power, providing extremelylong battery life (between 500 and 1,000 hours) and theycan be purchased anywhere. Stylish cabinet is two-toneblue molded plastic with gold inlay and measures 9" L.x 7" H. x 33/4" D. Shpg. Wt. 6 lbs.

MODEL X R -1L : Identical to XR-1P except in handsomeleather case instead of plastic case. Leather carrying strapincluded. Shpg. Wt. 7 lbs.

LEATHER CASE: Can be purchased separately if de-sired. Fits all XR-1P and earlier XR-1 chassis. No. 93-1.Shpg. Wt. 3 lbs. $6.95.

NAVIGATE BYPORTABLE RADIO

HEATHKITMODEL DF-2

$69952 -BAND TRANSISTORPORTABLE RADIODIRECTION FINDER KIT

Enjoy the safety, convenience and .entertain-ment of this self-contained, self -powered,six -transistor superheterodyne radio direc-tion finder. it receives aeronautical and ma-rine beacons as well as standard band broad-casts with startlingly clear tone reproductionover a long range. Covering the beacon bandfrom 200 to 400 kc and broadcast band from540 to 1620 kc, the DF-2 is designed totake directional "fixes" on both aircraft andmarine beacons as well as standard broad-

cast stations, while providing the entertain-ment of a high quality transistor portableradio. You are able to receive aircraftweather reports every thirty minutes andconstant Coast Guard beacons on the 200 to400 kc band. A dial light is provided fornight operation. Power is supplied by sixstandard flashlight batteries which will lastyou up to one year under normal operation.Shpg. Wt. 9 lbs.

MODEL XR-1L $3495

MODEL PC -1

$2495

POWER CONVERTER KIT

Now you can operate your TV set, radio,razor, and other AC electrical equipmentdirectly from your 12 -volt boat or car bat-tery. With the Heathkit Power Converteryou can enjoy the convenience of homeelectricity whether boat cruising or onautomobile trips. Two power transistorsare employed for years of trouble -free, de-pendable service. No moving parts to wearout, no tubes to replace. Shpg. Wt. 8 lbs.

MODEL IA -1

$5995

ELECTRONIC IGNITION ANALYZERKIT

Ideal for use on automobiles, boats, air-craft engines, etc., the IA -1 checks ignitionsystems with the engine in operation (400to 5,000 RPM). Shows the condition ofcoil, condenser, points, plugs and ignitionwiring. Shows complete engine cycle or justone cylinder at a time. Two test leads aresupplied, each 10' long, which will enableyou to reach either the breaker points orthe spark plug wires. Shpg. Wt. 20 lbs.

MODEL TI -1

82595

ELECTRONIC TACHOMETER KIT

Useful on inboard and outboard boats, aswell as in automobiles, the TI -1 operatesdirectly from the spark impulse of the en-gine. Use on any spark ignited 2 or 4 cycleengine of any number of cylinders. Com-pletely transistorized, it works with 6, 8,12, 24 or 32 volt DC systems. Indicatesrevolutions -per -minute from 0 to 6,000.Calibration control provided for adjustingto engine type. Easy -to -build and easy -to -install. Shpg. Wt. 4 lbs.

APRIL, 1959 63

PROFESSIONAL OSCILLOSCOPE KITEverything you could possibly want in an oscilloscope is found in thenew Heathkit model OP -1. Featured are DC coupled amplifiers andalso DC coupled CR tube un-blanking. The triggered sweep circuitwill operate on either internal or external signals and may be eitherAC or DC coupled. The polarity of the triggering signal may also beselected, and any point on the waveform may be selected for the startof the sweep by using the "triggering level" control. An automaticposition is also provided, in which the sweep recurs at 50 cycle rate,but can be driven over a wide range of frequencies with no additionaladjustment. Prewired terminal boards are used for rapid, easy assem-bly of all critical circuits. Power supply is transformer operated utiliz-ing silicon diode rectifiers and is fused for protection. Handsomecabinet features silver anodized front panel with red and blacklettering and matching knobs. Shpg. Wt. 34 lbs.

VARIABLE VOLTAGEREGULATED POWERSUPPLY KITInvaluable in experimental anddesign work, the PS -4 eliminatesthe need for building up a sepa-rate power supply for each newcircuit tried. It provides a con-venient source of variable regu-lated B+, variable bias voltageand filament voltage for labs andwork shops. The PS -4 suppliesregulated B+ output continuouslyvariable from 0 to 400 volts DCat up to 100 ma, bias voltage vari-able from 0 to -100 volts DC at1 ma, and filament voltage of 6.3volts AC at 4 amps. Separatepanel meters continuously moni-tors voltage and current output.Rugged, top -rated componentsused throughout for long, reliableservice. Shpg. Wt. 16 lbs.

TEST OSCILLATOR KITProvides the test frequencies mostoften used by servicemen in re-pairing and aligning modernbroadcast receivers. Five fixed -tuned frequencies (262 kc, 455 kc,465 kc, 600 kc and 1400 kc) arequickly selected for troubleshoot-ing or alignment of the IF fre-quency and high and low end ofthe broadcast band for propertracking. Shpg. Wt. 4 lbs.

MODEL SG -8 $1950RF SIGNALGENERATOR KITA "must" for any beginning serv-iceman, this indispensable instru-ment is used for aligning tunedcircuits quickly and tracing signalsin faulty RF, IF and audio cir-cuits. Covers 160 kc to 110 mc onfundamentals in five bands andfrom 110 mc to 220 mc on cali-brated harmonics. Coils are pre -wound and calibrated. Completewith output cable and instruc-tions. Shpg. Wt. 8 lbs.

HEATH COMPANY [1.1bsidiary of Daystrom, Inc.

"EXTRA DUTY" 5"OSCILLOSCOPE KITLaboratory quality at utility scope pricemakes this instrument an unusual value.The Heath patented sweep circuit func-tions from 10 CPS to better than 500 kc infive steps, giving you five times the usualsweep obtained in other scopes. Verticalfrequency response extends from 3 CPSto 5 mc +1.5 db -5 db without extraswitching. An automatic sync circuit withself-limiting cathode follower providesexcellent linearity and lock -in character-istics. Extremely short retrace time andefficient blanking action are characteristicof this scope. Frequency response of thehorizontal amplifier is within t I db fromI CPS to4200 kc. Horizontal sensitivity is0.3 volts RMS-per-inch. Construction issimplified through the use of two etchedmetal circuit boards and precut, cabledwiring harness. Complete step-by-stepinstructions and large pictorial diagramsare supplied for easy assembly. An idealscope for all service applications as wellas in standard or color TV servicing.Shpg. Wt. 22 lbs.

MODEL AG -9A $3450AUDIO SIGNALGENERATOR KITThis unique generator uses threerotary switches to select twosignificant figures and a multi-plier to determine audio fre-quency, allowing return to theexact frequency previously mea-sured when making multiple fre-quency measurements. Covers10 CPS to 120 kc with less than.1 of 1% distortion between 20and 20,000 CPS. Shpg. Wt. 10lbs.

MODEL TS -4A $4950TV ALIGNMENTGENERATOR KITTV service technicians will ap-preciate the outstanding featuresfound in this sweep generator.Provides essential facilities foraligning FM, monochrome TVor color TV sets. The all -elec-tronic sweep circuit employs atrouble -free controllable induc-tor which varies frequency bymagnetic means. An unusualbuy at this low price. Shpg. Wt.16 lbs.

MODEL CD -1 $5995COLOR BAR ANDDOT GENERATORThe CD -1 combines the twobasic color servicing instru-ments, a color bar and white dotgenerator in one versatile andportable unit, which has crystalcontrolled accuracy and stabil-ity for steady lock -in patterns.(Requires no external syncleads.) Easy -to -build and easy -to -use. No other generator onthe market offers so many fea-tures at such a great price sav-ing. Shpg. Wt. 13 lbs.


ETCHED CIRCUIT VTVM KITTime proven for dependability, accuracy andoverall quality, the V7 -A is one of the wisestinvestments you can make for your electronicworkshop or lab. Its multitude of uses will makeit one of the most often used instruments inyour possession. Use it to measure all operatingvoltages and potentials such as B+ and AC -DC,or straight AC power supplies, filament voltage,bias voltage, AVC voltage, line voltage, etc.Ideal for measurements in all types of AM, FMand TV circuits. Checks discriminator or detec-tor operation, AVC or AGC performance,while the ohmmeter may be used to measurecircuit continuity, circuit resistance, to test outindividual components with resistance measure-ment, or to trace circuit wiring through cables orchassis openings. Front panel controls consistof rotary function switch and a rotary rangeselector switch, zero -adjust and ohms -adjustcontrols. Precision I% resistors are used in thevoltage divider circuit for high accuracy and anetched circuit board is employed for most of thecircuitry. The circuit board not only simplifiesassembly but permits levels of circuit stabilitynot possible with ordinary conventional wiringmethods. Shpg. Wt. 7 lbs.

TUBE CHECKER KITBrand new in every respect, the TC-3 features outstanding performance andease of operation. Sockets are provided for 4 -pin, 5 -pin, 6 -pin, 7 -pin, large,7 -pin miniature, 7 -pin sub -miniature, octal, 'octal, and 9 -pin miniature tubes.Protection against obsolescence is provided by a blank socket to facilitatemodification for checking newly added tube types. A 10 -lever switch makes itpossible to connect any element to any other element regardless of the pinnumbers involved. A neon bulb indicator shows filament circuit continuity andleakage or shorts between elements. A specially designed spring loaded rollchart mechanism permits the roll chart to run freely throughout its entire

length without binding.Thumb wheel drive knobs areprovided on both sides of thepanel to accommodate theleft handed operator. Com-pact and small in size, theTC-3 is ideally suited for port-able applications. Both theroll chart and the meter areilluminated to facilitate usein darkened areas. Shpg. Wt.12 lbs.

MODEL BE -5 $3995LOW RIPPLE BATTERYELIMINATOR KITCompletely up to date the BE -5will power all the newest tran-sistor circuits requiring 0 to 12volts DC, and the new hybridautomobile radios using bothtransistors and vacuum tubes.An extra low -ripple filter circuitis employed holding AC rippledown to less than .3%. Doublesas a battery charger or marineconverter. Shpg. Wt. 21 lbs.

MODEL T-4

$1 995VISUAL -AURALSIGNAL TRACER KITNew in every respect the T-4features a built-in speaker andelectron beam "eye" tube forsignal indication, and a uniquenoise locator circuit. Ideal foruse in AM, FM and TV circuitinvestigation. Transformer op-erated for safety and high effi-ciency. Complete with test leadsand informative constructionmanual. Shpg. Wt. 5 lbs.

HANDITESTER KITIdeal for use in portable appli-cations when making tests awayfrom the work bench or as an"extra" meter in the serviceshop. The combination functionrange switch simplifies opera-tion. Measures AC or DC volt-age from 0 to 10, 30, 300, 1,000and 5,000 volts. Direct currentranges are 0 to 10 ma and 0 to100 ma. Ohmmeter ranges are 0to 3,000 and 0 to 300,000. Topquality, precision componentsused throughout. Small andcompact, take it with you wher-ever you go. Very popular withhome experimenters and elec-tricians. Test leads and 11/2 voltsize C battery are included withthe kit. Shpg. Wt. 3 lbs.

20,000 OHMS/VOLTVOM KITPortable and accurate, this kitfeatures a 50 ua 41/2" meter and1 e'r, precision multiplier resis-tors for high accuracy. No ex-ternal power required. Providesa total of 25 meter ranges on atwo-color scale. Sensitivity is20,000 ohms -per -volt DC and5,000 ohms -per -volt AC. Mea-suring ranges are 0-1.5, 5, 50,150, 500, 1,500 and 5,000 voltsAC and DC. Measures directcurrent in ranges of 0-150 ua,15 ma, 150 ma, 500 ma and 15 a.Resistance multipliers are X I,X 100 and X 10,000. Covers-10 db to +65 db. Housed inan attractive bakelite case withplastic carrying handle. Bat-teries and test leads included.Shpg. Wt. 6 lbs.

MODEL AV -3

$2995

MODEL C-3 $1950CONDENSERCHECKER KITCheck unknown condenser andresistor values quickly and ac-curately as well as their oper-ating characteristics with thisfine instrument. All values areread directly on a calibratedscale. An electron beam "eye"tube indicates balance and leak-age. A valuable addition to anyservice shop or lab. Shpg. Wt.7 lbs.

AUDIO VTVM KITThis vacuum tube volt meteremphasizes stability, broad fre-quency response and sensitivityfor accurate measurement ofcritical AC voltages. Featuresa large 41/2" 200 ua meter withincreased damping in the metercircuit for stability in low fre-quency tests. Measures AC froma low value of 1 millivolt to amaximum of 300 volts AC(RMS). Voltage ranges are:0-.01, .03, .1-, .3, 1, 3, 10, 30, 100and 300 volts. Db ranges cover-52 to +52 db. 1% precisionmultiplier resistors used formaximum accuracy. Frequencyresponse is essentially flat from10 CPS to 200 kc. Shpg. Wt.6 lbs.

MODEL CT -1 $795IN -CIRCUITCAPACI-TESTER KITThis handy kit checks capaci-tors for "open" or "short" rightin the circuit. Detects open ca-pacitors from about 50 mmf,not shunted by an excessive lowresistance value. Checks shortedcapacitors up to 20 mfd (notshunted by less than 10 ohms).Checks all bypass, blocking andcoupling capacitors of the paper,mica or ceramic types. (Doesnot detect leakage nor checkelectrolytic condensers.) Elec-tron beam "eye" tube is usedfor quick indication. A 5 -posi-tion function switch is featuredwhich controls the power to theinstrument and selects the testbeing made. Easy to build andeasy to use. Test leads includedShpg. Wt. 5 lbs.

APRIL, I 9 5 9 65

Built-in cooling fan

Rotating Slide Rule Dial

Compact, Stable, VFO

Provision for SSB Adapter

$50.00 required on C.O.D. orders. Shipped motor freightunless otherwise specified.

HEATH COMPANYBenton Harbor 20, Michigan

a'sitbsidiary of Daystrom, Inc.

"APACHE" HAM TRANSMITTER KITThis beautifully styled transmitter has just about everything youcould ask for in transmitting facilities. The "Apache" is a highquality transmitter operating with a 150 watt phone input and180 watt CW input. In addition to CW and phone operation,built-in switch selected circuitry provides for single-sidebandtransmission through the use of a plug-in external adapter. Acompletely redesigned, compact and stable VFO provides lowdrift frequency control necessary for SSB transmission. A sliderule type illuminated rotating VFO dial with full gear drivevernier tuning provides ample bandspread and precise fre-quency settings. The bandswitch allows quick selection of theamateur bands on 80, 40, 20, 15 and 10 meters (11 m withcrystal control). This unit also has adjustable low-level speechclipping and a low distortion modulator stage employing twoof the new 6CA7 /EL34 tubes in push-pull class AB operation.Time sequence keying is provided for "chirpless" break-in CWoperation. The final amplifier is completely shielded for greaterTVI protection and transmitter stability. A formed one-piececabinet with convenient access hatch provides accessibility totubes and crystal socket. Die-cast aluminum knobs and frontpanel escutcheons add to the attractive styling of the trans-mitter. Pi network output coupling matches antenna impe-dances between 50 and 72 ohms. A "spotting" push button isprovided to allow tuning of the transmitter before switchingon the final amplifier. This feature also enables the operatorto "zero -beat" an incoming frequency without placing thetransmitter on the air. Equip your ham shack now for toptransmitting enjoyment with this outstanding unit. Shpg.Wt. 110 lbs.

SINGLE SIDEBAND ADAPTER KITDesigned as a compatible plug-inadapter for the model TX -I it can alsobe used with transmitters similar to theDX -100 or DX -100-B by making a fewsimple circuit modifications and still re-tain the normal AM and CW functions.Easy to operate and tune, the adapteremploys the phasing method for gener-ating a single sideband signal, allowingoperation entirely on fundamental fre-quencies. The critical audio phase shiftnetwork is supplied, completely pre -assembled and wired in a sealed plug-inunit. Features include single -knob band -switching for operation on 80, 40, 20,15 and 10 meters, an easy -to -read panelmeter, built-in electronic voice controlwith anti -trip circuit. Enjoy the advan-tages of SSB operation by adding thisfine kit to your, ham shack now. Shpg.Wt. 14 lbs.

MODELDX -100-B

$18950$50.00 deposit required onC.O.D. orders. Shipped mo-tor freight unless otherwisespecified.

DX -100-B PHONE & CW TRANSMITTER KITThe same fine performance of the time proven DX -I00 is retained in theDX -100-B with improvements in the crystal and loading circuits. The one-piece formed cabinet has convenient access hatch for changing crystals, etc.and the chassis is punched to accept sideband adapter modifications. Featuresa built-in VFO, modulator and power supply, complete shielding to minimizeTVI, and a pi network output coupling to match impedances from 50 to 72ohms. RF output is in excess of 100 watts on phone and 120 watts on CW.Covers 160 through 10 meters. Single -knob bandswitching and illuminatedVFO dial and meter face. RF output stage uses a pair of 6146 tubes in parallel,modulated by a pair of 1625's. Designed for easy assembly. Measures 1ln"H. x 191/2" W. x 16" D. Shpg. V.I. 107 lbs.

MODEL DX -40 $6495

DX -40 PHONE & CWTRANSMITTER KITOperates on 80, 40, 20, 15, 11and 10 meters, using a single6146 tube in the final for 75 wattplate power input CW, or 60watts phone. Single -knob band -switching, pi network output,complete shielding, provisionfor three crystals and VFO.D'Arsonval movement panelmeter. Shpg Wt. 25 lbs.

MODEL DX -20 $3595DX -20 CW TRANSMITTERKITThis fine unit covers 80, 40, 20,15, 11 and 10 meters with single -knob bandswitching. Featuresa 6DQ6A tube in the final for50 watt plate power input, pinetwork output, completeshielding to minimize TVI. Easyto build with complete instruc-tions supplied. Shpg. Wt. 19 lbs.


"MOHAWK" HAM RECEIVER KITDesigned for ham band operation and for maximum stabilityand accuracy, the Heathkit "Mohawk" receiver will let youenjoy ham activities to the utmost. This 15 -tube receiver fea-tures double conversion with IF's at 1682 kc and 50 kc andcovers all the amateur frequencies from 160 through 10 meterson seven bands. An extra band is calibrated to cover 6 and 2meters using a converter. The "Mohawk" is specially designedfor single-sideband reception with crystal controlled oscillatorsfor upper and lower sideband selection. A completely pre -assembled, wired and aligned front end coil /bandswitch as-sembly assures ease of construction and top performance.Many more important features are provided in this outstand-ing receiver for dependable and effective amateur communi-cations. Ruggedly constructed with well rated componentsthroughout. Shpg. Wt. 66 lbs. Matching accessory speaker kit;optional extra. Model AK -5. $9.95. Shpg. Wt. 8 lbs.

Prewired and AlignedCoil/Bandswitch Assembly

Crystal ControlledOscillators for

Drift -Free Reception

HEATHKITMODEL AR -3

(LESS CABINET)

ALL -BAND RECEIVER KITA fine receiver for the beginningham or short wave listener. Fre-quency coverage is from 550 kc to30 me in four bands. Features in-clude bandswitch, bandspread tun-ing, phone-standby-CW switch, an-tenna trimmer, noise limiter, RFand AF gain controls and head-phone jack. Easy to build. Shpg.Wt. 12 lbs.

"SENECA" VHF TRANSMITTER KITBrand new in every respect, the modelVHF -1 "Seneca" is the latest additionto our line of ham transmitters. Thisself-contained 6 and 2 meter transmitterfeatures built-in VFO, modulator, anddual power supply. A pair of 61,46 tubesare employed in the push-pull final am-plifier stage and features up to 120 wattsinput on phone and 140 watts input onCW in the 6 meter band. Slightly less inthe 2 meter band to prolong amplifiertube life. Panel controls allow VFO orcrystal control, phone or CW operationon both amateur bands. Four switch -selected crystal positions. Complete RFshielding to minimize TVI. Spottingpush-button provided. The VFO sliderule type dial features edge -lighting andvernier tuning. An ideal transmitter forthe ham who wants to extend operationinto the VHF region. Shpg. Wt. 56 lbs.

MODEL AM -2 $1595REFLECTED POWER

METER KITCheck the match of your an-tenna transmission system bymeasuring the forward and re-flected power or standing waveratio from 1:1 to 6:1. Handlesa peak power of well over 1 kilo-watt and may be left in antennafeed line. No external power re-quired. 160 through 6 meters.For 50 or 75 ohm lines. Shpg.Wt. 3 lbs.

MODEL B-1 $895BALUN COIL KITUnbalanced coax lines can bematched to balance lines ofeither 75 or 300 ohms by usingthis balun coil kit. Use withoutadjustment from 80 through 10meters at power up to 200 watts.May be located any distancefrom transmitter or antenna.Protective cover included. Shpg.Wt. 4 lbs.

MODELOF -1

$995

"Q" MULTIPLIER KITUse with any receiver with IF fre-quency between 450 and 460 kc toadd additional selectivity for sepa-rating two signals or to reject onesignal and eliminate heterodyne. Agreat help on crowded phone andCW bands. Not for use with AC -DCtype receivers. Simple to connectwith cable and plugs supplied. Shpg.Wt. 3 lbs.

MODELCA -1

$1395

"AUTOMATIC" CONELRADALARM KIT

This easy -to -build device gives in-stant warning and cuts AC power toyour transmitter when a monitoredstation goes "off -the -air". Use withany radio receiver having an AVCcircuit. A sensitivity control adjuststo various AVC levels. Incorporatesa heavy duty six -ampere relay andmanual "reset" button to reactivatethe transmitter. Complete instruc-tions provided for connection toreceiver. Shpg. Wt. 4 lbs.

MODEL VX-1 $2395ELECTRONIC VOICE

CONTROL KITThis unique device lets youswitch from receiver to trans-mitter merely by talking intoyour microphone. Provision ismade for receiver and speakerconnections and also for a 117volt antenna relay. Adjustableto all conditions by sensitivityand variable time delay controlsprovided. Shpg. Wt. 5 lbs.

MODEL VF -1 $1950VARIABLE FREQUENCY

OSCILLATOR KITFar below the cost of crystals to ob-tain the same frequency coveragethis VFO covers 160, 80, 40, 20, 15,11 and 10 meters with three basicoscillator frequencies. Better than10 volts RF output on fundamen-tals. Requires only 250 volts DC at15 to 20 ma, and 6.3 VAC at 0.45 a.Illuminated dial reads direct. Shpg.Wt. 7 lbs.

APRIL, 1959 67

Beautifully Styled With Plenty ofRoom For The Most Complete

Stereo System

MODEL SE -1 (center unit) $14995 Shpg. Wt. 162 lbs.

MODEL SC -1 speaker enclosure) $3995 each shpg.m.42 lbs.

CHAIRSIDE ENCLOSURE KITCombine all of your hi-fi equipment into one com-pact control center and, at the same time add a beau-tiful piece of furniture to your home. The CE -1 isdesigned to house AM and FM tuners (BC -1A andFM -3A) and the WA -P2 preamplifier along with themajority of record changers which will fit in the spaceprovided. Changer compartment measures 171/4" L.x 16" W. x 95/4" D. Adequate space is provided in therear of the unit to house any of the Heathkit ampli-fiers designed to operate with the WA -P2. Goodventilation is achieved through properly placed slotsin the bottom and back of the enclosure. Overalldimensions are 18" W. x 24"H x 351/2" D. All parts areprecut and predrilled for easy assembly. The Con-temporary cabinet is available in either mahogany orbirch, and the Traditional cabinet is available in ma-hogany suitable for the finish of your choice. Beauti-ful hardware supplied. Shpg. Wt. 46 lbs.

68

STEREO EQUIPMENT CABINET KITThis superbly styled cabinet ensemble is designed tohold your complete home stereo hi-fi system, con-sisting of a "stereo equipment ()enter" flanked bytwo individual "stereo wing speaker enclosures".The unit has room for all the components requiredfor stereo sound. Although designed to hold Heath -kit stereo components, it is not frozen to this ar-rangement. The kit is supplied with mounting panelsprecut to accommodate Heathkits, but interchange-able blank panels are also furnished so you canmount any equipment you may already have. Theprecut panels accommodate the Heathkit AM -FMtuner (PT -1), stereo preamplifier (SP -1 & 2), andrecord changer (RP -3). Record changer chassis pullsout easily for convenient loading and unloading.Adequate space is provided for record storage and apair of matching Heathkit power amplifiers (from 12to 70 watts). The stereo wing speaker enclosures areopen backed, cloth grilled cabinets designed to holdthe Heathkit SS -2 or similar speaker systems. Thecabinets are available in beautifully grained 1/4" solidcore Phillipine mahogany or select birch plywoodsuitable for the finish of your choice. The matchedgrain sliding tape deck access door on top pops -upflush when closed. Entire top features a shaped edge.Hardware and trim of brushed -brass and gold finish.Rich toned grille cloth is flecked in gold and black.No woodworking experience required. All parts pre-cut and predrilled for easy assembly. Maximumoverall dimensions (all 3 pieces): 821/4" W. x 361/2" H.x 20" D. Center Cabinet: 471/2" W. x 361/2" H.x 20" D.

HEATH COMPANY a bsidiary of Daystrom, Inc.

HIGH FIDELITYRECORD CHANGER KITEvery outstanding feature you could ask for in arecord changer is provided in the Heathkit RP -3, themost advanced changer on the market today. Theunique turntable pause during the change cycle saveswear and tear on your records by eliminating thegrinding action caused by records dropping on amoving turntable or disk. Record groove and styluswear are practically eliminated through proper weightdistribution and low pivot point friction of the tonearm. Clean mechanical simplicity and precision partsgive you turntable performance with the automaticconvenience of a record changer. Flutter and wow, amajor problem with automatic changers, is held toless than 0.18% RMS. An automatic speed selectorposition allows intermixing 331/3 and 45 RPM rec-ords regardless of their sequence. Four speeds pro-vided: 16, 33%, 45 and 78 RPM. Changer is suppliedcomplete with GE VR II cartridge with diamond LPand sapphire 78 stylus, changer base, stylus pressuregauge and 45 RPM spindle. Shpg. Wt. 19 lbs.

RADIO -ELECTRONICS

"BASIC RANGE" HI-FI SPEAKERSYSTEM KITThe popularity of this modestly priced speaker sys-tem attests to its high fidelity performance. The SS -2provides an ideal basic speaker for your home hi-fisystem. Flexibility of design allows it to be used as atable top model or as an attractive consolette withoptional legs. May also be used as a supplementaryspeaker in more advanced systems or as replacementspeaker for TV sets, etc. The specially designedtweeter horn rotates 90 degrees allowing you to usethe speaker in an upright position if desired, as in theHeathkit stereo wing speaker enclosures. Total fre-quency range is from 50 to 12,000 cycles -per -second.An 8" mid -range woofer covers from 50 to 1,600 CPSwhile a compression -type tweeter with flared horncovers 1,600 to 12,000 CPS. Both speakers are byJensen. A variable balance control allows level ad-justment of the high frequency speaker. Power ratingis 25 watts. Constructed of 1/2" veneer -surfaced ply-wood suitable for light or dark finish. All wood partsare precut and predrilled for simple, quick assembly.An added feature of the SS -2 is that, although anoutstanding performer in its own right, it may becombined with the SS -1B "range extending" speakersystem later to extend the frequency range at thehigh and low ends of the audio range. Build in justone evening for many years of listening enjoyment.Shpg. Wt. 26 lbs.

ATTRACTIVE BRASS TIP ACCESSORY LEGSconvert SS -2 into handsome consolette. 14" legsscrew into brackets provided. All hardware included.Shpg. Wt. 3 lbs. No. 91-26. $4.95.

Assemble it inJust One Evening

DIAMOND STYLUS HI-FIPICKUP CARTRIDGE

MODEL MF-1 $2685Replace your present pickup with the MF-1and enjoy the fullest fidelity your library ofLP's has to offer. Designed to Heath specifica-tions to offer you one of the finest cartridgesavailable today. Nominally flat response from20 to 20,000 CPS. Shpg. Wt. 1 lb.

ExtendedFrequency Range

for Your SS -2

"RANGE EXTENDING"HI-FI SPEAKERSYSTEM KIT

Designed exclusively for usewith the SS -2, the SS -1B em-ploys a 15" woofer and a supertweeter horn to extend therange of the SS -2 to an overallresponse of t5 db from 35 to16,000 CPS. When used to-gether the two units form anintegrated four -speaker sys-tem and are designed to com-bine into a single piece of at-tractive furniture. Impedanceof the SS -1B is 16 ohms andpower rating 35 watts. A con-trol is provided to limit theoutput of the super tweeter.Constructed of beautiful 3A"veneer -surfaced plywood suit-able for light or dark finish ofyour choice. All parts are pre-cut and predrilled for simpleassembly. No woodworkingexperience required. All hard-ware included. Shpg. Wt. 80lbs.

OPTIONAL LEGSNO. 91-26 $4.95

"LEGATO" HI-FI SPEAKERSYSTEM KITIt is difficult to describe in words the performance ofthis magnificent speaker system. You may never findabsolute perfection in reproduced sound, but theLegato comes as close to achieving it as anything yetdevised. Perfect balance, precise phasing, and ade-quate driver design combine to produce the superbquality of reproduction inherent in this instrument.The crisp, clear high frequencies and rich full bassengulf you in a sea of life -like tone. Two 15" AltecLansing low frequency drivers cover frequenciesfrom 25 to 500 CPS while a specially designed ex-ponential horn with high frequency driver covers 500to 20,000 CPS. The unique crossover network isbuilt-in making electronic crossovers unnecessary.The legato emphasizes simplicity of line and form toblend with modern or traditional furnishings. Con-structed of 3A" veneer -surfaced plywood in eitherAfrican mahogany or white birch suitable for lightor dark finishes of your choice. All parts are precutand predrilled for easy assembly. Shpg. Wt. 195 lbs.

APRIL, 1959 69

High Fidelity AM

and FM receptionin a Single Set

Professional Stereo -Monaural AM -FM Tuner KitEnjoy stereophonic broadcasts as well as outstanding individual AM and FM radioreception with this deluxe 16 -tube AM -FM -stereophonic tuner combination. Featuresinclude three etched circuit boards for high stability and ease of construction, prewiredand prealigned FM front end, built-in AM rod antenna, tuning meter, FM -AFC(automatic frequency control) with on -off switch, and flywheel tuning. A multiplex jackis also provided. AM and FM circuits are tuned individually making it ideal for stereoapplications since both AM and FM can be used at the same time. A switch selectedtuning meter functions on either AM or FM. Cathode follower outputs with individuallevel controls are provided for both AM and FM. Other features include variable AMbandwidth, 10 kc whistle filter, tuned-cascode FM front end, FM AGC and amplifiedAVC for AM. Anywhere from 1 to 4 limiters or IF's assure smooth, non -flutter recep-tion on weak or strong stations alike. The silicon diode power supply is conservativelyrated and is fuse -protected assuring long service life. Flywheel tuning combined withnew edge -lighted slide -rule dial provide effortless tuning. Use of three printed circuitboards greatly simplifies construction. Vinyl -clad steel cover is black with inlaid golddesign. Shpg. Wt. 20 lbs.

MODEL FM -3A

*2695HIGH FIDELITY FM TUNER KITThe Heathkit FM -3A Tuner will provide you withyears of inexpensive hi-fi enjoyment. Features broad -banded circuits for full fidelity and better than 10 uvsensitivity for 20 db of quieting. Covers the completeFM band from 88 to 108 mc. Stabilized, temperature -

compensated oscillator assures neglible drift afterinitial warmup. Employs a high gain cascode IF am-plifier and has AGC. Power supply is built-in. IF andratio transformers are prealigned as is the front endtuning unit. Two outputs provided, one fixed, onevariable, with extra stage of amplification. Shpg.Wt. 8 lbs.

MODEL W-6 $0995"HEAVY DUTY" 70 WATTHI Fl AMPLIFIER KITDesigned for "rugged duty" calledfor by advanced hi-fi systems andP.A. networks. Silicon diode rec-tifiers assure long life and heavyduty transformer provides excel-lent power supply regulation. Vari-able damping control providesoptimum performance with anyspeaker system. Quick change plugselects 4, 8 and 16 ohm or 70 voltoutput and the correct feedbackresistance. Shpg. Wt. 52 lbs.

MODEL W-5 $597625 WATT HI FlAMPLIFIER KITEnjoy the distortion -free high fi-delity sound from one of the mostoutstanding hi-fi amplifiers avail-able today. Features include aspecially designed Peerless outputtransformer and KT66 tubes. Fre-quency response is ±I db from 5to 160,000 CPS at I watt andwithin 2 db 20 to 20,000 CPS atfull 25 watts output. Hum andnoise are 99 db below 25 watts.Shpg. Wt. 31 lbs.

MODEL BC -1A

*2695HIGH FIDELITY AM TUNER KITThe BC -IA incorporates many features not usually ex-pected in an AM circuit particularly in this low pricerange. It features a special detector using crystal diodesand broad band -width IF circuits for low signal dis-tortion. Audio response is 1 db from 20 CPS to 9 kcwith 5 db of pre -emphasis at 10 kc to compensate forstation rolloff. Covers the complete broadcast bandfrom 550 to 1600 kc. Prealigned RF and IF coilseliminate the need for special alignment equipment.Incorporates AVC, two outputs, two antenna inputsand built-in power supply. Shpg. Wt. 9 lbs.

MODEL W-4AM $3975

SINGLE CHASSIS 20 WATTHI Fl AMPLIFIER KITA true Williamson -type high fidel-ity circuit, the W-4AM features5881 push-pull output tubes anda special Chicago -Standard out-put transformer to guarantee youfull fidelity at minimum cost. Har-monic distortion is 1.5% and IMdistortion is below 2.7% at full 20watt output. Hum and noise are95 db below full output. Taps for4, 8 or 16 ohm speakers. Shpg.Wt. 28 lbs.

iggMODEL W-3AM $4975

DUAL CHASSIS 20 WATTHI Fl AMPLIFIER KITAnother famous Williamson -typehigh fidelity circuit, the W-3AMfeatures the famous AcrosoundTO -300 "ultralinear" output trans-former and 5881 tubes. The powersupply and main amplifier are onseparate chassis for installationflexibility. Harmonic distortion isless than 1% and 1M distortion isless than 1.2% at 20 watts. Shpg.Wt. 29 lbs.


Monaural -Stereo Preamplifier Kit(2 -Channel Mixer)This unique kit allows you to purchase it in the monauralmodel if desired and then add the second or stereochannel later. The SP -2 features 12 separate inputs, sixon each channel, with input level controls. Six dual con-centric controls consist of: two 8 -position selectorswitches, two bass, two treble, two volume level and twoloudness controls, a scratch filter switch and a 4 -positionfunction switch. A separate on -off switch is provided.The function switch provides settings for stereo, 2 -channel mix, channel A or B for monaural use. Inputsconsist of tape, mike, mag phono and three high-levelinputs. NARTB equalization and RIAA, LP, 78 recordcompensation are provided. A remote balance controlis included. Printed circuit boards for easy assembly.Built-in power supply. Shpg. Wt. 15 lbs.

MODEL W -7M

$5495

MODEL

MODEL SP -1 (MONAURAL)

$3795 Shin. Wt. 13 lbs.

C -SP -1 (CONVERTS SP -1 TO SP -2)

$2195 5.t; Wt. 5 lbs.

"EXTRA PERFORMANCE" 55 WATTHI Fl AMPLIFIER KITEnjoy this high fidelity power amplifier at lessthan a dollar per watt. Full audio output andmaximum damping is conservatively rated at55 watts from 20 CPS to 20 kc with less than2% total harmonic distortion throughout theentire range. Features famous "bas-bal" cir-cuit, EL -34 output tubes and special 70 volt out-put. Shpg. Wt. 28 lbs.

MODEL A -9C $3550

GEN ERAL PURPOSE20 WATT AMPLIFIER KITDesigned for home installation aswell as for PA requirements, theA9 -C combines a preamplifier,main amplifier and power supplyall on one chassis. Four switch -selected inputs are provided aswell as separate bass and trebletone controls offering 15 db boostand cut. Detachable front plateallows for custom installation.Shpg. Wt. 23 lbs.

"UNIVERSAL" 12 WATT HI FlAMPLIFIER KITThe versatility and economy of this fine kitmake it a truly "universal" hi-fi amplifier. Anideal basic amplifier for any hi-fi system or aperfect addition to gear your present hi-fi sys-tem to stereo sound. Uses 6BQ5/EL84 push-pull output tubes for less than 2% harmonicdistortion throughout the entire audio range.Shpg. Wt. 13 lbs.

MODEL SW -1 $2495

SPEEDWIN DER KITA real timesaver, the SW -I leavesyour tape recorder free for opera-tion while rewinding tape at therate of 1200 feet in 40 seconds.Prevents unnecessary wear to thetape and recorder. Handles up to101/2" tape reels. Handles 800'reels of 8 and 16 millimeterfilm as well. Automatic shutoffprevents whipping at end of re-wind. Shpg. Wt. 12 lbs.

NO. 401-6

$750

"MASTER CONTROL"PREAMPLIFIER KITControl your hi-fi system withthis compact unit. Features 5switch -selected inputs to accom-modate a record changer, taperecorder, AM tuner, FM tuner,TV receiver, microphone, etc.,each with level control. Provisionalso for a tape recorder output.Equalization for records throughseparate turnover and rolloffswitches for LP, RIAA, AES andearly 78.s. Shpg. Wt. 7 lbs.

MODELX0-1

$1895ELECTRONICCROSSOVER KITThis unique instrument separateshigh and low frequencies and feedsthem through 2 amplifiers intoseparate speakers. Located aheadof the main amplifier, it virtuallyeliminates IM distortion andmatching problems. Note: Notfor use with Heathkit Legatospeaker system. Shpg. Wt. 6 lbs.

12" UTILITY SPEAKER KITReplace inferior speakers in radioor TV sets to obtain better tonequality or set up an auxiliaryspeaker for testing purposes withthis convenient, high qualityspeaker. The speaker will handleup to 12 watts with a frequencyresponse of ±5 db from 50 to9,000 CPS. Speaker impedance is8 ohms and has a 6.8 oz. magnet.An outstanding dollar value.Shpg. Wt. 7 lbs.

MODEL TK-1 $995

COMPLETE TOOL SETThese basic tools are all you needto build any Heathkit. The pliers,diagonal side cutters, 2 screw-drivers, and soldering iron are allof top quality case hardened steelfor hard duty and tong life. Pliersand side cutters are equipped withinsulated rubber handles forsafety. A good example of justhow easy Heathkit building reallyis. Shpg. Wt. 3 lbs.

APRIL. 1959 71

HIGH FIDELITY TAPERECORDER KITThe model TR-1A tape deck and preamplifiercombination provides all the facilities you needfor top quality monaural recording /playbackwith fast forward and rewind functions. 71/2 and33/4 IPS tape speeds are selected by changing beltdrive. Flutter and wow are held to less than 0.350;Frequency response at 71/2 IPS t2.0 db 50-10,000CPS. at 33% IPS X2.0 db 50-6,500 CPS. Bothunits may be mounted together or separatelyaffording high flexibility in every application.Features include NARTB playback equalization-separate recording and playback gain controls-cathode follower output and provision for mikeor line input. Signal-to-noise ratio is better than45 db below normal recording level with less thanlc,; total harmonic distortion. A filament balancecontrol allows adjustment for minimum humlevel. Complete instructions provided for easyassembly. Overall dimensions of tape deck andprcamp is 151/2" W. x 131/2" H. x 8" D. Shpg. Wt.24 lbs.

includes tape deck assembly,preamplifier and roll of tape.

HEATHKITT E-1

$3995Tape preamplifier sold separatelyif desired. Shpg. Wt. 10 lbs.

Many more Heathkits to choose fromhi-fi: Amplifiers-Preamplifiers-Speaker Systems-AM FM Tuners-Equip-

ment Cabinets-Record Player-Tape Recorder-Electronic Crossover-Stereo Equipment.

test: Oscilloscopes-Voltmeters- RF Signal Generators-AF Generators-Analyzers-Battery Eliminators-Tube Checkers-Condenser Checkers-Computer-Color Bar & Dot Generator-Sweep Generator-ImpedanceBridge-Power Supplies-Probe Kits-R C Decade & Substitution Kits.

ham radio: Transmitters-Receivers-Antenna Accessories-Voice Con-trol-Conelrad Alarm-Variable Frequency Oscillator-SSB Adapter-"Q" Multiplier.

marine: Direction Finders - Marine Converter - Rudder PositionIndicator-Fuel Vapor Detector-Charge Indicator-Power Meter.

general: Tool Set -6 -Transistor Portable Radio-Radiation Counter-Electronic Timer-Crystal Receiver-Superheterodyne Receiver.

e.tothst fin, describing over 100 easy -to -buildelectronic instruments in kit form. Complete specifications and detailed informa-tion on Hi-Fi-Test-Ham and Marine kits.

Save with Heathkits...the quality name in kitform electronics.


"BOOKSHELF" 12 WATTAMPLIFIER KITHere are a few of the reasons why this attractiveamplifier is such a tremendous dollar value. Youget rich, full range, high fidelity sound reproductionwith low distortion and noise . . plus "modernstyling". The many features include full range fre-quency response 20 to 20,000 CPS t 1 db with lessthan 2% distortion over this range at full 12 wattoutput-its own built-in preamplifier with provisionfor three separate inputs: mag phono, crystal phono,and tuner-RIAA equalization-separate bass andtreble tone controls-special hum control-and it'seasy -to -build. Complete instructions and pictorialdiagrams show where ever part goes. Cabinet shellhas smooth leather texture in black with inlaid golddesign. Cabinet measures 121/2" W. x D. x 43/8"H. Output transformer has taps at 4, 8 and 16 ohmsto match the speaker of your choice. An ideal unitto convert your present hi-fi system to stereo sound.Shpg. Wt. 15 lbs.

NOTE: all prices and speci-fications subject to changewithout notice.

Enclosed find f 1 checkI money order. Please

ship C.O.D. l 1

On Express orders do notinclude transportationcharges-they will be col-lected by the express agencyat time of delivery.

On Parcel Post Orders in-clude postage for weightshown. All prices are NETF.O.B. Benton Harbor,Michigan, and apply toContinental U.S. and Pos-sessions only. 20% Depositrequired on all C.O.D.orders.

An Amplifier, Preamplifierall in one!

Order direct by mail...Save 1/2 or more over equivalentready-made products by buyingdirect and assembling them your-self. Heathkit Style, Performanceand Quality are unsurpassed!

the World's Largest Manufacturerof Electronic Instruments in Kit Form

HEATH COMPANY BENTON HARBOR 20, MICH.I a subsidiary of Daystrom, Inc.

Name

Address

City & Zone

QUANTITY

,LEASE PRINT)

ITEM

SHIP VIA

Parcel PostExpress

Freight Best Way

MODEL NO. PRICE

E SEND FREE HEATHKIT CATALOGPOSTAGE

TOTAL

HEATHKITS are also available at your Dealer soenenies:lpgage

APRIL, 1959 73

AUDIO -HIGH FIDELITY

Fig. 2-Two types of stylus pressure gauges. Direct -measurement type (left):pickup arm is rested near fulcrum of spring -steel strip and pressure read directlyon scale. Balance type (right) : arm is rested on protruding platform, indicator

is pushed downward with finger until pointer is centered in oval window.(Continued from page 61)

with a reliable gauge (Fig. 2). Adjustit to within the limits specified by thecartridge manufacturer, neither morenor less. Make sure that no lead wiresproject below the arm to touch therecord.

Check vertical alignment of stylus.Tilted pickup arms, improperly seatedcartridges and bent stylus wires arecommon troublemakers that all toooften go unobserved and uncorrected.Jr the turntable pad can be removed,do so. Make a stack of seven 25 -centpieces on the turntable, raise the armand push the stack under the front ofarm so that the needle may be placedon the back edge of the top quarter(Fig. 3-a). Set the long edge of amachinist's scale (% x 6 inches) onthe turntable, facing front, and checkthe cartridge Correctany deviation from parallel to the topedge of the scale.

Next, determine whether the verticalaxis of the needle is at 90° to the turn-table (Fig. 3-b). Use a strong frontlight or a forehead reflector, and mag-nification (a thread -count glass is best;its folding frame acts as a stand). Withthe scale held as before, use its end asa square to check alignment of the

PICKUP ARM CARTR DOE

SHOULD BEPARALLEL {

TURNTABLE

7 QUARTERS

a

END OF SCALE

Fig. 3-Checking vertical alignmentand tilt of stylus.

STYLUS

1/2"STEELRULE

DOTTED LINESHOWS RIGHTANGLE OF STYLUSB TOP OF STEELRULE

12 RECORDS ARM IN HORIZONTAL

11 j POSITION

I RECORD6 RECORDS

Fig. 4-Proper position for a cartridgeis parallel to the record surface, as inprofessional type arms. Automaticchanger arms can be parallel at onlyone point of the automatic load (inthis case six records). Refer to manu-facturer's recommended setting for each

model.needle. Correct any deviation, prefer-ably with a new stylus. If bending isattempted, use needle -nose pliers, nottweezers, and grip only the stylus wire,not the needle point.

Check level of arm. Replace the turn-table on a record. Profes-sional type arms usually parallel therecord surface. Automatic arms arecustomarily parallel when half theautomatic load is on the table (Fig. 4),but, because of considerable variationwith different makes, manufacturers'recommendations should be consultedfor correct adjustment.

Check for tracking error. For propertracking, the lateral or modulation mo-tion of the stylus must be directlyacross each groove, at a right angle tothe groove, Therefore, the stylus andthe cartridge should align with thegroove at every playing position (wherethe stylus is offset in the cartridge, onlythe stylus aligns). With pivot -mountedarms, this ideal can be only approxi-mated.

To determine stylus -angle error, asimple template is useful (Fig. 5). Cuta 13 -inch circle from light cardboardand draw a radial line. Measuring fromexact center, mark points on the lineat 2, 2%, 41/4 and 5% inches. Thesepoints will be referred to as needlepositions. At each needle position, aligna protractor with the radial line, thereference point at the needle position.Mark dots at 88°, 90° and 92°. Drawheavy black lines at 90° 2% inches oneither side of the radial line. Draw redlines at 88° and 92% 2 inches on eitherside of the radial line. Carefully markthe center -hole radius of .0143 inchand punch it out.

Place the template on the turntableand set the needle on the outer needleposition. The stylus should align with

PICKUP ARM

5- 3/40

4-1/4°2-1/2"

CARTRIDGE

EACH DASH LINEIS 2° OFF 90°

TURNTABLE

Fig. 5-Use of cardboard template todetermine stylus tracking error. At allcheck points the stylus should alignwith the 90° tangent line, and in nocase exceed the angle of dash lines.the black tangent line. If its alignmentexceeds either of the red angle linesat this or at any of the other threepositions, there is undesirable error. Theposition nearest the center is the innerplaying radius for 45 -rpm records; theother three positions represent inner,midway and outer playing radii of 12 -inch LP's. Points nearest the centerrequire the highest accuracy of align-ment. With some types of arms andcartridges it may be more accurate touse the arrangement recommended byMr. Crowhurst and shown in Fig. 6.

(A more detailed discussion of recordtracking was presented in RADIO -ELEC-TRONICS, October, 1957, pages 40-43.)

A straight arm should be replacedwith a good offset arm. If an offset armhas error, try relocating the mountingpoint or substitute another arm with amore effective offset.

Test for mechanical feedback. Eitherplay the record at minimum volume orturn off the amplifier and listen toneedle talk. If there's no skip, probablespeaker feedback through the cabinetcan be proved by disconnecting setspeakers and checking behavior with aremote speaker.

Remaking a "one -room cabinet" ismore than a repair job, but how aboutsuspending or cushioning the pickuptable ? Perhaps it's inadequate, or, if

I SET PROTRACTOR SO 0,180°LINES UP WITH CENTER OF TURNTABLE 'I

2.SET STYLUS ON CENTER OF PROTRACTOR

3. LOON IN THIS DIRECTIONTO ALIGN STYLUS ARIA WITH 90°LINE

Fig. 6-Another method of checkingtracking visually.



the set was bought at "wholesale,"maybe still bolted down!

Check pickup arm friction. Tie a loopabout 2 inches in diameter at the endof an 18 -inch piece of soft cotton string.Slide the loop over the pickup arm nearthe needle and hold the other end sothat the needle clears the turntable.

Move the arm slowly over the playingarea, while watching the angle of thestring from perpendicular. Comparelong and short arms, those of profes-sional quality and those of changers,and you will soon get the feel of afriction -free arm. Those that show un-usual resistance should be disassembledand bearing parts checked, cleaned andpolished. On changers, additional fric-tion is added when the reject trip leversare reached. When skipping cuts asingle deep trench on the inside half ofthe record, the trip system is usuallythe cause. Run the changer through acycle until arm is at the start position.Now swing the arm, with the string,over the outer quarter of the recordradius. Gradually work the arm towardthe center and listen for the slight clickwhen the lever is first engaged.

If the groove was gouged at thispoint, there's your trouble. If not, kickthe lever along a little at a time andnotice (by the click) whether a similarswing always moves the lever an equaldistance inward. Remember that thelever remains at the point to which ith pushed, until it triggers. If a harderkick is needed at a point where therecord is gouged, there may be a burron the lever or adjacent stampings.Remove the parts and rub over extrafine abrasive paper, laid on a smooth,flat surface. Wipe clean of oil or grease,and powder lightly with graphite.

Cartridge substitution. If all theforegoing factors are normal and skip-ping persists, the remaining sure cureis a more compliant cartridge. As com-pliance improves, output voltage usual-ly decreases, so choose cartridges thatare within the input requirements ofthe amplifier. Always check and adjuststylus pressure after changing a car-tridge. If a crystal is in use, try a goodceramic. If a ceramic is in use, try ahigh -output magnetic. If a magnetic isir use, try one of somewhat less out-put. END

ELECTRONICS CONFERENCEThe Eleventh Annual Mid -America

Electronics Conference (MAECON-1959) will be held this year in theKansas City Municipal Auditorium andHotel Muehlebach on Nov. 3, 4 and 5.Technical papers are wanted on engi-neering management, engineering edu-cation, astronautics, electromagnetics,nucleonics, airborne electronics, medicalelectronics and other electronic subjects.

Abstracts of approximately 100 wordsshould be sent not later than July 1to: Dr. Sheldon L. Levy, Midwest Re-search Institute, 425 Volker Blvd., Kan-sas City 10, Mo., or Dr. Charles Halijak,Kansas State College, Manhattan, Kan.

Convenient "over-the-counter" delivery isnow available through any of the AuthorizedHeathkit Dealers listed below. Although youwill find the price of Heathkits slightly higherwhen buying locally, we're sure you'll agreethat this increase is justified. Your dealerabsorbs all transportation charges, carriesa complete stock of kits for immediate de-

livery, provides demonstration facilities,offers you a reliable source for parts andfast service ... and stands ready to counselor advise you on any problem that mightarise.

This new service does not affect yourcontinued privilege to buy directly fromHeath Company if you prefer.

NOW READY TO SERVECALIFORNIA

BAKERSFIELDKiesub Corporation2615 "F" Street

BERKELEYzacKIT Corporation2002 University Avenue

CHICODunlap Radio & TV928 Main Street

EL CAJONTetrad Electronics182 East Main Street

FRESNODunlap Radio 6 TV2617 Tulare Street

LONG BEACHKierulff 8. Company1501 Magnolia

LOS ANGELESKierulff Sound Corporation12024 Wilchire Boulevard

LOS ANGELESKierulff Sound Corp. (Capkit)820 West Olympic Boulevard

LOS ANGELESKierulff A Company6303 E. Corsair

MARYSVILLEDunlap Radio 6 TV5th a "J" Street

MERCEDDunlap Radio 6 TV234 West 17th Street

MODESTODunlap Radio 6, TV

NATIONAL CITYTelrad Electronics639 National

ONTARIOKlesub Corporation124 N. Benson

OXNARDKierulff A Company508 E. Date Street

PALO ALTOZack Electronics654 High Street

SACRAMENTODunlap Radio .1. TV1800 22nd Street

SAN BERNARDINOKierulff 6 Company390 South Mt. Vernon

SAN DIEGOTetrad Electronics3453 University Avenue

SAN FRANCISCOZack Electronics1422 Market Street

SANTA BARBARAzacKIT Corporation513 State Street

STOCKTONDunlap Radio 8. TV27 North Grant Street

TARZANAKierulff Sound Corporatiqn18841 Ventura Boulevard

VAN NUYSKleruiff 6 Company14511 Delano

VISALIADunlap Radio 8. TV1725 Mooney Avenue

DELAWAREWILMINGTON

Radio Electric Service Co.Third 6 Tatnall Streets

FLORIDACOCOA

Thurow Distributors, Inc.540 St. Johns Street

MIAMIThurow Distributors, Inc.1800 Northwest 23rd Street

INDIANAINDIANAPOLIS

Golden Ear, Incorporated24 West Washington

WEST LAFAYETTEGolden Ear, Incorporated108 Northwestern

KENTUCKYLOUISVILLE

Golden Ear, Incorporated610 Third Street

LOUISIANALAFAYETTE

Sterling Radio Products, Inc.1005 Cameron Street

MARYLANDSALISBURY

Radio Electric Service Co.736 South Salisbury Boulevard

MASSACHUSETTSBOSTON

Audionics, Incorporated1348 Boylston Street

MICHIGANALLEN PARK

Volta Electronics6716 Park Avenue

DETROITHigh Fidelity Workshop16400 West Seven Mile Road

MINNESOTAMINNEAPOLIS

Audio King Company913 West Lake Street

NEW JERSEYATLANTIC CITY

Radio Electric Service Co.452 North Albany Avenue

CAMDENRadio Electric Service Co.513 Cooper Street

MOUNTAINSIDEFederated Purchaser, Inc.1021 U. S. Route #22

NEWARKFederated Purchaser, Inc.114 Hudson Street

NEW YORKBELLEROSE

Cross Island Electronics, Inc.247-40 Jericho Turnpike

BROOKLYNAcme Electronics, Incorporated59 Willoughby Street

FARMINGDALEGem Elec. Distributors, Inc.34 Hempstead Turnpike

FOREST HILLSBeam Electronics, Incorporated101-10 Queens Boulevard

HICKSVILLEGem Elec. Distributors, Inc.236 Broadway

MINEOLAArrow Electronics, Incorporated525 Jericho Turnpike

MT. VERNONDavis Radio Distributing Co., Inc.70 East Third Street

NEW YORKArrow Electronics, Incorporated

65 Cortlandt StreetNEW YORK

Harvey Radio Company103 West 43rd Street

NO. CAROLINACHARLOTTE

Southeastern Radio Supply Co.1200 W. Morehead Street

GREENSBOROSoutheastern Radio Supply Co.404 N. Eugene Street

FAYETTEVILLESoutheastern Radio Supply Co.525 Gillespie Street

KINSTONSoutheastern Radio Supply Co.408 N. Heritage Street

RALEIGHSoutheastern Radio Supply Co.414 Hillsboro Street

YOU ...OREGON

PORTLANDEccles Electric Company237 Northeast Broadway

SALEMCecil Fames Company440 Church Street, Northeast

PENNSYLVANIAALLENTOWN

Federated Purchaser, Inc.1115 Hamilton Street

EASTONFederated Purchaser, Inc.925 Northampton Street

PHILADELPHIAAustin Electronics, Inc.1421 Walnut Street

PHILADELPHIARadio Electric Service Co.701 Arch Street

PHILADELPHIARadio Electric Service Co.3412 Germantown Avenue

PHILADELPHIARadio Electric Service Co.5930 Market Street

WILLOW GROVERadio Electric Service Co.29 York Road

YORKRadio Electric Service Co.1114 Roosevelt Extension

RHODE ISLANDPROVIDENCE

A ud Ionics, Incorporated790 North Main Street

TEXASBEAUMONT

Sterling Radio Products, Inc.1160 Laurel Street

BRYANSterling Radio Products, Inc.2615 Texas Avenue

DALLAS .

Hillcrest Records, Inc.6309 Hillcrest Avenue

HOUSTONSound Equipment, Incorporated2506 Crawford Street

HOUSTONSterling Radio Products, Inc.1616 McKinney Avenue

LUFKINSterling Radio Products, Inc.428 Atkinson Street

VIRGINIAARLINGTON

Key Electronics, Inc.126 South Wayne Street

WASHINGTONSEATTLE

Seattle Radio Supply, Inc.2117 Second Avenue

WISCONSINMADISON

Hi-Fi Corner401 State Street

MADISONSatterfield Electronics, Inc.1900 South Park

MILWAUKEEHi-Fi Center4236 West Capitol Drive

MILWAUKEENetzow's2630 North Downer Avenue

Careful selection of reliable qualified dealers is a slowprocess . . . so please bear with us if your area has notbeen covered. Thank you.

HEATH COMPANYBenton Harbor, Mich.

A Subsidiary Of Daystrom. Inc.ir

APRIL, 1959 75

AUDIO-HIGH FIDELITY

ULTRA -STEERED -STEREO PROJECTOR

Photo A-Open air orchestra with invertedacoustical bowl which projects sounds over alarge audience without electronic amplification.

Photo B-Stereo arrangement for homes requirestwo 12" and two 25" parabolic aluminum re-flectors. Loudspeakers throw sounds into largereflectors, then scatter sounds over the room.

By MOHAMMED ULYSSES FIPS, IRE*

This totally new tech-nique, "elegant as simplic-ity," may render most ofour stereo thinking-andequipment-obsolete

RECENTLY I visited the New YorkHigh Fidelity Show, which was amisnomer because the show wasmostly stereo. The more I saw

and heard, the more confused I became.The things that were going on com-pletely flabbergasted me, so much sothat I came away quite dazed.

The stereo demonstrations which Iwitnessed were, to my mind, only forthe well heeled. Not only that, but mostof the gadgets now in use are too cum-bersome. Furthermore, why must stereobe so earsplittingly loud? What we needis a completely new approach to sound,sound stereo, and the thoughts airedhere, I hope, will bring it about soon.

To begin with, why do we need elec-tronic amplification? Have you everbeen to an outdoor concert where themusicians sit in an inverted sound bowland the music is thrown forward toreach the audience several hundredfeet away? (See Photo A.) No elec-tronic amplification here! The more Ithought about this, the more convincedI became that any other approach wasunsound. I then started to go back to*Itinerant Radio Engineers.

- IIII.IIIIIIIIPI.I

111I4I III Nil-1,11[111,10;111'Ni

FIG 163.

uuum 1,11111

111/11111111111111111111211111

NX.

Reflection of Light and Sound.

Fig. 1-Sound of ticking watch in the focusof reflector B at right can be heard in focusof A, 35 feet away, without amplification.



acoustic fundamentals and soon cameacross what I was looking for.

This was an ancient book entitled"Experimental Science," by George M.Hopkins.f From this book, I reproduceFig. 163 with the caption: "Reflectionof Light and Sound," and a shortdescription (Fig. 1).

"Place two reflectors, A and B, 4 or 5feet apart, with their concave surfacesfacing each other, as shown in Fig. 163.Place a short candle on the stand, D, soas to reflect a parallel beam that willcover the reflector, B, as nearly as pos-sible. Then place a watch, E, in thefocus of the reflector, B, upon the stand,F. Now hold the funnel, C, with itsmouth facing the reflector, A, and

- immediately behind the candle, or,better, remove the candle and place thefunnel in the position formerly occupiedby the candle flame. With the funnel atthis point the ticking of the watch will

- be distinctly heard, but a slight move-ment of the funnel in either directionwill render the ticking inaudible. Thisexperiment shows that the laws govern-ing the reflection of light and soundare the same."

A similar illustration on the nextpage of the book shows the same setupwith a large ear trumpet. The articleconcludes with this significant andalmost unbelievable statement: "Withthis arrangement the watch may beheard twenty or thirty feet away."Mind you, this was all done 70 yearsago, without benefit of electronic ampli-fication. The Capitol in Washington,D. C., is well-known for its "whisper-ing" acoustic phenomenon. If you standon one marked spot and merely whisper,your friend standing on another markedspot 44 feet 6 inches away will hearyou clearly. These experiments will giveyou food for thought, as they gave me.The result is shown in these pages.

I wanted to satisfy myself as towhether it would be possible to accom-plish stereo in a revolutionary newmanner, and I am pleased to state herethat I succeeded. Furthermore, thecost of this new amplificationless stereois piddling.

Some of the components needed mustbe made; namely, four reflectors. Werequire two 25 -inch parabolic reflectorsfor the wall and two 12 -inch loudspeakerreflectors for the console. I did not useexpensive speakers, either, but securedtwo secondhand radio speakers. I foundit quite unnecessary to match thespeakers closely.

The arrangement which is shown inour illustration (Photo B) can be usedanywhere. No placement dimensionshave been given because they varydepending on the physical makeup ofthe room.

The secret of this new type of stereolies in the focusing of the reflectors. It isquite critical! If it's not done correctly,the results will not be good.

Textbooks will tell you that the lawsof sound and light are similar forexperiments of this type. As the old(Copyright 1889, 1893, 1895, Munn & Co. (Scien-tific American), New York.

Photo C-An actual photograph oflarge reflector, showing its sizecompared to girl, Larayne Limitone.

Photo D-This shows the the two loudspeakers as theyare trained on the large wall reflectors. The blocks ofsupporting wood are mounted on metal straps so theycan be moved in any direction and permanently fixed.

illustration shows, the candle must beadjusted in such a manner that bymoving it closer or further away fromthe mirror, you hear the watch tickloudly, even though it is 25 feet away.With correct adjustments, the rays ofthe candle will be in the exact focus ofmirror, A. The same is true of watch,E, and mirror, B. Here, too, the watchmust be in the exact focus for bestresults.

Therefore, when you assemble thestereo outfit, you may use a watch andcandle for correct focusing.

You will see from Photo B that thetwo lower audio beams cross each other,and you might wonder why this is done.The reason, again, is borrowed from thelarge outdoor orchestra inverted -bowl -sound amplifier. If a musician plays atthe far right, the sound of his instru-ment is reflected not only from theright, but also goes to the far left, tobe reflected out to the audience. I callthis crossed -beam arrangement the"Audio Mixer," and in practice it worksout perfectly. From this you will under-

stand that, when you do the focusing,the right speaker is focused with theleft -wall reflector while the left loud-speaker is focused with the right -wallreflector.

The wall reflectors must be sound -insulated so they do not transmit extrafrequencies by vibration to the wall.For that reason I used three heavywool or nylon cords to suspend eachwall reflector. The illustration showsthe arrangement. The two small reflec-tors are mounted on a horizontal board,as shown (Photo D). To guard againstextraneous sound transmission to theboard, a heavy felt pad is placed be-tween the wooden post and reflector toinsulate the latter acoustically. Thisdeadens the sound perfectly.

The arrangement gives excellentstereo reproduction without electronicamplification. Of course, such naturalamplification does not give an ear-splitting output. It gives beautiful,soft, undistorted music..

Naturally there is nothing to prevent(Continued on page 80)

APRIL, 1959 77

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452 -page 1959ALLIED CATALOGSend for this value -packedcatalog featuring thecomplete KNIGHT -KIT line,as well as the world'slargest stocks of everythingin Electronics. Write todayfor this leading, money-saving Buying Guide

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Fig. 2-A high -output pickup and twospeakers with ordinary output trans-formers, hooked up as shown, constitute

the whole circuit.

(Continued from page 77)you from using an amplifier if you musthave a fortissimo audio output. For myown purposes, I like soft mellow music,without the effects produced by largeamounts of feedback.

The connectionsIf you wish to try the new improved

system without electronic amplification,buy a ceramic type high -output stereocartridge. Obtain two telephone typeinduction coils with high -ratio second-ary. Hook them up with the secondarytoward the cartridge and the primarytoward the voice coil. Or you can useinexpensive replacement type outputtransformers that sell for 60 to 90cents. Hook them up as in Fig. 2. Useunshielded types. With this arrange-ment, no power or batteries are re-quired.

Practical hintsSmall reflectors can be of almost any

size in relation to diameter of large re-flectors, but the larger the better.

Radius of curvature should be similarto that of large reflector: parabolic is best.

Small reflector does not have to be inexact focal line with large reflector, butshould approximate it. Material of whichreflectors are made should be thick enoughso they do not vibrate at their own res-onant frequency. I used aluminum No. 15B & S gauge.

Beam of sound waves from small re-flector will scatter sidewise so it willcover a good part of area of large re-flector.

Small reflector should be placed at focalpoint of large reflector. This figures outto about 8 to 9 feet for 2 -foot -diameterlarge reflector.

For electronic amplification, speakersto be connected in usual way to audio -frequency amplifier outputs.

Speaker units may be placed about 4 to5 inches from center inner surface ofsmall reflectors. Small reflectors used insetup here shown are 12 inches in diam-eter with center of curvature about 2inches from chord of reflector, with sim-ilar proportions for large reflector.

Keep shifting all four reflectors untilfinal sound suits you best.

Always remember the focusing of re-flectors is very critical.

The reflectors cannot be bought readily,but any good metal spinner can make them.The reflectors shown were made in Brook-lyn, cost only $9, and are made of fairlystiff aluminum. On receipt of a reply postalcard, we shall be pleased to give you thename of the spinner who makes such re-flectors at low cost.

* * *

After I finished this article, I hadsome serious misgivings. I wonderedhow the boss would feel when he sees

RADIO -ELECTRONICS

AUDIO-HIGH FIDELITYmy latest effort. Fortunately, he's awayon vacation, and I have considerabledoubts that he would have allowed meto print the article, for these simplereasons:

First, he hasn't seen my demonstra-tion-he always must stick his noseinto everything! Then there is theAdvertising Department, who haven'tseen the article either. What will theysay when they find out that you canget fine stereo results for only a fewdollars? Finally, how will the speakerand amplifier manufacturers feel?

I know that, on the whole, peoplethese days are amenable to reason andnormally will not stand in the way ofprogress, even if it hurts their pocket-books temporarily. I am certain thatthey will welcome my effort. But fortheir protection (so I don't get intotrouble), I felt it best not to publish asyet my most important later improve-ment, by which it is possible to floodthe entire room with perfect stereoreproduction, which the system de-scribed here can't do. No more puttingyour head in a small stereo spot!

For these reasons, I know that myfaithful readers will be patient for alittle while. My new Stereo FrequencyDispersor, when attached to the twowall reflectors, will make four-dimen-sional stereo possible. It's great! Themost! I intend to publish it next year, on

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APRIL, 1 9 5 981

AUDIO-HIGH FIDELITY

ALL

ABOUT THEPart II-Reflex enclosures areeasy to tune, and tuning is neededfor good results

By P. G. A. H. VOIGT

IN Part I* we took a look at the historyand some of the basic principlesbehind the reflex enclosure. We endedby stating that "when we take the

Helmholtz resonance into account wefind that the motion of the air in theport builds up and helps the cone evenmore." The reasoning behind this state-ment is this:

If the drive is maintained at theappropriate the buildup con-tinues until the losses balance the driv-ing energy. Since a large part of the"loss" above is useful and in the formof sound output at the port, the reso-nance is one way of increasing thesystem's efficiency in that frequencyregion considerably.

The air -flow buildup at the port isaccompanied by a corresponding pres-sure -variation buildup within the cabi-net. This increases the load into whichthe rear of the cone is working andthus diminishes the cone's motion am-plitude.

When cone motion becomes excessive,several undesirable things happen.First, the elastic support of the movingparts is rarely linear in its action. Thisnonlinearity introduces harmonics atlarge amplitudes. If the coil moves farenough to pass out of the region ofmaximum flux, there is further distor-tion of the low frequencies, and, shouldother frequencies be present just then,IM distortion as well. Lastly, since thecone is usually also the source of simul-taneous higher frequencies, these areaffected in another way. If they areemitted while the cone moves forward,the pitch rises slightly (Doppler ef-fect) while, as it goes backward, thepitch drops. In this way, a high noteis frequency -modulated by the lowerone. The deviation depends on and getsworse as cone velocity increases.

The first group of undesirable effectsdecreases if cone displacement isreduced and the last if cone velocitySee also Correspondence page 24 this issue.

82

is reduced. Loading the cone, whichdecreases both displacement and ve-locity, is highly desirable.

It is at the natural resonance of thecoil-cone system that it is most likelyto move excessively and is most sensi-tive to the effects of extra loading. Anaccepted theory for optimum conditionsin a reflex system is that the enclosure'snatural resonant frequency (at whichit provides maximum loading) shouldbe made to agree with the speaker'snatural resonant frequency.

With both resonances at the samefrequency, you might expect serioustrouble. Fortunately, things are notas bad as they seem. The load on theback of the cone diminishes cone ex-cursion and velocity considerably, re-ducing troubles due to excess cone ve-locity and displacement. The sound out-put at the cone face is also reduced.This compensates to some extent forthe sound output from the port.

There is also an interaction betweenthe speaker and the air cushion. Thisproduces an effect resembling the dou-ble -humped or double -peaked effect ofan overcoupled bandpass circuit. Themarked resonance of the speaker, whichrepresented a prominent package oftrouble, is replaced by two smaller ones,one above and one below the basic reso-nance frequency, each being far lessoffensive than the original. Finally,if the overall output is excessive atlow frequencies, the Q (Quality) ofthe Helmholtz resonance can be re-duced by damping.

In the early stages of the argumentwe assumed that cushion pressure wascaused solely by the motion of thespeaker cone. This was a simplifica-tion, for both the cone motion and theair flow at the port contribute to thetotal compression. At the frequencywhere the two motions synchronize,cone and air flow at the port share thecompressibility of the air in the cavity.This makes the air cushion seem stiffer

(as though its volume had been re-duced) and raises the resonant fre-quency. This corresponds to the upper"hump" or peak.

Next, if air is rushing in at the portand there is no signal at the speaker,instead of the air pressure in the en-closure backing up as it would in asimple Helmholtz resonator, it acts onthe rear of the cone and drives thatoutward against the cone's controlelasticity. To the air moving in at theport, this makes the air in the chamberseem more compressible (as though thevolume were greater) and lowers theresonant frequency. Further, since theair in the cabinet is now flowing as awhole (from port to speaker and backas though these were in series) , it isnow moving in a way quite differentfrom that effective at the upper peakwhen speaker and port acting in paral-lel share the air cushion between them.

With the series motion more of theair in the cabinet is moving, and themass of the cone which the air isdriving along with it has to be addedin too. The overall increase of mass inmotion lowers the frequency still fur-ther-down to that corresponding tothe lower "hump" or peak.

At the frequency corresponding tothis lower peak, cone motion does notsynchronize with that of the air in theport. When the appropriate signal isapplied to the cone, therefore, the twodo not reinforce one another as effec-tively as at the higher frequency. Youmight even think that they would can-cel one another and that the sound -producing efficiency would drop to zero.

Complete cancellation demands twoequal sources 180° out of phase. At thislower frequency, the volume flow at theenclosure port, which is not limited bythe elastic control of the cone, is domi-nant. Further, even if two sourcesare equal and 180° out of phase at thecabinet, it does not follow that they are180° out of phase at the listener's ear.

RADIO -ELECTRONICS

AUDIO-HIGH FIDELITY RADIO TELEVISION INDUSTRIAL ELECTRONICS

// rj

7/7///,fi

INDIRECT WAVES, PATH LENGTHSNOT EQUAL

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DIRECT WAVES OF EQUALPATH LENGTHS

Fig. II-1-If two equal sources are 180°out of phase, but do not coincide inspace, they will not cancel each other

completely in all directions.

That will depend on the paths of sound.Even if the direct paths are of equallength, some reflected paths, say via theceiling, might be different in length andthus introduce a time (phase) differ-ence which prevents complete cancel-lation (see Fig. II -1).

Thus, while a high sound output isnot expected at this lower frequency,the output is generally greater thanthat obtainable with the same speakerin a simple box baffle of equal volume.Therefore, the reflex boosts the re-sponse slightly at that lower frequency.Below this lower resonant frequency,the sound output drops off very rapidlyindeed. The opening in the cabinetthen permits air flow from one side ofthe cone to another and the disadvan-tages of the port come into effect. How-ever, with a suitably designed reflexcabinet, this occurs at frequencies solow that the speaker was already veryinefficient anyway and the extra lossthere is a worth -while exchange for thegain higher up.

We can now summarize the reflex -cabinet designer's objective when try-ing to match the cabinet to a speaker.He tries to arrange matters so thereflex cabinet quenches the natural res-onance of the speaker to some extent,reducing speaker amplitude buildupand possible distortion. Also, he wantsto use the phase -reversal characteris-tic of the air -chamber system to helpfill out, as much as possible, the generallow -frequency region. Thus he kills twobirds with one stone and produce a moreacceptable overall result.

Matching speaker and enclosureNow, our study of the theoretical

background of reflex cabinet design isover. From it, the desirability of match-ing the cabinet to the speaker becomesobvious. What, then, should be saidof the practice of many hi-fi salons offitting a selection of speakers to anumber of reflex cabinets, identicalexcept for the diameter of the speakeropening, and then A-B testing fromspeaker to speaker?

Certainly most of the differences the(Continued on page 88)

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Here are just a few of the sub-jects covered: Components andTheir Troubles ; Basic Trouble-shooting Methods ; "Static" and"Dynamic" Testing; PracticalTroubleshooting Tips and Ideas:AC/DC, 3 -way Portable and Bat-tery Set Troubleshooting Prob-lems Servicing CommunicationsReceivers ; a Complete Guide toTelevision Service; AM, FM, andTV Realignment Made Easy; Re-sistor, Capacitor, Inductor andTransformer Problems ExplainedServicing Tuning, Selector andSwitching Mechanisms ; Loud-speakers; Servicing Record -play-ing Equipment . . . and dozensmore. 417 illustrations. ReadTROUBLESHOOTING AND RE-PAIR for 10 days AT OUR RISK!

Price only $7.50 Ior see money-saving combination offer).

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LEARN BASIC CIRCUITS FULLY... andwatch service "headaches" disappear

It's amazing how much easier andfaster you can repair radios, televisionsets and even industrial electronicequipment when you know all about cir-cuits and what makes each one "tick."

You locate troubles in a jiffy becauseyou know what to look for and where.

You make repairs lots faster, better,and more profitably!

Actually, there are only a compara-tively few BASIC circuits in modernequipment. Radio & Television RE-CEIVER CIRCUITRY AND OPERA-TION by Ghirardi and Johnson givesyou a complete understanding of theseas well as their variations. It teachesyou to recognize them . . . to under -

The books that explainSERVICE PROCEDURES

so you can reallyunderstand them!

Almost 1300 pages and over 800 pic-tures and diagrams in these two newbooks explain things so clearly it's nextto impossible for you to go wrong.

stand their peculiarities and likely"troublespots" . . and shows howto eliminate useless testing andguesswork in making repairs.

A COMPLETE GUIDE TOMODERN RADIO -TV CIRCUITS

Throughout, this 663 -page bookwith its 417 clear illustrations givesyou the kind of above -average pro-fessional training that fits you forthe better, big pay jobs in either serv-icing or general electronics. Covers allcircuits in modern TV and radio re-ceivers, amplifiers, phono-pickups, rec-ord players, etc. Price only $6.75 . . .

or see money -saving offer in coupon.Examine it 10 days at our risk!

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FREE EXAMINATION...easy terms!Dept. RE -49, RINEHA CO_ Inc.232 Madison Ave., New York It, N.Y.

Send books indicated for FREE EXAMINATION. In10 days, I will either remit price indicated (plus postage)or return books and owe you nothing.

Radio & TV TROU- FT Radio & TV CIRCUIT-BLE-SHOOTING AND LI RY AND OPERATIONREPAIR (Price $7.50) (Price $6.75)

I-1 MONEY -SAVING COMBINATION OFFER . . .

LI Both books only $13.00. (Regular price $14.25 ... yousave $1.25). Payable at rate of $4 (plus postage) after10 days and $3 a month thereafter until $13.00 has beenpaid. SAVE! Send full payment with order and we paypostage. Same 10 -day return privilege with money refunded.Name

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City, Zone, StateOUTSIDE U.S.A.-$8.00 far TROUBLESHOOTING & REPAIR: I$7.25 for CIRCUITRY & OPERATION; $14.00 for both. Cash awith order, but money refunded if you return books in 10 days.

5immoimiwmmonmminimmilmommommmi a

APRIL, 1959 83

SUPERIOR'S NEW MODEL 77

VACUUM TUBE VOLTMETERWITH NEW 6" FULL -VIEW METER

Compare If to any peak -to -peak V. T. V. M. made by al= other manufacturer at any price!6. Model 77 completely wired and calibrated with

accessories (including probe, test leads andportable carrying case) sells for only $42.50.

Model 77 employs a sensitive six inch meter.Extra large meter scale enables us to print allcalibrations in large easy -to -read type.

so Model 77 uses new improved -SICO printed cir-cuitry.

60 Model 77 employs a I2AU7 as D.C. amplifier andtwo 9006's as peak -to -peak voltage rectifiers toassure maximum stability.

So Model 77 uses a selenium -rectified power supplyresulting in less heat and thus reducing possibil-

Model 77-VACUUM TUBE VOLTMETER... Total Price $42.50-Terms: $12.50 after10 day trial, then $6.00 monthly for 5months f satisfactory. Otherwise return,No explanation necessary!

ity of damage or value changes of delicatecomponents.

so Model 77 meter is virtually burn -out proof. Thesensitive 400 microampere meter is isolated fromthe measuring circuit by a balanced push-pullamplifier.

so. Model 77 uses selected I% zero temperaturecoefficient resistors as multipliers. This assuresunchanging accurate readings on all ranges.

AS A DC VOLTMETER: The Model 77 is indis-pensable in ID-FI Amplifier servicing and a mustfor Black and White and color TV Receiver servic-ing where circuit loading cannot be tolerated.

AS AN AC VOLTMETER: Measures RMS values ifsine wave, and peak -to -peak value if complex wave.Pedestal voltages that determine the "black" levelin TV receivers are easily read.

AS AN ELECTRONIC OHMMETER: Because of itswide range of measurement leaky capacitors showup glaringly. Because of its sensitivity and lowloading, intermittents are easily found, isolatedand repaired.

SPECIFICATIONS DC VOLTS -0 to 3/15/75/150/300/750/1,500volts at 11 megohms input resistance. ACVOLTS (RMS) -0 to 3/15/75/150/300/750/1,500 volts. AC VOLTS (Peak to Peak) -0 to8/40/200/400/800/2,000 volts. ELECTRONICOHMMETER -0 to 1,000 ohms710,000 ohms/100,000 ohms/1 megohm/10 megohms/100megohms/I,000 megohms. DECIBEES -10db to -I- 18 db, -I- 10 db to + 38 db, + 30 db to

58 db. All based on 0 db = .006 watts (6 mw)into a 500 ohm line (1.73v). ZERO CENTERMETER - For discriminator alignment with fullscale range of 0 to 1.5/7.5/37.5/75/150/375/750volts at 11 megohms input resistance.

Model 77 comes complete with operating instructions, probe and test leads.Use it on the bench-use it on calls. A streamlined carrying case, included atno extra charge, accommodates the tester, instruction book, probe and leads.Operates on 110-120 volt 60 cycle. Only 12"NET

SUPLISON NEW SUPER -METER - WITH NEW 6" FULL -VIEW METER

of ldea4e4514 VOLT -OHM MILLIAM METER

Pea4 CAPACITY, REACTANCE, INDUCTANCE ANDDECIBEL MEASUREMENTS.

Aga" 7e4t4 SELENIUM AND SILICON RECTIFIERSSILICON AND GERMANIUM DIODES.

601111111.

Model 79-SUPER-METER . . . Total Price$38.50-Terms: $8.50 after 10 day trial,then $6.00 per month for 5 months ifsatisfactory. Otherwise return, no expla-nation necessaryl

The Model 79 represents 20 years of continuous ex-perience in the design and production of SUPER -METERS, an exclusive SICO development.In 1938 Superior Instruments Co. designed its firstSUPER -METER, Model 1150. In 1940 it followed withModel 1250 and in succeeding years with others in-cluding Models 670 and 670-A. All were basicallyV.O.M.'s with extra services provided to meet chang-ing requirements.Now, Model 79, the latest SUPER -METER includesnot only every circuit improvement perfected in 20years of specialization, but in addition includesthose services which are "musts" for properly serv-icing the ever increasing number of new componentsused in all phases of today's electronic production.For example with the Model 79 SUPER -METER youcan measure the quality of selenium and siliconrectifiers and all types of diodes-components whichhave come into common use only within the past fiveyears, and because this latest SUPER -METER neces-sarily required extra meter scale, SICO used itsnew full -view 6 -inch meter.

SftecedicatioadD.C. VOLTS: 0 to 7.5/15/75/150/750/1,500.A.C. VOLTS: 0 to 15/30/150/300/1,500/3,000.D.C. CURRENT: 0 to 1.5/15/150 Ma. 0 to 1.5/15 Amperes.RESISTANCE: 0 to 1,000/100,000 Ohms. 0 to 10 Megohms.CAPACITY: 001 to 1 Mfd. 1 to 50 Mfd.REACTANCE: 50 to 2,500 Ohms, 2,500 Ohms to 2.5 Megohms.

INDUCTANCE: .15 to 7 Henries, 7 to 7,000 Henries.DECIBELS: -6 to +18, +14 to +38, +34 to +58.

The following components ore all tested forQUALITY at appropriate test potentials. Twoseparate BAD -GOOD stoles on the meter areused for direct readings.

All Electrolytic Condon from 1 MFD to 1000 MFD.All Germanium Diodes.All Selenium Rectifiers.

All Silicon Rectifiers. All Silicon Diodes.

Model 79 comes complete with operating instructions andtest leads. Use it on the bench-use it on calls. A stream-lined carrying case included at no extra charge accom-modates the fester, instruction book and test leads. __Only '38 50NET

1

SHIPPED ON APPROVAL Try for 10 days before you buy! If completely satisfied, send down payment alter trial andpay balance at indicated monthly rate - NO INTEREST OR FINANCE CHARGES ADDED

NO MONEY WITH ORDER - NO C.O.D. If not completely satisfied, return to us, no explanation necessary

SEE PAGE 87 FOR COMPLETE DETAILS

MOSS ELECTRONIC, INC. 3849 TENTH AVE., NEW YORK 34, N. Y.


For the first time ever: ONE TESTER PROVIDES All THE SERVICES LISTED BELOW!SUPERIOR'S1

E:L 7 164EW ALL PURPOSE BRIDGE

Model 76 BRIDGE ... Total Price $26.95-Terms: $6.95 after 10 day trial, then $5.00monthly for 4 months if satisfactory. Otherwisereturn, no explanation necessary!

RESISTANCE BRIDGE SECTION2 Ranges: 100 ohms to 5 megohms.Resistance can be measured without discon-hecting capacitor connected across it. (Ex-cept, of course, when the R C combination ispart of an R C bank.)

IT'S A IT'S A

CONDENSER BRIDGE RESISTANCE BRIDGEwith a range of .00001 Microfarad to 1000 Microfarads(Measures power /actor and leakage too.)

IT'S A

SIGNAL TRACERwhich will enable you to trace the signal from antennato speaker of all receivers and to finally pinpoint theexact cause of trouble whether it be a part or circuitdefect.

SPECIFIC

CAPACITY BRIDGE SECTION4 Ranges: .00001 Microfarod to 1000 Micro -farads. Will also locate shorts, and leakagesup to 20 megohms. Measures the power fac-tor of all condensers from .1 to 1000 Micro -farads. (Power factor is the ability of a con-denser to retain a charge and thereby filterefficiently.)

TV ANTENNA TESTER SECTIONLoss of sync., snow and instability are onlya few of the faults which may be due to abreak in the antenna, so why not check theTV antenna first? 2 Ranges: 2' to 200' for 72ohm coax and 2' to 250' for 300 ohm ribbon.

with a range of 100 ohms to 5 megohms

IT'S A

TV ANTENNA TESTERThe TV Antenna Tester section is used first to determineif a "break" exists in the TV antenna and if a break doesexist the specific point (in feet from set) where It is.

ATIONS:

SIGNAL TRACER SECTIONWith the use of the R.F. and A.F. Probes in-cluded with the Model 76, you can makestage gain measurements, locate signal lossin R.F. and Audio stages, localize faultystages, locate distortion and hum, etc, Pro-vision has been made for use of phones andmeter if desired.

Model 76 comes completewith all accessories includ-ing R.F. and A.F. Probes;Test Leads and operatinginstructions. Nothing elseto buy. Only 2"NET

SUPERIOR'S NEW MODEL TV -50A

Model TV -50A GENOMETER . . . TotalPrice $47.50-Terms: $11.50 after 10 daytrial, then $6.00 monthly for 6 monthsif satisfactory. Otherwise return, no ex-planation necessary)

R. F. SIGNAL GENERATOR: The ModelTV -50A Genometer provides completecoverage far A.M. and F.M. alignment.Generates Radio Frequencies from 100Kilocycles to 60 Megacycles on fundamen-tals and from 60 Megacycles to 180 Mega-cycles on powerful harmonics.

CROSS HATCH GENERATOR: The ModelTV -50A Genometer will project a cross.hatch pattern on any TV picture tube. Thepattern will consist of non -shifting, hori-zontal and vertical lines interlaced toprovide a stable crosshatch effect.

sfteci6'ceite:04dVARIABLE AUDIO FREQUENCY GENERA-TOR: In addition to a fixed 400 cycle sine -wave audio, the Model TV -50A Genometerprovides a variable 300 cycle to 20,000cycle peaked wave audio signal.

DOT PATTERN GENERATOR (FOR COLORTV) Although you will be able to use most

of your regular standard equipment forservicing Color TV, the one addition whichis a "must" is a Dot Pattern Generator.The Dot Pattern projected on any color TVReceiver tube by the Model TV -50A willenable you to adjust for proper colorconvergence.

GENOMETER7 Signal Generators in One!R. F. Signal Generator for A.M. Bar GeneratorR.F. Signal Generator for F. M. 11 Cross Hatch Generator

11 Audio frequency Generator Color Dot Pattern GeneratorMarker Generator

A versatile all-inclusive GENERATOR which provides ALL the outputs for servicing:A.M. Radio F.M. Radio Amplifiers Black and White TV

Color TV

BAR GENERATOR: The Model TV -50A pro-jects an actual Bar Pattern on any TVReceiver Screen. Pattern will consist of4 to 16 horizontal bars or 7 to 20 verticalbars.

MARKER GENERATOR: The Model TV -50Aincludes all the most frequently neededmarker points. The following markers areprovided: 189 Kc., 262.5 Kc., 456 Kc., 600Kc., 1000 Kc., 1400 Kc., 1600 Kc., 2000Kc., 2500 Kc., 3579 Kc., 4.5 Mc., 5 Mc.,10.7 Mc., (3579 Kc. is the color burstfrequency)

THE MODEL TV -50Acomes absolutelycomplete withshielded leads andoperating instruc-tions.

'47"NET

SHIPPED ON APPROVALNO MONEY WITH ORDER-NO C.O.D.

Try for 10 days before you buy! If completely satisfied, send down payment after trial andpay balance at indicated monthly rate - NO INTEREST OR FINANCE CHARGES ADDED.If not completely satisfied, return to us, no explanation necessary.

SEE PAGE 87 FOR COMPLETE DETAILS

MOSS ELECTRONIC, INC. 3849 TENTH AVE., NEW YORK 34, N. Y.

APRIL, 1959 85

SUPERIOR'S NEW MODEL TW-11

STANDARDPROFESSIONAL TUBE TESTER

Model TW-11-TUBE TESTER . . . TotalPrice $47.50-Terms: $11.50 after 10 daytrial, then $6.00 per month for 6 monthsif satisfactory. Otherwise return, no ex-planation necessary!

* Tests all tubes, including 4, 5, 6, 7, Octal, Lock -in, Hearing Aid, Thyratron, Minia-tures, Sub -miniatures, Novals, Sub-minars, Proximity fuse types, etc.

* Uses the new self-cleaning Lever Action Switches for individual element testing.Because all elements are numbered according to pin -number in the RMA basenumbering system, the user can instantly identify which element is under test.Tubes having tapped filaments and tubes with filaments terminating in morethan one pin are truly tested with the Model TW-11 as any of the pins may beplaced in the neutral position when necessary.

* The Model TW-11 does not use any combination type sockets. Insteadindividual sockets are used for each type of tube. Thus it is impossible todamage a tube by inserting it in the wrong socket.

* Free -moving built-in roll chart provides complete data for all tubes. Alltube listings printed in large easy -to -read type.

* NOISE TEST: Phono-jack on front panel for plugging in either phones orexternal amplifier will detect microphonic tubes or noise due to faultyelements and loose internal connections.

EXTRAORDINARY FEATURESEPARATE SCALE FOR LOW -CURRENT TUBES. Previously, on emission -type tubetesters, it has been standard practice to use one scale for all tubes. As a result,the calibration for low -current types has been restricted to a small portion of thescale. The extra scale used here greatly simplifies testing of low -current types.

The Model TW-11 operates on 105-130Volt 60 Cycles A.C. Comes housed in abeautiful hand -rubbed oak cabinet com-plete with portable cover. $475°NET

SUPERIOR'S

NEW MODEL 83 CO ROT. TESTERTests and Rejuvenates ALL PICTURE TUBES

ALL BLACK AND WHITE TUBES

Model 83-C.R.T. TUBE TESTER . , . TotalPrice $38.50-Terms: $8.50 after 10 day trial,then $6.00 monthly for 5 months if satisfactory.Otherwise return, no explanation necessary!

Model 83 comes housed in handsome $portable Saddle Stitched Texon case-complete with sockets for all black andwhite tubes and all color tubes. Only ...

From 50 degree to 110 degree types-from 8" to 30" types.

ALL COLOR TUBESTest ALL picture tubes-in the carton-out of the carton-in the set!

zoo Model 83 is not simply a rehashed black and white C.R.T. Tester with a coloradapter added. Model 83 employs a new improved circuit designed specifically totest the older type black and white tubes, the newer type black and white tubesand all color picture tubes.

por Model 83 provides separate filament operating voltages for the older 6.3 typesand the newer 8.4 types.

joof Model 83 employs a 4" air -damped meter with quality and calibrated scales.

koW Model 83 properly tests the red, green and blue sections of color tubes individually-foreach section of a color tube contains its own filament, plate, grid and cathode.

I/ Model 83 will detect tubes which are apparently good but require rejuvenation. Suchtubes will provide a picture seemingly good but lacking in proper definition, contrastand focus. To test for such malfunction, you simply press the rej. switch of Model 83. Ifthe tube is weakening, the meter reading will indicate the condition.

50'' Rejuvenation of picture tubes is not simply a matter of applying a high voltage to thefilament. Such voltages improperly applied can strip the cathode of the oxide coatingessential for proper emission. The Model 83 applies a selective low voltage uniformly toassure increased life with no danger of cathode damage.

SHIPPED ON APPROVALNO MONEY WITH ORDER -NO C.O.D.

Try for 10 days before you buy! If completely satisfied, send dawn payment after trial andpay balance at indicated monthly rare - NO INTEREST OR FINANCE CHARGES ADDED.If not completely satisfied, return to us, no explanation necessary.

See following page for complete details

MOSS ELECTRONIC. INC. 3849 TENTH AYE.. NEW YORK 34. N. Y.


SUPERIOR'S NEW MODEL 82A Multi -Socket Type

TUBE TESTERTEST ANY TUBE IN10 SECONDS FLAT!

Model 82A - TUBE TESTER ... TotalPrice $36.50 - Terms: $6.50 after 10day trial, then $6.00 monthly for 5months if satisfactory. Otherwise return,no explanation necessary.

Production of this Model was delayed a full year pending

careful study by Superior's engineering staff of this new

method of testing tubes. Don't let the low price mislead you!

We claim Model 82A will outperform similar looking units

which sell for much more - and as proof, we offer to ship it

on our examine before you buy policy.

To test any tube, you simply insert it into a numbered socket

as designated, turn the filament switch and press down the

quality switch - THAT'S ALL! Read quality on meter. Inter.

element leakage if any indicates automatically.

OTurn the filament selector switch toposition specified.

OInsert tube into a numbered socket asdesignated on our chart (over 600types included).

0 Press down the quality button -

THAT'S ALL!Read emission quality direct on "BAD.GOOD" meter scale.

SfreeetlicatecutdTests over 600 tube types

Tests OZ4 and other gas -filled tubes Employs new 4" meter with sealed air -damping chamber resulting in

accurate vibrationless readings Use of 22 sockets permits testing all popular tube types and prevents

possible obsolescenceDual Scale meter permits testing of low current tubes7 and 9 pin straighteners mounted on panelAll sections of multi -element tubes tested simultaneously

.Ultra -sensitive leakage test circuit will indicate leakage up to 5 megohms

$36:SHIPPED ON APPROVALNO MONEY WITH ORDER NO C.O.D.

Model 82A comes housed in handsome,portable Saddle -Stitched Texon case

Only

MOSS ELECTRONIC, INC.Dept. 0-S 9 0 3849 Tenth Ave., New York 34, N.Y.

Please send me the units checked on approval. If completely satisfiedI will pay on the terms specified with no interest or finance chargesadded. Otherwise, I will return after a 10 day trial positively cancellingall further obligation.

Name

Address

City .......... . Zone StateAll prices net. P.0 N. Y. C.

0 Model 77 Total Price $42.50$12.50 within 10 days. Balance $6.00 monthly for 5 months.



El Model TV -50A Total Price $47.50$11.50 within 10 days. Balance $6.00 monthly for 6 months.

1:1 Model TW-11 Total Price $47.50$11.50 within 10 days. Balance $6.00 monthly for 6 months.


0 Model 82A Total Price $36.50$6.50 within 10 days. Balance $6.00 monthly for 5 months.

APRIL, 1959 87

TOBE MYLAR* MOLDED TUBULAR CAPACITORS

Molded of DuPont Mylar, one of the finest insulation materialsever developed.

Thermoset Case Construction secures leads and sections firmly towithstand extremes of handling, vibration, shock and solderingtemperatures.

High Insulation Resistance: Average megohm values per unit10,000 at 25°C. Small capacitance variation with thermal change.

Temperature Operating Range: -55° to +130°C. Moisture Resistant: Exceeds JAN -C-91 requirements. Non -Inductive: Extended foil construction insures low resistance

connections and low RF impedance.

Today, orderyour Tobe MylarKit from your

Tobe Distributor

DESIGNED FOR SERVICE DEALERS

NEW TOBE MYLAR* CAPACITOR KIT

FREE KIT CONTAINS

80 CAPACITORS

ONLY

$1 5 84Compact, clear -plastic dispenser contains an assort..ment of 80 Tobe Mylar capacitors in the most popularsizes, ratings and quantities for quick, efficient servic-ing. Covers over 60 different ratings at 200, 400 and600 working volts and from .0001 to 1.00 mfd. Dealerpays only for the Tobe Mylar capacitors, kit is free.

CAPACITORS

AUDIO-HIGH FIDELITY(Continued from page 83)

listener hears will be due to differencesbetween the particular speakers beingcompared, but is it fair to any speakerto pair it with a cabinet which mightnot suit it at all? I, for one, certainlydon't think so. The result of such testsmay well be the selection of an inferiorspeaker, which gave better sound onthat particular occasion simply becausethe cabinet matched it. A better speakermight have been rejected because thestandard cabinet was so out of matchit couldn't do its best.

Either good box baffles, large enoughto be neutral in their effect should beused, or, with reflex cabinets, at thevery least, each cabinet should be tunedto suit the speaker fitted in it.

Very little electronic equipment isneeded. An audio generator, a 1,000 -ohm

SPKR AC VOLTMETER

AUDIO GENIS V OUTPUT

Fig. 11-2-Simple circuit for locatingmain lower -speaker impedance peak.

resistor and a suitable ac voltmeterwill do. Laboratory accuracy is notnecessary. All that is needed is to showthe approximate frequency and heightof the main lower speaker impedancepeak-first, when measured with thespeaker in free air (no baffle at all, layit on its back or hang it up on a wire)and again while in the cabinet.

The simple circuit for tuning isshown in Fig. 11-2. The 1,000 -ohmresistor and the speaker are in seriesacross the audio generator. Keep thegenerator's output constant and slowlytune across the band of approximately20 to 250 cycles while watching themeter for the sharp peak that showsthe speaker's resonant frequency. If thegenerator delivers 15 volts and thespeaker has a nominal impedance ofabout 16 ohms, the voltage across thespeaker should be about 0.25. If themeter circuit has a resistance of 1,000ohms or more, meter current will notdisturb the reading significantly.

The speaker's impedance is partiallydue to the dc resistance of the coil andpartially to the voltage generated whenthe coil moves in the magnet's gap.When the speaker is in free air (clearof any baffle or cabinet) and fed withconstant current at various frequencies,coil motion builds up at the speaker'smain lower resonance frequency. Thisdrives the coil velocity up and the backemf generated in the coil peaks also.This shows up clearly on the voltmeteras a peak in the reading.

At the peak, the meter reading maybe expected to rise to 1 or 2 volts, some-times even higher. Thus the exact lowerresonant frequency can be discovered.The voltmeter reading gives an idea ofthe peak's height.

If minor irregularities are ignored,a typical speaker has an impedance

Ourent trademark TOBE DEUTSCHMANN CORPORATION, NORWOOD, MASSACHUSETTS

MOST of us are familiar with theage old problem of checking anelectrolytic capacitor. We have

tried capacitor testers, in -circuit testersand circuit analyzers, only to find thatthe only real answer to checking anyelectrolytic accurately is to substituteit with another capacitor. Of course,this presents certain problems; theright value capacitor of the properoperating voltage is usually the onethat you installed in the last repair jobthat you did and you don't have an-other around the shop for substitution.Then, too, there is always the dis-charge spark that does little good increating good -will with your customer,to say nothing of the harm that it cando to the capacitor.The intermittent electrolytic capacitoris the worst headache, especiallywhere the trouble in the receiver iscorrected when another capacitor isconnected across it. This we call ca-pacitor healing due to the sudden out -rushing current from the capacitorbeing paralleled. The ES -102 Electro-Sub is especially made to make sub-stitution easy and is ideal for serviceshop, laboratory or any other placewhere design, service or experiment-ing is taking place.

WHY THE ELECTRO-SUB NOW?

The need for an electrolytic substitution unit has increased recently becauseof the sharp increase in the use of elec-trolytic capacitors. Hi-Fi amplifiers, forexample, use up to 12 electrolytics. Thisincreased again with the advent of stereosound. One bad electrolytic will makea thousand dollar Hi-Fi sound like a tendollar AC -DC radio. Portable TV receiv-ers also use more electrolytic capacitorsthan conventional TV. The filter capaci-tors are more critical, especially whenthe portable uses a fuse resistor.

What Electrolytic Capacitors Will TheES -102 Substitute For?

The ES -102 is especially designed to substitute for all capacitors from 2 MFDto 400 MFD. The actual values selectedand some of their uses are shown below.

4 MFD ... especially handy for tran-sistor radios

10 MFD ... very handy for adding ca-pacity to see if it will reduce hum

20 MFD ... popular in many low costAC -DC radios and TV bypass

40 MFD ... used in most AC -DC radiosand some TV receivers

60 MFD ... used in many low cost TVreceivers

80 MFD ... used in most TV receiversand higher priced radios

100 MFD ... used in many TV receiversand low cost Hi-Fi amplifiers

150 MFD ... very prevalent in Hi-Fi am-plifiers

225 MFD ... used in some Hi-Fi ampli-fiers

350 MFD ... used only in very highpriced Hi-Fi and special applications.Very handy for design work and fortrouble shooting hum.

When substituting for in between values,select the nearest value.

WHAT VOLTAGE CAN BEAPPLIED TO THE ES -102?

Any voltage from 2 to 450 volts can beapplied to the ES -102 capacitors withoutcapacity change. This is because thecapacitors used are special dry electro-lytics.

Time -Saver of the MONTH!by Herb Bowden*

ELECIRO--00-SUBin s1GEtii(it`7Ry41YTlC5

nompi.ii,

Model ES -102Electro-Sub

Dealer Net 515.95

How the ES -102Prevents Capacitor

Healing and DischargeSparking

The ES -102 has a special charge and dis-charge circuit called a surge protector.This magic device is a development ofSencore and is very unique in operation.The surge protector action is shown infigure 1. Following the action of thesurge protector, note the three positionsof the switch as it slides from left toright. In position 1, the leads are con-nected to the circuit under test, but thesubstitute capacitor is not connected.In position number two, the capacitor isconnected to the circuit through the 500ohm resistor. Position number 3 shortsout the resistor and completes the sub-stitution. The action is in reverse asthe surge protector switch is released.

TO500 CIRCUITOHMS UNDER

10 WATT TEST

Fig 1A. Position 1 places resistor across ca-pacitor and only test leads connected to circuit.

500 OHMS

TOCIRCUIT

UNDERTEST

10 WATTFig. 1B. Position 2 showing resistor in serieswith capacitor to "slow down" current in -rushwhich may heal capacitor being paralleled.

TOCIRCUITUNDERTEST

500 OHMS 10 WATTFig. 1C. Position 3 of surge protector "shortsout" series resistor leaving only electrolyticin circuit.

[ADVERTISEMENT] [ADVERTI

When it is returned to the ex-treme left, the 500 ohm resistordischarges the ES -102 capacitorcompletely within a few seconds.The remaining portion of theES -102 schematic is screened onthe front panel as shown.

Is The Surge ProtectorCritical In Operation?

It may appear that the surgeprotector switch must be movedto the right carefully in order toaccomplish the connections de-scribed. However, this is not thecase, as the switch can be com-pressed as fast as desired andas often as required. The con-nections and capacitor dischargeare automatic.

Can The ES-IO2 BeSubstituted Permanently?

The surge protector switch is returnedby an external spring. This spring islocated under the front panel. To usethe capacitors for engineering or experi-mental work, you may want to discon-nect the spring. Be sure to rememberthat the surge protector is not operatingwhen the spring is disconnected.

CAN YOU GET A SHOCKFROM THE ES -102?

It is impossible to get a shock from theES -102 as the test leads are disconnectedand the capacitor discharged the instantthat the surge protector switch is re-leased. As a matter of fact, you canrelease the surge protector, disconnectthe leads and then touch the leads toyour hands without the possibility ofshock. This is important, especiallywhere customers or small children mayget near your service bench.

DOES THE ROTARY SWITCHARC WHEN SWITCHING

CAPACITORS?The rotary switch does not arc whenswitching capacitors because the surgeprotector switch disconnects the voltagesource. This reduces switch wear great-ly. One should be careful not to hold thesurge protector to the right while chang-ing capacitors.

IS IT NECESSARY TODISCONNECT THE CAPACITOR

BEING CHECKED?If a capacitor is suspected of beingopen, you do not need to disconnect itfrom the. circuit. If it is suspected ofbeing shorted, it is necessary to discon-nect it while substituting one of thecapacitors from the ES -102.

WHERE TO PURCHASETHE ELECTRO-SUB

Over 1000 parts distributors in theUnited States and Canada carry thecomplete line of Sencore time savers.These distributors now carry the Electro-Sub in stock. Dealer net is $15.95 (lessthan your cost of the electrolytic ca-pacitors).If, for some reason, your distributordoes not carry the Sencore line, pleasedrop us a note at the factory, 121 OfficialRoad, Addison, Illinois. In Canada, pleasewrite . . . Active Radio and TV Dist., 58Spadina Avenue, Toronto 2 B. Look forthe colorful Sencore display.*PRESIDENT SENCORE

SEMENT]

APRIL, 1959 89

41111M4T/C

PT5RECTIFIERS

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RADIO RECEPTOR5ezeic46,0,

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Don't be fooled by an "all or nothing at all"approach. Selenium and Silicon rectifiersboth have a place in today's TV sets ... and

General Instrument supplies the very best!

Radio Receptor "Safe Center" selenium rectifiers have proved theirreliability and long life in millions of circuits through the years.When your replacement calls for selenium there is no betterrectifier.AUTOMATIC PT5 Silicon rectifiers are the first choice of leadingTV set manufacturers switching to silicon in their new models.When replacing or converting to silicon, install the PT5 for maxi-mum performance and picture brightness.Both these outstanding rectifiers are brought to you by GENERAL.INSTRUMENT, your finest source of semiconductor components!

General Instrument Distributor DivisionRADIO RECEPTOR COMPANY, INC.

Subsidiary of General Instrument Corporation240 Wythe Avenue, Brooklyn 11, N. Y. EVergreen 8-6000

See us in May in Chicago at the Electronic Parts Distributor Show-Booth 590

AUDIO-HIGH FIDELITYcurve like that shown by the solid linein Fig. 11-3.

If that speaker is fitted into a reflexenclosure, the vented air chamberaffects matters by loading the rear ofthe cone. In the frequency range wherethe load is effective, cone and coil motionare diminished. The coil velocity drops,as do the impedance and the voltmeterreading. Therefore, the frequency atwhich the load is greatest can be ascer-tained easily, for at that frequency thespeaker impedance drops substantiallybelow its free -air level.

If both impedance curves are plotted(with the speaker in air and again inthe cabinet) and the two curves arecompared, it will seem almost as thoughthe effect of the air resonance was totake a bite out of the impedance curve.The position of the bite indicates thefrequency region of maximum cabinetload.

Tune the portThe maximum -load frequency can be

made to agree with the speaker's res-onance frequency if the cabinet is madeso that the air resonance is adjustable.The hi-fi dealer using reflex cabinetsneeds the simplest method of tuningpossible. He cannot alter the volume ofhis cabinets to adjust the resonancefrequency. Instead, he will adjust theair inertia of the port. The simplestway is to alter the port area.

If the port is made as shown in Fig.11-4 and he obtains the inexpensiveextra parts shown, he can do this easily.

A simple way of arriving at thecorrect adjustment is to leave the audiogenerator set at the speaker resonancefrequency, and adjust the port openingwhile keeping an eye on the voltmeter.By this method it is not even necessaryto know what the resonant frequencyreally is. Just leave the knob set wherethe free -air reading shows the peak.Now, when the voltmeter reading is atits lowest, the cabinet is adjusted formaximum loading.

Fig. II-3-Typical speaker impedancecurves: solid line for speaker in freeair; Basked line for same speaker insmall (0.66 -cubic -foot) reflex enclo-

sure.


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NOTCH FOR CLAMP

PORT

REFLEXENCLOSURE

C - CL AM P

COVER

BRAZED OR WELDEDTO PREVENTRATTLES

PORT

BACKINGSTRIPCEMENTEDTO CLAMP

Fig. II-4-Simple method of tuning reflex enclosure calls for an adjustable port.Clamp fits into slot in port and cover is adjusted for best results. At this position,

clamp is tightened and cover fixed in place.

If the speaker impedance curve isplotted now, it will look something likethe dashed curve in Fig. 11-3. In addi-tion to taking a bite out of one fre-quency region, the neighboring regionsabove and below resonance are pushedup into minor peaks. These indicateincreased cone velocity at their respec-tive frequencies.

The region of lowest voltmeter read-ing lies in the trough between thesepeaks and is therefore not very pre-cise. Fortunately the tuning accuracyrequired is not high and, if in doubtabout the tuning, rocking a little toeither side of the basic generator set-ting helps locate the middle of thetrough.

It would be convenient if exact tun-ing was indicated by equal height ofthe two peaks. In practice this cannotbe relied on, because damping (whethernatural, accidental or deliberate) affectstheir individual heights. However, in areflex system without special dampingthat is tuned to provide maximum loadat speaker resonance, the lesser peakis usually at least half as high as thegreater one. The peaks are also aboutequally spaced on either side of thespeaker's free -air resonance frequencywhen plotted on the usual logarithmicgraph paper.

Tune the cabinetCabinets can be tuned without fitting

the speaker if the resonant frequency ofthe speaker to be used is known. (Don'tgo by published specifications. Speakersvary, measure it.)

If a cabinet, after the port has beencut but before the speaker opening iscut, is considered as a Helmholtz res-onator, it has a resonant frequency. Ifthe cabinet is placed with its portfacing upward as in Fig. 11-5, a carbon,crystal or other type of pressure -operated microphone' can be suspendedso as to be within the enclosure. Now,suppose a sound of variable frequency

'If no pressure microphone is available, aheadphone earpiece will do.

sweeps by. At the frequency of theHelmholtz resonance, there will be aconsiderable buildup of sound pressureinside the cabinet. (Relative to thepressure at the microphone in theabsence of the cabinet, a buildup ofbetween 10 and 30 times is normal.)Thus, by varying the frequency andwatching the output from the mikeamplifier on a scope or meter it is easyto determine the resonant frequency ofthe air system very accurately. Bymodifying the port, the frequency canthen be adjusted as desired.

If the speaker opening has alreadybeen cut, the same method can be used,provided the speaker opening is sealedoff by a reasonably airtight cover. Ifthe speaker has already been fitted, itneed not be removed as it will notdisturb results appreciably as long asthe cover over the speaker opening iseffective.

The port and resonanceExperiments show that when a

speaker and a reflex cabinet aremarried, a slight change in the Helm-holtz tuning may be desirable for max-imum effect. Therefore, the precedingmethod should be treated as a quickpractical way of getting close to the

Fig. II-6-Effectof changing portarea on the en-closure's reso-nant frequency.Graph for cab-inet with 3.25 -cubic -foot in-ternal volume.

AUDIO -HIGH FIDELITYcorrect port area. The perfectionist,chasing subtleties, will take the imped-ance curve as well and then makefurther corrections if necessary.

The graph plots in Fig. 11-6 showthe kind of variations in the Helmholtztuning frequency to expect when theport is changed. The graphs were takenfor a well-built cabinet with a 3.25 -cubic -foot internal volume.' Note thatthe tuning frequency is not inverselyproportional to the port area or evento the square of the port area. At first,changes in port area for a given fre-quency change seem to be inconsistentand out of proportion. For instance,the graph of the 8 -inch slot of varyingwidth has a slope corresponding to a15.5 -to -1 area change per octave, whilethe 1 -inch slot of varying length showsa 6.5 -to -1 area change per octave.

This difference arises because thearea of the port alone is not decisive.The shape of the port is involved, and

SOUND WAVES

\ \

PRESSURE MIKE

HELMHOLTZ RESONATOR

Fig. II-5-If a microphone is placedinside Helmholtz resonator, and soundat resonant frequency sweeps by, therewill be considerable buildup of sound

pressure inside.

in both graphs the shape was changing.Experiments show that for the sametuning frequency with a square port,a bigger area is used than with a slot -shaped port.

To eliminate variations due to portshape, rectangular ports having sidedimensions in the ratio of 4 to 1 wereused for each of the points plotted in

am indebted to Mr. 0. C. Schwartz, tradingas American Radio and T.V. Supply Co. ofToronto, Canada, for the use of lab facilitiesto obtain the experimental results shown inFigs. 11-6 and 11-7.

100rb

90

80

70

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35

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3 4 5 10 20PORT AREA IN SO INCHES

30 40 50 100

APRIL, 1959 93

AUDIO-HIGH FIDELITY

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AREA OF 4:1 RECTANGULAR PORT500 800

Fig. 11-7 (heavy line). This relates toa well-built cabinet with an internalvolume of approximately 6.4 cubic feet.The ports were located well clear ofother surfaces as this affects the re-sults. The experiments show that withconstant port shape, a change of portarea of between 8 and 9 to 1 is requiredfor a 1 -octave change in the Helmholtzresonance frequency.

In theory, information from onecabinet can be translated to cabinets ofdifferent volumes, if you rememberwhile scaling up or down that volumesvary as the cube, areas as the square,resonant wavelength directly and fre-quency as the inverse of the linearchange.

Another way of translating is totreat cabinet volume as equivalent toelectrical capacitance. The tuning fre-quency then drops by an octave if theinternal cabinet volume is quadrupled.

Theoretically, both ways of trans-lating should give the same answers.However, in practice they don't quiteand as the latter seems more accurateit was used to obtain the family ofderived curves shown in Fig. 11-7.From these, the Helmholtz resonancefrequencies expected from larger orsmaller cabinets with rectangular 4 -to -1 ports can be read off. In practice,results are within about 10f,', , so foran initial design the port area shouldbe made on the large side, and providedwith some kind of adjustment.

From Fig. 11-7 it will be noted that,if cabinet volume is increased and noth-ing else is changed, the tuning fre-quency drops. This will seem naturalto those acquainted with electronic cir-cuits, in which the tuning frequencydrops when the capacitance (C) isincreased. To retain the tuning fre-quency in the electronic circuit whenC is increased, the inductance (L, themagnetic inertia) must be reduced.

Port area and air inertiaWith reflex cabinets, the air -inertia

factor at the port corresponds to L.Therefore, if a bigger cabinet (moreC) is used, a lower air -inertia factor'is required to preserve the tuning. It

might be expected that the port areawould have to be reduced to obtain alower air -inertia factor and keep theair resonance frequency constant. Yet,examination of Fig. 11-7 shows that forthe same Helmholtz resonance fre-quency, a larger cabinet requires alarger port. Also, from the resultsplotted in Figs. 11-6 and 11-7, we findthat to raise the frequency (whichrequires a reduction of the air -inertiafactor) port area has to be increased.All this seems rather odd!

More air is involved when a biggerport area is used, so one might expectthat there will be a greater inertiafactor. Sometimes first impressions aremisleading and this is one of thosetimes.

The air -inertia factor, though con-cerned with the inertia of the volumeof air around the port, is also affectedby other matters. It is really a measureof the energy of motion (kinetic energy)which is tied up when a given volumedisplacement oscillates in and out atthe port.

If, instead of moving in and outthrough one port, that volume movesthrough two ports exactly like the firstand therefore through double the area,each port handles only half the air flow.With half the air flow per port, the airvelocity is halved. Kinetic energy isproportional to velocity squared whenother things are equal. So the kineticenergy-that is, the energy tied up inair inertia-is only one -quarter at eachof the two ports. The two ports togethertie up a total of only half as muchenergy as a single similar port handlingthe same total volume. The overall air -inertia factor is halved. Thus, twosimilar ports in parallel and far enoughapart not to affect one another appre-ciably resemble two similar air -coreinductances in parallel and far enoughapart for their fields not to interact.

With a single port, made by cuttingan opening into the cabinet wall, thekinetic energy of motion is tied uppartly in the slice of air occupying theport itself and partly in the surroundingair layers on both sides of the port.If that single port has its area doubled,

Fig. 11-7-Chart show-ing relationships betweenHelmholtz resonance ofreflex enclosures, portarea and cabinet volume.

those surrounding layers are not in-creased in the same proportion. Theair -inertia factor therefore does notvary inversely as the port area. But ina general way, the larger the port areathe lower is the inertia factor. This isconfirmed by experiments such as lead-ing to those Figs. 11-6 and 11-7 andthe experience that with a larger cab-inet (greater C) a larger port (reducedL) is needed to keep the resonant fre-quency constant.

So, when a large cabinet is selectedfor a certain speaker, a relatively largeport with a low inertia factor is neededfor correct tuning. If a little cabinet isselected instead, correct tuning demandsthe higher inertia factor provided bya small port.

It should not be thought that cor-rect adjustment of the port area aloneautomatically produces the best reflexsystem for a specific speaker. Thereare other ways of tuning-usingmultiple ports, ducted ports, etc. Thereis damping, and extremely importantis the fact that cabinet volume has moreeffect than just to alter the tuning.

Ideally each speaker manufacturershould issue information regarding eachof his speaker types and specify detailsof the perfect reflex cabinet to go withit. Dealer demonstrations without sucha cabinet should then be prohibited.

Unfortunately there is no such thingas the perfect reflex cabinet. Reflexcabinets are necessarily a compromise,and the commercial designer tries toproduce an overall system which is amultisided compromise between effi-ciency, unwanted hangover, responseuniformity, size, appearance, weight,cost and perhaps a few other mattersbesides. What may be the best cabinetfrom one point of view cannot be thebest from all the others. As the enthu-siast becomes more discriminating,when he obtains a different speakeror perhaps moves to a new addresswith larger rooms, the best which heonce thought so marvelous ceases tobe acceptable, and this may well ac-count for the succession of new designsthat keep popping up as the yearsroll by. TO BE CONTINUED


AUDIO-HIGH FIDELITYDO any spoils belong to the vector? A tenta-

tive answer is possible now that additionalrecords have been released by Cook Laboratoriesin the so-called Vector -Stereo process. Althoughthe idea was suggested by CBS Labs over a yearago, Cook is the first manufacturer to promotethe process in his releases. Under the Cook sys-tem, the stereo cutter incorporates a reductionof vertical component through feedback. Thefirst half dozen releases in Vector -Stereo exhibitsome of the characteristics of Cook monophonicdiscs. In all instances, output is significantlygreater and overall sound no longer has thebottled -up quality found in earlier stereo items.Comparison of the original stereo King of Organsrecord (Bill Floyd at the Paramount Theatre[New York] 1150) and the Vector -Stereo job re-vealed considerably more presence in the newrelease, especially in the upper mid -range and thehighs. The Vector record includes room noise inpassages where the first one did not. Two Vectorsymphonic albums, Brahms First (1060) andthe Haydn Military and Mozart 40th (10659),had little or no sign of compression. Unfor-tunately, review copies of these two releases haddefective surfaces. Occasional distortion still ex-ceeds that found on other labels' finest records.Hugo Winterhalter Goes LatinWinterhalter Orchestra

RCA Victor Stereo Tape CPS -156(7 -inch; playing time. 25 min. $8.95)

My first impression on hearing this item wasthat something had gone haywire in my tapemachine. The rest of the system sounded normala few moments earlier when playing stereo discs.I then switched to an older RCA tape. It wasnormal. The following day, I carried the reelto the station where I tried it on the professionalAmpex. Although flattered to some extent bythe station's monitor speakers that are alsowidely used by the record industry, CPS -156still sounded unlike any other 7.5-ips RCA tapeI had ever encountered. The middles are sopeaked that it is difficult to recognize individualinstruments. Highs can barely be heard beyondthe exaggerated mid -range. Output level is al-most double that of average tapes. Perhapssomeone goofed and applied to a 7.5 reel the 3.75characteristic of the forthcoming quarter -tracktape magazines designed for the consumer un-familiar with two -track, open -reel stereo tapes.DeFALLA: El Amor BrujoALBENIZ: El PoloSURINACH: Sinfonletto FlamencoCarlos Surinach conducting L'Orchestre

Radio-Symphonique de ParisMontilla Stereo Record FMS -2042

The first Montilla classical releases go rightto the top in technical features we now expectin stereo records. Distortion is held to a veryimpressive low. Extra mikes may account forthe warmth and presence in the woodwinds,normally a shy and retiring lot. Yet the cohe-sion of the full orchestra is never lost. The seat-ing arrangement of the players was carefullyplanned to bring out the inner sorcery ofEl Amor Brujo (Love the Magician). Surinach'sSinfonietta Flamenco, with its allusions to theflamenco music of the gypsies, also fares wellunder this setup. Highly recommended.Damiron-Piano and Rhythm

Toreador Stereo Disc TS -534The Toreador label is a lower priced subsidiary

of Montilla Records. At $3.98, it offers danceand folk music from Spain, Cuba, Mexico andother Latin American countries in stereo. Soundquality is surprisingly good, full range, fine out-put and quiet surfaces. Damiron, a Dominicanpianist, plays with authority a collection ofmerengues, mambos, sones, guarachas andboleros.

Oklahoma! (Motion Picture Sound Track)Capitol Stereo Record SWAO-595

A highly successful transfer to stereo disc ofthe movie's multiple -channel recording that fea-tures the familiar cast headed by Gordon MacRaeand Shirley Jones. Intended for professionalstereo playback in theatres, the orignal recordingtechnique is first-rate. The sound of voices andorchestra takes to the air on huge sound stagesthat are ideal for stereo.BEETHOVEN: Symphony No. 3 in E Flat fEroica)Bruno Walter conducting Columbia Symphony

OrchestraColumbia Stereo Record MS -6036

This is the second release in a major projectunder way on the West Coast. The nine Bee-thoven symphonies are being recorded in stereo

Reviewed by

Chester SantonStation WQXRNew York City STEREO and MONO

by Bruno Walter. In this symphony and thePastoral already released, smoothly spread stereoreveals his special skills. The interplay of instru-ments is guided with the sure touch of a con-ductor who has devoted a lifetime to the studyof this music. The width of the sound sourcemakes up for the slight restriction in frequencyrange that still distinguishes stereo disc frommono.

BACH: Harpsichord Concerto No. 1 in D MinorHarpsichord Concerto No. 4 in A Major

Ruggero Gerlin, HarpsichordVictor Desarzens conducting Cento Soli

Orchestra of ParisOmega Stereo Disc OSL-13

There is fresh new bite in the sound of theseconcertos. This is the first time I've heardharpsichord and orchestra in stereo. The soloinstrument emerges with far more body andcharacter than it shows in mono. Gerlin is nostranger to recording microphones. In pre -LPdays, he recorded a great deal of baroque key-board music for French labels. If proof everwas needed that Bach spoke an internationallanguage, this crisp -sounding record provides it.The soloist is Italian. A Swiss conductor leads apredominantly French orchestra. Smart Ameri-cans will enjoy it.RAVEL: BoleroBIZET: Carmen SuiteAlfred Wallenstein conducting Virtuoso

Symphony Orchestra of LondonAudio Fidelity Stereo Disc FCS-50,005

AF's first classical releases are aimed at theconsumer with component equipment. Try thebeginning of the Carmen Suite with a compliantpickup of good design. The bass drum on thisrecord goes down to the region covered by onlythe best present-day woofers. The responsereaches far below that of the bass drum on therecent Mercury stereo disc of the Carmen Suite(Paray and the Detroit Orchestra). Dynamicrange is excellent. Overall response rivals that ofa good mono disc. The miking is a bit closer thanaverage but the hall maintains the stereo spreadwith ease. There is some overload in the climaxof the Bolero. In several respects, this is themost impressive item of the month.Stereo Test Record

Audio Fidelity FCS-50,000This stereo test record is part of Audio Fidel-

ity's release devoted to classical music. One sidefeatures symphonic excerpts (mislabeled on mycopy) from companion releases. The usual claimfound on previous AF stereo discs decorates thejacket of this test record. The musical selectionsare still said to contain a frequency range ex-tending to 25,000 cycles-using the RIAA curve.Yet the test tones on this record end at 15,000cycles, and the RIAA curve is not used to reacheven that relatively conservative test frequency.It is interesting to find that the only time RIAAis used above 1,000 cycles is in the two bandsthat test channel separation. These offer 3,000cycles in the left channel and 800 cycles in theright. The procedure is reversed in the next band.Otherwise, all tones above 1,000 cycles are re-corded in phase in both channels at a constantstylus velocity of 5 cm/sec. This calls for play-back in a flat position. Frequences below 1,000

cycles, including a sweep from 70 to 15 cycles,are recorded according to the RIAA curve.Audio Test Record

Institute of High Fidelity IHF 473The institute has released to subscribers a test

record that offers a quick check of mono andstereo systems. One side (blue label) is mono;the other side (red label) is stereo. Essentiallythe same test material is found on each side.Tones include 15,000, 12,000, 10,000, 100, 70, 50and 30 cycles. Frequency sweeps cover threeareas -50 to 500, 500 to 5,000 and 5,000 to 10,000cycles. The musical excerpts represent the workof four record firms.

Note: Records below are 12 -inch LP and playback with RIAA curve unless otherwise indicated.WAGNER: Die Gott erdamerung , Act 3:

Brunnhilde's ImmolationTristan and Isolde: Prelude and LiebestodEileen Farrell, Soprano

Charles Munch conducting Boston SymphonyOrchestra

RCA Victor LM -2255The middle of the recording curve used here

is more than Wagnerian in scope. Owners ofmoving -coil pickups in particular may find thatadditional rolloff is required in the vicinity of theupper middles to tolerate the highs. Once theresponse is brought under control, the Farrellvoice is a cargo of gold riding the vast sound ofthe Boston Symphony Orchestra.TCHAIKOWSKY: Symphony No. 4 in F MinorLeonard Bernstein conducting New York

PhilharmonicColumbia ML -5332

Lessons learned in the processing of stereodiscs are being put to good use by Columbia inits recent mono records. This one is a beauty.Smoothly extended range with no recourse toartificial emphasis at either end. Bernstein's freshoutlook favors the score's inner voices.DVORAK: Concerto for Cello and OrchestraPablo Casals, CellistGeorge Szell conducting Czech Philharmonic

OrchestraAngel COLH-30

Another valued reissue of a classic of the pastin Angel's Great Recordings of the Centuryseries. Recorded in 1937 and processed formaximum range in the recent transfer to LP,the Casals tone conveys an ardor that today'splayers cannot duplicate. The recent Angelrecording by Janos Starker (35417) offers ex-cellent contemporary sound and a splendid per-formance of this warm-blooded concerto.GROFE: Grand Canyon SuiteFrederick Stark conducting Symphonic

Orchester GraunkeDisneyland Records WDL-4019

This is the mono disc version of the originalsound track of the Disney film "Grand Canyon"as recorded in Munich, Germany. The pressing,although a shade beneath today's finest, conveysmost of the characteristics of today's wide -rangeGerman recording techniques. END

Name and address of any manufacturer ofrecords mentioned in this column may be ob-tained by writing Records, RADIO -ELECTRONICS,154 West 14th St., New York 11, N. Y.

APRIL, 1959 95

SHIPPED ON APPROVAL 0an IN -CIRCUIT CONDENSER TESTER

THAT DOES THE WHOLE 4108!

The CT -1 actually steps in

and takes over where allother in -circuit condensertesters fail. The ingeniousapplication of a dual bridgeprinciple gives the CT -1 a

tremendous range of opera-

tion . . . and makes it an

absolute 'must' for every

serviceman.

IN -CIRCUITCONDENSER

TESTER merlt

Model CT -1 - housed in sturdy $I11.Thammertone finish steel case

50

complete with test leads only Net

in -circuit checks:% of all condensers

even with circuit shuntQuality of over 80resistance present

...(leakage, shorts, opens, intermiftentsi

V Value of all condensers from200 mmfd. to .5 mfd.

,. Quality of all electrolytic condensers (theabiilty to hold a

i Transformer, socket and wiring leakage capacitycharge)

out- oif -ocfi r1c0u0i t

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halel cknse:users...(leakage, shorts, opens

Qudlintermt0en4s)

ii Value of all condensers from 50 mmfd. to .5 mfd.

v Quality of all electrolytic condensers(the ability to hold a

charge)v High resistance

leakage up to 300 megohms

New or unknown condensers . -transformer, socket, compo-

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OUTSTANDING FEATURES

Ultrasensitive 2 tube drift -free circuitry Multi -color direct

scale precisionreadings for both quality and value .. Ain -circuit

or out of circuit) Simultaneousreadings of circuit capacity

and circuit resistance Built-in hi -leakage indicator sensitive to

over 300 megohms 0 Cannot damage circuit components

Electronic eye balanceindicator for even greater accuracy

Isolated power line

Check all power rectifiers in -circuitwhether SELENIUM,

GERMANIUM,

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with the

Model SRT-1-housedin sturdy hammertonefinish steel case

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IN -CIRCUITRECTIFIERTESTER MIWith the growing trendtowards compactness, porta-bility and low price, TV manu-facturers are resorting moreand more to producing series -string TV sets employing sele-nium, germanium or siliconpower rectifiers. Now the needfor an in -circuit rectifier testeris greater than ever.

THE SRT-1 CHECKS ALL POWER RECTIFIERS IN -CIRCUITAND OUT -OF -CIRCUIT WITH 100% EFFECTIVENESS FOR:1.0' Quality pa' Fading v. Shorts 1,0 Opens Arcing y Life Expectancy

OUTSTANDING FEATURES Checks all types of power rectifiers rated from 10 ma. to500 ma. (selenium, germanium, silicon, etc.) both in -circuit orout -of -circuit. Will not blow fuses even when connected to a dead short. Large 3" highly accurate multi -color meter... sensitive yetrugged.

Separate meter scales for in -circuit and out -of -circuit tests. Cannot damage or over heat rectifier being tested.

SIMPLE TO OPERATEJust clip SRT-1 test leads across rectifier under test right in thecircuit without disconnecting rectifier from circuit. Press testswitch and get an instant indication on the easy -to-read three -color meter scales ...

ALL CENTURY INSTRUMENTSARE GUARANTEED FOR ONE FULL YEAR

The extremely low prices are made possible becauseyou are buying direct from the manufacturer.

TRANSISTORTESTER Model TT -2

Every day more and more manufacturers are develop excessiveleakage, poor gain, shorts or

. in hearing aids, intercoms,amplifiers, indus-

The TT -2 is an inexpensivequality instrument

using transistors in home portable and car radios opens.

trial devices, etc. Since transistors go bad the designed for accurate and dependabletests of all

need for TRANSISTORTESTER is great. They can transistors and diodes - quickly and accurately.

Checks all transistors, including car radio, power output, triode, tetrads andunijunction types for cur-

rent gain, leakage, opens, shorts, cut-off current Checks all diodes for forward to reverse current

gain All tests can be made even if manufacturers' rated gain is not available Less than half a

minute required for tests of either transistors or diodes Large 3" meter is extremely

sensitive yet rugged ... with multi -color scales designed for quick easy readings

Power is supplied by an easy to replace 6-volt battery - current drain so small, service

life almost equal to shelf life. Battery cannot be drained due to accidental shorting of

test leads Cannot burn -out its own meter or damagetransistor or diode under test

Long test leads and insulated test clips enable tests without entirely removing tran

tor from circuit Test leads areidentified by E.I.A. color code so that connection to the

correct terminal is Comes complete with replaceable transistor set-up chart

that fits into a special rear compartment.

new type transistors as they are introduced. New listings will be furnished at no cost.

OUTSTANDING FEATURES

as

IMPORTANT FEATURE:The TT. -2 cannot become obsolete as the

cuitry is engineered to enable you to check all

Model TT -2 -housed insturdy ham-mertone finishsteel casecomplete withtest leads .only

245!

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FOR 10 DAY FREE TRIALConvince yourself at no risk that CENTURY instru-ments are indispensable in your every day work. Sendfor instruments of your choice without obligation ...

try them for 10 days before you buy ... only then, when satisfied, pay in easy -to -buy monthly installments - without anyfinancing or carrying charges added.

STILL THE BEST SELLING

1086 TESTER IN THE FIELD

ST-CHECKFA ModelTUBE TESTER

Model FC-2The greatest testi-monial ever paidan instrument ..over 20,000 soldin a little orethan a year-

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still selling asfast as we canproduce them.See for yourselfat no risk why somany service-men choose theFAST -CHECKabove all othertube testers -regardless ofprice.

Model FC-2 - housed in hand- $695°SIZE: W: 145/e"

rubbed oakH:111/4" CI: 43/s"

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plete with CRT adapter . . only Net

Just 2settings on the FAST-CHEK TUBE TESTER tests over

700 tube types completely, accuCrately - AND IN SECONDS!

PICTURETUBETESTADAPTER RANGE OF OPERATION

INCLUDED WITH FAST -CHECK ve Checks quality of over 700 tube types,

Enables you to check all employing the time proven dynamic

picture tubes (includingcathode emission test. This covers more

the new short -neck 110than 99% of all tubes in use today, in-

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at any price can match the 1, Checks for gas content.

value of the FAST -CHECK. v. Checks for life -expectancy.

IMPORTANT FEATURES

No time consuming multipleswitching ... only two settings are re-

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annoying roll chart checking . . tube chart listing over 700 tube types

is located insidecover. New listings are added without costly roll chart

replacement Checks eachsection of multi -section tubes and if only

one section is defective the tube will read "Bad" on the meter scale

41 phosphor bronze beryllium tube sockets never need replacement

7 -pin and 9 -pin straightenersmounted on panel Large 41/2 D'Arson-

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protected againstaccidental burn-out o Special scale on meter for low

current tubes . Compensation for line voltagevariation 12 filament

positions Separate gas and short jewelindicators Line isolated -

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ECONOMY MULTIPLE SOCKETTUBE TESTER without sacrificing

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MINI -CHECK TUBE TESTERModel MC -1

Here is a multiple ,-.....awAgoRAsocket tube tester de-signed to meet limitedbudgets. Although lowin price it boasts aunique circuitry thatenables you to checkover 600 tube types -and has a range of op-eration that far exceedsothers in its price class.

a 4 tift tit (10 qb

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Model MC -1 - housed insturdy wrinkle finish steel $3950case onlyNet

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0: 23/4"OUTSTANDING FEATURES Checks emission, inter

-element shorts and leakage of over600 tube types. This covers OZ4s, series -string TV tubes, gasregulators, auto 12 plate volt, hi-fi and foreign tubes 3 set-tings enable a test of any tube in less than 10 seconds Employs dynamic cathode emission test principle 31/2"D'Arsonval type meter - most accurate type available ... itsgreater sensitivity means more accuracy ... its jewel bearingmeans longer life 17 long lasting phosphorbronze tubesockets Combination gas and short jewel indicator 9filament positions Handy tube chart contained in specialback compartment New tube listings furnished periodicallyat no cost Detachable line cord

plusthese BONUS FEATURES ... foundin no other low price tube tester

1.0 Checks for cathode to heater shorts v Checks forgas content -' Checks all sections of multiple pur-pose tubes . . . will pickup tubes with one "Bad"section 1.-.0 Line isolated - no shock hazard v Var-iable load control enables you to get accurate resultson all tubes s Positively cannot become obsoleteas new tube types are introduced.

CONVENIENT TIME PAYMENT PLANNO INTEREST ORFINANCING CHARGES

CENTURY ELECTRONICS CO., INC.I CHECK INSTRUMENTS DESIRED

Model CT -1 In -Circuit Condenser Tester $34.50[ I $9.50 within 10 days. Balance $5 monthly for 5 months.

Model SRT-1 In -Circuit Rectifier Tester $29.50$4.50 within 10 days. Balance $5 monthly for 5 months.

El Model TT -2 Transistor Tester$4.50 within 10 days. Balance $5 monthly for 4

$24.50months.

Model FC-2 Fast -Check Tube Tester $69.50I $14.50 within 10 days. Balance $11 monthly for 5 months.

Model MC -1 Mini -Check Tube Tester $39.50I $9.50 within 10 days. Balance $6 monthly for 5 months.

111 Roosevelt Avenue, Dept. 104. Mineola, New YorkPlease rush the instruments checked for a 10 day free trial. If satisfied I agree to paythe down payment within 10 days and the monthly installments as shown. If notcompletely satisfied I will return the instruments within 10 days and there is nofurther obligation. It is understood there will be NO INTEREST or FINANCINGcharges added.

Name

Address

Prices Net F.O.B. Mineola, N. Y. City State

Please print clearly

LIIIII MIMI NM MI EN MN MI MO MN MN INNI NMI =I ME MI INE NM MI In IN MI Ell Ell mi .11

APRIL, 1959 97

ELECTRONICS

OLD -CATHODE

Reyolutionary

NewI. N.Heaterless

TubeBy ERIC LESLIE

AST month this magazine announcedthat the Signal Corps and Tung -Sol Electric had unveiled, at aspecial demonstration, a new tube

said to be "the first major breakthroughin tube design in more than 30 years."

Outwardly, the tube that was demon-strated is conventional in appearance-for the very good reason that it wasconstructed in an existing tube enve-lope. Its internal construction (see Fig.1) is less conventional, but old-timers

INPUTLOAD

Fig. 1-Internal construction and basicCircuit.

will recognize the space -charge circuitthat enjoyed a slight popularity for atime in the '30's, using tetrodes suchas the type 49.

It is the cold cathode that makes thistube a "major breakthrough." Almostsince the triode was invented, peoplehave wished for a tube that would notwaste power heating the cathode. Dr.Dietrich Dobischek of the Signal Corpsdiscovered in 1962 the effect that wasto lead to such a cathode. He was bom-barding a thin layer of magnesiumoxide with an electron beam, to producesecondary emission. The emission wasenhanced by maintaining a high posi-tive field near the surface of the layer.Dr Dobischek was startled to find thatthe emission continued after the bom-barding beam was turned off. The mag-nesium oxide was emitting electrons onits own, under the influence of the posi-tive field near its surface.

Experiments were immediately begunto see if the newly discovered phe-nomenon could be adapted to use inelectronic tubes. Cathodes were made ofvarious magnesium compounds (somegood ones were actually made of drug-store milk of magnesia) and improvedmethods of preparing and applying the

oxide to the nickel sleeve that supportsthe cathode layer were developed. Tung-Sol scientists concentrated particularlyon methods of making cathodes thatcould be adapted to mass production.The end result was a sprayed -on coat-ing of porous pure magnesium oxide.

When bombarded by electrons to pro-duce secondary emission, the surface ofthis layer becomes highly positive. It issuspected that this high electric chargedraws electrons from the interior of thethin layer and that an avalanche effectsimilar to that in some semiconductordevices is produced. A characteristicblue glow develops and-with the helpof the external field supplied in the newtube by the first grid-the emission con-tinues till the external circuit is broken.

This brings us to the greatest dis-advantage of the new tube-the emis-sion is not self-starting. The disad-vantage is not too serious-very littleis required to start the tube working.In the tube demonstrated, part of theB -supply power was used to light (forless than a second) a tiny filament soplaced that light and electrons emittedfrom it would strike the cathode. Otherproposed methods include mixing alittle radioactive substance with thecathode material, which would make itself-starting. Or a photoemissive ma-terial could be used, which would causeordinary light to start the action.

COLD CATHODE AF PWR AMPL

FROM

PFTEAMP-DRIVER

(A) Meter maysustaining current.

(8) Meter may be insertedcurrent.GI Emission sustaining grid.

Fig. 2-Typical circuit for cold -cathodementary switch is pressed

.05

50K

2

be inserted to measure emission

to measure plate

Once the tube has been started, itcould be maintained by a keep -alivecircuit in many types of equipment. Theemissive action continues down to lessthan .01 ;la per sq cm. A resistor in theorder of megohms around the on -offswitch would keep the tube at standby.

Another disadvantage cited againstthe tube is the high voltage -300 to 500-required to operate it. This voltagehas already been reduced in some tubes,and it is believed that tubes will bebuilt to use no more than 180 volts.

The great advantage is, of course,the power economy. In many receiverand industrial electronic applications,the heater consumes practically all thepower used by the tube. Its almostinstant starting is an important featurein many applications. And the cathodehas an indefinite life, some cathodeshaving already run 14,000 hours withno signs of deterioration. The servicetechnician will also note the impossi-bility of a cathode -heater short.

The only type so far constructed is apower amplifier tube. An amplifier(Fig. 2) using one of these soundedexactly like what would be expectedfrom similar equipment using hot -cathode tubes. The tube was also usedto operate relays at the Signal Corps-Tung -Sol demonstration. It flashedlights or closed relays in milliseconds,from a cold start.

Tung -Sol plans to put the new typeon the market as soon as a completeline of tubes is worked out. Work isalso under way on a cold -cathode elec-tron gun for cathode-ray tubes (some-thing which should bring true portabletelevisers even closer).

But the future of the new cathodematerial does not stop there. Accordingto Dr. A. M. Skellet, Tung -Sol directorof research, the material may makepossible a flat picture -on -the -wall dis-play device for TV or radar. It mayalso lead to great advances in amplifiertubes employing secondary emissionmultiplication. It may have applicationseven in the field of lighting, producinga lamp similar in appearance to presentfluorescent types, but with greaterbrightness and longer life. It wouldwork as well at 50° below zero as inthe 100° -plus of the tropics. END

OUTPUTTRANS

2W

CROSSOVERNETWORK

+300-500V

6.3V AC/DC

WOOFER

TWEETER

G2 Control grid.G3 Screen grid.

SF Starter filament.K Cathode.P Nate.

audio power amplifier. Double -pole mo-to start cathode emission.


ELECTRONICS

A team headed by electronics' most famous scientists and inventorshas developed a system for complete guidance and control ofautomobiles on the highway, now ready for a full-scale road test

Electronics Guides Your Car

By VLADIMIR K. ZWORYKIN*and LESLIE E. FLORY

URING the past 5 years we havebeen giving increased attention tothe problem of improving high-way safety through the use of

electronic controls. Our interest in thisfield has been stimulated by the obviousneed to reduce traffic accidents, andthe availability of electronic tools andtechniques which may meet this need.

The need has become increasinglyapparent as a direct consequence ofimprovements in road and vehicle engi-neering. Because they permit higherroad speeds and eliminate mechanicalcauses of accidents, the importance ofthe human driver has been emphasized.The minimal effort demanded in guid-ing a modern car along turnpikes andlimited -access roads makes it easierfor the driver's attention to stray, andinadequate reaction speed, inattentionand drowsiness have become majorcauses of accidents.

At the same time, the simplicity ofthe driving process suggests that itcan be handled by a mechanical device,much more reliable and faster -acting* Honorary vice president, Radio Corporation ofAmerica.t Research engineer, RCA Laboratories.

VLADIMIR K.ZWORYKIN

LESLIE E.FLORY

The two -tube road-side detector unitused in the Nebraskatest (left) has al-ready been replacedby more compactand reliable transis-tor equipment

(right).

-AO

within its range than the human brain.This suggestion becomes even morereasonable since miniaturization andthe transistor have put at our disposalcomponents for control devices whichexcel in permanence, compactness andlow power consumption.

In approaching the problem ofvehicle control on the highways, werecognized two basic requirements.

The first is the visualization of anultimate system of vehicle control, towhich all intermediate steps must con-tribute. The development of gadgetsto meet specific needs without a commongoal is wasteful and can retard prog-ress toward the final objective.

The second requirement is that thesystem can be introduced graduallyand compatibly. It is obvious thatneither our entire road system nor100% of our motor vehicles can beconverted to automatic operation ina single step. We must expect the co-existence of equipped and unequipped

roads as well as equipped and un-equipped vehicles for many ye4rs aftera program of automatic vehicle controlhas been initiated. Therefore, it isessential that every new road installa-tion contribute to the safety and con-venience of all vehicles, equipped orunequipped. Similarly, equipping vehi-cles with automatic control devicesmust not work to the disadvantage ofunequipped vehicles.

Does three jobsThe functions of the ultimate vehicle

control system are threefold: detection,guidance and collision prevention.

Detecting vehicles on the highwaygives the traffic -control authority com-plete information on traffic conditions.

Guidance serves to keep vehicles cen-tered in their traffic lanes, changinglanes or routes when required by exter-nal conditions or a preset program inthe vehicle.

Collision prevention involves speed

APRIL, 1959 99

ELECTRONICS

control and lane selection to preventhitting other vehicles in following apreset route.

In practice, these functions are inter-locked. The detection system does morethan provide the authorities with asurvey of the traffic situation. Its pri-mary purpose is to provide the intel-ligence to actuate the collision pre-vention system. Again, while it is thefunction of the guidance system tokeep the car in its proper course,choices between alternate courses, suchas staying in lane or switching toanother lane to pass a slower vehicle,are determined by signals which forman integral part of the collision -prevention system.

In the system which we shall de-scribe', as much of the control systemas possible is part of the road. Sincehigh-speed road systems-limited-accessroads and turnpikes-are under con-tinuous skilled supervision, this seemspreferable to concentrating the equip-ment in the vehicle. We can visualizethree stages in the development of thesystem.

In the first, only the roadway ismodified-the vehicles are completelyunequipped. Detectors in the roadwayactuate warning lights on the side ofthe road which warn the driver of acar ahead of him in his own lane or ofvehicles approaching in the oppositedirection (Fig. 1). Such arrangementsare especially valuable where visibilityis obscured by a curve, a hill or someother obstacle and should be equallyuseful in areas subject to fog, smog,etc.

With the next stage, in which visualor auditory indicators are installed inthe vehicle, the scope of the system isgreatly extended. The detector systemin the roadway now excites a "flyingtail" of electromagnetic warning sig-nals behind every vehicle on the road,which is picked up by radio receiversin vehicles following in line. The re-ceiver translates the flying tail into 'awarning indication within the car,which replaces or supplements warninglights installed along the roadside. Thesignal within the car has the obviousadvantage of being uninfluenced byexternal weather conditions and poorvisibility.

Also, the signal which warns thedriver he is getting too close to anothervehicle or obstacle may be supple-mented by a second indication showinghis position with respect to the centerof the lane. Thus, an auditory signalindicating departure from the center ofthe lane reduces the hazards of drivingunder conditions of poor visibility.

In the final, fully automatic stage,the collision -prevention signals actdirectly on the accelerating and brakingsystems in the vehicle and the guidancesignals control the steering. Thus, aslong as the vehicle is on the electron-ically controlled road system, the driver

I Developed by a research group including theauthors and Winthrop S. Pike and George W.Gray of RCA Laboratories.

WARNING LIGHTS

0 / ../ //.../ /O /- /....../// // /

1/ ///. //

DIRECTIONCAR

4- 4-

\ \N. 4. \

\ \c\\

"Nc.'

ti J

LO

Fig. 1-An application of the electronic highway -control system for which nospecial equipment is required in automobiles. The diagram represents an overheadview of a curve in a three -lane highway. The approach of a vehicle in the centerlane causes a sequential series of warning lights to flash on around the curve aheadof the car, warning approaching vehicles that the center lane is occupied. Dottedrectangles in center strip represent electronic detector units buried in the highway.

DIRECTION OF TRAVEL..<___

DETECTION SYSTEM ROAD WARNING SYSTEM ROAD AREA GUIDANCE SYSTEM/SHOULDER

ACABLE TAIL ANTENNA ,.. --DETECTOR LOOP

,-----1 t--- -i r----- ---z'

I1 1

I I II It

- LI 1 1

f-- '-'I 1---i r:_L-CON_,-I CONTROL 1 4 CONTROL I DET CONTROL TROL uii_TTi_i 1-Tr1-1 Trr J H Tr j

DET

1LOOPS=

DET DET CONTR

r11-_. -I --I I - I.

RF SUPPLY CABLE

DET

Fig. 2-Basic elements of the electronic control system.

is relieved of his responsibilities andthe vehicle proceeds along a presetcourse. When the vehicle leaves thecontrolled road system, it shifts fromautomatic to manual control. The situa-tion is essentially similar to the pilot-ing of long-range aircraft, where theautopilot may take over except neartakeoff and landing.

Of course, for many years thesestages will overlap, with cars in allstages of automation using the high-way simultaneously.

How if worksAfter this very brief description of

the vehicle control system, let usexamine its practical realization. Takea look at the road installation. A sim-plified diagram of a short, straightsection of a single lane is shown inFig. 2. Here we see the detection,warning (or collision -prevention) andguidance systems.

The most conspicuous element of thedetection system is a sequence of rec-tangular loops, about the length of acar, which are inserted in the hardtopand form part of detection circuitswhose active components are buried incapsules by the side of the road. Theloops can be installed quite simplyduring road construction and have been

installed experimentally in existingroads by using a diamond -saw tech-nique. Detector units used up to nowhave two vacuum tubes. Replacingtubes with transistors in new units nowbeing designed will reduce power con-sumption and increase reliabilitygreatly.

When a vehicle passes over a loop, itchanges the loop's inductance. Thischange, acting through the detector,gates the roadside control unit so thatwarning signals are fed to a sequenceof antennas buried in the roadway andextending some distance behind thevehicle in question. These signals, whoseamplitude decreases as their distancebehind the vehicle increases, constitutethe "flying tail" for warning followingcars. The same signals may also actuatewarning lights by the side of the road,either behind the car or ahead of it.Fig. 3 illustrates the flying tail concept.

Power for the detection units and theflying -tail signals is supplied by a cablecarrying high -frequency currents, bur-ied alongside the road. However, thesecurrents themselves, tranmitted withan amplitude determined by the open-ing or closing of the detector gates,must not serve as the warning signal.Otherwise a failure in the road instal-lation which would suppress the flying


tail altogether might be wrongly inter-preted as a clear road ahead.

The difficulty is avoided by feedingthe high -frequency currents continu-ously to the flying -tail antennas andimpressing a suitable modulation onthem through the detector gate. Thereceiver on a following vehicle will inferthe distance from the source of themodulation from the modulation factorof the high -frequency carrier and cor-rectly interpret the absence of the car-rier as a system failure.

What about the danger of rear -endcollision if a vehicle stalls on theelectronic highway? The flying tailwhich extends behind the vehicle keepsoperating, even when the vehicle stops,providing an automatic warning to thefollowing cars. In the completely auto-matic system, this warning would bepicked up by a receiver that wouldactivate the brakes or steering mecha-nism of the following car, causing iteither to stop or steer around thestalled vehicle by changing lanes.

Provision may also be made for anoff switch that would let the driver ofthe following car cut off the automaticsystem and take control of the car him-self to steer around the obstruction. Asan additional safety factor, the com-plete system would include a supple-mental warning in case another carwere approaching in the passing lane.

The guidance system forms the lastpart of the road installation. Along astraightway it can take the form of acable laid in the center of the lane,using the same construction techniquesas for the detector loops. This cablemay carry a high -frequency current ofa frequency different from that of theflying -tail carrier although in a modi-fication of the system the two functionsmay conceivably be combined.

Equipment in the vehicleLet us now turn to the equipment of

the vehicle. It must he stressed thatessential equipment in the vehicle ispassive. It consists of sensing devices

which are linked, either through thedriver or directly, to the vehicle's me-chanical controls. No signals are trans-mitted by it. The car influences follow-ing vehicles only through its presence,which, through the detectors in theroadway, modifies the electromagneticfields radiated by the buried antennasfor some distance to the rear-formsthe flying tail. It follows that theflying tail of warning signals will beformed behind any car or similar ob-stacle, regardless of its equipment orwhat the driver does.

In early stages, the vehicle's equip-ment could be detachable and be in-stalled in the car at the entrance gatesto the controlled road system. Of course,more advanced equipment would neces-sarily form part of the vehicle con-struction.

The warning signal detector consistsof an antenna attached to the under-carriage of the vehicle and a radio re-ceiver whose rectified output may con-trol a buzzer, warning light or otherdashboard indicator or, in a fully auto-matic system, the car's power brakes.Automatic gain control makes the out-put signal independent of the preciserelative location of the detecting an-tenna and flying -tail antennas in theroadway, and makes it proportional tothe depth of modulation impressed bythe presence of the obstacle on the high -frequency field. The warning and brak-ing signal amplitude may, in addition,be amplified in a manner dependent onthe speed of the vehicle and upon itsspeed relative to the obstacle. Thelatter may be derived from the rateof change of the flying -tail signal. Thus,car spacing is controlled by the actualas well as the relative speed of thevehicles. In addition, the overall modu-lation may be adjusted from the high-way, permitting external control ofspacing to conform to traffic or high-way surface conditions.

In past experimental installations,the guidance signal has been obtainedfrom two tuned antennas mounted on

ELECTRONICS

the left and right sides of the frontbumper. As the car deviates to the rightor left of the lane's center, the currentinduced by the field of the guidancecable in the left antenna exceeds thatinduced in the right antenna and viceversa. The difference in the rectifiedsignal from the two antennas controlseither an indicator in the car or, in anautomatic system, the hydraulic controlvalves of the steering mechanism.

Thus, with properly stabilized servocontrols, the car proceeds down thecenter of the lane without wavering,unless the driver takes deliberate actionwhich supersedes the automatic guid-ance mechanism.

Aural instructions to driverThe high -frequency carrier current

in the guidance cable permits voicecommunication from highway controlstations to the driver without any addi-tional road installation. Thus the drivercan be informed of route numbers,destinations and other pertinent dataas he approaches an intersection. Warn-ings of weather changes, unfavorableroad conditions and hazards along theroute may contribute to traffic safety.Voice modulation of the guidance signalmay also be used to transmit importantnews flashes and emergency orders andeventually, information regarding com-mercial facilities in the area, such asmotels, restaurants or service stations.

Similarly, the detectors may do doubleduty as traffic counters and speed con-trollers. For instance, circuits measur-ing the time interval between the trig-gering of successive detector units cancontrol illuminated signs informing thedriver (and others) that he is exceed-ing the speed limit. In a more sophis-ticated system, the warning may equallywell appear inside the offending carand, if desirable, might be used as acontrol signal to set the maximumspeed.

Still another function is the timingof traffic signals at intersections so

(Continued on page 104)

Fig. 3-Illustration of the "flying -tail" warning signals that extend behind movingvehicles.

---.1A4,"...".......er.v....r.................*,................-...-. - - ----- 2_,Z._:-. ' ' . . - - ' .. ... .. .

......

.A.* 2...."___-.---::-----:"1 ' ., I

---...........

.,

141444

APRIL, 1959 101

WHEN CUSTOMERS ASK

RC

RCASilverama

SILVERAMA is RCA's premium picture tube --that means tops in the industry! Manufacturedwith all -new glass and parts, it's the finest pic-ture tube made-for the customer who prefersand expects the very best.

Command premium price and profits! SellRCA SILVERAMA with assurance that you aredelivering a completely all -new picture tube.

A CHOICEOF -RCA PICTURE

TUBES 'TO MEET THE

OF TWO MAR

DEM AND

KETS

lwant the best that

f your customers

money can buy,offer them RCA.

SILVERAMA..the picture tube that's

ALL-NW through and through.lfthey

want the economyof a rebuilt tube, offer

them RCA'MONOGRAM

..ther's no

finer rebuilt made. Either way, you pro-

vide the quality assuranceof the RCA

name...areal quality

choicefor your

custorners...areal opportunity

for you

to simplifyboth your buying

and selling

by offeringthe best in TV picture tubes.

IS

provides you

GET FULL DETAILS FROM YOUR AUTHORIZED RCA DISTRIBUTOR TODAY


IT NEW OR REBUILT?

with a positive answer!

RCAMonogram

RCA MONOGRAM...no finer rebuilt picturetube made. Factory -rebuilt by RCA to qualitystandards, this tube assures dependable perform-ance and fewer call-backs. It is backed by a brandname you sell with confidence-a brand nameyour customers buy with confidence.

Yes, top rebuilt quality at economy pricesmakes RCA MONOGRAM your best buy forpicture tube replacements where price is the pri-mary consideration.

BACKED BY THE GREATEST'PRE-SELLINGCAMPAIGNIN PICTURE

TUBE xxsToRr!To makesure your customers

know thefull sake

all the advantagesof

using either RCA SILVERAMAor

RCA MONOGRAMfor replacement

inATV set, there's

a big, big advertis-ing program

scheduledby RCA.Hard-hitting

ads thatpre -sell for you

are appearingin LIFE,

SATURDAY

$and TV GUIDE.

You'll seehard -selling commercials

on top TVshows.

You'll hear reradioradio commercials.And your RCA

dis-tributor

can supplyyou with everything

Your own ad rnats.

you need...fromwindow

displaysto

ifirA RADIO CORPORATION OF AMERICAElectron Tube Division Harrison, N. J.

APRIL, 1959 103

ELECTRONICS

A

TUBE PROBLEM:An amplifiermanufacturer wasplagued by noise,microphonics and humthat developed in thehigh gain stages of hisamplifiers. Sonotoneengineers wereconsulted on theproblem.

SONOTONESOLVES IT:Sonotone engineersdiscovered that theycould correct all threecomplaints byredesigning just onetube.

RESULTS:The heater elementwas changed to a coilheater, eliminatingthe hum. And rigidcontrols on the mountstructure andprocessing reducedmicrophonics andnoise. This resulted inthe Sonotone reliabletype 7025. It's nowavailable for initialequipment andreplacement purposes.

Let Sonotone helpsolve your tubeproblem, too.

Sonotone C0® P.

Electronic Applications Division, Dept. TE-49

ELMSFORD, NEW YORKLeading makers of fine ceramic cartridge; speakers, micro-phones, tape heads, electron tubes.

In Canada, contact Atlas Radio Corp., Ltd., Toronto

COMPUTER

HYDRAULIC POWER -STEERINGSYSTEM

POWER SUPPLY

CONTROL VALVE

PICKUP COILS

MAGNETIC FLUXLINES Ili

/

ROAD CABLESTEERING ACTUATOR

VELOCITY TRANSDUCER

POSITION -SERVO TRANSDUCER

Fig. 4-Automatic steering equipment used by General Motors in test of the RCAguidance system. Glove compartment control -center computer is fed data on carlocation (from difference of voltages induced in pickup coils), wheel angle (fromposition servo transducer) and speed (from velocity transducer). When pickup -coil voltages are unequal, it develops a "command voltage" which activates thecontrol valve, adjusting the angle of the wheels through the conventional hydraulic

power steering system.

(Continued from page 101)green -light periods for the two roadsare always proportional to the flow oftraffic along each. Their use for push-ing a row of lights ahead of a vehicleapproaching a hill or curve to warnvehicles proceeding in the opposite di-rection against passing has alreadybeen mentioned. Other applications, ofvalue particularly in the early stagesof the system's development, will beapparent to anyone faced with prac-tical problems of traffic control.

The basic features of the vehicle con-trol system which we have describedhave recently been tested and demon-strated in cooperation with Mr. L. N.Ress, State Engineer of Nebraska'sDepartment of Roads. The road instal-lation was made on a 300 -foot sectionat a newly constructed intersection inLincoln, Neb.

The demonstration covered the oper-ation of the vehicle detectors with bur-ied loops, the tail warning system em-ploying both lights and radio signals,and the guidance system. Dashboardindicators permitted a manually con-trolled car to be driven safely along thelane's center, adjusting its speed to thatof preceding vehicles, even when thewindshield was completely covered tosimulate automatic -control conditions.

A similar system with automaticsteering control of a standard 1958Chevrolet has recently been demon-strated along a 1 -mile check track at theGeneral Motors Technical Center inWarren, Mich. The guidance cable hadbeen inserted in the road surface bythe diamond -saw technique alreadymentioned. The electrical signals de-rived from two bumper -mounted pickupcoils controlled the steering by means ofa hydraulic power piston (Fig. 4).

The results of these and earlier testshave confirmed our belief that a largemeasure of automatic control is tech-nically possible. Furthermore, we areconvinced that it is essential if the

The electronic techniques developed sofar indicate a way to realize the de-sired objective. However, an optimized,workable system demands the cooper-ation of many groups, including as aminimum, highway engineers, auto-mobile manufacturers and the elec-tronics industry.

The results of their efforts must betested on an enlarged test facility per-mitting the operation of controlled ex-perimental vehicles at normal speeds.In this manner we can determine theoptimum length and shape of the flyingtail, the preferred dimensioning of thedetector loops, the best ways of gener-ating and applying the control signalswithin the car and many other factorswhich must be known before vehiclecontrol systems are installed on publicroads. Clearly, much remains to be done.The urgent need to reduce the accidenttoll on our highways demands that thework get under way. ENDThis is the second article of a series on highwaysafety and electronics, the first of which ap-peared in January. The next will appear in anearly issue.

ADVANCE ANNOUNCEMENTThe 14th Annual Old -Timer's Nite

Round -Up and Banquet will be heldSaturday, April 18, 1959, in the GrandBallroom of the Hotel Stacy -Trent indowntown Trenton. The party will bestag and a turkey dinner will be served.Contact Ed G. Raser, 19 BlackwoodDrive, Trenton 8, N. J., for details. Thesponsor is by the Delaware Valley RadioAssociation.


-or your money backThe Master Course in Electronics will provide you with the mentaltools of the electronics technician and prepare you for a First

Class FCC License (Commercial) with a radar endorsement.When you successfully complete the Master Course, if you failto pass the FCC examination, you will receive a full refund ofall tuition payments.

"License and Good Job . . . Thanks""After finishing your Master Course, I passed theFCC exam for the 1st class license. I had my ticketfor only one week and I got a job at WOC-TV,AM -FM. Incidentally, WOC is the oldest radio sta-tion west of the Mississippi. I sincerely feel that ifit weren't for taking your Master Course, I wouldnot have received my 1st class ticket. So I want totake this occasion to again thank you for such afine, complete and composite study for electronicswork." Francis J. McManus

Davenport, Iowa

Cleveland Institute training results in job offers like these:

Service Technician:Man needed in Cleveland, Ohioto service and maintain electronicmedical instruments and equip-ment. Must have a solid knowledgeof electronic fundamentals. A caris required. Company benefits in-clude retirement plan.

Radio Operators & TechniciansAmerican Airlines - Chicago, De-troit, St. Louis, Cincinnati andCleveland-has openings for radiooperators and radio mechanics.Operators musf have a 2nd classFCC license and ability to type40 wpm. Many company benefits.

CLEVELAND INSTITUTE OF RADIO ELECTRONICSDesk RE -28 4900 Euclid Avenue Cleveland 3, Ohio

We guarantee Mail Coupon Nowto train you until you receive

Your FCC license and get all three FREEWe can train youto pass your Li-cense Exnms ifyou've had anypractical ex-aerienee

amateur, mili-tary, radio ervic-ing. or otter. Ourproven plan canhelp put yod on theroad to success.

Opportunities

in Electronics

for You

Accredited by the National Home Study Council

Cleveland Institute of Radio ElectronicsDesk RE -28,r 4900 Euclid Ave. Cleveland 3, Ohio........ NE

Please send Free Booklets prepared tohelp me get ahead in Electronics. I

have had training or experience inElectronics as indicated below.E MilitaryE Radio -TV ServicingE ManufacturingE Amateur RadioIn what kind of work areyou now engaged?

Your FCC ticketwill be recognizedby employers asproof of yourtechnical ability.

good train, ngdoesn't cost. . . it pays!

E BroadcastingEl Home ExperimentingE Telephone Company

OtherIn what branch of Elec-tronics are you interested?

Name Age

Address

City Zone StateRE -:?R

APRIL, 1959 105

Precision cutting... a simple jobwith the new

SK -2

SHAFT -KWIC

TOOL

Now you can cut controls andcontrol the cut . . . precisely and exactly.CENTRALAB'S Shaft-Kut Tool is a precision instrument, guaranteed

to make a really simple job of cutting shafts to the exact size you need.

With this tool you can cut any single or dual control ... or switch shaft,and get cuts that are accurate to !6th of an inch! The tool and calibratedjig are made of case hardened tool steel, designed to last a lifetime.

You can't make a wrong cut with the CENTRALAB Shaft-Kut Tool! And theprice is less than half what you'd expect to pay for a precision device of thiskind ... a low $4.95 dealer net. Ask your distributor to show you how easyit is to use this new tool.

Cen8-5931

A DIVISION OF GLODEUNION, INC.9220 E. KEEFE AVE. MILWAUKEE 1, WIS.

IN CANADA: 804 Mt. Pleasant Rd. Toronto 12, Ont.

CONTROLS ROTARY SWITCHES CERAMIC CAPACITORSPACKAGED ELECTRONIC CIRCUITS ENGINEERED CERAMICS

NEWT

TUBES

7SE1111-

COI1DOCTORS

All-""="THE past month has provided us

with an array of new units. Keep-ing step with transistor develop-ment are three vhf Mesa tran-

sistors. A high -frequency junctiontransistor, switching transistors and a21 -inch 110° picture tube are listed.

2N660A high -frequency p -n -p fusion alloy

junction transistor for computer andswitching applications.

BASE

EMITTER COLLECTOR

.200"2N660

Maximum ratings of the Raytheon2N660 are:

VCB 25VEB 12

VCE 1 1

VCE ( VBE = O. 1 ) 16

Ic (amp) I

Average characteristics at 250°Care:

hFE 65 (lo = 10 ma, VCE = 0.35)fan (mc) 15

2N670A p -n -p germanium alloy junction

transistor intended for use in high -voltage pulse -amplifier and high -cur-rent switching circuits.

BASE

EMITTER COLLECTOR

.200"

ACTUALSIZE

II (APPROX)2N670 I a

EMITTER CONNECTED TO CASE

Maximum tentative ratings of thePhilco 2N670 are:

VCB 40VCE ( VBE = 1.5) 40VEB 40Ic (amps) 2

Pro., (mw) (25°C) 300Typical electrical characteristics at

250°C are:hr. 100 (VcE = 1.5, Ic = I amp)fan (kc) 650 (Vat = 2, Ic = 100 ma)

6E395, 8BQ5Power pentodes in a 9 -pin miniature

envelope intended for use in the audiooutput stage of radio and television


NEW TUBES & SEMICONDUCTORS (Contra')

P

IC

61305,813Q5IC.INTERNAL CONN (DO NOT USE)

receivers and in phonographs. The6BQ5 has a 6.3 -volt 760 -ma heater.The 8BQ5 has an 8 -volt 600 -ma heaterwith controlled warmup for use inseries -string heater circuits. All otherspecs hold for both tubes. The 6BQ5 isan exact replacement for the EL84.

The 6BQ5 and 8BQ5 are made byRCA. Maximum ratings in class -Alamplifier service are:

Vr 300VG2 300V01 (pos bias value)IK (ma) 65P, (watts) 12

G2.Kpur (watts)* 2

*must not exceed 4 watts under maximum -signal conditions.

2NI 141, -142, -143Three p -n -p germanium high -fre-

quency Mesa transistors featuringalpha cutoff frequencies up to 750 mcand power dissipations of 750 mw.All are designed for reliable rf opera-tion in the vhf range.

EMITTER

BASE

2NI1412N11422N 1143

COLLECTOR

.200"

Maximum ratings of these TexasInstruments transistors are:

VCE

VEB

Ic (ma)Is (ma)Prow (mw)

Typical characteristics at 25°C are:2N1141 -42 -43

fab (mc) 750 600 480(db) 12 10 8

(VoK = 10, lc = 10 ma, f = 100 mc)

2 1EQP4Another addition to the line of 110°

picture tubes, the 21EQP4 is a 21 -inchrectangular glass tube made by Syl-vania. It has a spherical faceplate,aluminized screen and a straight gun

G3 WO..ULTOR

GI

2N1141 -42 -4335 30 25

0.7 0.5100 100 100100 100 100750 750 750

(OUTER CONDUCTIVECOATING)

IC( INTERNALCONN)

21E0 P4design which needs no ion trap. Its6.3 -volt 600 -ma heater has an 11 -second controlled warmup for use inseries -string heater circuits.

Maximum ratings of the 21EQP4 are:

a real sweet combination....the new

FASTATCH FDIC -100Dual Control Kit

with theCert R,ab®s K-2

Shaft -Hut ToolPELEE!

If you have a birthday any timethis year, CENTRALAB has a present for youNOW ... a real money -saving offer that givesyou a $41.90 value for only $32.70.

This $9.20 saving is yours when you buy thenew CENTRALAB Fastatch FDK-100 Dual Con-trol Kit and SK -2 Shaft-Kut Tool combination.The handy kit contains 24 controls and 9switches-that let you quickly snap togetherany of 720 different dual control combinations.

The Shaft-Kut Tool assures you of precise con-trol or switch shaft length . . . accurate to ;4thof an inch. It is available separately, at $4.95,actually less than half the price you wouldexpect to pay for it.

So don't waste any more time with special tripsto your distributor when you need a dual -concentric. Have the control you need at yourfingertips with this wonderful kit -and -tool com-bination. But don't delay ... this money -savingoffer is for a limited time only!

116 5940

al!),

HERE'S WHATYOU GET

REGULARPRICE

24 controls and 9 switches $32.70all factory assembled and tested

Sturdy steel cabinet 4.25

Shaft-Kut Tool 4.95

Actual value $41.90

You get all this for $32.70-the costof the controls alone! The Shaft- KutTool and steel cabinet are FREE!

A DIVISION OF GLOBE -UNION, INC9220 E. KEEFE AYE. MILWAUKEE 1, WIS.

IN CANADA: 804 Mt. Pleasant Rd. Toronto 12, Ont.

CONTROLS ROTARY SWITCHES CERAMIC CAPACITORSVulfor 20,000 PACKAGED ELECTRONIC CIRCUITS ENGINEERED CERAMICS

APRIL, 1959 'I 07

How to make

Your HI-FI

LOOK AS GOOD

AS IT SOUNDS!

Your system probably sounds beautiful-but if you live in a jungle of dials, wires,lights, and boxes-you're not really happywith it. But you can be-and this bookshows you how.

If you want to design and build, yourself,it tells you how-from choosing the righttools on up. If you want to buy-it tellsyou what to look for. If you want to havea cabinet custom built-or work withkits, it helps you there too. It explainsdesign principles, types of wood, furniturestyles, finishing, care and room arrange-ment for better appearance-and listen-ing. Every hi-fi fan should own this one tomake his system look better-and soundbetter.

SAVE $1.25 ON THIS DELUXE BOOK!

You can buy DESIGNING AND BUILDINGHI -Fl FURNITURE and other luxuriously-

DESIGNING and BUILDING

HI-FI FURNITUREBy Jeff Markel!.

Deluxe gold stamped $5 00hard cover editionbound $5.00 books for only $3.75-a sav-ing of 25%-through the G/L Hi-Fi BookClub. Build a complete hi-fi library-onebook at a time with no budget strain-and no risk. Look each book over in yourown home before you buy. Keep and payonly for the books you want.

The greatest boon to hi-fi fans since LPrecords!

JOIN NOW, select DESIGNING AND BUILDING HI-FI FURNITURE orof these books already published.AUDIO MEASUREMENTS-By Norman H.Crowhurst. Covers audio measurementsfrom service shop to laboratory level.Shows how to make tests, what instru-ments to use, how to interpret results.H. A. HARTLEY'S AUDIO DESIGN HANDBOOK

-This expert explains design principlesso the non -engineering hi-fi fan candesign his own equipment.

ELEMENTS OF TAPE RECORDER CIRCUITS-

By Herman Burstein and Henry C. Pol-lak. Answers all your questions aboutthe electronic aspects of a tape re-corder. What to look for when you buy-whatvarious types will and will not do.

any one

MAINTAINING HI-FI EQUIPMENT- ByJoseph Marshall. Covers the specializedtechniques necessary to repair hi-fiequipment. Includes acoustical and me-chanical as well as electronic faults.UNDERSTANDING HI-FI CIRCUITS-ByNorman H. Crowhurst. Now have thesystem best suited to your tastes-andbudget. Crowhurst tells you whichphase inverter is best, weighs fixed vs.self bias, triode vs. pentode, answershundreds of other questions.BASIC AUDIO COURSE - By Donald C.Hoefler. Explains everything aboutaudio from the theory of sound to discand tape recording techniques.

HOW TO JOIN THE 0/1 AUDIO -HI Fl BOOK CLUB

Select one book from those listed on the coupon. SEND NO MONEY-we will send you the book on approval. If you like it send your

remittance for the special club price of $3.75. New books are released about every four months. You receive these automatically

on the same no -risk plan.

You may cancel any time after you have accepted four books-no time limit.

MAIL THIS COUPON NOWGernsback Library, Inc., Dept.49 C154 West 14th Street, New York 11, N. Y.

Enroll me in the G/LAUDIO -HI Fl BOOK CLUB.

Send me the book checked on approval.(Please check one only)

Nome

Street

City

O Designing and Building Hi-Fi Furniture

O Audio MeasurementsO Audio Design HandbookO Elements of Tope Recorder Circuits Maintaining Hi-Fi Equipment Understanding Hi-Fi Circuits Bosic Audio Course

please print

Zone Stole

OM

NEW TUBES & SEMICONDUCTORS (Coed)

V93

V92

V91 (neg bias value)

700700154

(neg peak value) 220(pos bias value) 0(pos peak value) 2

R51 c.r..i (megohms) 1.5

2N561, 2N1014Germanium, p -n -p, alloy -junction

power transistors for applications inpower -switching, voltage -regulator,multivibrator, dc -to -dc converter andpower -supply circuits. They may also

EMITTER

30'

BASE

2N56I,2N 1014

COLLECTORCONNECTED TOMOUNTING FLANGE

be used in audio oscillator service andin large -signal class -A or class -B push-pull audio amplifiers.

Typical ratings of these RCA tran-

500PULSEGEN

2N561,2N1014

560 OUTPUTVOLTAGE

28V

sistors in an on-off powercircuit (see diagram) are:

R9 (ohms)R,,,, bias (ohms)RL (ohms)IB (turn -on) (ma)

(turn-off) (ma) 0

Switching time:Ton (psec) 140

(usec) 110On condition:

Ic (amp) 0.49VBE 0.36VCE 0.25Pdriving (mw) 2.34

(mw) 123Power gain (db) 33.7Efficiency (%) 99.3Poo (watts) 13.1

The 2N1014 differs from the 2N561in that it has a higher maximum peakcollector -to -base and collector -to -emittervoltage rating.

VCB ( peak)VCE ( peak)

281.5

5015056

6

2NI014 2N56I100 8065 50

END

CORRECTIONThrough a printer's error, there are

discrepancies between the diagram,parts list and text of the article "Duo -Rectifier Power Supply" on page 49 ofthe February issue. The values of R10and R11 are correct on the diagramand incorrect in text and parts list.

We thank Mr. Sidney Wolin, FortWayne, Ind., and others for callingthis to our attention.


`REAL z Z. AC/

Here's WhyRADIO SHACK'S 1959SOLO Speaker Is WorthTwice Our Price!

If made in this country, Radio Shack's exclusive "SOLO"speaker system would cost more than twice its low price.Here at last is a VERY SMALL SPACE HI-FI speaker withreal lows and clean highs. It's designed by the same RadioShack engineering staff that created the world famousELECTROSTAT-3 tweeter. And its magnificent performanceis matched in appearance by its handsome furniture -finished dark mahogany enclosure with blending grill.Size 141/2" x 11" x 101/2" deep; 8 ohms to match any hi-fi ampli-fier, console or TV set; sealed back with terminal strip; cabinetfinished on four sides for horizontal, vertical or suspended use;2 runners of matching mahogany included; response is 50-14.000 cps. Quality -wise, space -wise and budget -wise . . .

there's no other speaker to compare with our "SOLO"!

The World Famous5,000-25,000 cps

TWEETER

REAL/S*77C"ELECTROSTAT-3"

$27.50Radio Shack's REALISTIC ELECTROSTAT-3 adds anew acoustic brilliance to any speaker system ...smooth, silky response from 5,000 cps to beyondthe range of human hearing. It's the tweeterthat's been getting the rave notices . thetweeter the whole world wants most, regardlessof price. Mahogany, blond or walnut finish,Size 111/4" wide x 51/4" high x 41/2" deep.

REALISTIC ELECTROSTAT-3 CROSSOVER NET-WORK KITS include coils, condensers and Lpad, complete with simple assembly instruc-tions. Either 8 or 16 ohm kit .... each $4.95

/ifEALASTIC"SOLO"$15.95

2 for Stereo $29.50

Heavylaminatedmahogany

cabinet

Ultra -compliant suspension conespeaker consisting of a woofer witha coaxially mounted "whizzer "

/ Tuned, vented, duct -type enclosure. . . Helmholtz resonator . . . espe-cially designed to extend the rangeof the SOLO with REAL lows

Iit AEA L IS TIC

"TRIO"$44.50

2 for Stereo$79.50

Radio Shack's REALISTIC "TRIO"is a magnificent 3 -speaker system

that compares brilliantly with $100 systems. and includes features no other speaker system

has . . . such as the patented center -mounted acoustic cut-off filterin the 8" woofer. This provides clean lows without h -f interference.

The superbly engineered dual tweeters have a smooth wide range andare mounted at offset angles for dispersing the sound uniformly in all

directions. In addition to being solidly encased, they are so mountedthat they may be rotated 90° for maximum effectiveness in either up-right or lowboy positions. Dual hipass filter; response 35-17,500 cps;

8 ohms: laminated dark mahogany furniture -finished on 4 sides; size22,/2" x 13" x 111/2" deep; complete with 2 separate, matching runners.

ExtraheavyAlnicomagnet

Acoustic\ lining

throughoutfor clean

sound

Ask for our 64 -pageHI-FI BUYING GUIDE --

17/0 sw.iticArCORPORATION

167 Washington St., Boston 8, Mass.STORES 3 730 Commonwealth Ave., Boston 17, Mass.

230-240 Crown St., New Haven 10, Conn.

RADIO SHACK CORPORATION, Dept. 4E730 Commonwealth Ave., Boston 17, Moss.

Please send me the following:Quan. REALISTIC Sh. Wt. Order No. Sale

SOLO Speaker 12 lbs. 90LX250 $15.95TRIO Speaker 25 lbs. 90LX210 44.50ELECTROSTAT-3 7 lbs. 36CX017Y 27.508 -Ohm X -Over 2 lbs. 91L500 4.95

Radio Shack 1959 Hi-Fi Buying Guide Check Money Order C.O.D.Name

Address

City Zone State

APRIL, I 9 5 9 109

POSTAGE STAMP MIKEtO ti.111111

88cIten75 -FT. TV TWINLEAD

Ranked. "IIIleg.1;':Ni0. ".. 88c10 ELECTROLYTICS

t!;"1.1gi, T,N;,Reg. $12.

60 RADIO -TV KNOBS

ea. 2 lbs. 88c!tea. $17.4 POWER WOOD BITS til!-QReg.

long- ggc$3.10 TUBULAR ELECTROS Art4..per types. AC

" "k 3 88c111S. Reg. $1 4.20 ARTISTS' BRUSHES Si r pure bristle;

$2.50es 1.6. Reg. 88c.

75 MICA CONDENSERSle I 2111,

value s'.. Reg.. $21-1. 2' 88c15 -PC DRILL SETO V16" 419u by

brat er143!.ahs'e It/e'3.;'.11-113. 88c75 RESISTOR SPECIAL!

carbon.le tYlles

:3 lbs. 88cWorth $15.60 CONDENSER SPCLI

P

P;7 !..

2 Ihs7 ROLLS WIRE

88c2 lbs It. t1500 PCS. HARDWARE

"'IBCReg. 86.6 -PC. HACKSAW SET

88c70 TERMINAL STRIPSD Veoldg2 lbs.

60 COILS, CHOKESintl., slug-

tI227.. SIT: 3 88c300 -FT. HOOKUP WIRE

sizes.

Reg. 75. 88c100 HALF-WATTERS

ttt.,.:Itt. vats,- ,:111,..11 I tslsturs5"//r

. 88c

30 MOLDED COND'S'RS88c

15 ROTARY SWITCHES0 ;;;-- 88c

Reg. $5. 88c10 PANEL SWITCHESn Asstd. 115VAC. power,LJ SPSTDPST. DPOT. 2 lbs. 88cReg. $540 SUB -MINI RESIST'RS

" 1031g.2U values:I to 1,1 mess. 88c

Reg. Sti5" HOBBY SPEAKER

For rod los. eotle °se..Intercoms. 2 lbs. 880Reg. $5.TEN 3 -SECOND TIMERn Mechanisms: Precision" geared. 2 lbs. .8ocReg. $30.2 TRANSISTOR IF'Sn ttouldtttlItt.ti. 011IN.

88c2 N -P -N TRANSISTORSL mans pOp.

88c2 P -N -P TRANSISTORS

Popular,omtite! dozens of

$5 value.2 VARI-LOOPSTICKS Atp. 5411 - 1500 kcs.T atimistor radios. 88c

etc. I lb.RADIATION DETECTORO ;r"=,i',:"1:,1!leilq Vic*"dlatlon uses, Iteg. $20-60 MINUTE TIMER

r,.i'irei,1:41mmt,Tti.1"%shoP:2 MS.Hee. $o0.15 VAC MINI -METERD nuii.l..

70 TUBULARCONDENSERS

(-I Paper. 11101,1tl, oil.- pOre.. 50 .5111f 10 1000V. 2 lbs. 88cit

WIRE STRIPPERell. itook-up

Nt- 16111'''' 88C

5 -IN -1 DRILL BIT

Hand on pow., 1.111. 88c15 INSTR. KNOBS

n Knurled black bakellte, w / pointer: brass in-serts. set -screws.

10 RCA PLUG -N -JACKis. matched. Most88c

LEKTRON131 Everett Ave.

CHELSEA 50, MASS.

APRIL SHOWER OF SAVINGSFOR ALL LEKTRON SHOPPERS!

CASH DISCOUNT

SAL

MINI -RADIO KITri2 x 1 1". Loopstick,jocks. diode. etc., w !IntRt rttet Ions. 1 88ceg. a.

40 -RECORD CADDYn Wrot3ghtiron. Holdsrefocus albums.Reg,. 82.95. 88c8 SUB -MINI SOCKETS

Nlica-filled. For tran-" sstors.too. 88c40 SUB -MINI C'ND'S'RS

For transistor. printed" rcuit work. 88c1 11,. Reg. $7.8 -SCREWDRIVER SETn 8 asstd. drivers with" wall lack. Plastic

hang Iles. I lb. 88cList $3.50.60 PLUGSnRECEPT'CLESI-1 Audit,. power, line,1_1 batten v. sok, . 111003 lbs. Reg. .$7.$25 SURPRISE PACK

Lat ge varlet] asort-" ment radio, 88cTV parts. 3 lbs.100 CERAMICCONDENSERS

1114/ 0.11101.11, tou .1,1 cif. 2 880Reg. $ 12.0-6 AMP. MINI -METERn At

lb.. 15," diameter.

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TECHNICIANS'

NE )iTWO ESFETA MEETINGS

The Empire State Federation ofElectronic Technicians Associations washeld February 8 at Syracuse, N. Y.A meeting of ESFETA delegates andrepresentatives of TV set manufac-turers to discuss printed circuitry inTV receivers was held the previousevening. The manufacturers' case wasstated by Dan Creato of RCA, SteveMihalic of G -E and Mac Romey ofWestinghouse. At the end of the dis-cussion, it was the unanimous opinionof ESFETA that printed circuitry ishere to stay, even though at presentit is the cause of considerable conster-nation to the service industry. It wasfelt that certain problems will be solvedthrough cooperation between manufac-turing and service, and that futuredevelopment of printed circuits mayadvance both the servicing and manu-facturing industry. ESFETA has estab-lished liaison with the manufacturers'service departments, through which itis hoped to be possible to supply properservice data to the membership.

Chief subject discussed at the regularbusiness meeting was the proposed billfor certifying TV repair technicians,which was to be introduced to the NewYork State Legislature immediately.The meeting favored some changes andrevisions in the bill proposed by theAttorney General. Most important ofthese were those referring to qualifica-tion of technicians and to the composi-tion of the board that would administerthe Act. The proposed bill would qualifytechnicians on the basis of a practicalexamination. The association feels thatthis might pass school graduates whowould not be efficient service techniciansand proposes a minimum of 1,000 hoursof study in a recognized course plusthe equivalent of 2,000 hours of expe-rience under a qualified technician.(See "Guild Talks Certification," be-low.) However, the requirement of 1,000hours of school might be dispensedwith if the applicant had morethan 4,000 hours' experience. ESFETAalso feels that the administering boardshould include five men with at leasteight years of servicing experience(proposed bill calls for two, with fouryears of experience each, on a three-man board).

GUILD TALKS CERTIFICATIONDiffering views about TV service

technician certification were the majortopic for discussion at a recent meet-ing of the Radio & Television Guild ofLong Island. The legislation, as pro-posed by the State Attorney General'soffice, would set up a certification board

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to pass on the qualifications of servicetechnicians. Those who met the board'srequirements would be certified. How-ever, a noncertified technician couldstill operate a shop, as the certificationwould be on a voluntary basis.

Among those opposed to the proposalis Max Leibowitz, a member of theAssociated Radio -Television Servicemenof New York. He appears to feel thatsuch a bill cannot prevent technicians-certified or not-from claiming thatthey are authorized dealers and fullyqualified to service TV receivers.

On the other side is Murray Barlowe.A former Guild president, he says that,should the bill be passed, it will giveTV technicians the same status enjoyedby certified public accountants.

Requirements of the proposed bill,which were worked out with the help ofRobert Larsen, Guild president, are:

1. Service techs must have com-pleted television studies totaling atleast 1,000 hours.

2. Service techs must have workedunder proper supervision for at least2,000 hours.

3. They must pay a yearly fee of$30.

The certification board of examinerswould include two representatives ofservicing with four years of experience,a representative of television education,a manufacturer's service manager, adealer with five years' experience sell-ing receivers, a licensed engineer anda representative for the public.

PROTEST CAPTIVE SERVICEThe Radio -TV Association of Santa

Clara Valley (Calif.) moved againstan invasion by Packard -Bell captiveservice, the RTA Magazine reported ina recent issue. A formal letter of pro-test was sent to P -B's regional man-ager, Kenneth R. Johnson, and GeorgeGillespie, local P -B distributor.

The protest was sent after memberslearned in general meeting that P -Bwas getting ready to open a servicecompany shop in San Jose.

The letter said, in part:"Surveys have established quite

clearly that the many fully equipped,well staffed service shops are well ableto meet TV and radio service needs inthis area.

"It is our firm conviction thatPackard -Bell and its representativesdo not wish to be responsible forintroducing the problems attendantwith captive service in, Santa ClaraValley and environs. . . ."

SELF -REGULATION IS AIMOF CONNECTICUT GROUP

The Norwalk Association of Tele-vision Servicemen has adopted a planfor testing and certificating TV repairtechnicians, apprentices and installers.The plan was drawn up as an alternateto a proposal that the city adopt ordi-nances covering TV servicing. NATSbelieves that TV service regulationshould come from within the industry

(Continued on page 114)

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APRIL, 1959 111

How far can you go in electronics

without a degree?A few years ago, Lincoln E. Kitchin had noformal degree and knew nothing about electroniccomputers.He still doesn't have a degree, yet today, he isa Field Engineer on one of America's biggestelectronics projects. He helps maintain one ofthe largest computers in the world. He's doingwork ordinarily done by engineers-an oppor-tunity usually denied to men without a degree.This is a story of unusual significance to everytechnician who feels himself handicapped by lackof a formal degree.

Taking noses in IBM Field Engineering class

"It all started back at the Base," Link recalls,"about two years ago. We were having lunch.One of my fellow Aircrewmen described an inter-view he had just had-with IBM.

"It sounded good to me-particularly the fieldengineering aspects. I wasn't anxious to start mycivilian electronics career stuck in a corner ofsome plant. Here was a chance to work in thefield-with all the advantages of a permanentlocation. I made a note to add IBM to the com-panies I was considering for civilian work."

Discussing a SAGE display console Fron view of computer frame

Interviewed by IBM

A month later, Link sat across the desk from an IBMinterviewer. "Frankly," confesses Link, "I was scared atthe thought of this interview. I didn't know the differ-ence between an analog and a digital computer. I didn'texpect to get the job."The interviewer put Link quickly at his ease. A check ofhis background revealed Link's Service training -28 weeksof Class "A" aviation electronics plus Class "C" school-ing in LORAN, RADAR and SONAR. He took a test,which indicated excellent aptitude for computer work.Then Link learned how IBM would train him in elec-tronics-for five months at full salary-to become a FieldEngineer on the SAGE Program. He learned about SAGE,part of our nation's radar defense net, which is builtaround giant' IBM computers-each containing 50,000vacuum tubes plus 170,000 diodes. He heard about IBM'sexcellent company benefits, especially interesting to Linkwho had a wife and child. By the time the interview wasover, Link had decided that IBM and the SAGE Programwere what he was looking for. He decided then and therethat he wanted to come with IBM.

Receives 20 weeks' trainingLink reported to Kingston, N. Y., for training. In theIBM "school," he studied basic computer circuits, corn-

puter logic and programming, card punch machines-allpart of the twenty -week course a Computer Units FieldEngineer takes. "The instruction was excellent," he re-calls. "Our teachers, experienced field men, often madepoints not in the textbooks." Formal classroom lecturesaccounted for half his time, the other half being spent inthe laboratories, where he worked on actual computerequipment for SAGE. During his training period, Linkreceived a living allowance in addition to his salary.

Assigned to site in home state

His twenty weeks' training completed, Link was assignedto the SAGE site at Topsham, Maine. "IBM makes everyeffort to assign you to a location of your choice whereverpossible," Link, who is a native State-o'-Mainer, points out.

At Topsham, Link has completed the installation phaseof the computer. Now, his work consists of preventivemaintenance and "keeping the customer happy" -thecustomer, in this case, being the Air Force personnelwho man and operate the computer. "Installing this giantcomputer was a significant engineering feat," Link recalls."First we ran 2,509 cables from 4 to 300 feet long. Thenwe bolted the computer sections together and hooked upthe cables. Next came the testing phase in anticipationof Air Force acceptance tests.


A p-oStem ii pluggable units Working on manual input board of SAGE computer Recording daa on main core memory unit

"I'm in the Display Group," Link continues, "which hasresponsibility for over one hundred display consoles. Eachof these has a 19 -inch and a 5 -inch cathode ray tube(similar to a TV tube) plus associated circuits. Theknowledge of complex circuitry which we learned in the]BM school is essential for this work. We also maintainour own test equipment-oscilloscopes, meters, signalgenerators and specially designed pluggable unit testequipment."

What does the future hold?Link looks forward to a rewarding career as a Computer-Units Field Engineer. Promotion -wise, he could become,with further training, a Computer Systems Field Engi-neer, a Group Supervisor or Group Manager. Most im-portant, however, he believes, is the excellent electronicsbackground he's acquiring for the years ahead "I've hada new engineering dimension added to my career-thanksto IBM's willingness to spend time and money trainingtechnicians to assume engineering responsibilities."

A career for you with IBM?Since Link Kitchin joined IBM and the SAGE Program,opportunities are more promising than ever. This long-range program is destined for increasing national im-portance and IBM will invest thousands of dollars inthe right men to insure its success.

If you have a minimum of 3 years' technical schooling-or equivalent experience-you may be eligible for ad-vanced training for 5 months as a Computer Units FieldEngineer. While training, you receive full pay plus livingallowance before assignment to a permanent location.You are paid a salary, not hourly wages, plus overtime.

From then on, you can go as far as your abilities andambition will take you. IBM is the leader in a field thatoffers you unlimited horizons. And, as you may alreadyknow, at IBM you receive company -paid benefits thatset standards for industry today.

Mr. N. H. Heyer, Room 649DWRITE TODAY TO: Military Products Division

IBM Corp., Kingston, N. Y.

You will receive a prompt reply. Personal interviewsarranged in all areas of the U. S.

MILITARY PRODUCTSAPRIL, 1959 113

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TECHNICIANS' NEWS (Continued from page

instead of from without, says RalphBoyle, president of the group. To thisend, NATS has also named a grievancecommittee and a code of ethics com-mittee.

1 -HOUR SERVICE PULLSFOR FORT WORTH SHOP"TV service while you wait" is offered

by Advance TV Service of Fort Worth,Tex., according to the newspaper HomeFurnishings Daily. The owners, JohnTurner and Dave Simon, say that manyowners who hesitate to have sets re-moved from their homes bring them inwillingly if they feel that the work canbe done immediately and they can taketheir TV's home again.

Rates are $6.50 per hour for benchwork, plus cost of parts. When servicecalls are made, Advance TV charges$4.50 per call.

OLD-TIMER HEADSPA. FEDERATION

Dave Krantz of Philadelphia waselected president of the Federation ofRadio & Television Service Associationsof Pennsylvania (FRTSAP) at theirrecent annual meeting. Krantz was oneof the founders of the federation 12years ago, and served as its presidentfor the first 6 years of its life. Earlier,he had been active in the Philadel-phia Radio ServiceMen's Association(PRSMA). Leon Helk of Carbondale,another veteran association worker, waselected corresponding secretary.

RAYTHEON AD NOTEDBY COLUMBUS TECHS

The January issue of Radio -Tele-vision Service Dealers' News (Colum-bus, Ohio) calls attention to the Rayth-eon ad pictured here, which ran inTime, Newsweek and other magazines.

before you tall aTV -Radio Senice Realer...

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It pictures a housewife and states:"Before you call a TV -Radio ServiceDealer ask yourself these four questions1. Does he have an established businessfacility? 2. Does he guarantee his workand parts? 3. Does he charge a fair

111)

price for a home service call? 4. Doeshe provide an itemized bill?" "Get acopy of one of these magazines," saysARTSD News "and see what Raytheonis doing for you."

I.D.E.A. DISCUSSESTV SERVICE POLICIES

Communications from TV manufac-turers on their plans or lack of plansto supply repair service directly to theuser of home TV receivers constitutedthe most important business of theChicago meeting of the IndependentDealers Electronic Activities Commit-tee, held in January.

Robert Sickels of Indiana acted aschairman in place of Karl Heinzman,who was ill. Service association mem-bers representing 84 associations in 13states were present.

Ten of 12 television manufacturerscontacted replied to the request ofI.D.E.A. for a statement. Though insome cases these statements werevaguely worded (resulting in occasionalcries of "double-talk" from the dele-gates), the concensus was favorable toindependent service. Replies rangedfrom Sylvania's "We have never beenin captive service and do not plan anychange" to "Our customers . . . dependupon the independent service dealer forthe vast majority of service," but that"we cannot abdicate our service re-sponsibility," which paraphrases thereplies of two or three of the largercompanies.

Committee officers for 1959, electedat the meeting, were Karl Heinzman,Detroit, president; Al Niehaus, SanAntonio, vice president; John Perez,Columbus, secretary. A July meetingwas decided upon; exact date and cityto be set later.

PUBLISHER OFFERSOLD-TIME DIAGRAMS

Supreme Publications announces theavailability of schematics and servicedata on equipment dating back as faras 1926 and continuing to the present.Individual radio schematics will beavailable for 40c, TV data 75c permodel. A manual covering the most -used sets of the 1926-38 period is alsoavailable at $2.50.

Some of these sets are of purely his-torical interest, but a recent requestfor old photos by this magazine un-earthed a surprising number of sets 25and 30 years old that are described bytheir owners as "still operating per-fectly."

SAN ANTONIO TRAINSHANDICAPPED WORKERS

Texas Electronics Association of SanAntonio has completed a draft programfor training handicapped individuals.Under the plan, according to the localtechnicians' panel. SARTA News,each interested shop would take one ortwo of these state -supported people andtrain them in basic radio and televisionwork. The state contributes $40 monthly


TECHNICIANS' NEWS (Continued)

to the shop owner and, for the first 9months, the shop pays no salary.

"These men," says SARTA News,"will be screened by our own commit-tee as to their aptitude and willingnessto learn the trade, and then sent to theshop desiring to cooperate. After the9 -month training period, the shop mayhire the man as a regular employee,but is not required to do so."

NEED THREE PARTS SHOWS,SAYS MOCH OF NATESA

The service industry would welcomeand support three or more regionalelectronic parts shows a year, as pro-posed by the executive committee ofthe electronic reps association, in theopinion of Frank J. Moch, executivedirector of the National Alliance ofTelevision and Electronic Service Asso-ciations (NATESA).

"Particularly attractive to servicegroups would be the feature of theproposed shows which would give serv-ice organizations an opportunity toparticipate in the event as customersof the distributors," Moch said.

"We have long felt that a single dis-tributor show in Chicago to which thedistributor's customers, the servicebusiness operator, is not admitted, isnot, in any sense of the word, an all -industry show," he said. "We believethe pattern set at a recent independentregional parts show, to which servicepeople were admitted, is the type of

industry exposition vitally needed atthis time. The idea of holding shows inthree or more markets is, in our opinion,a good beginning. At least it wouldbring a manufacturer's products to hiscustomer, the distributor, instead of at-tempting to introduce such a show inone area to which manufacturer's cus-tomers must come, and to which thedistributor's customer cannot come.

"As for the educational feature ofthese shows which now is being empha-sized, it would provide the manufac-turer and distributor with an ideal op-portunity to conduct a service seminarwhere it would do the most good."

SOVIETS HAVE TROUBLESWITH TV REPAIRS

Some newspaper "exposés" wouldlead one to believe that sharp practicesin TV repair were limited to this coun-try. But the Soviet trade -union news-paper Trud came out with a blast atpoor service and dishonest dealings.

The regimented employee of thestate-owned repair shops was the targetof TT ud's denunciations. The newspaperstated that some TV and refrigeratorrepairmen just don't come through withservice unless the customer slips theman illegal bonus. One man, says thenewspaper, lugged his set from shop toshop, finally leaving it at one for 2

months, but was unable to get it fixedat the state -set price. He tipped therepairman-the job was done. END

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MOBILE POWER -SUPPLYKIT, model MP -1. Heavy-dutytransistor supply furnishes 120watts of de power, up to 150watts intermittently. Designed

to power manufacturer's MT -1transmitter and MR -1 receiver.Includes connecting -cables. Oper-ates from 12 -volt battery. Con-tains push -to -talk power -switch-ing relay. 9 1/16 x 4% x 2inches.-Heath Co., Benton Har-bor, Mich.

TRANSISTOR POWER SUP-PLY, Sencore Transi-Pac PS -103. Isolated power supply re-

places batteries while repairingtransistor radios. Provides 0-24volts output with a 1.5 -volt tapfor radios with a tapped supply.Delivers up to 200 ma on peaks,100 ma continuously. Meter givescontinuous output indication.-Service Instruments Corp., 121Official Rd., Addison, Ill.

CERAMIC CAPACITORS,Cerafil line. Ultra -miniatureunits; compared with standardcapacitor in photo. Values from10 f to 1.0 of in working

1163:131MI

voltages of 30 and 100. -Aero-vox Corp., New Bedford, Mass.

REPLACEMENT FLYBACKSStancor HO -301 (shown) re-places Admiral parts 79D65-2and 79D65-4. HO -300 for Wells

Gardner 53X355. H0-307 forSetchell-Carlson T-123, T-124,WF-14 and FW-70. 110-308 forSetchell-Carlson T-201, T-132,T-133, WF-71 and WF-80.-Chicago Standard TransformerCorp., 3501 W. Addison St.,Chicago 18, Ill.

VEINIER VARIABLE RE -

ELECTRONIC FIELD ENGINEERSFIELD SERVICE TECHNICIANS

SISTOR. Contact arm rotates1° for each 13.5° shaft rotation.Type VA -45 is 15/16 -inch -diam-eter unit only 5/32 inch deeperthan standard nonvernier type45. Resistance range, 250 ohmsthrough 5 megohms. Availablein variety of resistance tapers.-Chicago Telephone SupplyCorp., Elkhart, Ind.

AIR -CORE INDUCTORS forcrossover networks. 80 values inNo. 17 wire range from .05 to12.0 mh. 52 values in No. 16 wirerange from 5.0 to 20 mh. Induc-tors are oven -baked, calibratedand have spaghetti applied to a7 -inch tinned lead. Then they

are cotton wrapped, dipped invarnish and baked. -C & MCoils, 3016 Holmes Ave. NW.,Huntsville, Ala.

MOBILE HAM TRANSMIT-TER KIT, Cheyenne MT -1. 90watts input on phone. Covers

80, 40, 20, 15 and 10 meters.Built-in vfo, modulator, 4 rfstages , 6146 final and pi -net-work output coupling. Requires

Act fast for new, challenging assignments in U.S, Europe, Mediterranean, Far East,

Alaska, Iceland and South America ... including openings in

SPACE EXPLORATION PROGRAMELECTRONIC FIELD ENGINEERS

Engineering degree or equivalent experiencein electronic systems required.

FIELD SERVICE TECHNICIANS

Technical school, plus three years experiencerequired. Military service acceptable.

EXPERIENCED IN RADAR, GROUND COMMUNICATIONS, COMPUTERS, GCAObtain these advantages: Prestige of representing the leader in its field Opportunity forprofessional development and advancement Excellent salary Liberal field allowance Both U.S. & overseas assignmentsDrop us a line, briefly outlining your education andexperience. Mail replies to MR. 0. A. BOWMAN,DEPT. V, FIELD ENGINEERING.

"Our Laboratory... the Universe"

dP/10e/ 7:0/.0DIVISION OF BENDIX AVIATION CORP.

Owings Mills, Maryland


ON THE MARKET (Continued)

500-600 volts dc at 150 ma and300 volts de at 100 ma. -HeathCo., Benton Harbor, Mich.

COMMUNICATIONS RE-CEIVER, NC -400. AM, CW andSSB. 18 -tube receiver has range

of 540 kc to 31 me in 7 hands.Selectivity range of 16 kc to 150cycles with if and crystal filterssupplied. With accessory filters,selectivity range is 16 kc to 500cycles. Sensitivity is approxi-mate 1 AV for a 10-db signal-to-noise ratio. -National Co., Inc.,Malden, Mass.

MOBILE HAM RECEIVERKIT, Comanche MR -I. 8 -tubesuperhet for AM, CW and SSB

reception on the 80-, 40-, 20-, 15 -and 10 -meter Amateur bands.3-nic lattice type if filter per-mits single conversion withoutimage interference. Includedare rf stage, converter, 2 if am-plifiers, 2 detectors, noise lim-

iter, 2 audio stages and avoltage regulator. Sensitivitybetter than 1 AV on all bands.Signal-to-noise 10 db down at1 AV input. 2 -watts undistortedaudio output -Heath Co., Ben-ton Harbor, Mich.

AMATEUR BEAM ROTA-TOR, HM 120 Powerotor. Low-cost precision -built unit withcontinuous -reading accurate di-rection indicator. Heavy-dutythrust bearing supports anten-

nas weighing up to 50 pounds. -Moran Products Co., 2925 E. 55St., Cleveland 27, Ohio.

FM RADIO ANTENNA, modelFM3T. Mounts on TV antenna

mast. 4 bays can be stacked with300 -ohm line. Anodized gold fin-ish.-Winegard Co., 3000 Scot -ten Blvd., Burlington, Iowa.

TV ANTENNA MOUNT,

Fastmount TV Au ten na Holder.Mount can be placed in anylocation on a roof, regardlessof pitch. Eases one-man instal-lations.- Vokar Co., 201 E.Catherine St., Ann Arbor, Mich.

STYLUS MICROSCOPES,MX/ (bottom) and MX -40. Used

to check stylus wear. -RobinsIndustries, 36-27 Prince St.,Flushing 54, N. Y.

MAGNETIC RECORDINGTAPE, Continental Series. 5% -inch tape reel holds 850 feetBrown -Band, 850 feet Green -Band, 850 feet Shamrock, 1,150feet long -play (Mylar), 1,150feet long -play (Acetate) or1,650 feet double -play tape. In-

tended for use with Europeantape recorders. - ORRadio In-dustries Inc., Shamrock Circle,Opelika, Ala.

REPLACEMENT STYLI, forColumbia CD stereo phono car-tridges. CD-1SMD is diamond

version. CD -ISMS sapphire. -Available through CBS-Hytron,Danvers, Mass. and ColumbiaRecord distributors and dealers.

RECORD CLEANING KIT,Stardust. Aid for washing rec-ords in running water without

7lecod oj SUPREME Radio & TV Manuals18 RADIO VOLUMES

195

\ I NO

l)i.At1:.01...*-

RADIO DIAGRAMSSupreme Is your beet source for all

needed RADIO diagrams and service data.Covers everything from the most recent 1958radios to pre-war old-timer,: home radios,auto sets, combinations, changers, HI-FI,FM, and portables. Sensational values. Only$2 for many volumes. Every manual hasextra large schematics, all needed align-ment facts, parts lists, voltage values,trimmers, dial stringing, and helpful hints.Volumes are large in size, 81 x11 inches.about 190 pages. See coupon below for acomplete list of Sheer low-priced manuals.

TELEVISION SERVICING COURSELet this new course help you in TV servicing.

Amazing bargain complete, only $3, full price forall lessons. Giant in size, mammoth in scope,topics just like a $200.00 correspondence course.Lessons on picture faults, circuits, adjustments,short-cuts, UHF, alignment facts, hints,antenna problems, trouble -shooting, test Tequipment, picture analysis. Special, only

SIMPLIFIED RADIO SERVICING BY COMPARISONFix any radio easily.New, different COMPARISON method finds faults

quickly. Covers every radio set -new and old models. Introductory trainingincluded. Simple picture suggestions tell you where to look for 50faults. No testers needed for most jobs. Data on all tubes.Manual form, 96 large pages, 8t x 11". Special price, only

RADIO SERVICING COURSEHere is your most amazing bargain in radio training.For only $2.50 (full prieel you can obtain a practicalradio course of 22 easy -to -follow lessons. Covers everytopic in radio. Review fundamentals, learn new servic-ing tricks, prepare for television. Conspireslesson -by -lesson with the best $150.00 home -study correspondence courses. With self-$testing questions. Large size: 81/2x11". New1959 edition. Amazing value at only

50

Supreme PublicationsSold by All Leading Parts Jobbers

O 1958 Radio Diagrams, $2.50O 1957 Radio Manual. $2.50 1956 Radio Diagrams, $2.50O 1955 Radio Manual, only $2O 1954O 1953O 1952O 19511:1 1950O 1949O 1948O 1947O 1946O 1942O 1941

1940O 1939 J k EACHO 1926.1938 Manual. $2.50O Radio & TV Master INDEX, 254

These annualRADIO volumesspecially pricedat only $ 50each...

THIS GROUPONLY

$2

Me - Ne4,1

1-959_

TelevisionServicing Ini,rmainn

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New 1959 TV manual coversall important sets of everymake. Includes all data neededfor faster TV servicing. amaz-ing bargain. A whole year ofervice material for only....

ALL NEEDED TV DATASupreme TV manuals for faster,

easier repairs. All needed material onevery popular TV set of every Importantmake. Easy -to -use, practical, factory -pre-pared data simplify TV servicing and ad-justment. These giant TV manuals havecomplete, large double -page schematics, allneeded alignment facts, printed board views,recommended changes, waveforms, voltagecharts, etc. Only $3 per large volume. Thechoice of 126,000 wise servicemen.

AMAZING BARGAINHere are your error -free service instruc-

tions to help you do expert work quicker;and priced at only $3 for a mammoth yearlymanual. Greatest bargain in service data.Repair any TV model ever made by havingin your shop all 14 volumes listed in cou-pon. Special price for all 14, only $40. Ortry the new 1959 TV manual for only $3.See no risk coupon below.

NO -RISK TRIAL ORDER COUPONSUPREME PUBLICATIONS, 1760 Balsam Rd., Highland Park, ILL.Radio Diagram Manuals Rush RADIO and TV manuals checked 0 in coupon.

o New Television Servicing Course, complete.... $3.O Simplified Radio Servicing by Comparison. .$1.50O Radio Servicing Course (all 22 lessons) . . .$2.50 Nete 1959 Television Servicing Manual, only.. 53.O 1958 Television Manual, $3. 0 Early 1957 TV, $3.0 Additional 1957 TV, $3. 0 1956 TV Manual, $3.O Early 1955 TV, $3. 0 Additional 1955 TV, $3.O 1954 TV, $3. 0 1953 TV, $3. 0 1952 TV, $3.O 1951 TV, $3. 0 1950 TV, $3. 0 1949 TV, $3.O 1948 TV, $3. 0 1957-58 RCA Victor TV, $1.50

O I am enclosing $ Send postpaid.O Send C.O.D. I am enclosing $ deposit.

Name:

Address:

APRIL, 195 9 117

MECNAMOAL rartiesetir-UISHEIRille

CONTROLS 14

SALFLTIAr1"" 11.31" La" a raa:aa CHEMIST

SILLS fit "- n TO............ woo ittM er111RTIMOS 4,40Vi '47)4g Minn ,..1".111,10....r..;'.\ .4 N.

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Ya'DESIGN EktaitERST -14*namon available with ivell-estabibh. -

only 21 monthsfor engineering degreeUnlock your talents. Start to realize your dreamof becoming an Electronic Engineer. Then pro-motion will not pass you by. You will have anexciting career and share rewards awaiting col-lege graduates . . . higher income, rapid advance-ment. Important firms visit Tri-State campusto interview seniors. Year-round operation. Ap-proved for Veterans.Bachelor of ScienceDegree in 27 Months inElectrical Engineeringwith either an Electron-ics or Power major . . .

also in Mechanical,Civil, Chemical, Aero-nautical Engineering.In 36 Months a B. S.degree in Business Ad-ministration (GeneralBusiness, Accounting,Motor Transport Man-agement majors). Forearnest, capable stu-dents. Small classes.More professional classhours. Well-equipped labs. Illustration showsTri-State student in supervised radiation checkon a radar transmitter. Beautiful campus. Mod-est costs. Enter June, Sept., Jan., Mar. WriteJ. G. McCarthy, Director of Admissions, 2449College Avenue, Angola, Indiana, for "YourCareer in Engineering and Commerce" andCatalog.

TRI-STATE COLLEGE

ON THE MARKET (Continued)

damaging label or record. Alsoserves as airtight holder forsponge, kept wet for wiping anddampening records just beforeplaying.-C & D Products Co.,Old Marlboro Rd., East Hamp-ton, Conn.

STEREO CONTROL KIT,model 83 Y 778. For centralizedcontrol of stereo hi-fi systems.Has volume and balance con-

trols. Function switch select -stereo, reverse stereo, mono-phonic operation. Phase reversalalso provided. - Allied RadioCorp., 100 N. Western Ave.,Chicago 80, Ill.

STEREO TAPE RECORDER,Crown Stereo X. 2- or 4 -trackheads. 3 speeds, 3 motors. 4mike inputs. At 15 ips, responseis within 2 db from 30 to 30,000

cycles. Flutter and wow measure.06%; noise ratio 57 db down.At 7.5 ips, 20-20,000 cycleswithin 2 db; flutter and wow,.08%; noise ratio 54 db. At 3/75ips, 20-11,000 cycles within 3db; 0.18% flutter and wow;noise ratio 51 db. - Interna-tional Radio & ElectronicsCorp., Elkhart, Ind.

STEREO AMPLIFIER, Caril-lon model 6060. 60 -watt output-30 watts per channel. Lessthan 1% third -harmonic distor-tion at 30 watts. Frequency re-

sponse flat within 1 db from15-30,000 cycles. Hum level 71db below rated output. 7 dualinputs - mike, NARTB tapehead, magnetic phono, ceramicphono, tuner, tape preamp, aux-iliary. Selector switch; right -and left -channel bass and treblecontrols; balance and volumecontrols; low -filter, high -filter,function, speaker -selector leverswitches. Dual 4-, 8-, 16 -ohmand high -impedance outputs.-Bell Sound Div., ThofripsonRamo Wooldrige Inc., 555Marion Rd., Columbus 7, Ohio.

ULTRA -LINEAR POWERAMPLIFIER, EICO kit modelHF35. 35 -watt output. 1.5% IMdistortion at 35 watts. Har-monic distortion less than 1%at any frequency between 20and 20,000 cycles within 1 db of35 watts. Response within 0.1db from 20-30,000 cycles at 35watts. 0.43 -volt input gives full

output. Hum 90 db down. 4-, 8-,and 16 -ohm cutputs.-ElectronicInstrument Co. Inc., 33-00Northern Blvd., Long IslandCity 1, N. Y.

DIRECTED -SOUND ENCLO-SURES, Swivel -Master. Enclo-sures pivot on base, can beangled in any desired direction.Mahogany, cherry, blond, wal-

nut and ebony finishes.-Uni-versal Woodcrafters Inc., La-Porte, Ind.

KITS, CABINETS, ENCLO-SURES, finished and unfinished.Line includes speaker enclo-sures, equipment cabinets andphono mounting boards. Model

EC equipment cabinet illus-trated.-Stereo Craft, Div. of20th Century Woodworking Co.,79 Clifton Pl., Brooklyn, N. Y.

FURNITURE CABINETS for75 and 85 series tape decksand related components. WSSXis used for 75 or 85 deckand single recording amplifieror two playback preamps.W4SX for tape deck and tworecording amplifiers for stereosystems.-Viking of Minneap-olis, 9600 Aldrich Ave., Minne-apolis, Minn.

COMPONENTS CABINET.Model KN-1400K is kit version,KN-1400 is assembled unit.Houses record changer on base,tuner, amplifier and records.Finished in mahogany, limedoak or walnut. 27 inches high,

331,4 inches wide, 16 inches deep.-Allied Radio Corp., 100 N.Western Ave., Chicago 80, Ill.

SPEAKER ENCLOS-URES. The Hague (shown) is aback -loaded folded -horn en-closure designed for 12 -inchspeakers. Other smaller unitsare distributed -port bass -re-flex types for 8 -inch speakers.-North American Philips Co.,


DX -16 Super Deluxe TV KITTh70' or 90° - operating all 17", 21", 24" and 27" PICTURE TUBES

NEW IN DESIGN -Mounts Horizontally or Vertically

Dimensions 1J:Z,,"""a °Shipping

* Produces a 16 -Tube Chassis with 30 -Tube performance.* Latest Intercarrier Circuitry and Multi -section Tubes.* Standard Neutrode Tuner for Selectivity & Fine Definition.* 5 Microvolts Sensitivity (20V peak to peak at CRT grid).* Fast Action AGC for Drift -Free Steady and Clear Pictures.* 3 Hi -gain Video I.F. Stages for fine Contrast and Details.* AGC Level Control, for adjusting reception to signal area.* All Video and I.F. Coils factory pre -aligned and tuned.* Large 250ma Power Transformer for dependable service.* 12" Speaker or Twin -cone 6" x 9" Speaker.

Includes LIFE-SIZE step-by-step Building InstructionsMost Up -To -Date and Practical Course in Television

COMPLETE KIT with SET of WESTINGHOUSE TUBES4-6C116 and 6U8, 6T8, 6C4, 1214H7, 68N7, 61106, 6W4, 6K6, 1X211, 5U4,6BN4, and 6CGS included in the Tuner (less l'ItT1

$7997

COMPLETE KIT Including WESTINGHOUSE PICTURE TUBE17 g: tt 17AV P4A 599." 21" gpc 11XE11:A $108.86 24", 24DP4A $126'51

Also sold on EASY -PAYMENT -PLAN Buy LIFE-SIZE Instructions $249 -and buy Parts as you

BUILD Yoc,:g CABINET :cg TV CHASSISComparable to the type that Top Mfrs. use on high priced TV sets.

CABINET KIT with 900'6 of the job done, includes -

FRONT SECTION in Solid Mahogany, Walnut or Blond Ko-rina. TOP, SIDES, BACK, MASK, SAFETY GLASS, ETC.

And EASY -TO -FOLLOW ASSEMBLY INSTRUCTIONSFront, Top :did Side, ,applied in a beautiful Piano Finish Knob panelundrilled For matching Mash specify type or number of CRT used.Same price- Nialliicaw. walnut or Mona. le lbs.)

L...Only

for WALL INSTALLATio\ 8 InfO).1.- Ma1 " " "FRONT SECTION m..Safety Glass. Decals and Illtrated li, imet ion,. 21 $17'45 24 or 27 22.97Complete as pictured (undrilled), ready to install in Mahogany. Walnut, Blond or

I $

Natural (unfinished) for your con color application, to match the decor of the room. J

21" CABINET KIT 26 H 25 W 22 11 '24 95

PULSE KEYED AGC KITFinest. most accurate and the easiest Kitto install -in any make TV RECEIVER YComplete incl. 6AU6 Tube E. Instructions.

TV PLASTIC OPEN MASKS211" -Rectangular 18" x 221/2" $2.3824" -Rectangular 21" x 26" 4.9327" -Rectangular 21" x 26" 4.93

On 21" specify type number of CRT used

TV SAFETY GLASS in HANDY SIZES16" x 20" 53.94 I 201/4" x 25" $5.4718" x 221/2" 5.16 21" x 26" 5.87

("90° TV CONVERSION KITSConvert any Size, any make TV RECEIVERto operate the 24" or ANY 90° PICTURE TUBE.COMPLETE SET OF ESSENTIAL PARTS includesmatched set of 90° YOKE & 18kv FLYBACK,30kv FILTER, 6AX4 TUBE, BRACKETS, WIDTHCONTROL, CONDENSERS, RESISTORS, ETC.

Your si 5.98 List Price $39.75Price I Incl. CONVERSION MANUAL with

Step -by -Step Instructions 6 Diagrams

\,...Similar Kit for any 70° CRT stI 3,97

STEREO - Selected as BEST for Quality, Performance & Price598 DeWald =M-1000 "AMBASSADOR AM -FM TUNER" both Stereo & Monaural $71.95598 DeWald =M-1200 "CONCERTO 30 -WATT AMPLIFIER" both Stereo & Monaural $71.95$59 BASS REFLEX CABINET for 12" or 15" Speaker, in Mahogany, Walnut or Blond $32.82528 12" HI -F1 UNIVERSAL TYPE SPEAKER woofer & tweeter range 50 to 15000 cps $12.38$49 DELUXE VM 4 -SPEED RECORD CHANGER incl. Cartridge plays all Stereo & Monaural $26$332 "COMPLETE PACKAGE DEAL" includes ALL FIVE ITEMS as shown above for only $199599 NORELCO =9762M HI-FI 12" SPEAKER.$35.97 GARRARD =RC -121 4 -SPEED CHANGER.$32.49S20 UNIVERSAL "BIG -12" HI -F1 SPEAKER.. 6.97 GARRARD =RC -88 4 -SPEED CHANGER. 46.82$14 SONOTONE =8TS STEREO CARTRIDGE. 5.99 GARRARD .=RC -98 4 -SPEED CHANGER. 54.98

TUBULAR CONDENSERS -85°C TOP QUALITY -Equally as good for Radio or TV work..0047-400v, ,01-400v, .02-400v, ,047-400v, .001-600v, .0047-600v, .01-600v, .02-600v Sc ea.I -400v, .25-400v, .47-400v, .047-600v, .1-600v, .25-600v, .001-1000v, .01-1000v 8t ea.035-1000v, .047-1000v, .1-1000v, .015-1600v, .03-1600v, .001-6000v, .005-6000v 14e ea.

ELECTROLYTIC CONDENSERS -85°C 1-50v, 1.150v, 2-450v, 5-150v, 8-150v,..19.2 ea.20 20-150v, 50/30-150v, 40-150v, 10.450v, 20-450v, 30-450v, 40-450v, 60-450v, 80-450v 34c ea.

CARBON RESISTORS -Regular factory stock in Stackpole, I.R.C., Speer, etc.I" WATT 10./o 10, 39, 47, 100, 120, 150, 270, 330, 390, 470, 560, 680, 820, 1k, 1800' 2c ea.

12 WATT 100/0 2700, 3300, 3900, 4700, 5600, 6800, 8200, 10k, 15k, 18k, 22k, 27k, 33kll 2c ea.'2 WATT 10% 39k, 47k, 50k, 56k, 68k, 82k, 100k, 120k, 150k, 180k, 220k, 270k, 3301W 2c ea.'2 WATT 10% 390k, 470k, 560k. 680k, 820k,'2 1, 1.2, 1.5, 2.2, 6.8, 10, 15 MEGt' 20 ea.

1 WATT 10% 3.3, 10, 39, 100, 120, 150, 330, 470, 560, 680, 820, 1k, 1800, 2700, 47000 30 ea.1 WATT 109/6 6800, 10k, 15k, 22k, 27k, 33k, 39k, 47k, 68k, 82k, 100k, 150k, 470k, 6801441. -3; ea.2 WATT 10% 3.9, 18, 22, 82. 100, 180, 2200, 4700, 6800, 8200, 18k, 22k, 100k, 470E2 40 ea.

CERAMIC CONDENSERS 1, 2, 3, 5, 6, 10, 22, 25, 47, 50, 51, 56, 82, 100, 120, 200 .°f 3c ea.CERAMIC CONDENSERS 220, 250, 270, 330, 470. 1k, 1200, 1500, 2k, 5k, 6800, 15k 3e ea.MICA CONDENSERS 5, 25, 50, 60, 68, 75, 100, 120, 150, 220, 270, 330, 470, 510 mmf 3c ea.MICA CONDENSERS 560, 680, 820, 1k, 1500, 2k, 2500, 3300. 4700, 6k, 6800, 8k, 10k 30 ea.

"ONE DOLLAR:,.

As much as $15 worth - Everything Brand Newand sold to you with a money back guarantee.

DEDUCT 10% MINIM:(ON THESE DOLLAR BUYS)

Plus a FREE SURPRISE PACKAGE$15 - "JACKPOT" TELEVISION PARTS $14 - RCA :.=1 U4 TUBES 1T4 $11 - RCA 70° FLYBACK TRANS. #75240 511 -$11 TODD 60° DEFLECTION YOKE $1

0 40 - ASST. PRECISION RESISTORS sizes $11 - 5" PM SPEAKER .,,,,,,,, 5 magnet $120 - TUBULAR CONDENSERS .05.800e $120 - TUBULAR CONDENSERS .,,,,t-t000v $150 - ASSORTED FUSES $1100 - ASST. V2 WATT RESISTORS ,,,me 3` . $170 - ASSORTED 1 WATT RESISTORS,ome s',.$1

0 35 - ASSORTED 2 WATT RESISTORSsorno $150 - ASST. TUBULAR CONDENSERS... $110 - 6' ELECTRIC LINE CORDS with plugs $1

n 5 - TV CHEATER CORDS both plugs $14 - 50' SPOOLS HOOK-UP WIRE 4 colors. 5150 - STRIPS ASST. SPAGHETTI hest sixes_ $1100 - ASST. RUBBER GROMMETS hest sines $1100' - TWIN LEAD-IN WIRE 300'2 heavy duty 5150' - FLAT 4 -CONDUCT. WIRE 111.111y purposes $125' - INSULATED SHIELDED WIRE.... $1

0 32' - TEST PROD WIRE ,1,1,0,c, rod or black), $10 1 - $7 INDOOR TV ANTENNA 3 section 510 20 - ASST. TV KNOBS, ESCUTCHEONS, Etc S10 3 - ASST. TOGGLE SWITCHES apat, ete $10 6 - ASST. SLIDE SWITCHES .p". dna, etc 510 100' - FINEST NYLON DIAL CORD best sixe $10 200 - SELF TAPPING SCREWS j s C tv, $10 35 - ASST. RADIO KNOBS -,11V, and push -on 510 100 - KNOB SPRINGS ajar '1," $10 100 - ASSORTED KNOB SET -SCREWS $10 25 - ASSORTED CLOCK RADIO KNOBS $10 600 - ASST. H'DWARE ,,ots, rivets, ete $10 50 - ASST. SOCKETS ,,,t.,,. noval and miniature $1D 20 - ASSORTED TUBE SHIELDS hest sizes $1 50 - ASST. MICA CONDENSERS -,,,,e in 5ei $1D 50 - ASST. CERAMIC CONDENSERS " $1D 10 - ASST. VOLUME CONTROLS less switch $10 5 - ASST. VOLUME CONTROLS switch $10 100 - VOLUME CONTROL HEX NUTS $1D 20 - ASST. PILOT LIGHTS popular types .... 310 10 - PILOT LIGHT SKTS. 1,ivonet type. 5511,(1... .510 50 - ASST. TERMINAL STRIPS 1. 2. 11. 4 lug' .$10 10 - ASST. RADIO ELECTRO. CONDENSERS.$1E 5 - ASST. TV ELECTROLYTIC CONDENSERS.$10 25 - ASST. MICA TRIMMER CONDENSERS $1D 2 - ELECTROLYTIC COND. II, ,,, $1 30 - FP CONDENSER MOUNTING WAFERS 510 3 - ELECTROLYTIC CONDENSERS $,,-7'", $10 3 - ELECTROLYTIC COND. 30-150, $10 10 - HV TUBULAR CONDENSERS ..06-1600v $1E 10 - HV TUBULAR CONDENSERS mot.u000e, $1E 10 - HV TUBULAR CONDENSERS 005-6000v 51E 35 - MICA COND, 20-10C mmf & 15-270 mmf $1C 35 - MICA COND. 20-470 mmf & 15-680 mmf 51C 35 - MICA COND, 20-920 mmf & 15-1000 mmf $1El 35 - CERAMIC COND. 20-5 mmf & 15-10 mmf 51E 35 - CERAMIC COND. 20-25 mmf & 15-47 mmf $1

35 - CERAMIC COND. 20-56 mmf & 15-82 mmf $1"1 35 - CERAMIC COND. 20-100 mmf & 15-150 mmf 51

35 - CERAMIC COND. 20-270 mmf & 15-470 mmf $1- 35 - CERAMIC COND. 20-1000 mmf 15-1500 mmf $1- 35 - CERAMIC COND. 2'-20 0 mmf& 15-5030 mmf $1

50 - 1001! 1/2 WATT RESISTORS 5% $175 - 4701(12 1/2 WATT RESISTORS 10% $1

C 10 - ASST. WIREW'ND RES. 5. 10, 20 watt _31 3 - AUDIO OUTPUT TRANS. 5111.11 type, $1C 3 - AUDIO OUTPUT TRANS. stun or IWO type 51C 3 - I.F. COIL TRANSFORMERS 456 he $1C 3 - I.F. COIL TRANSFORMERS 10.7 me. FM, 5117 4 - OVAL LOOP ANTENNAS hi -gain types $1C 3 - LOOPSTICK ANT. ,,,-, It° adjUStabie 51C 12 - RADIO OSCILLATOR COILS 456 ...31C 3 -1/2 MEG VOLUME CONTROLS with switch ,51E 5 - 50K VOLUME CONTROLS less switch $10 10 - SURE GRIP ALLIGATOR CLIPS $10 1 -GOLD GRILLE CLOTH, l's14"or12".18" 511=1 5 - SETS SPEAKER PLUGS wired $1 10 - SETS PHONO PLUGS and PIN JACKS $10 2 - 52.50 SAPPHIRE NEEDLES 4000 piayings $1D 5 - DIODE CRYSTALS 2-1N21 2-iN22 1-1N64 $11 3 - DIODE CRYSTALS I-1.0110, 1-1N114, 1-1N69 $1C 2 - SELENIUM RECTIFIERS I-8 5ma & ma$1

15 - ASST. TV COILS peaking, width, etc. .516 - SPIN TIGHT SOCKET SET it Ili- to 7/16'1 511 - LB. SPOOL ROSIN CORE SOLDER $1

E 3 - TV ALIGNMENT TOOLS assortment 1:1 $1El 3 - TV ALIGNMENT TOOLS assortment .A2 $10 3 - TV ALIGNMENT TOOLS assortment x3 $1El 3 - TV ALIGNMENT TOOLS ..:ei-stnetit It 4 $10 3 - TV ALIGNMENT TOOLS assortrnent xs $1EACH ALIGNNIENT TOOL is different and valued at over$1

HANDY WAY TO ORDER -Simply tear out advertisementand pencil mark items wanted (X in square is ,ancient);enclose

with mney order or check. You will receive anew copy of this ad for re -orders.ON SMALL ORDERS -Include stamps for postage. excesswill be refunded. Larger orders shipped express collect.

BROOKS RADIO &TV CORP., 84 Vesey St., Dept. A, New York 1, N.Y. cyrvanl,APRIL, 1959 119

ON THE MARKET (Continued)RADIO and ELECTRONICS TRAINING AT HOME

BUILD 16 RADIOCIRCUITS with DELUXE

1959 ProgressiveRADIO "EDU-KIT"1

PRACTICAL onlyHOME 95RADIOCOURSE

NOW INCLUDES* 12 RECEIVERS* TRANSMITTER* SIGNAL TRACER* SIGNAL INJECTOR* CODE OSCILLATOR

Reg. U.S.Pat. Off.

No Knowledge of RadioNecessaryNo Additional Parts orTools neededExcellent Background for TVSchool Inquiries InvitedAttractively Gift Packed

FREE EXTRAS SET OF TOOLS RADIO & ELECTRONICS TESTER ELECTRICSOLDERING IRON TESTER INSTRUCTION MANUAL MEMBER-SHIP IN RADIO -TV CLUB: CONSULTATION SERVICE HI -Fl GUIDE QUIZZES TV BOOK FCC AMATEUR LICENSE TRAINING

RADIO BOOK PRINTED CIRCUITRY PLIERS -CUTTERS ALIGNMENT TOOL WRENCH SET CERTIFICATE OF MERIT

VALUABLE DISCOUNT CARD

WHAT THE "EDU-KIT- OFFERS YOUThe "Edu.Kit' offers you an outstanding PRACTICAL HOME RADIO COURSE at

a rock -bottom price. Our kit is designed to train Radio & Electronics Technicians,making use of the most modern methods of home training. You will learn radiotheory. construction, servicing. basic and TV repairs, code, FCC amateurlicense requirements.

You will learn how to identify radio symbols. how to read and interpret sche-matics. how tomount and layout radio parts. how to wire and solder, how to operateelectronic equipment, how to build radios. Today it is no longer necessary to spendhundreds of dollars fora radio course. You will receive a basic education in radio,worth many times the small prier' you pay, only 522.95 complete.

THE KIT FOR EVERYONEThe Progressive Radio "Edu-Kit" was specifically prepared for any person whohas a desire to learn Radio. The Edu-Kit" has been used successfully by young

and old le all parts of the world, by many Radio Schools and Clubs in this countryand abroad. It Is used for training and rehabilitation of Armed Forces Personneland Veterans throughout the world.The Progressive Radio "Edu.Kit" requires no instructor. All instructions areincluded. Every step is carefully expiained. You cannot make a mistake.

PROGRESSIVE TEACHING METHODThe Progressive Radio "Edu.Kit" is the foremost educational radio kit in the

world, and is universally accepted as the standard in the field of electronics training.The 'Edu-Kit" uses the modern educational principle of "Learn by Doing."Therefore, you will construct radio circuits, perform jobs and conduct experimentsx

to Illustrate the principles which you learn.You begin by earnining the various radio parts included in the "Edu-Kit." Youthen learn the function, theory and wiring of these parts. Then you build a simple

radio. With this first set, you will enjoy listening to regular broadcast stations,learn theory, practice testing and troubleshooting. Then you build a more ad-vanced radio, learn more advanced theory and techniques. Gradually, in a pro-gressive m and at your own rate, you will find yourself constructing moreadvanced multi -tube radio circuits, and doing work like a professional RadioTechnician.

Included In the "Edu-Kit" course are sixteen Receiver, Transmitter. Code Oscil-lator, Signal Tracer and Signal Injector circuits. These are not unprofessional"breadboard" experiments, but genuine radio cuits. constructed by means ofprofessional wiring and soldering on metal chassisirc. plus the new method of radioconstruction known as "Printed Circuitry." These circuits operate on your regularAC or DC house current.

In rrder to provide a thorough, well -integrated and easily -learned radio course,the "Edu-Kit" Includes practical work as well as theory; troubleshooting in addi-tion to construction; training for all, whether your purpose in learning radio befor hobby, business or job; progressively -arranged material, ranging from simplecircuits to well -advanced topics in and TV. Your studies will be further aidedby Quiz materials and our well-known FREE Consultation Service.

THE "EDU-KIT" IS COMPLETEYou will receive all parts and instructions necessary to build 16 different radio

and electronics circuits, each guaranteed to operate. Our Kits contain tubes, tubesockets, variable, electrolytic, mica, ceramic and paper dielectric condensers. resisto, tie strips, coils, hardware, tubing, punched metal chassis. Instruction Manuals, hookup wire, solder. etc.

In addition, you receive Printed Circuit materials, including Printed Circuit chasspecial tube sockets, hardware and instructions. You also receive a useful setsis, otools. a professional electric soldering iron, and a self -powered Dynamic Radio 6.Electronics Tester. The "Edu-Kit" also incl udes Code Instructions ad the Progressive Code Oscillator, in addition to the F.C.C.-type Questions andAnswers fo

Radio Amateur License training. You will also receive lessons for servicing itthe Progressive Signal Tracer and the Progressive Signal Injector, and a HigFidelity Guide and Quiz Book. Everything is yours to keep..1. Statatis, of 2S Poplar Pl., Waterbury, Conn., writes: "I have repaired severssets for my friends, and made money. The "Edu-Kit" paid for itself. I was readyto spend $240 for a Course. but I found your ad and sent for your Kit."

UNCONDITIONAL MONEY -BACK GUARANTEEThe Progressive Radio "Edu-Kit" has been sold to many thousands of indi-

viduals, schools and organizations, public and private, throughout the world. Itis recognized internationally as the ideal radio course.

By popular demand the Progressive Radio "Edu-Kit" is now available inSpanish as well as English.It is understood and agreed that should the Progressive Radio "Edu-Kit" be

returned to Progressive "Edu-Kits" Inc., for any reason whatever, the pur-hase orice will be refunded in full, without quibble or question, and withoutdelay.

The high recognition which Progressive "Edu-Kits" Inc.. has erned throughits many years of service to the public is due to its unconditional insistenceupon the maintenance of perfect engineering, the highest instructional stand-ards, and 100% adherence to its Unconditional Money -Rack Guarantee. As aresult. we do not have a single dissatisfied customer throughout the entireworld.

ORDER FROM AD-RECEIVE FREE BONUS RESISTOR ANDCONDENSER KITS WORTH $7.00

O Send "Edu-Kit" Postpaid. I enclose full payment of $22.95.O Send "Edu-Kit" C.O.D. I will pay $22.95 plus postage.O Send me FREE additional information describing "Edu-Kit."Name

Address

Progressive "EDU-KITS" Inc. "" BitioeWil'etaty:Ni?e?!

Inc., High Fidelity ProductsDiv., 230 Duffy Ave., Hicksville,N. Y.

STEREO TAPE HEAD, modelTLD-L. Laminated in -line rec-ord -playback unit. Pole piecesare laminated. For 4 -trackstereo tape systems. Recordsand reproduces frequencies be-tween 30 and 15,000 cycles attape speed of 3% ips. Perform-ance nearly identical to singlelaminar heads at 71/2-ips tapespeed. Gap thickness less than100 -millionths of inch.-Nor-tronics Co. Inc., 1015 S. 6th St.,Minneapolis 4, Minn.

SLEEP TEACHER, ElectronicEducator, is a self-containedtape recorder that uses endlesstape cartridges. Can also beused as standard tape recorder

as it has record, playback anderase functions. - Sleep -Learn-ing Research Association, P.O.Box 24, Olympia, Wash.

MUTUAL -CONDUCTANCETUBE TESTER, model 800. In-corporates a transistor and

diode check. 5 -inch meter. Teststubes under simulated operatingconditions. - Hickok ElectricalInstrument Co., 10531 DupontAve., Cleveland 8, Ohio.

TUBE TESTER, Mini -Check,model MC -1. Multiple -socketunit tests more than 600 tubetypes. Employs dynamic cathode-

* **QBis

emission test, checking emis-sion, interelement shorts andleakage. 3 settings, and testeris ready to check tube. 31/2 -inch meter, detachable line cord.-Century Electronics Co. Inc.,

111 Roosevelt Ave., Mineola,N. Y.

REPLACEMENT TV KNOBS.Exact replacements for 1953

and 1954 RCA TV receivers arenow part of this firm's line ofreplacement knobs. - ColmanElectronic Products Inc., P.O.Box 7026, Amarillo, Tex,

SHIELDED EXTENSION JAXattaches to end of shieldedcable. 3 models. Terminatescable in 2 -conductor jack for1/4 -inch phone plugs; in 2 -con-ductor jack for Tini-Plugs; in3 -conductor jacks for 1/4 -inch

121

131 125

3 -conductor phone plugs.-Switchcraft Inc., 5555 N. ElstonAve., Chicago 30, Ill.

4 -INCH UNIMETERS. Ob-tain variety of panel meters bycombining dial component withbasic meter movement. Assem-bly slides together. Ac and dc

linear scales. dustproof con-struction. - Triplett ElectricalInstrument Co., Bluffton, Ohio.

DOUBLE PLUGS. ModelMDP, (top schematic) attachesto cable of user's choice. Plugsrated at 15 amps and 5 kv.Available in 10 colors. ModelMDPS (bottom) has internal

y y

I I

earn-:

shorting bar. Model MDPR(center) has precision 1% re-sistor molded in.-I'omona Elec-tronics Co., Pomona, Calif.

OFFICIAL TUBE SURGE -GUARD reduces initial surgecurrent when radio or TV re-ceiver is turned on. Plugs intoline outlet.-Alfred Barone Co.,488 E. Delvan Ave., Buffalo 11,N. Y. END

rAll specifications on these pages arefrom manufacturers' data.


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APRIL, I959

TRY

ONE

FILE CLEANING KINKWhen files are used on soft materials

such as plastic, aluminum, solder, cop-per and brass, the flutes have the tend-ency of becoming clogged with filings.This makes it almost impossible to cleanfine smoothing files with an ordinaryfile card or wire brush, as the largebristles cannot reach deep enough intothe gullets where the filings are im-bedded. A small gob of modeling claypressed firmly against the file will, how-ever, remove the filings and restore thefile's bite.

Kit builders, experimenters, servicetechnicians and others who work withfiles will find this kink especially useful.-John A. ComstockEXPERIMENTAL CONNECTORS

Old tube sockets can be taken apartand their contacts used as connectorsfor temporary experimental hookups.Just break the insulator away with

pliers and the contacts will fall free.Solder wires to the contacts and usethem for making fast temporary con-nections to tube base pins or standardphone tips. Also use tube base pinsremoved from old tube bases as maleconnecting plugs.-J. C. Alexander

ERASER FIXES RECORDCHANGER

Ever run into a V -M changer with amissing rubber tip on the size indexfinger? This is a simple thing to re-pair. Cut the eraser off an ordinarypencil, punch a slot in it with a smallscrewdriver and mount it with a dabof cement.-E. Slitsko

SWITCHING WITHVIDAIRE MS -6

In the April, 1958, issue of RADIO -ELECTRONICS (page 36, Fig. 9), youshow the wiring layout and equivalentcircuit arrangement for six speakersconnected in series -parallel. Switching

You learn more from

THIS qtRigIlOOKS

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"101 Ways to UseYour Oscilloscope"

by Bob Middleton

A practical and invaluableguidebook for anyone usingoscilloscopes. Covers allstandard uses of this instru-ment as well as many un-

I ."'- common ones. Describes con-nections required, equipment

needed, proper test procedures and evaluationof results for each scope use. Over 400 illustra-tions of waveforms and test setups are included.Invaluable for technicians, engineers, studentsand experimenters. 180 pages, 535 x 835".Only $2.50(Companion to Middleton's"101 Ways to Use Your Sweep Generator")

"Tape Recorder Manual"-Vol. 3Complete analysis of 22 taperecorders produced in 1957-58, including Ampex, Geloso,Knight, RCA, Revere,Silvertone, Webcor, Wilcox -Gay, Wollensak. Includesgeneral description,operationdata, troubleshooting andmaintenance facts, partslists, diagrams, etc. Has spe-cial editorial section on basictypes of tape transport mech-

anisms; with cumulative index. 160 pages,835 x 11". Only $2.95

"Servicing Hi-Fi" Series

SERVICING HI -Fl AM -FMTUNERS. Complete servicedata analysis of 18 AM -FMtuners produced in 1957-58.Thorough coverage: dia-grams, photo views, trouble-shooting, parts lists, etc. In-cludes special editorial sec-tion "Highlights on FM",covering FM signal, AFCcircuits, alignment. 160 p.,835 x 11". Only $2.95

SERVICING HI -Fl PREAMPSAND AMPLIFIERS. Covers 33leading models made in 1957-58. Full technical analysis ofeach model (schematic,photos, charts, parts lists);special section on "ServiceFacts About Preamps andAmplifiers." 160 p., 835x11".Only $2.95

HOWARD W. SAMS & CO., INC.

Order from your Sams Distributor today,or mail to Howard W. Sams & Co., Inc., Dept. D-292201 E. 46th St., Indianapolis 6, Ind.Send me the following books: "101 Ways to Use Your Oscilloscope" (TEM-2) "Tape Recorder Manual" (TR-3) "Servicing Hi-Fi AM -FM Tuners" (HF-3) "Servicing Hi-Fi Preamps & Amplifiers" (HF-4)$ enclosed. Send Free Book List

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121

11 nnicSTEREODYNE

PHONO PICK UPThis new, unique pickup is madein Denmark by Bang and Oluf-sen. It features a push pull mag-netic principle (patent pending)which permits realization of thefull potentialities of the mostmodern recording techniques. Thespecial attributes which make theStereodyne an dutstanding stereopickup make it equally excep-tional for monophonic discs. Onany type of record the Stereodyneoffers smooth and natural sound-firm clean bass and sparklingtreble-while its light trackingpressure insures negligible recordwear.

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Wide frequency responseSmooth peak free response from 30cps to over 15 Kc

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No hum pickupBalanced coil structure plus low im-pedance plus complete shieldingeliminate hum from external fields

High output7 miillivolts per channel even on lowlevel stereo discs provides gain tospare

No magnetic pullSpec.al magnetic circuit eliminatesattraction to steel turntables

Easy installationComDact size and standard mountingcenters simplifies mounting. 4 ter-minals to avoid hum loops.

Low priceOnly $29.95 net including .7 mil dia-mond stylus (replaceable in 2 sec-onds)

Available from leading high fidelitydealers everywhere

DYNACO INC.617 N. 41st St., Phila. 4, Pa.

Export Division: 25 Warren St.. New York, N. Y.

TRY THIS ONE (Continued)

Fig.I1

facilities for substituting resistors letyou cut out speakers and still maintainproper impedance matching to the am-plifier's output.

As stated in your description of Fig.9 "A different wiring arrangement is

EQUIVALENT CIRCUIT

411

40

4S1

40411 -"\oVv

4 411

147.330ZT

Fig.2

needed" (see Fig. 1). Fig. 2 is theequivalent circuit. Here is just such asetup using the Vidaire model MS -6switching panel.

The resistor and voice coil for speakerNo. 4 should have a wattage ratinghigh enough to handle the total currentin the circuit.-John J. Haskell

RECORD CHANGER HUMRubber washers are generally used

between the motor mounting bolts andthe changer base. If the rubber hardensor if the bolts are tightened excessively,motor vibration may be transfered tothe changer's frame and thence throughthe turntable to the record and needle,causing hum. If the hum stops whenyou short the pickup terminals with ascrewdriver while the needle is restingon a stationary record (speed selectorin neutral) , motor vibrations are theprobable cause. Examine the motormounting and replace the rubber wash-ers if necessary.-Warren J. Smith

AIMING ANTENNASWe find a trouble light in the form

of a long extension cord a simple aidto aiming a TV antenna during installa-tion. Poke the light out a window whereit can be seen by the man on the roof.

The person watching the screenimage flashes the light fast if the an-tenna is way off and slows the flashingto a stop as the correct orientation isreached.-H. J. Miller END

000000000000 enRADIO AND TV

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SYLNANIA II k-0,1:', 1-518-1

Picture smear was evident on thisset, on all stations and at all settingsof the contrast control. Therefore, the

I2BY7VIDEO AMPLV7

FROM

VIDEO DET -9250aCONTRAST

TO HORIZ OUTPUTCATH CKT

Shunting capacitor C146, a 0.22-pfunit, removed the smear. Replacementwas the final cure. C146 couples the

15K4.7 ppf

4.5 MCTRAP

6.8K

trouble was obviously due to poor re-sponse of the video amplifier and not inpreceding sections of the set. Operatingvoltages of the video amplifier weretested and found normal. Tubes werechecked by substitution. Next came acheck of components.

FROMSOUND IF

AMPLPLATE

THA FROM SYNC AMPLFROM VERT OUTPUT PLATE

120 V

270 K PIX

C 146.22

3.9 K

3.9 MEG

590 V

10

plate of the video amplifier to the pic-ture tube cathode. The lowered capaci-tance of this capacitor increased itsreactance to low -frequency signals andresulted in smear. A capacitor checkershowed its value had gone down to.0035 pf.-Eugene Rollins

CROSLEY MODEL F-24COLH6A L5

4.5 MC RATIO DETRATIO DET TRANS

L-

OPEN

270 a

This set suddenly developed syncbuzz. A check of the 5-g electrolyticin the ratio -detector circuit showednormal capacitance. Bridging the 330 -µId capacitor with a 250-Asf unit re -

GREEN -GUThis was a large -screen RCA re-

ceiver. The setting of the green screencontrol was unstable, as if the controlwere faulty. However, the trouble wastracked to the picture tube.

When the neck of the tube wastapped, the green field fluctuated errat-ically. On a hunch, we tilted the cab-inet forward and tapped the neck of

3.3K .005 TO

1-4 VOLx.001 CONT

duced the buzz. A check showed thatthe capacitor in the set was practicallyopen. Replacing the open unit put arapid end to the sync buzz.-James A.McRoberts

N GUNK?the picture tube sharply. This treat-ment corrected the trouble.

The green screen control responsewas normal, and the receiver has beenoperating several days with no signof the trouble. Probably some gunklodged in the green gun, which causeda leakage path. The treatment waseffective.-Robert G. Middleton

TAPE RECORDER ROLLERWhen the rubber -covered pressure

roller of a tape recorder has becomeglazed, dented and worn from use (Fig.1) and there's no replacement available,here's a method that often works to re-new its nonslip surface and shape. Startup the machine without tape on thespindles and set the controls for eitherplayback or record. This will cause theroller to engage the capstan and startrotating. Now, while the roller is turn-ing, hold a fine-cut file lightly to theroller to relevel the roller's uneven sur-

REPAIR

Fig. 1

Now! the fastest, easiestway to master the 'scope!

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SAUNDERS SHOWS YOUHOW STEP BY STEP with 26Projects, 200 Diagrams

Actually demonstrating the'scopes many uses in radio, TV,transistors, vacuum tubes,other work.

USE IT AT YOUR BENCH!Complete Working Manual!

Oscilloscope Checks, Calibra-tion Procedures, Wave FormAnalysis, Circuit Tests, Fre-quency Measurements, CrystalDiode and Transistor Analysis,etc. . . .

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Enclosed is $ for copies 0$4.00 of "Working with theOscilloscope':

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APRIL, 1959 123

have a

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New! Improved!TRANSISTORCHECKERAmerica's newest, mostpopular test instrumentSimple to Operate. Controls are occur-ately set for each transistor byreferring to replaceable set-up charton rear. Test leads or socketprovides for fast hook-up.

NOW CHECKS:* Transistors for opens, shorts, leakage and current gain.

Only tester that tests power transistors as used incar radio outputs.

* Crystal Diodes checks forward to reverse current ratioon all diodes.

* Selenium Rectifiers checks forward and reverse currents.SERVICE INSTRUMENTS CORPORATION

121 OFFICIAL ROAD, ADDISON, ILLINOISSee oth, SENCOvE ads in this issue.

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manufacturers.

TECHNOTES (Continued)

Fig. 2

face (Fig. 2). (Don't remove any morerubber than absolutely necessary andhold the file flat against the roller'ssurface.) The renewed roller will atleast be satisfactory until an exactduplicate roller can be obtained forthe machine.-John A: Comstock

WESTINGHOUSE MODELH -600T16

The set had a thin vertical line onthe screen. Tubes were OK. Voltagechecks revealed no B plus at the hor-izontal output tubes. Circuit tracingled to an open width control. A quickreplacement and the job was finished.-Carl Hennig

EMERSON 120087 D CHASSISComplaint: Vertical foldover at bot-

tom of picture, poor vertical linearity,inadequate height after warmup.

The vertical oscillator's plate loadresistor (R97), normally 470,000 ohms,had increased in value. Replace it witha 1 -watt unit. Also, the 100,000 -ohmresistor (R93) connected to the verticaloscillator transformer's secondary hadgone up. Replace it with a 1 -watt unittoo.-Harry C. Keller

BENDIX MODEL 235M1This receiver had a severe case of

vertical jitter. After checking the ver-tical integrator and sync amplifier cir-cuits half of a (6SN7) I noticed thatthe 6SN7 plate and decoupling resistorswere charred. Replacing these resistorsand the tube restored normal operation.-Wilbur J. Hantz END

"This one came complete!"


KWHREGULATED POWER St PPLY

This supply delivers a continuouslyvariable output voltage at currents upto 4 amps. Maximum available outputvoltage is dependent on the battery,which acts as the voltage reference for

2N554 (4)EMITTERS NOT USED

circuit used is commonly called anemitter -follower regulator in which V3and V4 act as a variable resistor inseries with the load.

The regulator's internal impedance

2N554 (4)

RI22002W

2000µfCI C21__ 25 V + 500pf

+1- 25 V

NEON# TRIAD

'INDICATOR F -48U

LAMP OR EOUIV 2N554

VI

+4:R2

V2

loon 4W

V3 V4

-E

OUTPUT

+O o-2 V BATT OR 12 V

OR 13 V ZENER DIODE

OE

0 OO 0©B

the supply. For better results, replacethe battery with a 12 or 13 -volt Zenerdiode.

Ac ripple at the output varies from10-80 my, depending upon the load.However, ripple is reduced by a factorof 3 by adding C2 (the 500-µf capacitorshown in dashed lines). The regulator

DIFFERENT V0Re: "Stiffer Voltage Divider," by

Leonard E. Geisler, Noteworthy Cir-cuits. RADIO -ELECTRONICS, December,1958, pages 121-22.

I'd like to submit a circuit that isvery simple, yet rarely used by anyoneexcept radio amateurs. It has been inuse in my home station for severalyears. In one application it drops thehigh voltage down to supply the multi-plier and driver stages of my trans-mitter. In another it acts as a screencontrol resistor and is used to varythe output power of my transmitter'sfinal amplifier.

By far, the best application I'vefound for it is as a grid -controlled rec-tifier supplying various voltages for themany pieces of equipment I have aroundthe shop.

The circuit requires only a resistora pot) and a capacitor and a tube.

Although I use a 6AS7, just about anyother tube will also work-excludingdiode types.

The plate of the tube (a triode, ortriode -connected tetrode or pentrode)is connected to the supply voltage.The cathode is connected to the load.A 500,000 -ohm pot is connected be-tween the cathode and ground, with the

....-COLLECTOR CONNECTED TO CASE

0-12V0- 4A

(RIPPLE= 50MVAT 2 A)

is about 0.5 ohm. V3 and V4 shouldbe asthey dissipate up to 60 watts at lowoutput voltages and high output cur-rents. V1 and V2 should also have smallheat sinks as they dissipate approxi-mately 1 watt apiece.-Motorola Semi-r(indoe i'S

1."I'AGE DIVIDERgrid connected to the arm. This potcontrols the output voltage. By varyingthe pot you vary the grid-cathode bias,which in turn varies the tube's conduct-ance.

The minimum output voltage shouldnot be less than the maximum allowableplate voltage of the tube. That is, ifthe maximum plate voltage is 400 and

ON:

+ HV

3ND

a 900 -volt supply is used, the lowestpermissible output voltage should notbe less than 500 (Eut = Esupply -E.,. or the tube will be damagedby excessive voltage.

The maximum current that can bedrawn is limited only by the tube'smaximum current rating. The 40-µfcapacitor across the output smooths

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This tremendous demonstration record, pro-duced by the foremost manufacturer of high-fidelity loudspeaker systems, explains briefly(and simply) the wonderful world of high-fidelity and the really easy -to -u iderstandcomponents required for the finest homemusic system. You'll be startled by the thrill-ing sounds on this record-many of themspectacular stereo "firsts.

Write for it now: Enclose eithe- check ormoney order for $1.50 and send to:

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Enclosed is $1.50. Please send your fascinatingStereo -monaural 12 LP record.To:

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APRIL, 1959

ZONE_ __STATE

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Send 250 for Catalog.1U4 4/11 OHS .59 12BH7 .99 4X150 7.501US .89 655 .59 128Y7 1.00 4X250 35.00IX2A .68 6.16 .59 12827 .99 4X500 38.00304 .68 61(6 .59 12CU6 1.45 SBP1 4.98305 .86 687 .741 125117 1.29 58P4 4.98354 .68 6L6 1.19 12507 .89 35T 4.003V4 .99 654 .59 12587 .89 100T 7.00SR4 1.25 638 .99 12557 .75 250T 20.005U4 .59 65A7 .69 12587 .94 388A 1.00SYS .89 65117 1.10 12507 .96 418A 14.00t 051/36/1E146AC76AG76AH66AKS6AL56AQ56AS76AT6

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Wastrel Surplua Electronicr from schools.59 6SC7 .89 19806 2.15 430T 43.00.59 6507 .79 19T8 1.16 807 1.29.79 65147 .69 25808 1.39 808 1.00.89 6557 .69 25L6 .72 809 3.00.99 65187 .72 25W4 .77.4-4001142.00.69 651.7 .89 25Z5 .72 811 3.00.59 65187 2/51 2526 .75 812 3.00.66 6507 .74 EL34 3.49 813 9.00

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Wanted 904 II futp! Too 5 95 Paid1.29 6U8 .98 35W4 .52 8398 8.001.19 6V6 1.39 35Y4 .69,832A 7.00

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1.00 6X5 .49 5005 .69 5881 2.70.69 6Y6 .80 50L6 .69 6550 3.90.59 7147 .801513P1 5.00 5842 11.00

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NOTEWORTHY CIRCUITS (Continued)

any minor voltage variations and pre-sents a low -impedance source to theload. Several tubes may be paralleledfor higher output currents, or placedin series for larger voltage drops ordifferent output voltages. Any tubecombination can be used for any out-put power desired. The tube type isdependent upon power and space con-siderations.

One novel feature of this circuit isthat the grid can never go positivewith respect to the cathode. This un-doubtedly prevents damage to the tubeand provides for longer life. The out-put voltage regulation is dependentupon, but no different than, the supplyvoltage regulation. -Leonard J. D'Airo

NOVEL NEON BLINKERThe output frequency of this circuit

is obtained by multiplying a singlelamp's repetition rate times the numberof lamps used. Unfortunately, insta-bility increases rapidly once you go

+90-135220K

/W1f1

01111R .1 MEG

c1.470µµf T0.1

.001 pl1-.43

NiThNE -2(5) .001 pf

0

220K K

CHOSEN FOR STABILITYUSUALLY .001 TO .1

C,"'

beyond five or six. I have tried usingvarious capacitances between the lampsas shown, and the results are interest-ing. Where a single lamp will notoscillate past a certain frequency, fiveor seven of them will. Nothing special,just something to do when no one islooking. -Robert D. Holm

TRANSISTOR AMPLIFIERWith a 20-mv input this simple three -

transistor circuit delivers a 100 -mwoutput. It is of the complementary -symmetry type and uses one n -p -n and

2N2I7 2N217DRIVER AUDIO OUTPUT

4511SPKR

one p -n -p transistor in its push-pulloutput stage. The circuit provides avery low output impedance for the out-put stage, making it possible to drivea 45 -ohm speaker directly -no outputtransformer is necessary. -RCA Tran-sistor Spec Sheet END

POWERING4 OUT OF 5of the world'sgreatest hi-fiamplifiers

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6CA7's in push-pull has been successfullyused in power amplifiers delivering up to100 watts undistorted output.

Ask your Amperes distributor about Amperes voltageamplifier, rectifier and output tubes for hi-fi circuits

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MULTIPLEXED STEREOPatent No. 2,851,532

Murray G. Crosby, Riverhead, N. Y.Stereo can be transmitted over a single FM

channel with the help of a subcarrier (about45 kc). See Fig. 1. The audio components areused. The difference between microphone sig-

I(D.

o0Q

RFC

PREAMPL a gPREEMPHASIS

PREAMPLPREEMPHASIS

DISCRIM

nals (A - B) modulates the subcarrier. Theirsum (A B) modulates the main carrier.

At the receiver (Fig. 2) the A -B compon-ent is recovered from the subcarrier afterfiltering. A + B is detected from the carrieras usual. Transformer T combines them, the

much larger one, the resultant remains nearlyequal to the latter. Thus the speakers havenearly equal noise output for true stereo. Fur-thermore, the poorer of the channels (A -B)is associated with a double -strength (2B) audiosignal so there is a definite gain in signal-to-noise for it.

The system is compatible. The 2A componentin the upper speaker would be used for mon-aural listening, so the A -B channel of Fig. 2would not be needed.

A+8

Mk 2-5

AFAMPL

FRED MODOSC FORSUBCARRIER

Fig.l

COMBININGCIRCUIT

A+B

FRED MODOSC FORCARRIER

FILTER LIMDISCRIM DEEMPHASIS

NETWORK

sum 2A feeding the upper speaker, the differ-ence 2B feeding the lower.

Due to small deviation, the subcarrier signal-to-noise ratio is high. The noise in A -B maybe 10 times worse than in A B. Now whena small voltage is added or subtracted from a

Yes, you get this big, brand new book, "150Radio -Television Picture Patterns and Dia-grams Explained", absolutely FREE! Complete11x22" Schematic Diagrams on leading modelsRadio and TV Sets help cut your servicingtime. Easy -to -read, large 81/2x11" pages, with full instruc-tions on how to use the diagrams. A "must" in everyrepair kit. You get this book as a FREE Gift for asking tosee Coyne's new 7 -book set, "Applied Practical Radio -Television"!At Last! Money -Making "Know -How"

On Transistors, Color TV and ServicingCoyne's great 7 -volume set gives you all theanswers to servicing problems-quickly! Forbasic "know-how" that's easy to understandyou'll find everything you want in VOlumes 1 to5 on over 5000 practical facts and data. Everystep from fundamentals to installing, servicingand trouble -shooting all types of radio and TVsets. So up-to-date it includes the latest onCOLOR TV and UHF. All this plus Volume 7-TRANSISTOR CIRCUITS-the most completebook ever published on the applications of tran-sistors in electronics. New! Set has colorful de-sign, washable covers.

EXTRA! 1168 -Page TV Cyclopedia Included!For speedy on-the-job use, you also get Vol. 6-famousCoyne CYCLOPEDIA. Answers problems on servicing,alignment, installation. etc. in easy ABC order. Usethis 7 -volume TV -RADIO LIBRARY FREE for 7 days;get the Servicing Book FREE!

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APRIL, 1959 127

PATENTS (Continued)

ANOTHER GREAT

TRIO®TV ANTENNA FEATURE

wing dipole andwing director

MEM

Today's most powerful combination.The Wing Dipole contains 3 activeelements on the highs, forward Veeto the low band section, plus inte-grated director. The Wing Directorobtains maximum results from theWing Dipole.

Just one of the features that makes Trio themost advanced TV Antennas in the world.Choose from Trio's complete Zephyr andColor Series Antennas.

GRIGGSVILLE, ILLINOIS

"Hold it, Ed! One of these car-tridges is a JENSEN."

RADIOPatent No.

William .4. Coles,This patent discloses a method for making

surgical incisions with a minimum of damage tolive tissue. Shock hazard is minimized also.

866-A(2)

THERMALTIME -DELAYRELAY

II 11

-0SI

-mod b117 V AC

-K

.0102

6.3

KNIFE2,835,254Upper Darby, Pa.

Output leads include blocking capacitators.The dispersive element is a conductive platewhich grounds the patient. The other lead is

2.5 V CT

9

V3

The cutting edge, which may be a needle, knifeor wire loop, is fed with high -frequency current.

The diagram shows a full -wave rectifierpair, VI and V2, which converts line power todc. The de is fed to triode V3's plate. V3 oscil-lates at about 3 me. A Hartley circuit is used.

812-A

2.5MH

40K50W

o rm,

4K10'N

DISPERSIVEELEMENT

C .002 A( .=-

/./.p.f

.004

either A or B. The first delivers greater cur-rent if needed. Capacitor C is an output control.

Note that Si turns on the filament circuits,but no rf is delivered until S2 is also thrown.All blocking capacitors are rated at 2.5 kv, butcapacitor C has a breakdown rating of 5 kv.

ZENER DIODE TESTPatent No. 2,847,646

Frank C. Marino, Montclair, N. J. (Assigned toBell Telephone Labs, Inc.)

Here is a quick, convenient test that displays relay, and assures that diode D is forward..the diode characteristic on a scope. It is de- biased by the low -voltage ac when the relay armsigned especially for diodes of the Zener type, is down. Diode current flows through RI, the

PHASE SHIFTER

OSYNCHRONIZEDAC GENERATORS

P

RELAY r ----- - 1OF ARM I

I

I I>

R2

I 1

-i,

11 41:I

,

,

_

,

I

LRELAY COIL

DIODECHARACTERISTICPATTERN

RI

INPUTS c.___VERT HORIZGND GND

which require small forward voltage but rela-tively high bias in the reverse direction to reachbreakdown.

The circuit switches automatically from lowforward to high reverse voltage. A few volts ofac are applied to the scope's horizontal inputterminals. Another voltage source, synchronizedwith the first, drives the relay coil through anR -C phase shifter. This synchronizes sweep and

SIGHT FORPatent No.

Joseph D. Shaw,

BRAINELECTRODES

PHOTO TUBE

voltage drop being applied to the scope's ver-tical terminals.

During the next alternation the relay armmoves up. This adds a large de voltage in serieswith the ac to assure a high enough reverse biason D. Now the reverse portion of the diode char-acteristic is scanned on the scope. Note that thisportion corresponds to the negative half of theac sweep.

THE BLIND2,721,316

Cincinnati, Ohio.The December 1958 issue of this magazine

described on page 53, actual experiments whichmake it possible for the blind to see. This patentdescribes somewhat similar instrumentalities.

A photocell or phototube is held by the blindperson and is biased with dc from a battery.Light falling on the cell charges Cl. Uponreaching a predetermined voltage, thyratron Vbreaks down and permits C2 (previouslycharged through R1) to discharge through thetransformer. The intensity of this pulse iscontrolled by R2.

The pulse is fed to a plastic socket attachedby surgical means to the skull of the blindperson. Conductors through tiny holes in theskull terminate at the vision area of the brain.Each pulse produces the sensation of sight.

The equipment shown in the diagram producesa single light spot at any time. If a light andshadow pattern is desired, multiple sets must beused, each terminating in a different part of thevision area of the brain.

1 28 RADIO -ELECTRONICS

From the pioneer in ceramics for electronics

USINESSand

PEOPLESprague Products, North Adams,

Mass., is offering service technicians a

HE DIDN'T KNOW THE

SET WAS LOADED!series of newspaper advertising mats todiscourage do-it-yourself TV repairs.

Electronic Instrument Co., Long Is-land City, N. Y., manufacturer of Eico

kits and other electronic products, ispromoting its vtvm and scope probeswith a new package and display stand.

Curtis R. Hammond (left), assistantvice president of Raytheon Mfg. Co.,Waltham, Mass., is now corporate di-rector of regional commercial adminis-tration as part of a move to strengthencommercial sales by the establishmentof six regional sales offices across thenation. Regional executives in Boston,

New York, Baltimore, Cleveland, Chi-cago and Los Angeles will report tohim. Dr. W. Crawford Dunlap (right),former supervisor of solid-state re-search at Bendix Aviation, joined Ray-theon Research Div. as director ofsemiconductor research. John L. Herrejoined the Semiconductor Div., Need-ham Heights, Mass., as government andspecial accounts sales manager. Heformerly supervised government salesactivities for Philco.

Approx.Twice

Size

"ERIEMir,

-a

the new singleceramic element

Stereophonic

cartridge

DYNAMIC BALANCING MAKES THE DIFFERENCEDYNAMIC BALANCING during manufacture provides full stereo repro-duction. SINGLE ELEMENT DESIGN offers balanced outputs; excellentseparation of 20 db over full audio -frequency range, with equal outputsfrom both channels. Compatible with stereo and monophonic discs.

SPECIFICATIONSRESPONSE: 20 to 16,000 cps. OUTPUT VOLTAGE: 0.5 vrms at 1 KC each channel. COMPLIANCE:3 x 10-6 cm/dyne, vertical & lateral. RECOMMENDED LOAD: 2 megohms. RECOMMENDEDTRACKING PRESSURE: 5-6 grams. CHANNEL SEPARATION: 20 db. STYLI!: Dual tip; 0.7 mil dia-mond or sapphire, and 3 mil sapphire. MOUNTING DIMENSIONS: EIA Standard Ye& Y2' centers.

For additional information, see your Authorized ERIE Distributor

ERIE RESISTOR CORPORATIONMAIN OFFICES: ERIE, PA., U. S. A.

CARTOONSRADIO -ELECTRONICS pays $3.00for good cartoon ideas and $15 andup for finished work.

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TELEVISION

AT HEALDS YOU LEARNBY DOING IN MODERN

ELECTRONICS LABORATORIES

HEALDENGINEERING COLLEGE

Established 1863Van Ness at Post, RESan Francisco, Calif.

Never before in American history has theneed been so great for Trained Engineersand Technicians. No other type of trainingcan compare with actual shop practice youget at Healds under expert instructors.

Bachelor of Science Degree, 27 Months Radio -TV Technician including Color TV (12 Months) Electronics Technician (12 Months) Industrial Electronics Technician (12 Months) Electronics Engineering (B.S. Degree) Electrical Engineering (B.S. Degree)

Mechanical Engineering (B.S. Degree)Civil Engineering (B.S. Degree)Architecture (B.S. Degree)Heald College ranks FIRST West of theMississippi in "Who's Who in America"

Approved for VeteransDAY AND EVENING CLASSES

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APRIL, 1959 129

N D N E E R S

JUNIOR SENIOR PROJECT

STEP UP TO LEAREngineers, if you are experienced in the design anddevelopment of air and/or ground based communica-tion and navigation equipment, here is the opportunityyou have been looking for.

Lear, for twenty eight years a pioneer in aircraftradio communication, navigation equipment, auto-matic flight controls and flight indicators, is movingahead in many new fields.

Lear offers unlimited opportunities for advance-ment and greater responsibilities to creative minded,electronic engineers.

If you would like to work in sunny SouthernCalifornia on varied electronic projects, write to:

L. S. PECK, ManagerIndustrial Relations

LEAR, INC., 3171 South Bundy Drive Santa Monica, California

A

TV TUNERS REBUILT411 MAKES & MODELS

VHFor

UHF

EXCHANGEDOR

OVERHAUL ED

.95$9 NET

90 DAYSWARRANTY

COMBINATIONUHF/VHF

UNITS

$19.90

ALIGNED TO ORIGINAL STANDARDS ]

Price includes worn parts only; defectivetubes and damaged major parts are extraat net prices.

Forward defective tuner complete withtubes, shield cover and any damaged parts.

QUOTE MAKE AND MODEL

F.O.B. CHICAGO OR TORONTOWe will ship C.O.D.

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tiesOFFICIAL

ORDER BOOKfor every TV -Radioservice call

Triplicate forms serveas order form, invoiceand office record withspaces for completeinformation on everyjob. Separate listingsfor receiving tubes,pix tube, parts, serialnumbers, labor and tax charges, signatures,etc. 75c a book, $6.50 for dust -proof boxof 10.

OFFICIAL ORDER BOOK

. and for customer's prices on every replace-ment part, plus flat rate and hourly servicecharge data, regional and national, Dave Rice's

OFFICIAL PRICING DIGESTlisting over 6.9,000 items. $2.50

In stock at your distributor, or write

ELECTRONIC PUBLISHING CO. INC.180 North Worker Drive Chicago 6, Illinois

BUSINESS AND PEOPLE (Continued)

EIA Annual Unit Production and SalesTV set production

19584,920,428

19576,399,345

Total radioproduction 12,577,243 15,427,738

FM radio production(July -Dec.) 376,114 not availablet

TV retail sales 5,140,082 6,560,220Radio retail sales 8,631,344* 9,721,286*Receiving -tube

factory sales 397,366,000 456,424,000TV picture -tube

factory sales 8,252,480 9,721,008Transistor factory

sales 47,050,814 28,738,000*Excluding auto setsMast available figure -1955-252,880 FM sets

J. Frank Leach(right) has beenpromoted to vicepresident and gen-eral manager ofthe Amphenol Con-nector Div. of thenewly merged Am -phenol -Borg Elec-tronics Corp., Chicago. He had beenvice president, manufacturing, of Am -phenol Electronics Corp. Robert E.Svoboda, distributor sales manager ofAmphenol, is now general manager ofthe Amphenol Distributor Div.

Frank P. Vende-ly (right) is nowEastern region-al sales managerof the P. R. Mal-lory & Co., Inc.,Distributor Div.,Indianapolis, Ind.He started withthe company as a distributor salesmanand later served as merchandise man-ager. Leon Robbin, a Mallory vice presi-dent for the past 18 years, was electedto the board of directors and namedpresident of the newly formed subsid-iary, P. R. Mallory International, Inc.

Neal W. Turner (left), merchandis-ing manager of Heath Co., Benton Har-bor, Mich., was promoted to director ofproduction planning. Robert K. Swan -

der advanced from purchasing agentto director of purchasing. Ellis Grear,assistant purchasing agent, succeedshim. William E. Johnson (right), for-mer assistant advertising manager ofWhirlpool Corp., joined Heath as dealersales manager. John T. Caviezel, ex -Bell & Howell, joined Heath as dealersales representative.

Charles Molitoris now with Elec-tro-Voice, Inc.,Buchanan, Mich.,as chief industrialengineer. He comesto Electro - Voicefrom Allen Elec-tric Equipment Co.,where he was factory manager.


BUSINESS AND PEOPLE (Continued)

Edward I. Flaxman (left), vice presi-dent in charge of sales for Service In-struments Corp., Addison, Ill., is shownpresenting the Sencor "Rep of the

Year" award to John Havercamp andJack Collins, as Sencore president HerbBowden (right) looks

Thomas H. Mosshas been appointedvice president ofthe Turner Co., Ce-dar Rapids, Iowa.He joined the com-pany in 1952 andwas appointed gen-eral sales managerin 1956, which position he still holds.

Hans D. Sylten,electronics researchengineer, joinedWinegard Co., Bur-lington, Iowa, ashead of the ex-panding researchdept. a

Thomas L. Eckersley, radio pioneerwith English Marconi from 1919 until

1SENCORECIRCUITI TESTERly

'iSave Time with SENCORESave costly call becks by testing the circuit beforereplacing fuse, fuse resistor or circuit breaker.Individual scale for each value fuse resistor-no interpretation,just read in red or green area.

* Measures line current and up to 1100 watts of power at 115 voltsusing line cord and socket. * Two convenient current ranges -0 to 2 amps and 0 to 10 amps. Test leads clip in place of fuse

or fuse resistor. * 5 ohm, 10 watt resistor preventsTV circuit damage,simulates operating conditions.

As Recommended by Leading ManufacturersSERVICE INSTRUMENTS CORPORATION

121 OFFICIAL ROAD, ADDISON, ILLINOISSee other SENCORE ads in this issve

recent years, died in February at theage of 72. His work in wave propaga-tion gave us much knowledge of theionosphere and of the earth's resistivity.He was a Fellow of the Royal Societyand of the IRE, and received the Fara-day Medal in 1951. END

50 E1ear, agoIn Gernsback Publications

HUGO GERNSBACK, FounderModern ElectricsWireless Association of AmericaElectrical Experimenter

190819081913

Radio News 1919Science & Invention 1920Television 1927Radio -Craft 1929Short -Wave Craft 1930Television News 1931

Some larger libraries still have copies of Modern Electricson file for interested readers.

In April, 1909, Modern ElectricsMajorana Aerophone Work, by A. C. Mar-

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Dr. Claude E. Shannon's historic 1938 paper given be-fore the American Institute of Electrical Engineers: "ASymbolic analysis of Relay and Switching Circuits,"12 pages. List of references to computer literature including"Minds and Machines" by W. Sluckin, published byPenguin Books (Baltimore), 1954, 233 pages, and otherreferences.

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APRIL, I 9 5 9 131

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RADIO -ELECTRONICS.154 West 14 St., New York 11, N. Y.

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`alit.HIGH-FIDELITY S1'EAKERS REPAIRED. AMPRITESpeaker Service. 70 Vesey St., New York 7. N.Y.BA 7-2580.CASH PAID! Sell your surplus electronic tubes. Wantunused, clean transmitting, special purpose, receiving,TV types. magnetrons. klystrons, broadcast, etc. Alsowant military & commercial lab test and communicationsgear. We swap too, for tubes or choice equipment. Sendspecific details in first letter. For a fair deal write, wireor telephone: BARRY. 512 Broadway, New York 12,N.Y. WAlker 5-7000.RECORDERS, Hi-Fi, Tapes. Free Wholesale Catalogue.CARSTON, 215-T East 88th St., New York 28. N.Y.STEREO TAPE RENTALS. For the very best at lowest

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MOM.Any or all of these catalogs, bulletins, or

periodicals are available to you on requestdirect to the manufacturers, whose addresses arelisted at the end of each item. Use your letter-head-do not use postcards. To facilitate identi-fication, mention the issue and page of RADIO -ELECTRONICS on which the item appears.UNLESS OTHERWISE STATED, ALL ITEMS AREGRATIS. ALL LITERATURE OFFERS ARE VOIDAFTER SIX MONTHS.

WIRE-CABLE-TUBING of all types aredescribed and illustrated in colorfulcatalog T-258. Everything from aerialand antenna wire through magnet wireto weatherproof cable.-Birnbach RadioCo. Inc., 145 Hudson St., New York 13.

ELECTRONIC COMPONENTS areoffered in 2 -color 4 -page illustratedfolder. Record changers, resistors, sol-dering guns, switches, wire, etc.-Brooks Radio & Television Corp., 82Vesey St., New York 7, N. Y.

STEREO PHONO CARTRIDGES andhow to use them is the topic of a 16 -pagebooklet Application Considerations inthe Use of Stereo Cartridges-publica-tion EP -681. The illustrated text dis-cusses factors influencing stereo per-formance, cartridge tracking force andloading, problem diagnosis, and car-tridge connections and input wiringpractices.-General Electric Co., Spe-cialty Electronic Components Dept.,West Genesee St., Auburn, N. Y.

HI-FI CABINETS, kits and assembledunits including speaker enclosures, andequipment and record storage cabinetsare shown in a colorful 4 -page folder.-Stereo Craft, Div. of 20th CenturyWoodworking Co. Inc., 79 Clifton Pl.,Brooklyn 38, N. Y.

STEREO SIMPLIFIED is a pocket -sizedbooklet that explains high-fidelitystereophonic reproduction of music inthe home. Covers the entire process ofstereo recording and reproduction.-Sonotone Corp., Elmsford, N. Y.

SOLDERING IRON TIPS are presentedin an enlarged catalog sheet No. 601.Plug-in and screw -in types are illus-trated. 124 shapes and sizes are covered.-Hexacon Electric Co., 186 W. ClayAve., Roselle Park, N. J.

CORRECT STEREO GEOMETRY andoptimum tonal range are described inan illustrated folder titled Pocket Facts.Circuitry for driving a third channelfrom the two stereo tracks is illustrated.-Klipsch & Associates Inc., 116 N.Louisiana St., Hope, Ark.

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DIAGRAMS FOR REPAIRING RADIOS $1. Tele-vision $1. Give make, Model. DALE CO. 319 West 14thSt.. N. Y.CIVIL SERVICE JOBS-mechanical, clerical, profession-al. List $1. CIVIL SERVICE BULLETIN, 115D Hay -path Road. Plainview, N.Y.LITERATURE TO HELP You Pass FCC Phone Exams.Free Information. WALLACE COOK, 16141 MortonRoad, Jackson 9, Miss.MAKE MONEY Collecting Names. Stamp Brings Details.HAMILTON'S, Hatch, New Mexico.UNUSUAL VALUES. components, tapes and taperecorders. Free catalog RE. STEREO CENTER. 51 W.35 St., New York 1, N. Y.BONGPOEMS and LYRICS WANTED! Mail to: TINPAN ALLEY, INC. 1650 Broadway, New York 19, N. Y.HI-FI CONVERTER. Console sound front your radio.television set, or record player, with new speakersystem kit. Write for free folder. WINDIIAVEN RADIO,Box 14D-74, Baroda, Mich.WHOLESALE Appliance Parts Catalogue 250. SIMMONS,26 South 20th Street, Birmingham 3, Ala.SAVE MONEY! Get our list price on all types Radio andTV tubes at MFRS PRICES! 100% Guaranteed, all brandnew and unused, no mechanical or electrical rejects, notwashed or rehranded! 24 -hour service! Write UNITEDRADIO COMPANY. 58 Market St.. Newark, N.J.PRACTICAL SERVICING-Closed Circuit TV-TheatreSound System-In Binder-$3 yearly. WESLEY TROUT,ENGINEER. Box 575, Enid, Oki: doom,

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LITERATURE (Continued)

High Fidelity details the componentsrequired for a hi-fi system, and explainsthe difference between stereo and monosystems in terms of results to be ex-pected. The 64 -page booklet is wellillustrated. Glossary of technical termsis included.-Bogen-Presto, Div. SieglerCorp., Box 500, Paramus, N. J., 25c.

FRACTIONAL -HORSEPOWER MOTORS,of all types are presented in MotorCatalog M 159. Complete specificationsincluding a dimensional drawing foreach type motor are included.-CarterMotor Co., 2711 W. George St., Chicago.

CORRECTIONMr. Snader reports that he had listed

the TONE EQUALIZATION control (R16Rand R16L) as 250,000 ohms in thediagram and parts list of his "TapeAmplifier for Stereo" in the Marchissue. The correct value for each sectionof the dual control is 5,000 ohms. Thecontrol should be set to about 2,500ohms for NAB equalization.

USING THE ECONOMYTUBE CHECKER

Mr. Jaski has received a number ofrequests for clarification of the operat-ing instructions for his Experimenter'sEconomy Tube Checker, described inthe December, 1958, issue and has sup-plied this additional information:

Testing rectifiers. Test each half ofa full -wave rectifier separately. Onesection may be bad while the otheris good. The load resistor in Figs. 2-band 2-c provides a normal full load forthe rectifier. Its value is determinedby Ohm's law. The maximum continu-ous current delivered by the tube islisted in tube manuals. There is nostandard test voltage. It depends onyour meter. With a 1 -ma meter, ap-proximately 30 volts ac is often used.The voltage is a matter of choice.

Amplification tests are made with dcplate and screen voltages listed in thetube manual under "typical operatingconditions." The load resistor must bedetermined from tube characteristicslisted in the manual.

Noise tests are made with normaloperating voltages on all elements. Ifthe plate and screen are normally oper-ated at 100 and 75 volts, respectively,match or approximate these voltagesfor the test.

Mr. Jaski also calls our attention towiring errors in the connections tothe plate- and screen -voltage selectorswitches in the diagram of his tubechecker on page 33 of the December,1958, issue. The 3- and 7.5 -volt posi-tions on S5 should connect to corre-sponding taps on transformer T2. The10 -volt position on S3 should go to the7.5 -volt tap on T2.

He also points out that he labeledthe instrument's screen -voltage switchS5 with the ac voltage level applied tothe rectifier and plate switch S3 withthe dc output from the plate -supplyfilter, and that this notation was carriedon to the schematic, causing some leadsto have two voltage readings.

UM.TRANSISTORELECTRONICS& SOLID STATEPHYSICS

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1 TRANSISTOR PHYSICSAND CIRCUITS

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a new simplified approach to theoperation and design of transistorcircuits by way of familiar phys-ical and electrical law without sac-illieing technical fidelity.

9 TRANSISTOR ELECTRONICSBy Lo. Endres, Zawels, Wald-

hauer, ChengHere's an exhaustive run-down ofmany specialized areas of tran-sistor work. from transistor opera-tion and circuit analysis to prac-tical circuit design. Full coverageof high frequency operation, osql-lators. modulation, demodulation,switching circuits. Convenient tab-ular forms help bring out finetmints of operation.

' TRANSISTORS HANDBOOKBy William D. Bevitt, Tran-

sistor Applications Engineer. CBS -H ytronPractical, on-thedoti guide to allmajor types of transistor eiteultswith full data on 56 differenttransistors. Gives scores of circuitdiagrams each with typical valuesof cimult eleinents-material thathelps you take out, try, and adaptthese tested cireults to your ownneeds.

A SOLID STATE PHYSICSProf. A. J. Dekker, Electrical

Engineering Dept.. University ofM i nnesotaThorough sillily of the rhysiealproperties of crystalline solids.Contains full Information on prop-erties of metallic lattices, ioniccrystals. semiconductors, magneticproperties of solids, electronicproperties of ionic crystals.

SSOLID STATE PHYSICAL

ELECTRONICSBy Prof. Aldert Van Der Ziel,Electrical Engineering Dept.. Uni-versity of MinnesotaProvides cmplete source of Info,-Mat lOn on

osolid state devices being

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EXAMINE 10 DAYS WITHOUT RISKMall V4,111,011 Is lint 10 Na1111111' 1111, I ahlahlt. 5-voittineLibrary. You lake till risk. But 1lon't delay-mail c011petnHMI

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APRIL, 1959 133

ELECTRONIC ENGINEERSfor expanding

Electronics DivisionPositions open at all levels for men with electronic, electro-mechanical and mechanical experience. Top level positions inapplications and sales for work on:

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and many other assignments for project, senior and juniorengineers. Plant location in Carlstadt, N. J. makes commutingeasy from New York City or northern New Jersey suburbs.

Send detailed resume including salary requirements to:T. W. Cozine, Mgr., Executive & Technical Placement, Curtiss-Wright Corporation, Dept. ED -25, Wood -Ridge, N. J.

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WORKING WITH THE OSCILLOSCOPE,by Albert C. W. Saunders. ElectronicTechnical Publishing Co., Inc., P.O. Box306, Boston, Mass. 81/2 x 11 in., 93 pp. $4.

This clean of electronic instructorshas designed a book especially for thestudent, including all the facts neces-sary for the absolutely green beginnerwithout being boring to the advancedstudent who is looking for a refresher.The book is divided into five parts.Part One discusses the electroscope,beginning with some simple principlesof electron optics, then describing theinterior construction clearly, with thehelp of diagrams and photographs.Part Two is devoted to oscillographicpatterns, showing the function of thetube elements in producing them. Thereare two sections on the time base andassociated horizontal circuits, and oneon the vertical deflection amplifier. Thelast part is a laboratory manual,describing 26 projects, ranging fromvoltage calibration to squaring the sinewave and measuring transistor char-acteristics. These 26 projects coverpractically all the uses of the scopethe student and technician are likelyto need.

The value of the book is enhancedby the excellent readability, due to thelarge, heavy modern type on goodpaper, and the number and quality ofthe drawings, schematics and photo-graphs.-F'SINTERNATIONAL RADIO TUBE ENCY-CLOPEDIA. Bernards, Ltd., The Gramp-ians, Western Gate, London, W.6.England. 7'/2 x 93/4 in. 768 pp. 63 shillings.

This is a small world, but it hasmany thousands of tube types. Thisencyclopedia lists no less than 27,500,and in such a way that full specifica-tions and ratings are available at once.The tubes are listed in groups. Thefirst contains types released before1949. The more recent types (including1958) appear in several supplements,with a master index making it easy tolocate any desired type. The same pagecontains all data and basing, so thereis no need to turn over.

Among other information are: equiv-alent types, wartime tubes, manufac-turers' names and addresses. Use ofthe book is explained in 15 languages.-IQIHFM STANDARD METHODS OF MEAS-UREMENT FOR TUNERS, prepared andpublished by Institute of High FidelityManufacturers, Inc., 125 E. 23 St., NewYork 10. N.Y. 7 x 10 in., 22 pp. $1.

Ratings of AM and FM tuners havebeen so ambiguous that it has oftenbeen impossible to compare one withanother from their specifications. Toestablish a uniform and unambiguous


BOOKS (Continued)

method of specifying such equipment,the institute has published this stand-ard. Terms-both for AM and FM-are defined; operating conditions andrequirements for testing apparatus areset forth, and test procedures are givenseparately for AM, FM and AM-FMtuners.-F'STV AND OUR SCHOOL CRISIS, byCharles A. Siepmann. Dodd, Mead & Co.,432 Fourth Ave., New York, N. Y. 51/4 x 8in., 198 pp. $3.50.

Education by remote control has beentried and found desirable. Courses inforeign languages, science, history andother subjects are given successfullyby TV. One physics course called "Con-tinental Class," originating from theUniversity of California, is broadcastweekday mornings to an estimated 270,-000 students over TV.

In this book the chairman of theDepartment of Education at New YorkUniversity reviews results of closed-circuit and open -circuit TV, and findsthem highly satisfactory. He believesthat the new medium will become evenmore important in the future.-IQ

MAGNETIC RECORDING TECHNIQUES,by W. Earl Stewart. McGraw-Hill BookCo., 330 W. 42 St., New York 36, N. Y.6 x 9 in.. 272 pp. $8.50.

Distortionless magnetic recording isa recent development, but already hasbecome important in science, entertain-ment and industry. Soon it will prob-ably supplant films for recordingmovies and TV. This engineering bookis well organized and complete incovering theory and practice. It de-scribes processes, materials and mecha-nisms. It shows how to obtain optimumperformance in recording.

Among paragraph headings are mag-netic media, recording and reproducingprocesses and ferromagnetism. Typicaltest and amplifier circuits (tube andtransistor) are illustrated and dis-cussed. The book closes with a chapteron "standards" which give dithensionsof tapes and films, terms and defini-tions, measurements, etc. Engineeringequations appear in the appendices.-IQ

ELECTRONIC MEASURING INSTRU-MENTS (Second Edition), by E. H. W.Banner. MacMillan Co., 60 Fifth Ave..New York 11, N.Y. 51/2 x 81/4 in., 496 pp.$7.95.

Modern industry, science and medi-cine rely heavily on specialized typesof measuring apparatus. This book dis-cusses many kinds: voltmeters, elec-trometers, transducers, radiation de-tectors, counters, electrocardiographs,pyrometers, photometers, among others.Its information is useful for engineers,students and users of the equipment.

The first two parts discuss indicatingmeters, tubes, transistors, photocellsand radiation meters. The last twodescribe instruments using these de-vices. Treatment is brief, but clear andcomplete. The author includes specifi-cations, block diagrams, schematics andphotos where helpful.-IQ END

SCHOOL

DIRECTORY

Be a "key" man. Learn how to sendand receive messages in InternationalMorse code. Communicate with opera-tor. around the globe. Learn at homequickly through famous Candler System.Used by best operators. Qualify forAmateur or Commercial License. Writefor FREE BOOK.

CANDLER SYSTEM CO.Dpt. 3-D Box 9226, Denver 20. Coln. USA

ELECTRONICSPr'Pa" ENGINEERING DEGREEfor unlim-tunities inited °prior. IN 21 MONTHSlectronics!B.S. Engineering degree (27 mo.): Mathematics, Electric -

cal Engineering, TV, advanced Radio Theory and Design.B.E. (36 mo.): Aeronautical, Chemical, Civil, Electrical,Mechanical, Metallurgical Eng. B.S. (36 me.): Math..Chem., Physics. Also preparatory courses. Earn board.G.1. approved. 20 bldgs., dorms, gym. Enter June.Sept., Dec., March. Catalog. Keeping pace with progress.INDIANA TECHNICAL COLLEGE

1549 E. Washington Boulevard, Fort Wayne 2. Indiana

GET INTO

ELECTRONICSV.T.I. training leads to success astechnicians, field engineers, special-ists in communications, guided mis-siles, computers, radar and automation.Basic and advanced courses in theoryand laboratory. Assoc. degree in elec-tronics In 29 mos. B.S in electronicengineering obtainable. ECPD ac-credited, G.I. approved. Graduates Inall branches of electronics with majorcompanies. Start September, February.Dorms, campus. High School graduateor equivalent. Catalog.

VALPARAISO TECHNICALINSTITUTE

Dept. C Valparaiso, Indiana

ENGINEERING DEGREES

PACIFICINTERNATIONAL

E.E.Option Electronics

or PowerEarned through

HOME STUDYResident Classes AlsoAvailable if Desired

PACIFIC INTERNATIONALCOLLEGE OF ARTS

& SCIENCESPrimarily a Correspondence

School5719-M, Santa Monica Blvd.,

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ELECTRONICSPREPARE FOR A GOOD JOB!

BROADCAST ENGINEERRADIO SERVICING AUTOMATION

TELEVISION SERVICINGBLACK & WHITE -a -COLOR

APPROVED FOR VETERANS AND SURVIVORSOF VETERANS

BUILDING AIR CONDITIONEDSEND FOR FREE LITERATURE

BALTIMORE TECHNICAL INSTITUTE1425 EUTAW PLACE, BALTIMORE 17. MD.

prepare for your career in

ELECTRONICS

COMPUTERSand other fields of

ELECTRICAL ENGINEERING

At MSOE, you can equipyourself for a careerin many exciting, grow-ing fields: MISSILESRADAR AUTOMATIONRESEARCH DEVELOPMENTELECTRICAL POWERAVIONICS ROCKETRY

When you graduate fromthe Milwaukee Schoolof Engineering, you areprepared for a dynamiccareer as an ElectricalEngineer or Engineer-ing Technician. Undera faculty of specialists,you gain a soundtechnical education inmodern, completelyequipped laboratoriesand classrooms. As aresult, MSOE graduate,,are in great demandand highly accepted byindustries nationally.

At MSOE you willmeet men from allwalks of life and allparts of the country- some fresh out ofhigh school or prepschool, others in their 1

twenties -veterans andnon -veterans.

You can start school in any one offour quarters and begin specializingimmediately. Engineering techniciansgraduate in 2 years with an Associatein Applied Science degree. For aBachelor of Science degree in Engi-neering, you attend 4 years. A 3 -monthpreparatory course also is available.

FREE CAREER BOOKLET!If you're interested in any

_ phase of electronics, radio or"rTI television, be sure to look

into the programs of studyoffered by the MilwaukeeSchool of Engineering. Just- - mail the coupon.

irApr

-I

MILWAUKEE SCHOOLOF ENGINEERINGDept. RE 459. 1025 N. Milwaukee St.Milwaukee, Wisconsin

Please send FREE Career BoOklet. I'm in-terested in 0 Electronics 0 Electrical PowerEl Television 0 Mechanical Engineering Radio 0 Electrical Engineering0 Computers 0 Industrial Electronics

PLEASE PRINT

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NIAPRIL, 1959 135

NEW! "Do -It -Yourself" LAFAYETTE Kits

LAFAYETTERADIO

ELECTRONICKITS

Include the verylatest electronicadvances. Are constantlybeing modernizedby Lafayette'sown EngineeringDepartment, bya leading con-sulting engineer-ing firm, and byyour own recom-mendations. Are a productof Lafayette's 38years of ElectronicLeadership.

LAFAYETTE'S1959 CATALOG

260 AGES -SIZE

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Complete listings of the NEWEST in Stereo and MonauralHi -Fl, Sher: Wave, Audio, Trans stor, and many other Lafayette

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36 -WATT STEREO BASIC POWER

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Send FREE LAFAYETTE Catalog 590

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APRIL, 1959 137

WRITE FOR LATEST TUBE CATALOGFREE!

Receiving, transmitting, special purpose tubes,diodes, transistors, etc. We have a large, diversi-fied stock at sensible prices. Tube cartons &stackers always in stock.

TRIMM COMMERCIAL HEADSETS. Highestquality lightweight Trimm No. 157-doubleheadsets -17,000 ohms impedance (reg. net$17.60). Original Cartons-Unused.Special $6.50

SNIPERSCOPE. See in Dark! Attach to rifle.Mfd. by American Optical. Model M-3. Withorig. power supply & cables. Comes withinfra -red light source and filter. Orig. box.(Orig. cost $2,000.00) Special Price $120.00

Raytheon Power Supply. Input: 6 volts D.C.Output: 117 VAC under load @ V2 to 3/4 AmpsAC (50 watts plus) new-original cartoned-heavy-duty unit - best parts (Original costover $100.00) Price $16.95

Heavy -Duty Test Leads. Tests to 10 KV forTV, etc. Red & Black Leads. ICA #4317.

- Price $1.25

Signal Tracer Probe For VTVM, Etc ICA#4310. Price $1.75

ICA 5 Way Binding Posts (Black or Red).Price 220 Each

81k or Red B Plugs For Above, Etc.3" Long. (Specify Color). Price 156 Each

Test Leads. Std. Set of Red & Blk LeadsW/Banana Jacks & 5" Probes. ICA #312.Price 50it Each

FTR MINIATURE CHOKE. BRAND NEW!Hermetically Sealed. 2 Hys. at 130 Ma. 23/4"H. x 11/2" W. x I" D. Stock No. 3C3I5-127.Price 404 Each

6 and 12 Volt (operates from either) InputCarter Duovolt Dynamotors: Medium SizeUnit Puts out 400 Volts @ 375 Ma $15.95Large Size Unit Puts out 620 Volts @280 Ma. --.$19.95All Units are brand new, genuine CarterDynamotors.

General -Radio Vance Type 200 CUH-Theoriginal continuously adjustable autotrans-former-Input voltage: 115 volts at outputvoltage of 0 to 270 volts @ 2 amps. Also willoperate from 230 volts and deliver from 0 to270 volts @ 2 amps. Brand new sealed inoriginal cartons-only $11.95 less knob & dial.With knob and dial .only $12.95

Choke-Approx. 6 HY. @ 500 MA. -26 OHMSD.C. Resistance unused Price $3.952 for $6.00

Westinghouse Choke 10 HY. @ 200 MA. -77OHMS D.C. resistance -5" x 5" x 31/2".Stock No. LI423117 $1.902 for $3.00

University Labs 10 Watt Outdoor Loud-speaker, 8 Ohms-300.5000CPS-Brand NewBoxed-with Mounting Bracket and 10 FootRubber Cord and Amphenol Connector madefor Navy-Black finish-finest construction-Excellent for portable Megaphone Amplifier

$12.95

HALF WAVE SELENIUM RECTIFIER. Mfd.by Radio -Receptor. Ideal for voltage dou-bling mobile power supply circuits. 225 VACinput 200 MA. Dimensions: 11/2" x 11/2" x 11/4"deep. Net weight 2 oz. Catalog #1090749

$1.50

Her. Sealed FILAMENT XFMR115 VACTAPPED SEC. 5V at 10 A. Hi -Volt. Ins. -Cat. #F90132. Price $3.00

Herm. Sealed FILAMENT XMFR115 or 230PRIM. SEC. 5V at 10 A. Hi -Volt. Ins.Price $3.75

Authorized factory distributors for: ADJUST -A -VOLT. B & W, DRAKE, EIMAC, GELOSO, GEN-ERAL ELECTRONICS, GLAS-LINE, GONSET,HAMMARLUND, HEXAGON, E. F. JOHNSON,NATIONAL CO.. NATIONAL ELECTRONICS.PENTA LABS, STACO, TECHNICAL MATERIELCORP.. TOBE, WESTINGHOUSE. VOCAL1NE,and Others. All prices F.O.B. N.Y.C. Specify methodof shipment. All merchandise insured and guaranteedfor cost of mdse. only. Send 25c for 1959 green sheet.Open Monday to Saturday-come in and browse-weare near Prince St./BMT Station-Spring St./IRTStation. I flight up -20,000 sq. feet of values. Thou -'ands of unadvertised specials. Phone: WAlker 5-7000.

BARRY ELECTRONICSCORP.

512 Broadway, Dept RE -3, N.Y. 12, N.Y.

138

116131

12139119

How to service these tricky sets -Jtechniques, what instruments to use,

pitfalls to avoid. Troubleshootinghints. Get this one now and watchyour servicing income grow.

No. 76-$2.90

Transistor TechniquesA handbook for the practical man.Very little math or theory but lotsof hints on testing, use, performance,measurements, construction.

ADVERTISING INDEXRadio -Electronics does not assume responsibility for any errors appearing in the index below.

Allied Radio Corp. 13, 78-79Amperex Electronic Corp. 126Arkay Radio Kits Inc. 111Audio Devices, Inc. 10Audio Fair 129

B & K Manufacturing Co.Barry Electroncis Corp.Bell Telephone LabsBendix RadioBerkeley Enterprises, Inc.Blonder -Tongue LabsBogen (David) Co., Inc.Brooks Radio & Television Corp

27, 8113814

CBS-HytronCapitol Radio Engineering

Institute 91-92Carston Studios 139Castle Television Tuner Service 130Centralab Div. of Globe Union....106-107Century Electronics Co., Inc. 96-97Cleveland Institute of Radio

Electronics 105Cornell-Dubilier Electric Corp. 80Coyne Electrical School 115, 127, 132Curtiss-Wright Corp. 134

28

Delco Radio Div. of GeneralMotors Corp. 23

DeRo Electronics 122Deutschmann (Tobe) 88DeVry Technical Institute 7

Dressner 139Dynaco Inc. 122

Editors & Engineers 115Electro-Sonic Labs 133Electro-Voice,

Inc. 125, Inside Back CoverElectronic Instrument Co.

(EICO) 29, 30Electronic Publishing Co., Inc. 130Electronic Technical Publishing Co 123Erie Resistor Corp. 129

General Instrument DistributorDiv. 90

Gernsback Library, Inc 108, 138Grantham School of Electronics 9

Heald Engineering College 129Heath Co. 62-73, 75Hudson Specialties Co. 131

Indiana Technical CollegeInternational Business

Machines (IBM)International Correspondence

Schools

Jensen Industries

Key Electronics Co

Lafayette RadioLansing (James B.) Sound, Inc

133

112-113

11

128

139

136-13726

'BE WISE...TRANSISTORIZE!Gil books show you howTransistors are coming on stronger and stronger.Want to learn more about them? Work withthem? Play with them? Experiment? GernsbackLibrary has the book for you. Attractive low-priced paper -bound editions. Order the ones youwant now.

Transistors-Theory and PracticeBy Rufus P. Turner (Second Edition)

THE .book on the fundamentals' oftransistors for the practical man.Over 30,000 copies of the originaledition sold. Now completely up-dated and enlarged. Covers-theory,characteristics, equivalent circuits,amplifiers, oscillators, tests andmeasurements. No. 75-$2.95

Servicing Transistor RadiosIBy Leonard D'Airo

IIIIIIIiii

No. 61-$.1.50 .:

Transistor CircuitsAnother Turner gem

Scores of amplifier, oscillator, powersupply and other circuits. Testedand debugged by the author. Agreat book for the man who wantsto experiment, learn and have funwith transistors. No. 63-$2.75

SEE YOUR DISTRIBUTOR OR USE THIS COUPON

Gernsback Library, Inc. Dept. 49154 West 14th St., New York 11, N. Y.

My remittance of $ is enclosed.Please send me the books checked below, postpaid.

13 76 0 75 0 63 CI 61

nameplease print

street

city cone state

RADIO -ELECTRONICS

Lear Inc. 130Lektron Inc. 110

Mallory (P. R.) & Co., Inc. 20Manco Manufacturing Co. 132Moss Electronic Distributing

Co., Inc. 84-87

National Radio Institute 3, 15National Schools 5

Opportunity Adlets 132, 133Oxford Components, Inc. 134

Paco Electroncis Co., Inc. 18Philco Techrep Division 140Picture Tube Outlet 139Prentice -Hall, Inc. 133Progressive Edu-Kits Inc. 120

RCA Electron TubeDivision 102-103, Back Cover

RCA Institutes 21Radiart Corp. 8Radio Receptor Co., Inc. 90Radio Shack Corp. 109Raytheon Manufacturing Co. 16-17Rinehart & Co., Inc. 83, 114

Sams (Howard W.) & Co., Inc.....25, 121Seco Manufacturing Co. 122Seg Electronics 81Service Instruments

Corp 89, 110, 124, 131, 132, 134, 139Sonotone Corp. 104Sprayberry Academy of

Radio Television 19Stereo-Ette Co. 115Supreme Publications 117

Tab 126Trio Manufacturing Co. 128Triplett Electrical

Instrument Co. Inside Front CoverTri-State College 118Tung -Sol Electric Co. 24

University Loudspeakers Inc. 22

Wen Products Inc. 121

Xcelite Inc. 124

SCHOOL DIRECTORY PAGE 135Baltimore Technical InstituteCandler System Co.Indiana Technical CollegeMilwaukee School of EngineeringPacific International College of Arts & SciencesValparaiso Technical Institute

BRANCH ADVERTISING OFFICES: Chicago: 1025 Harlem Ave., Glenview, Ill., Glenview 4-6900. Los Angeles:Harker-Husted-Coughlin, 600 South New Hampshire, Tel. DEnliiik 7-2328. San Francisco: Harker-Husted-Coughlin,444 Market St., Tel. GArfleld 1-2481.FOREIGN AGENTS: Great Britain: Atlas Publishing and Distributing Co., Ltd.. 18 Bride Lane, London E.C. 4.

Printed in the united states of America

TV PICTURE TUBESAt Lowest Prices

106P4 ....S 7.95 I7BP4 ....$I0.95 2IAMP4 519.95I2LP4 .... 8.95 I7CP4 .... 17.00 2IATP4 .. 20.95I4B/CP4.. 9.95 I7GP4 .... 17.60 2IAUP4 .. 20.95I6DP4 .... 14.95 I7HP4 .... 13.60 21EP4 .. 14.9516EP4 .... 15.90 I7LP4 .... 13.60 2IFP4 .... 15.9516GP4 .... 15.90 I7QP4 .... 11.95 2IWP4 .... 17.30I6KP4 .... 10.95 I7TP4 .... 19.30 2IYP4 .... 15.95I6LP4 .... 10.95 I9AP4 .... 19.30 2IZP4 .... 14.9516RP4 .... 10.95 20CP4 .... 13.90 24CP4 .... 23.95I6WP4 .... 15.20 20HP4 .... 17.95 24DP4 .... 26.95I6TP4 10.95 21AP4 .... 22.10 27EP4 39.95I7AVP4 .. 15.20 2IALP4 .. 20.95 27RP4 .. 39.95

1 year warrantyAluminized Tubes $5.00 more than above prices.Prices include the return of an acceptable similartube under vacuum. These tubes are manufacturedfrom reprocessed used glass bulbs. All parts andmaterials including the electron gun are brand new.

ALL PRICES FOB CHICAGO, ILLINOIS. Deposit required, when old tube Is not re-turned, refundable at time of return. 25%required on COD shipments. Old tubes musbe returned prepaid. Tubes shipped RailExpress.

WRITE FOR COMPLETE LIST.

-PICTURE TUBE OUTLET --3032 Milwaukee Ave., Chicago 18, III.

Dickens 2-2048

TAPE RECORDERSHI-FI COMPONENTSSLEEP LEARN KITS

MERITAPE UNUSUALLow co,t, high VALUESquality recording FREE

tape, in boxes or cans. 1959 CATALOGDRESSNER, 69.02RE 174 SL, Flushing 65, N.Y.

LOOKno further . if you'researching for hi-fi sav-ings. Write us your re-quirements now.

Key Electronics Company120-A Liberty St, N.Y. 6, N.Y.

EV 4-6071

0111r MAIL ORDER HI-FI -MPG1bu can no, purchase all your trout onereliable source and be assured of perfect delivery.Carstqn makes delivery from NY stock on most

Recorders and tape within 24 hours. SENDUS A LIST OF YOUR HI -Fl REQUIREMENTSFOR OUR WHOLESALE QUOTATION and ourFREE wholesale catalogue.

CARSTON STUDIOS 215 -RD E. 88 St.New York 28, N. Y.

SENCORE.AVSE '136

With. R C -Substitution Unit

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See other SENCOREads in this issue.

"36" -Most Often Needed Componentsat YOUR Fingertips!3 Pole, 12 position switch individuallyselects one of the "36" componentsfor direct substitution.Contains:* 12-1 watt 10% resistors from 10 ohms to 5600 ohms* 12-1/2 watt 10% resistors from 10K ohms to 5.6 megohms* 10-600 volt capacitors from 100-mmfd. to .5 mfd.* 1-10 mfd., 450V Electrolytic * 1-40 mfd., 450V Electrolytic

* For Shop, Lab, or outside serviceSERVICE INSTRUMENTS CORPORATION

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DEALER NET

Completely IsolatedAvailable at allPorts Distributors

IT'S TRUE WHAT THEY SAY ABOUT STEREO

Any stereo set -up -no matter whatthe cost - is only as good as thequality of the components that gointo it. To put it another way, thequality you want can only be sup-plied by a company with the experi-ence in sound engineering that themanufacture of superior stereo,components requires.

Everyone agrees that the making ofhigh-fidelity sound equipment is anextremely technical, highly special-ized phase of the electronics indus-try. And that years of experienceare required before a high degree ofmanufacturing excellence can beachieved. For over twenty-fiveyears, Bogen has been making spe-cial sound systems of proven excel-lence for schools, theatres, officesand industrial plants - as well ashi-fi components.

Here is the business end of a typ-ical Bogen school sound system.

Wherever professional sound qual-ity is needed -you'll find Bogen, thesound equipment made by profes-sionals. Best of all, the same soundquality that engineers and musi-cians insist on is yours to supply -and enjoy -with Bogen stereo high-fidelity components.

ILLUSTRATED BOOKLET: 64 -page explana-tion of hi-fi and stereo, "UnderstandingHigh Fidelity -Stereo Edition". Enclose25c. BOGEN-PRESTO co., Paramus, N. J.

A Division of the Siegler Corporation.

BOGENHIGH FIDELITY COMPONENTS

APRIL, 1959 139

LearnTRANSISTOR, COMPUTER ORRADAR TECHNOLOGY at home

Prepare now for advancement ... and for a secure andprofitable career in one of these growing fields of electronics

1.

2.

3.

4.

5.

6.

CHOOSE FROM 6 PROVEN COURSESSEMICONDUCTORS-Transistor Principles and Practices. Learn Theory, con-struction. application of all types of transistors.

INTRODUCTION TO ANALOG COMPUTERS-Covers theories and fundamentalsof all makes of analog computers.

ANALOG COMPUTER SYSTEMS (Advanced Level)-Covers the analog systemconcepts and methods.

AUTOMATIC DIGITAL COMPUTERS-Digital computer theory, maintenance,installation, programming.

PRINCIPLES OF RADAR CIRCUITS AND EQUIPMENT-Introduction to, anddetailed study of radar fundamentals.

RADAR SYSTEMS PRINCIPLES AND PRACTICES (Advanced Level)-Applicationsof radar components, systems, design ... performance measurement.

MAIL COUPON TODAY FOR FULL INFORMATION

PHILCO TECHNOLOGICAL CENTER TC R-122nd and Lehigh Ave., Phila. 32, Pa.Please send free booklet and complete course information on subjects checkedbelow. (No obligation)

1. Semiconductors2. Intro. to Analog Comp.3. Analog Comp. Systems

4. Automatic Digital Comp.--' 5. Principles of RadarE 6. Radar Systems

NAME

COMPANY POSITION

ADDRESS

CITY STATE

Expand your knowledge in one of these rapidlyadvancing fields of electronics and you'll be setfor a secure and profitable future. Transistortechnology is becoming one of the biggest fieldsin electronics. The use of automatic computers inautomated factories, business offices and militarysystems is outpacing the technical manpowerneeded to build and maintain them. New develop-ments in radar have given new life to this dynamicfield. Electronics men are in demand, but it takesspecialists to land the big jobs. Now's the time toprepare . . . advance and prosper in this new era.

Learn with proven home study courses fromthe Philco Technological CenterGet a practical, working knowledge with provencourses developed by experts in the electronicsindustry ... men who know what kind of knowl-edge you need .. . specialists in electronics andtraining.

The Philco Technological Center is a departmentof Philco TechRep Division, one of the world'sleading electronics field engineering organizations.

Send for full details. No salesman will call.

PHILCOTECHNOLOGICAL

CENTER22nd and Lehigh Ave.

Philadelphia 32, Pa.


NOW... AN e$kc®PUBLIC ADDRESS SPEAKER

FOR ANY APPLICATIONFor SUPERIOR SOUND CONTROLLED COVERAGE

See Electro-Voice public address projectors. They offerperfect voice penetration and full -range "musicasting."They're weatherproof, splashproof and blastproof.

Maconcentrating hornrange sound over great distances.

CDP (Compound Diffraction rolesign Patent 169,904. Additional Potent Pending.

Model 848 30 -Wait CDP. Forwide-angle cov-erage and ex-tended range.Standard ofthe industry.

$75.00LIST

Model 844 30 -Watt PagingUnit. Compact, economical unitfor quality, high -efficiency voicereproduction.

Model 847 25 -Watt CDP.Small-er version ofModel 848.

$46.33LIST

THESE ELECTRO -VOICE MICROPHONES AREESPECIALLY OUTSTANDING FOR PUBLIC ADDRESS

585.00LIST

Model 664 Cordioid Dy-namic. Broadcast -qualityfor every public addressinstallation.

$49.50LIST

Model 951 Cardioid Crys-tal. Excellent, wide -range,all-purpose microphone.

534.50

Model LS -12. Forinterior installa-tions requiringfull -range re-sponse.

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Model LS -8.Smaller versionof Model LS -12.

$30.00LIST

The Sound of Electro-Voice... Assures Superior Install-ations, Customer Satisfaction, Your Reputation!

gke..tor OfCC-' ELECTRO-VOICE, INC.

BUCHANAN, MICH.

In Conadb: E -V of Canada Ltd., 73 Crockford Blvd-, Scarborough, OntarioCables: ARLAB

The familiarRCA carton

is' the hallmark ofa quality repair job.

You know, yourself, how comforting it is to see a familiar face amongstrangers. Well, to the majority of your customers, TV is strange, too. They don'tunderstand it. They count on you to "keep 'em going". And, the "familiarface" is the famous RCA monogram. When they see it on that famousred/black carton, they know you know your business ... anduse the best replacement tubes and parts money can buy.

You can cash in on the built-in prestige of RCA.Make this best-known name your stock -in -trade. YourAuthorized RCA Tube Distributor handles a complete lineof RCA Tubes to meet your service needs.

RADIO CORPORATION OF AMERICAElectron Tube Division Harrison, N. J.

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