Price 25 Cents1

Aug. 1948

STRATOVISION BROADCAST STATION

(See Pages 3 and 15)

8th Year of Service to Management and Eng

J `Gives you the experience of the world's largest radio. manufacturer.

Backed by the facilities of the world's largest radio engineering organization.

Serviced by a nation wide service organization.

Plus a Free Engineering Consultation Service to analyze your requirements.

PHILCO FM RADIOPHONE

COMMUNICATIONS SYSTEMS Prompt Delivery on All Models

PHILCO PHILADELPHIA 34 PENNSYLVANIA

Industrial Division, Dept. Au5 Philco Corporation C and Tioga Streets Philadelphia 34, Penna.

Gentlemen:

Please send me information about the new PHILCO FM Radiophone Communications Systems.

NAME

ADDRESS__

CITY

Output of one of the marker oscillators used in setting sweep speeds to known values. This case repre- sents 0.2 microsecond/ inch.

1.2 lines of television signal. Horizontal synchronizing and blanking pulses at each end. Video modulation in center.

Television waveforms selected even to the scanning line and fraction of that line, for critical study or recording, with the new

DU MONT Type 280

iieeUi7rtcei -iicey OSCILLOGRAPH

Fractional part of a line. Horizontal synchroniz- ing and blanking are shown.

Vertical synchronizing and equalizer pulses as seen with 60- cycle -sweep repe- tition rate; used for check- ing interlace.

OTHER FEATURES ... Provisions for attaching recording camera. Fine, clear focus over entire length of trace.

Y -axis: Any degree of attenuation be- tween h1 and 1000:1; great expan- sion of negative polarity signal; un- distorted deflection of at least 2 "; frequency response within 3 db. from 10 cps. to 10 mc.

X -axis: Time -base duration variable from 1 to 15,000 microseconds. Hori- zontal deflection of at least 4 ". 5RP -A Cathode ray Tube. 12,000 volt accelerating potential.

Time -base can correspond with any horizontal line in either or both inter- laced fields. Calibrating generator for calibration of sweep -writing speeds by signals of 10. 1, and 0.2 microsec- ond /cycle. Wide range of sweep -writing speeds; continuous variation between 0.25 and 3000 microseconds /in. Delay ranges of 100 or 1000 micro- seconds selectable for linear time base.

Indication as to exact occurrence of time -base with respect to overall tele- vision picture.

Interval of 0.25 microsecond may be measured to plus /minus 0.01 micro- second.

Fractional part of line near center of line. Video modula- tion produced by wedge, is shown.

10 DU MONT proudly announces the new Type 280 Cathode -Ray Oscillo- graph especially designed for tele- vision studio and transmitter instal- lations. Here at last is a means for accurately determining the dura- tion and shape of the waveform contained in the composite tele- vision signal, as well as the charac- ter of the picture -signal video in conjunction with transmitter opera- tion, according to FCC standards and practices.

Excellent for research on all tele-

Fractional part of line near center of a test patternwhere wedge elements are more closely spaced. Note loss in amplitude of modulation.

Trailing edge of horizontal syn- chronizing pulse.

vision equipment. Also for study of wide -band amplifiers. Well suited for industrial use wherever high- speed single transients are studied. Consists of four units mounted on standard relay -rack type panels and chasses, and installed on mobile rack. Removable side and rear panels. Grouped controls for easy operation. By virtue of its great range of ap- plications, Type 280 becomes a "must" for television studio and research laboratory.

Further Details on Request! ALLEN B. DU MONT LABORATORIES, INC.

o 11

aede. 4 ALLEN B. DU MONT LABORATORIES, INC., PASSAIC, N. J. CABLE ADDRESS: ALBEEDU, NEW YORK, N.Y., U.S.A.

August 1948 - formerly FM, and FM RADIO- ELECTRONICS

HERE ARE THE ANSWERS TO Your Questions About TELEVISION!

ONO

Minimum Requirements For Initial Operation

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These and many more vital questions get a quick and complete answer in a set of four informative bulletins just produced by Raytheon. First released at the recent N. A. B. Convention, their practical, factual approach to the basic problems of television was hailed alike by executives, engineers and countless others inter- ested in the tremendous possibilities of this new industry.

Write for your copies today. They are yours for the asking - with the compliments of Raytheon, makers of complete equipment for AM, FM and TV stations.

RAYTHEON MANUFACTURING COMPANY FMT

Waltham 54, Massachusetts

Please send me your Bulletins DL -T -804, 805, 806 and 807 on equipment required for new television stations.

Name

Title

Affiliation

Address

City Zone State

AND TELEVISION * * Edited by Milton B. Sleeper * *

Formerly, 1'11 MAGAZINE and FM RADIO- ELECTRONICS

VOL. 8 AUGUST, 1948 NO. 8

COPYRIGHT 1948, by Milton B. Sleeper

CONTENTS WHAT'S NEW THIS MONTH

Set Production -FM Suit - Sales Technique- Second Rate Designs - In Case of War 4

POSSIBILITIES OF STRATOVISION Milton B. Sleeper 15

THE SHIFT TO HIGH FREQUENCIES Letters by Dr. C. B. Jolliffe and H. H. Beverage 18

COMPACT MOBILE RADIO UNIT - Part e L. P. Morris 19

FCC PREPARES FOR UPPER -BAND TV JTAC List of Issues, 23

MERCHANDISING TV RECEIVERS Stanley H. Manson 28

FM FOR N. Y. TUGS John M. Sitton 32

TELEVISION HANDBOOK, 11th Installment Madison Cawein 34

TV TEST TECHNIQUES Frank G. Marble 36

SPECIAL DEPARTMENTS Telenotes Products & Literature Special Services Directory Professional Directory Spot News Notes News Pictures Classified Advertising

6 8

10 1e 26 27 44

THE COVER DESIGN AND CONTENTS OF FM AND TELEVISION MAGAZINE ARE FULLY PROTECTED BY U. S. COPYRIGHTS, AND MUST NOT BE REPRODUCED IN ANY

MANNER OR IN ANY FORM WITHOUT WRITTEN PERMISSION

MILTON B. SLEEPER, Editor and Publisher CHARLES FOWLER, Business Manager STELLA DUGGAN, Production Manager

RICHARD H. LEE, Advertising Manager LILLIAN BENDROSS, Circulation Manager

Published by: FM COMPANY Publication Office: 264 Main St., Great Barrington, Maas. Tel. Great Barrington 500 Advertising Department: 511 Fifth Avenue, New York 17, Tel. VA 6 -2483 FM Magazine is issued on the 20th of each month. Single copies 250 - Yearly subscription in the U. S. A. $3.00; foreign $4.00. Sub- scriptions should be sent to FM Company, Great Barrington, Mass., or 511 Fifth Avenue, New York 17, N. Y. Contributions will be neither acknowledged nor returned unless accompanied by adequate postage, packing, and directions, nor will FM Magazine be responsible for their safe handling in its office or in transit. Payments are made upon acceptance of final manuscripts.

TELEVISION

511A1oVI51aN OPaA0a0.5i fiAl10I

Rth Year of Service la Management and Engineering

THIS MONTH'S COVER Here, indeed, is an example of

conversion from war to peace. This month's cover shows a B -29 bomber now used for television broadcasting. This is the West- inghouse- Martin Stratovision project, recently demonstrated to the press for the first time.

The specific advantage of broad- casting from a plane at 25,000 feet is that an enormous area can be covered, as compared to con- ventional ground installations. Also, shadow effects, caused by high ground between the transmit- ter and receiver, are eliminated.

As to coverage, one Strato- vision transmitter is equivalent to 12 or more ground stations. Also, coast -to -coast networking can be accomplished without cables or ground relays.

FM ASSOCIATION

O

Second Annual Convention SEPTEMBER 27 -28 -29

Hotel Sheraton CHICAGO, ILL.

ALL PHASES OF FM

AND FACSIMILE

Will be covered, not by so- called "experts" nor theorists, but by experienced pioneers in tomorrow's radio . . .

BROADCASTERS AGENCIES ENGINEERS TIME SALESMEN MANUFACTURERS DEALERS

You cannot afford to miss the only FM- Facsimile meeting of 1948.

REGISTRATION FEE

$20 per person before Aug. 15 $25 per person after Aug. 15

Write or Wire for Registration Blanks

FMA HEADQUARTERS, 101 Munsey Bldg. Washington 4, D. C.

Entered as second -class matter, August 22, 1945, at the Post Office, Great Barrington, Mass.. under the Act of March 3, 1879. Additional entry at the Post Office, Concord, N. H. Printed in the U. S. A.

MEMBER. AUDIT BUREAU OF CIRCULATIONS

THE NEW NATIONAL HFS

$125 (power supply extra)

Complete Coverage 27 mcs -250 mcs!

Covers all mobile com- munication services, as well as fixed services. Re- ceives CW, AM OR FM! Superheterodyne with superregenerative 2nd detector.

Mobile, Portable or Fixed!

Operates from standard 110 volt, 60 cycle Na- tional 5886 power sup- ply, National 686S 6- volt vibrator -type power supply or batteries! Built - in speaker. Light.

See your nearest National dealer listed in the classified section of your 'phone book.

NATIONAL COMPANY, Inc. M A L D E N , M A S S A C H U S E T T S

4

ITitviitt) 1. 11 .I. DIO SET l'1tO1)UCT1 )ti 2. A1 {MSTRONG FM SUIT 3. SALES TECHNIQUE 4. SECOND RATE DESIGNS 5. IN CASE OF WAR

The Production Barometer now re- II gisters the half -year mark for

1948. A M sets are 1,301,379 below the first six months of '47, but TV figures are up 230,517, and FM up 249,741.

Taking $30 as the average retail

price for A M sets, and $400 as the

average for FM and TV sets, such an

estimate indicates a retail volume for the first half of 1948 of more than $'/z- billion, with AM accounting for about 40% and FM- TV 60%.

Still, we hear complaints that business is off. The R MA figures don't confirm that. More likely, com-

plaints are coming from set and com-

ponents manufacturers and dealers who

'°-

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947 TOTALS

178,57 1,175.104

16,3 4 2.002

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-FM

-TV

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haven't adjusted themselves to the pássing of AM , and the advent of FM and TV.

We say that because, while low - priced AM sets are off 19%, expen- sive T V sets are up 49 %, and FM sets up 56% at the half -year mark over 1947.

Although sales volume has varied widely in different areas, the fig- ures indicate that set manufacturers' net sales should exceed $1- billion this year.

Production of cathode -ray tubes is

still the limiting factor of TV set output. The bottleneck there is the

glass envelopes. Corning Glass is the

sole source of quantity supply. No doubt, they could be produced by

other companies, but it appears that

Corning is the only concern set up for this particular item. Deliveries of envelopes in the different sizes has been allotted to RCA, Du Mont, North American Philips, and Sylvania.

They, in turn, have made their allot-

ments of tubes to the various set manufacturers. Therefore, as long as

TV sets can be sold as fast as they

are turned out, the production of en-

velopes will set the pace for re-

ceivers. It is hard to tell how long

this situation will continue since (Continued on page 10)

AM TV&FM-TV FM -AM FM-TV L FM-AM

ESTIMATED

TOTALS 1947 19 48 1947 & 45

18.342002 178 571

1.175104 1.264400

00 0 0 0 0 00 0 0 0 O O h N 10, vt N VJ_ n m 44'D - O N

6,617,621 278,696 695,304 634770

JFMAMJJASOND FM- TV &FM-AM -

ESTIMATED

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23,159,623 457,467

1,870408 2,099,170

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JFMAMJJASONDJFMAMJJASOND &FM-TV 194844-FM-AM 1948

J F M A M J J A S O N D

AM 1948

Prodution Barometer, Lased on. monthly figures released Gy tue 1>'MA

FM AND TELEVISION

O

New York Telephone Company men watch as a crossbar dial sys- tem reports to its test frames at exchange "Watkins 9," New York.

A Dial System Speaks for Itself

As dial systems have been improved, so also

have the means of keeping them at top effi-

ciency. Even before trouble appears, test

frames, developed in Bell Telephone Labora-

tories, are constantly at work sending trial calls along the telephone highways. Flashing

lamps report anything that has gone wrong,

and the fault is quickly located and cleared.

If trouble prevents one of the highways

from completing your call, another is selected

at once so that your call can go through with-

out delay. Then on the test frames lights flash

up telling which highway was defective and on

what section of that highway the trouble occurred.

Whenever Bell Laboratories designs a new

telephone system, plans are made for its main-

tenance, test equipment is designed, and key

personnel trained. Thus foresight keeps your

Bell telephone system in apple -pie order.

BELL TELEPHONE LABORATORIES PIONEERS IN THE RESEARCH

OF FM RADIO AND TELEVISION, AND ACTIVE IN DEVELOPING IMPROVEMENTS IN BOTH FIELDS TODAY

.11U /ust 1948 -- formerly FJ1, and i'll RADIO- ELECTROXTC's

WGN -TV SELECTS ANDREW

TELEVISION TRANSMISSION LINE and ANDREW

INSTALLATION SERVICE

Many of America's new television stations are selecting Andrew equip. ment because of the efficiency of Andrew's flanged coaxial transmission line and the added advantage of having Andrew consulting en- gineers install it. Because each television installation poses its own different, individual problem, those stations selecting Andrew have two big advantages: 1) they obtain transmission line and accessories specially designed for television, and 2) specialized Andrew consulting engineers are avail- able to direct the installation. These engineers have both the special instruments and the experience to engineer all or any part of the construction of a television station. NO OTHER TRANSMISSION LINE MANUFACTURER OFFERS YOU THIS COMPLETE IN- STALLATION SERVICE! Andrew TV transmission line meets official RMA standards and is specially designed for television. Mechanically, it's held to close television tolerances assuring an essentially "flat" transmission line system. Fabricated in twenty foot lengths with brass connector .flanges silver brazed to the ends, sections can be easily bolted together with only a couple of small wrenches. Flanges are fitted with gaskets so that a completely solderless, gas -tight installation results. Markings on the outer conductor indicate where twenty foot sections may be cut to maintain the characteristic 51.5 ohm impedance.

WANT A TELEVISION STATION DESIGNED AND BUILT -FROM THE GROUND UP? LET ANDREW DO IT! Write today for full details. Andrew will get you on the air.

Television antenna of WGN -TV - Chicago's newest and most powerful television station - showing Andrew 1 -5/8" flanged television trans- mission line.

C O R P O R A T I O N

363 EAST 75th STREET CHICAGO 19

TRANSMISSION LINES FOR AM, FM, TV DIRECTIONAL ANTENNA EQUIPMENT ANTENNA

TUNING UNITS TOWER LIGHTING EQUIPMENT CONSULTING ENGINEERING SERVICE

(i

r I'1IA1 ` S r,I1S .

Station for Houston: A $235,000 contract has been signed for G.E. television equipment to be installed for KLEE, Houston, Texas. The antenna is being designed for 50 -lb. wind loading, instead of the usual 30 -lb. load, to with- stand the high winds along the Gulf.

CBS Network Expansion: Timetable has been set up for 80- station net, to be served by films pending opera- tions by relays or cable. These are:

1948

Atlanta Baltimore Los Angeles New York Philadelphia

1949

Allentown Atlantic City Binghamton Birmingham Boston Charlotte Chicago Cincinnati Columbus Dallas Dayton Hartford Indianapolis Jacksonville Kansas City Louisville Pittsburgh Providence San Francisco Stockton,

Calif.

1950

Akron

Buffalo Cleveland Columbus,

Ga. Cumberland Denver Des Moines Detroit Fresno Harrisburg Houston Kalamazoo Macon Memphis Miami Milwaukee New Orleans Omaha Peoria Portland, Me. Portland,

Ore. Quincy, Ill. Richmond Rochester,

N. Y. Sacramento Salt Lake Seattle Shreveport South Bend Tampa

Topeka Troy, N. Y. Tulsa Wheeling Worcester Youngstown

1951

Anderson, S. C.

Asheville Austin Bakersfield Cedar Rapids Charleston Duluth El Paso Frederick,

Md. Ithaca Knoxville Nashville Oklahoma

C. Roanoke Sioux City Spokane Springfield,

Mass. W. Palm

Beach Wichita

Training Course: A complete plan for training servicemen in television work has been set up by Philco. Classroom and shop work instruc- tion will be given by factory- trained in- structors at various cities where distribu- tors are located. Information can be obtained from Philco Service, Broad and Somerset Streets, Philadelphia 32.

Los Angeles Plans: Don Lee and the Los Angeles Examiner will cooperate in program production for KTSL. Under a long-term agreement, they will pool their TV facilities and personnel.

More Power for WCBS -TV: A 5 -kw. video transmitter and a new antenna have been ordered by CBS for its New York City station. On completion, the range and picture quality will be im- proved, and interference reduced.

FM AND TELEVISION

performance -PLUS Maintenance- MINUS

Add hot -dip galvanizing to Blaw -Knox construction, and you've got the utmost in tower performance with maintenance costs close to zero. Illus- trated is a new Blaw -Knox Type N -16 insulated, self - supporting tower with "lifetime" protection of a heavy zinc coating on all members as

well as on inside climbing ladder and Electroforged Grating platforms. Painting to conform with CAA regulations is all that is required.

Hot -dip galvanizing is available on Blaw -Knox Antenna Towers of any height . . . We invite discussion on your plans for future station improvement.

BLAW -KNOX DIVISION of Blaw -Knox Company

2046 Farmers Bank Building Pittsburgh 22, Pa.

BLAW-KNOX TO WEBS August 1948 - formerly FM, and FM RADIO - ELECTRONICS

p1lODUl %TS

1

REPLACEMENT PARTS GUIDE: " Radio In- dustry Red Book" lists replacements for the nine principal components in 17,000 receiver models produced from 1938 to 1948. These parts are capa- citors, transformers, controls, IF coils, speakers, vibrators, tubes, phono cartridges, dial lights, and batteries. Manufacturers represented in replacement listings are Aerovox, Astatic, Burgess, Cornell- Dubilier, Clarostat, Eveready, IRC, Jensen

C -R TEXTBOOK: 63 -page primer is a Meissner, Merit, Quam- Nichols, Radi- non- technical discussion of cathode- art, Solar, Sprague, Sylvania, Stan - ray tube functions. Price 500. Spe- cor, and Thordarson. 500 pages, 8% ciel rates for schools. Bulletin by 11 ins. Price $3.50. Book 170. 374. Allen B. Du Mont Labs. , Inc. , Howard W. Sams & Co. , Inc. , 2924 E. 1000 Main Ave. , Clifton, N.J. Washington St. , Indianapolis 6, Ind.

PHONO NEEDLES: One mil radius nylon and sapphire needles for 33 RPM micro -groove records. Bulletin 89. Dulotone Co. , Inc. , 799 Broadway, N.Y.C.

BEAT - FREQUENCY OSCILLATOR: Improved accuracy and stability are features of oscillator covering 20 to 20,000 cycles. Output 0.3 watt with total distortion of less than 0.25% over most of range. Frequency drift less than 7 cycles in first hour. Relay - rack panel mounting. Bulletin 134.

General Radio Co., Cambridge, Mass.

ANTENNA EQUIPMENT: 24 -page price list of transmission line, antenna, and related equipment includes de- scriptions and prices of over 600 items. Catalog 10 -AF. Andrew Corp., 263 East 75th St. , Chicago 19, Ill.

TRANSCRIPTION PLAYER: Portable unit weighing less than 10 lbs. provides professional quality from 16 -in. 33 1/3 and 78 RPM records. Includes amplifier and 6 -in. speaker. Bulle- tin 291. Califone Corp., 1041 N. Sycamore Ave., Hollywood, Cal.

TRANSMITTING TUBE DATA: Character- istics and operating data on sixty different types of transmitting tubes, arranged for quick reference. Bulletin 403, Sylvania Electric Pro- ducts, Co., Emporium, Pa.

AUDIO FREQUENCY METER: Again avail- able after wartime discontinuance is a bridge -type audio frequency meter employing a Wien bridge circuit. Range is 20 to 20,000 cycles with an

accuracy of 0.5 %. Can also be used as an adjustable- frequency meter. Bulletin 141. General Radio Company, Cambridge 39, Mass.

MONITOR: Plug -in antenna coils ex- tend range of frequency and modula- tion monitor so that one instrument can check one to four frequencies between 25 and 170 mc. for deviation and percentage of modulation. Direct reading of modulation up to 20 kc.; peak flasher to show over -modulation adjustable for any value between 5 -20 kc.; sensitivity 500 microvolts or less. Bulletin 12 -F. Doolittle Radio Inc. , 7421 S. Loomis Blvd., Chicago.

VOLT -OHMETER: High- sensitivity AC -DC volt- ohm- milliameter features 25 scales brought individually into reading position by rotation of range selector switch. Bulletin 122. Simpson Electric Co., 5218 W. Kinsie St., Chicago 44, Iii.

CALCULATOR: Slide -rule type calcula- tor for 10- to 30 -mc. rotary beam antennas. Quickly computes length of director, driven element, reflector, wavelength, and element spacing. Price $1.60. Bulletin 288. Gordon Specialties Co., 542 S. Dearborn St., Chicago, Ill.

CAPACITANCE TEST BRIDGE: Exceptional wide range of 1 mmf. to 10,000 mfd. and accuracy of plus -or minus 1 %,

plus 1 mmf. are features of this portable bridge. Direct reading dials, arranged for maximum effi- ciency, show dissipation factor and capacitance. Bulletin 16 -A. General Radio Co., Cambridge 39, Mass.

TV ANTENNA: Stacked array greatly increases TV signal pickup of new antenna. Complete adjustability and pre -assembly of component parts re- duces installation time and expense. Bulletin 45. Ward Products Corp., 1523 E. 45th St., Cleveland 3, Ohio.

VACUUM TUBE VOLTMETER: Readings of .1 millivolt to 300 volts through a

frequency range of 20 cycles to 2

mc. Linear scale reads directly in RMS volts or db based on 1 milliwatt into 600 ohms. Maximum gain 54 db.; direct readings from minus 70 dbm to plus 52 dbm. Bulletin 27 -B. Hewlett - Packard Co., 395 Page Mill Rd., Palo Alto, California.

SMALL VARIABLE RESISTORS: New 15/16 -in. series, called Midgetrol, is described as having special advan- tages resulting from basic design improvements. Available with flat metal shaft to take all types of knobs, or phenolic shaft for use in television circuits. Bulletin 151.

P. R. Mallory & Co. , Inc. , Indiana- polis, Ind.

ROTARY CONVERTERS: A special line of converters for operating wire or tape recorders and sound projectors on DC. Bulletin 67.Carter Motor Co.,

2644 No. Maplewood Ave., Chicago.

TV PROJECTOR: Pictures up to 63 sq. ft. in area are obtainable with pro- jector using Schmidt -type reflective optical system. Bulletin 86. RCA- Victor, Camden, N.J.

FM TRANSCEIVER: Nine -pound FM trans- mitter and receiver has power output of % watt on 30 to 44 mc. , with re- ceiver sensitivity of 1% microvolts for 20 db silencing. Selectivity is 85 db down at 100 kc. and 40 db down at 40 kc. Two 2 -volt storage cells and vibrator provide power for six hours service. Size is 8 by 8 by 31%

ins. Bulletin 413. Doolittle Radio Inc., 7421 S. Loomis Blvd., Chicago.

COAXIAL CABLES: 12 -page catalog shows air - spaced articulated coaxial cables and hardware, with engineer- ing details. Catalog S-7. Transradio Ltd., 138A, Cromwell Rd., London S.W.7, England.

MICROWAVE IMPEDANCE METERS: Preci- sion instruments for determining im- pedance by measuring standing wave ratios and node positions in trans- mission lines. 2% accuracy through- out 650- to 40,000 -mc. range. Se- ries of nine instruments covers all standard sizes of waveguide from 3 by 1'% ins. to 0.360 by 0.220 ins., and rigid coaxial lines of 5/8 and 7 /8in. Bulletin F -22. Sperry Gyro- scope Co. , Great Neck, N.Y.

TUBE BASE DIAGRAMS: Index shows si- multaneously any three tube base diagrams out of a total of 475 list- ed. Bulletin 53. RCA-Victor, Cam- den, N.J.

CARRIER SYSTEM: Three telephone, nine telegraph, and three toll - dialing circuits are added to exist- ing open -wire voice -frequency tele- phone circuits by this newly -engi- neered carrier system. Bulletin 68. Lenkurt Electric Co. , 1129 County Rd., San Carlos, Calif.

PRE -AMPLIFIER: Amplifier- equalizer stage for Pickering and GE variable reluctance pick -ups plugs into stan- dard octal tube socket on amplifier chassis. Metal shield 1 3/4 by 2 by Z4 ins. contains tube and complete circuit. Output averages 0.5 to 1.0 volts, with less than 1% distortion. Price $11.50. Bulletin 232. Collins Audio Products Co., Inc., P.O. Box 368, Westfield, N.J.

SIGNAL GENERATOR: Precision ampli- tude- modulated signal generator cov- ers 88 -140 mc. in one range with an

accuracy of plus or nimus 0.25 %. Crystal -controlled frequencies also available, permitting accuracy stan- dardization to 0.025% distortion under 5% at 95% modulation; can be 100% modulated with internal oscil- lator, of 400 or 1000 cycles, or with external oscillator. Bulletin A -12. Boonton Radio Corp., Boonton, New Jersey.

FM AND TELEVISION

Here Are Important Facts about GENUINE FM BROADCAST RECEPTION

They Are Presented to Clear Up Some Current Misconceptions:

FVERY ONCE in a while, we come across a dealer, a serviceman, or a custom set -

builder who was a great FM enthusiast before the war, but isn't active in this field now. By asking them how -come, we've learned a great deal. Most of it, unfortunately, isn't true. By setting thèm straight, we have not only renewed their interest in FM, but we've helped them to get started again in extra -profit FM set sales.

Maybe we can assist you, too, in straightening out some misunderstandings. For example, we've been told:

THE NEW SETS DON'T PICK UP STATIONS ON THE HIGH BAND. That's true of some makes of sets. They have no sensitivity, and they only work in the immediate vicinity of FM stations. If you have had that experience, you'll get a real thrill from the super- sensitive performance of a BROWNING FM or FM -AM tuner, with a genuine Armstrong limiter -discriminator circuit.

FM RECEPTION IS NOISY. WE CAN'T CLEAR IT UP. That is typical of insensitive sets, and those which do not have limiter stages. But hook up a $ROWNING tuner and you'll hear the "silent background" that is characteristic of true FM reception. Noise is the fault of the set, not of FM broadcasting.

PEOPLE DON'T WANT OUTSIDE ANTENNAS. In many locations, the extreme sensitivity of a BROWNING tuner makes it possible to get perfect reception without an outside antenna. But even under those circumstances, more sta- tions can be picked up if an antenna is added. And isn't it . good sense, when a person buys a high -quality receiver, to spend a few dollars extra so as to get the maximum enjoyment from it? Television sets require antennas because they work in the upper frequencies. FM receivers need antennas for the same reason.

FM SETS ARE HARD TO TUNE. That just isn't true of BROWNING tuners. The tuning eye is just as easy to use as on any AM set. Or you can tune by ear, accurately and quickly.

FM SETS DON'T STAY. IN ALIGNMENT. We have investigated that complaint about upper - band FM sets very carefully. In every case, the

August 1948 - formerly FM, and FM RADIO -ELECTRONICS

fault was in the design of the components. That trouble is never experienced with BROWNING tuners. Thousands of our upper -band sets have been in use for more than two years, and are still in perfect alignment.

THE PROGRAMS ARE NO GOOD. That complaint is usually followed by the admission: `Well, I haven't listened to FM for a long time." Today, in almost any part of the USA, the long -distance FM range of a BROWNING tuner gives a greater range of fine entertainment than is avail- able on AM.

YOU CAN ONLY HEAR RECORDS ON FM. That was true during and immediately after the war, but it's not so now. Most FM stations are origi- nating an increasing amount of live- talent shows. Also, the best network programs have been avail- able on FM since last winter, when restrictions were lifted. Today, except in a few special areas, listeners have a wider choice of programs on FM than on AM!

IN SHORT: If you are not already an FM en- thusiast, it's almost certain that you haven't listened to FM lately, or you have been using a set of second -rate design. If that's the case, you're going to get a totally different conception of FM from the performance of a BROWNING FM or FM -AM tuner. It will be a new thrill in radio entertainment. Write today for literature and prices!

Browning Lubs., Inc. 750 Main Street, Winchester, Mass.

In Canada, Address: MEASUREMENT ENGINEERING, Ltd.

Arnprior, Ontario

BROWNING LABORATORIES, Inc. 750 Main St., Winchester, Mass.

Please send me technical details and prices on the following Browning precision products:

FM Tuners WWV Frequency Calibrator FM -AM Tuners Laboratory Oscilloscope

7 Frequency Meters n Sweep Calibrator

Name

Address

Company Connection

!)

Special Services Directory

METHODS ENGINEERS Materials & Methods engineers in America's leading mdnufacturing plants use T opflight's Printed Cellophane, Self - Adhesive Tape to meet A -N specs. - assembly line - follow through - instruction labels. Easy to Apply.

TOPFLIGHT TAPE CO. YORK PA.

KAY ELECTRIC CO. INCORPORATED

lfanufacturers of:

Television Test Equipment Laboratory Instruments

Electronic Devices

14 Maple Avenue Pine Brook, N. J. Tel. CAldwell 6 -3710

ettifom- guilt SPEECH INPUT EQUIPMENT

U. S. Recording Co. 1121 Vermont Avenue Washington 5, D. C.

District 1640

" Guarcl ian" 300 MM. CODE BEACONS

OBSTRUCTION LIGHTS

CODE FLASHERS

PACKAGED LIGHTING KITS

Send for Catalogue

HUGHEY & PHILLIPS 326 North La Cienega Blvd.

Los Angeles 36, Calif.

HIGH QUALITY REPRODUCTION

ENGINEERING and PRODUCTION The KLIPSCH SPEAKER SYSTEM

Standard and Custom Built Types for Private Homes, Auditoriums, Hotels, Theatres

BROCINER ELECTRONICS LABORATORY REgent 7 -6794

1546 -F SECOND AVENUE, NEW YORK 28

ELECTRONIC ENGINEERING MASTER INDEX

CONTAINS the most complete bibliography avail- able on Frequency Modulation, Television, UHF, Broadcasting, Radar, and over 400 other topics.

1925 -1945 edition $17.50 1935 -1945 edition $ 6.00

Descriptive literature on request

ELECTRONICS RESEARCH PUBLISHING CO. Dept. A 2 West 46th St., N. Y. 19

WHAT'S NEW THIS MONTH (Continued from page 4)

each new area of demand created by the completion of a broadcast station opens an added market. Meanwhile, im- proved methods and machinery are re- ducing production costs and the per- centage of rejects. One of these days, they will show up in lower' prices. No one knows exactly, but the reduction may amount to 50% from pre- sent lists. A drop of $5., for exam- ple, in the net price of a given tube might lower the retail price of the set in which it is supplied by $40. to 50. Right now, there is little to encourage the expectation of such a

change in the near future.

2On July 22, Major Armstrong filed , suit in the U.S. District Court,

Wilmington, Del., against RCA and NBC. The outcome of this action, long expected by the industry, may well prove to be the most interesting and significant court case in radio annals.

The specific patents involved, all issued to and owned by Major Arm- strong, are: No. 1,941,066, No. 1,-

941,068, and No. 1,941,069, all dated December 26, 1933; No. 2,098,698 dated November 9, 1937; and No. 2,- 215,284 dated September 17, 1940, and reissued as Reissue No. 21,660 on December 17, 1940.

The complaint alleges that the de-

fendants refused to accept a license under the Armstrong FM patents on the same terms as those offered to

and accepted by other manufacturers and broadcasters, and insisted on ob- taining a license either on the basis

of a lump -sum payment of money or up- on the basis of giving RCA the right to sublicense others. It is further alleged that RCA falsely represented to the industry that its system of FM broadcasting and its ratio- detec-

tor receiver " did not operate ac-

cording to the teachings of plain-

tiff's patents ", and in other ways

induced many members of the industry

to believe it was safe to infringe the Armstrong FM patents, and that

RCA would protect them from the con- sequences of such infringement, or

that RCA licensees did not need li-

censes under the Armstrong patents.

The New York firms serving as

counsel for Major Armstrong are Cra- vath, Swaine & Moore, and Byerly,

Townsend & Watson. Copies of the com-

plaint can be obtained from William

Prickett, Attorney, 404 Equitable Building, Wilmington 7, Del.

FM receivers should be easy to al sell because they offer important advantages to listeners that cannot

be obtained on AM. However, we have

been told by dealers: "We can't sell FM sets. We only carry them for cus- tomers who come in and want to buy them."

We can understand that, after lis- tening to some of the dealers when they talk about FM. The best way to explain their errors and the correct techniques is illustrated by a basic method used in selling automobiles:

Some years ago, theChrysler Cor- poration advertised a course in auto- mobile salesmanship. Knowing how carefully and smartly their sales methods are planned, we took that course. We learned a great deal, too.

One thing we were told, and we are reminded of it by dealers who can't sell FM sets, was this:

" There are four primary sales features of the Plymouth car. They are 1) beauty, 2) economy, 3) safety,

and 4) comfort.

"When you first greet a prospect, find out which of these four basic features interests him. Until you know that, avoid discussion of any specific feature. If he uses a car for business purposes, he will pro- bably want to know about economy. It's no use to tell him how his wife will love the paint job and the chro- mium.

" If he smashed up his last car and broke his arm by skidding into a tree, his mind will be on safety. He'll spend twice as much for gas and

oil if he can be sure of getting a car that will stay on the road."

Now, how easily and logically the

same principles of salesmanship can be applied to selling FM sets. No one automobile has four exclusive ad- vantages over all competitors, but

FM has four basic advantages over AM.

They are 1) static elimination, 2)

freedom from interference from other stations, 3) uniform day and night receiving range, and freedom from fading, and 4) superior audio qual- ity, and realism due to the presence -

effect.

As is true of the car buyer, the

prospect for a new radio is not in-

terested in all the features, but at

least one of them will give him the

improvement he wants over his old AM set.

If he lives in the city, near sev-

eral local AM transmitters, he may

have interference on certain favorite

programs from out -of -town stations.

He may want better audio quality than

his old set delivers, or perhaps

,appliances in adjacent apartments,

elevator motor switches, or leaky

neon signs are spoiling his recep-

tion.

If he lives in a suburb or in the

country, his AM reception may be

(Continued on page 12)

FM AND TELEVISION

IH THE BATTLE FOR THE LISTENER'S SAR...

Here's increased

coverage for your

tation!

MEMO TO

STATION MANAGERS

Increases modulation and thus makes signal reach farther, sound clearer.

Raises effective signal strength -this means increased coverage.

Low installation cost - quickly, easily mounted in G -E Audio Cabinet Rack.

In FM, too - protect your listeners against receiver distor- tion caused by transmitter over - swing. Dynamic range, so im- portant in FM, is maintained.

e

MEMO TO

ENGINEERS:

Increases average level of

modulation as much as 8 to 10 db.

Anticipatory circuit pre- vents overmodulation -even on the first half cycle of the over - modulation peak. Automatic re- covery time improves program fidelity!

Prevents distortion and ad- jacent channel splatter.

G -E popular hinged panel construction -easy to get at.

Vertical mounted for better ventilation.

LIMITING AMPLIFIER

FITS neatly into your audio cabinet- attractive, sturdy, quiet. But what a wallop it packs when

you want attention from Mr. Big -the listener!

Based on engineering developments by CBS engineers, the Limiting Amplifier has been de- signed by General Electric to give you greater coverage and more potential listeners without changing your present transmitter or antenna.

For more information, call your nearest G -E

broadcast equipment representative, or write us. General Electric Company, Transmitter Division, Electronics Park, Syracuse, New York.

G -E Limiting Amplifier at the 50,000 watt transmitter of WTOP, Washington, D. C.

LEADER IN RADIO, TELEVISION AND ELECTRONICS

GENERAL i' J I'll ( 1.1 .% I' .1/ , n l i i I I' .JI RADIO -ELECTRONICS

ELECTRIC

Professional Directory

09anihy & galley AN ORGANIZATION OF

Qualified Radio Engineers DEDICATED TO THE

SERVICE OF BROADCASTING

National Press Bldg., Washington, D. C.

Andrew Corporation Consulting Radio Engineers

363 EAST 75th STREET, CHICAGO 19

Triangle 4400

GARO W. RAY Consulting Radio & Television

Engineers

991 BROAD STREET

BRIDGEPORT 3, CONN.

Phones - 5 -2055 & 7 -2465

ANDREW ALFORD Consulting Engineers

ANTENNAS & RF CIRCUITS

Laboratory and Plant

299 Atlantic Ave., Boston 10, Mass

Phona. HAncock 6 -2339

DALE POLLACK FREQUENCY MODULATION

development and research transmitters, receivers

communications systems

352 Pequot Avenue New London, Conn. New London, 2 -4824

AMY, ACEVES & KING, INC. Specialists in the

Design and Installation of

HIGH -GAIN AM, FM, and TELEVISION

ANTENNA SYSTEMS

LOngacre 5 -6622 11 West 42nd Street, New York 18, N. Y.

WHAT'S NEW THIS MONTH (continued from page 10)

poor at night. He's almost sure to get co- channel interference, or he may have to switch off his set when- ever there is a bit of static in the air.

Give any AM set owner a chance to tell his troubles, and he'll give you a lead for selling him an FM re- ceiver. Or, as they told us at the Chrysler course in salesmanship: " Let the prospect talk first. If you do, he'll tell you exactly how to sell him what he wants to buy!"

The key that opens the door to FM sales is the question: " How is your old set working ?"

4While we're on the subject of , selling FM receivers, it might be well to add a few words about the comparative performance of different types. Dealers are still reporting that all too many FM-AM models do not give the reception their custom- ers expect from FM.

There are two possible answers. Either the FM circuits are badly de- signed and incapable of giving genu- ine FM-quality performance, or the receiving antenna in the customer's home is inadequate. The dealers are at fault in either case.

In the first place, .it doesn't make sense for a dealer to place an order for FM-AM sets until after he has checked a sample carefully for FM performance. And it's a safe bet that if a model doesn't give all four of the characteristic FM advantages in a dealer's store, it won't work any better in a customer's home.

In the second place, it's plain bad salesmanship to tell a customer about the advantages of FM, and then install the set with such an inade- quate antenna that those advantages can't be realized.

Of course, a few dealers still compound their mistakes by saying: " Oh, well, you'll get good FM re- ception when the stations increase their power. In the meantime, you can use the A M tuning and the phono- graph." The truth is that there are almost as many FM stations on the air as there were AM stations before the war.

Today, in any part of the U.S.A., a good FM set, properly installed, can give its owner better reception than he can get on A M. There are some exceptions, in isolated parts of the country, but in those areas there is no decent AM reception, either'

Dealers should realize that people are coming to know that fact, and the wise ones are not buying any more models that can give only second -rate

(Concluded on page 13)

Professional Directory

RAYMOND M. WILMOTTE Inc.

Paul A. deMars Associate

Consulting engineers radio & electronics

1469 Church St., N. W. Decatur 1234 Washington 5, D. C.

RUSSELL P. MAY CONSULTING RADIO ENGINEERS

* * *

1422 F Street, N. W. Wash. 4, D.C.

Kellogg Building Republic 3984

LYNNE C. SMEBY Consulting

Radio Engineers 820 13th St., N.W. EX 8073

WASHINGTON 5, D. C.

CONSULTING

RADIO ENGINEERS

DIXIE B. McKEY

ASSOCIATES

1820 JEFFERSON PLACE, N.W. WASHINGTON 6, D. C.

REpublic 7236 REpublic 8296

FREQUENCY MEASURING SER VICE

Exact Measurements - at any time

RCA COMMUNICATIONS, INC.

64 Broad Street, New York 4, N. Y.

NATHAN WILLIAMS AM FM TV

Allocations and Field Engineering Oshkosh, Wis. Phone Blackhawk 22

and affiliates:

DIXIE ENGINEERING CO. Columbia 1, S. C. Phone 2 -2742

l'._1l AND TELEVISION

Professional Directory

FRANK II.

MCINTOSH Consulting Radio Engineers 710 14th St. N.W., Wash. 5, D. C.

MEtropolitan 4477

WELDON & CARR CONSULTING RADIO ENGINEERS

Washington, D. C.

1605 Connecticut Ave. MI. 4151

Dallas, Texas 1728 Wood St. Riverside 3611

COMMUNICATIONS RESEARCH

CORPORATION System Planning- Engineering

Research & Development FM- TV- Facsimile

VHF Communications

Communications Research Corp., 60 E. 42nd St., New York 17, N. Y.

Mu 2 -7259

THE WORKSHOP ASSOCIATES

INCORPORATED

Specialists ht High- Frequency Antennas

66 Needham St., Newton Highlands, Mass.

Bigelow 3330

Radio Engineering Consultants,

Frequency Monitoring

Commercial Radio Equip. Co. International Building Washington, D. C.

603 Porter Building Kansas City, Mo.

WINFIELD SCOTT MCCACHREN AND ASSOCIATES

Consulting Radio Engineers

TELEVISION SPECIALISTS

PHILADELPHIA:

809B Windemere Ave. Drexel Hill, Pa. Sunset 2537 -W

410 BOND BUILDING

Washington, D. C.

District 6923

August 1948 - formerly FM,

WHAT'S NEW THIS MONTH

(Continued from page 12)

performance. There are plenty of sets

on the market that deliver all four

FM advantages over AM.

5, It's taken a long time, but the

State Department and apparently the War Department, too, have dis-

covered that FM broadcasting can't be jammed by signals from an un-

friendly source. In case of another

war, it might well happen that A M

broadcasting would be rendered vir-

tually useless by deliberate inter-

ference. Equipment for such purposes

was used widely in the last war. Even

now we have reports of interference

from Russia with AM broadcast recep-

tion in western European countries.

Also, there's the question of net-

work operation. It would be possible

to put all A M networks out of com-

mission by destroying a few nerve

centers, but FM stations could be

joined by rebroadcasting. Right now,

systems could be set up that would

cover all population centers in the

Country without using wires. With the

installation of S T links, no wires

would be used even between studios

and transmitters.

Recognition of the advantages of

FM broadcasting in time of national

emergency has raised another question

at the State and War Departments: Why

aren't FM station applicants getting

on the air faster, and why aren't FM

sets being sold in larger quantities?

Or, to put it differently, is there

any planned action to hold back FM? If so, by whom and for what reason?

If not, what encouragement can be

given to expanding broadcasting fa-

cilities and the public use of a sys-

tem that cannot be put out of use by

jamming or sabotage? Actually, if there is any reason

to complain about the production of

FM receivers, it seems to us that

the complaint should be directed to

the quality rather than the quantity.

In all too many models, FM, like

short -wave tuning, is added only as a

point -of -sale feature. The FM cir- cuits are so badly designed as to be

worthless except in the immediate vicinity of transmitters.

Manufacturers of such models oper-

ate on the theory that, even though

they don't work on the FM band, they

do give average AM reception. In

case of another war, however, AM broadcasting may be stopped from sun-

set to sunrise, if not altogether,

because waves on AM broadcast fre-

quencies travel far enough at night

that they would serve to guide enemy

planes. Then, FM- AM sets that can't

deliver adequate FM performance will

be worthless indeed!

and %'31 RADIO -ELECTRONICS

Professional Directory

McNARY & WRATHALL CONSULTING RADIO ENGINEERS

* * *

983 National Press Bldg. DI. 1205 Washington, D. C.

KEAR " KENNEDY Consulting Radio Engineers

1703 K St. N.W. STerling 7932

Washington, D. C.

GEORGE P. ADAIR Consulting Engineers

Radio, Cotntnunications, Electronics

1833 %1 st.. N.W.. Washington 6, D.C.

F..\ewrtire 1230

GEORGE C. DAVIS

Consulting Radio Engineers

501 -514 Munsey Bldg. - District 8456

Washington 4, D. C.

WATKINS 9-9117-8-9

J...- . ¿L axone Co. Consulting Engineers

MECHANICAL- RADIO -ELECTRONIC PRODUCT DEVELOPMENT & RESEARCH

Development Specialists in Circuits, Part Lists, Models, Manufacturing Drawings.

143 -145 W. 22ND STREET, NEW YORK 11

RATES FOR

PROFESSIONAL CARDS IN THIS DIRECTORY

$10 Per Month for This Standard Space. Orders Are Accepted

for 12 Insertions Only

13

Zeltrgrobaltrza DUBUQUE, IOWA

goes into FM in a big way!

KENNETH S. GORDON, General Manager of Telegraph- Herald radio in- terests, says,

"Above everything else the engineer- ing service and help we received from Western Electric was complete, thorough and above what we had reason to expect from an equipment manufacturer.

"Our new transmitter came out of the packing boxes and went together with ease. We did not have to fabricate any wiring and the only parts we had to sup- ply were three small screws.

"After three months of service we are delighted with the performance of our Western Electric 10 KW transmitter and are looking forward to the arrival of our 50 KW amplifier."

Perched atop a high bluff above the Mississippi, this 8 -bay Western Electric Clover -Leaf Antenna has an effective height of 650 feet -gives the 10,000 watt transmitter an effective radiated power of over 40,000 watts.

Western Electric 14

KDTH - FM uses

Western Electric transmitting and studio equipment throughout After seven years' experience with its AM radio station KDTH, the Dubuque Telegraph- Herald is now on the air with FM broadcasts, too.

At present, the Western Electric 10,000 watt transmitter is operating with an effective radiated power of over 40,000 watts. All provisions have been made to increase this effective radiated power to 180,000 watts by adding a 50,000 watt final amplifier to the present transmitter. When this is done, KDTH -FM will serve an area with a population of 1,300,000.

Other Western Electric equipment at KDTH -FM includes microphones, loud- speakers, turntables, consoles and antenna.

For full details on the complete line of Western Electric equipment for your FM station, call the nearest office of Graybar Electric Co. (located in 100 principal cities), or write to Graybar -420 Lexing- ton Ave., New York 17, N. Y.

QUALITY COUNTS

DISTRIBUTORS: IN THE U. S. A.- Graybar Electric Company. IN CANADA AND NEWFOUND- LAND - Northern Electric Company, Ltd.

FM AND TELF:VISION

FIG. 1, left: Sketch of Stratovision installation in a Martin 202. Right: With 14 planes, Stratovision can cover 51% of U.S. area and 78% of the population

POSSIBILITIES OF STRATOVISION ONE OF RADIO'S OUTSTANDING DEVELOPMENT PROJECTS HAS BEEN CARRIED TO

THE POINT. WHERE ITS POSSIBILITIES CAN BE APPRAISED -By MILTON B. SLEEPER

QTRATOVISION, a system for serving large ground areas by rebroadcasting

from transmitters in airplanes, may prove to be much more than a highly imaginative idea on which Westinghouse and Glenn Martin have staked a very considerable investment.

In fact, from personal and very critical observation of Stratovision in actual

operation, it appears that, technically, the system may be entirely practical.

Need for Investigation: The joint Westinghouse -Martin project is

a pioneering job of great magnitude. Basically, the idea of rebroadcasting from a plane, originally conceived by Westing- house engineer C. E. Nobles, is entirely

within reason. Martin 202's, flying in re- lays at 25,000 ft., can be operated on a schedule giving a degree of dependable service equivalent to that of ground stations.

But in any unusual undertaking which introduces new operating conditions, ad- verse factors are encountered which call for investigation before they can be

FIG. e. The converted B29 used for Stratovision TV broadcasting carries the audio and video antennas on an 8 ft. mast at the tail

1 , ' I ( ; .. ;. This view shows receiving antennas in detail. FIG. 4. Mounting of the transmitter antenna mast. Ring antenna is for audio eliminated. These may be matters of mechanical or electrical design, or merely of human experience calling for changes in operating methods.

To discover and examine these factors, and to find solutions to the problems they introduce in practice, the two com- panies behind this project have modified a B -29 bomber, as shown in the accom- panying illustrations, for use as a Strato- vision station.

Accomplishments to Date: Work with the test installation has pro- gressed to the point where the technical and practical problems have been deter- mined, and most of the faults in the initial installation have been corrected already.

For example, although the ambient temperature at 25,000 ft. is below 0 °F., heat in the radio compartment proved to be so great that elaborate cooling fa- cilities were found necessary. Also, the need of comfortable operating conditions set up the requirement of a pressurized radio compartment. With a 5 -kw. video transmitter, a 1 -kw. FM audio trans-

initter, and all the associated equipment, it was necessary to install air- condition- ing equipment of the capacity normally used in a 6 -room house!

Figs. 6 to 11 show the television equip- ment, its arrangement in the pressurized compartment, and the construction of the compartment. Along one side are the pic- ture monitors, Fig. 8; the receivers and audio monitors, Fig. 9; with the FM audio transmitter and power distribution panel, and the television transmitter opposite, Fig. 10. Also provided are transmitters and receivers for communicatiòns with the ground.

Figs. 3, 4, and 5 show the receiving antennas, and two views of the video and audio transmitting antenna assembly as it appears when drawn up under the fusilage for landing. The design of the an- tenna and the mechanism for forcing it down and holding it in place during flight was a major problem. Sixty -eight horse- power are required to overcome the wind resistance of the antenna. Recently, ice formed on the structure, indicating the need for further study of de -icing means.

During the long series of flights, studies have been made of propagation charac- teristics. None of the data has been dis- closed at this time. However, the file of reports from TV set owners shows that excellent reception from the Stratovision plane has been picked up at distances well in excess of 200 miles. Channel No. 6 has been used for transmission.

The Stratovision demonstration for the press, held at Zanesville, Ohio on June 23, was a rebroadcast of programs from WMAR -TV Baltimore. Signals were picked up by the plane on channel No. 2, and rebroadcast on No. 6. Signal strength was ample at the demonstration receivers. However, horizontal shadow bars were seen much of the time, traveling slowly down the picture. According to Westing- house engineers, this was caused by sig- nals picked up in the plane from WNBT New York City, also operating on Chan- nel No. 2.

Interference Problems: Because the receiving range at the plane is so great, and the service area of the

FIG. 8. Angus McDonald at the video monitors. FIG. 9. Audio monitors and plane -ground cue circuits operated by William Duckworth

FIG. 5. Video antenna at lower end of mast. FIG. 6 Part of airconditicning equipment. FIG. 7. Forward entrance to radio section

Stratovision transmitter is so extensive, new problems of interference and fre- quency assignments are encountered. That is easy to understand, since the serv- ice area of a TV ground station is perhaps 12,000 square miles, compared to some 200,000 miles for a Stratovision station. With only 12 low -band channels available, frequency assignments to ground stations are repeated within such relatively short distances that the plane receiver is almost certain, wherever it flies, to pick up two or more stations operating on the same channel. Similarly, the transmitter is liable to interfere with one or more ground stations.

This situation virtually rules out com- mercial Stratovision operation on the lower band. There just aren't enough channels, and there are too many appli- cants to provide interference -free opera- tion of Stratovision receivers and trans- mitters capable of receiving from and transmitting to such enormous areas. However, this condition on the lower band does not eliminate Stratovision as a practical, commercial service.

Upper -Band TV by Stratovision: The most serious objection to upper -band TV so far advanced is the matter of shadows resulting from high ground be- tween a transmitter and points within its nominal service area. It appears that shadow effects will be virtually elimi -

nated when signals originate from a plane flying at 30,000 ft. except, possibly, at some locations near the periphery of the coverage area.

Shifting to frequencies in the band from 475 to 890 mc. would call for a complete redesign of the Stratovision antenna over the type now in use. Possibly a reflector can be built into the fusilage of the plane, for increased effective radiation. Means might be required then to compensate for climb -and -bank effects. The question of polarization would have to be studied, since some variation of the conventional, horizontally polarized receiving antennas would undoubtedly increase the signal pickup.

Here is a fertile field for TV develop - (Concluded on page 45)

FIG. 10. Lawrence Smith handles the FM and TV transmitters. FIG. 11. 1V. C. Cryer at the antenna et ntrol, outside forward tunnel

THE SHIFT TO HIGH FREQUENCIES DR. C. B. JOLLIFFE AND H. H. ON THE DISCOVERY OF LO

FOLLOWING the publication of testi- mony before the House Committee on

Interstate and Foreign Commerce given by Dr. C. B. Jolliffe, executive vice presi- dent in charge of RCA Laboratories, Major Armstrong discussed this testi- mony at some length in a letter which appeared in our July issue.

In response to an invitation to com- ment on Major Armstrong's letter, we re- ceived a communication from Dr. Jolliffe, accompanied by a more detailed state- ment from Mr. H. H. Beverage. The com- plete texts were as follows:

RADIO CORPORATION OF AMERICA

RCA LABORATORIES DIVISION

PRINCETON, N. J.

July 23, 1948 Dear Mr. Sleeper:

You were kind enough to invite my at- tention to the letter of Major E. H. Arm- strong which appears in the July issue of FM AND TELEVISION. In his letter Arm- strong refers to testimony I gave before the House Committee on Interstate and Foreign Commerce in March and en- deavors to leave the impression that I claimed RCA was entirely responsible for the advance in communications brought about by the use of the higher frequencies.

Armstrong quotes two paragraphs of my statement, and says that Marconi and his associate, C. S. Franklin, are due the principal credit in this field.

Before the House Committee Arm- strong talked about the contributions of Armstrong and I talked about the con- tributions of RCA. In the first sentence of my first point I made it clear that I was dealing with the work of RCA engineers. To avoid any possibility of misunder- standing, I added this paragraph (which appears in my statement immediately preceding the two paragraphs Armstrong quoted):

"It is not meant to imply that RCA was the only one to pioneer in the higher fre- quencies. In addition to RCA, Marconi worked there, AT & T, Westinghouse and GE did, the Government did, the ama- teurs did, and many others."

Armstrong also mentioned the views of Beverage. I enclose a copy of a letter by Beverage to me, which includes these sen- tences:

"I cannot agree with Major Arm- strong's statement that it is not true that the world -wide revolution in communica- tion which brought about the obsolescence of the alternator was an ultimate result of anything that the Radio Corporation did.' I feel that the RCA played a leading role in this revolution and I am proud to have

18

BEVERAGE REPLY TO MAJOR NG- DISTANCE, SHORT -WAVE

been privileged to have worked with RCA during this period. At the same time, I also appreciate the very great and out- standing contributions made by my old friends and co- workers, Senatore Mar- coni and C. S. Franklin."

Sincerely Yours, C. B. JOLLIFFE

More detailed discussion is given in Mr. Beverage's letter to Dr. Jolliffe:

RADIO CORPORATION OF AMERICA

RCA LABORATORIES DIVISION 66 BROAD STREET

NEW YORK 4, N. Y.

July 21, 1948 Dear Dr. Jolliffe:

I have read with great interest Major Armstrong's letter of June 28, 1948 to the Editor of FM AND TELEVISION. Most of the statements upon which he bases his conclusions agree, in general, with my recollection. However, I believe that Major Armstrong might have arrived at somewhat different conclusions if he had been acquainted with all of the back- ground leading up to his observations.

It will be recalled that Dr. Frank Con- rad of the Westinghouse Company started experimenting with transmission on wave- lengths of about 100 meters in 1921 and obtained results which were quite inter- esting. Others became interested in this work, including the amateurs. According to Senatore Marconi's paper, "Radio Communication", published in the Pro- ceedings of the IRE for January, 1928, be undertook a series of systematic tests with long distance transmission on 97 meters in the spring of 1923, from which he concluded that the strength of the signals which could be received varied definitely and regularly in accordance with the mean altitude of the sun over the space intervening between the transmitter and the receiver. Strong signals were re- ceived at night up to distances exceeding 2,300 nautical miles from the transmitter at Poldhu, Wales. The RCA participated in some of these tests and made measure- ments of field strength at Riverhead, con- firming the good reception at night.

During 1923, the RCA constructed and installed a short wave transmitter at its station in Belfast, Maine for propagation tests to determine the feasibility of using the short waves for relaying longwave sig- nals picked up at Belfast to the Central Office in New York. This transmitter was designed to operate on wavelengths of 120, 90, 60 and 40 meters. During 1924, quantitative simultaneous field strength measurements of the radiations from the

E. H. ARMSTRONG'S LETTER DAYLIGHT PROPAGATION

transmitter were made at the RCA re- ceiving stations at Chatham, Mass. and Riverhead, L. I. at distances of about 200 miles and 310 miles, respectively. The ' conclusions from these tests were quite significant since it was found that the night signals on 120 meters and the day signals on 40 meters were stronger at Riverhead than for the shorter oversea path to Chatham. The following is quoted from a report on these tests, -

"There is strong evidence that for moderate distances short -wave signals, particularly on wavelengths below 60 meters, have transmission characteristics far below that predicted by the Austin formula, but as the distance is increased, the signal is fed down from above and may remain at constant intensity over a considerable increase in distance, and may actually increase with increase in distance for a certain critical distance."

Before this unusual and interesting ob- servation could be further checked, RCA was notified by Mr. Marconi that he was planning to transmit from Poldhu on a wavelength of 32 meters and requested the RCA to make observations and measure- ments. These transmissions resulted in the epoch -making discovery that if the wavelength is short enough, good trans- mission can be obtained during the day- light hours, contrary to previous experi- ence and teachings. This is the great dis- covery referred to by Major Armstrong. These 32 -meter test signals were received at Montreal, Buenos Aires and Sydney, Australia during the October, 1924 tests. Great credit is due to Marconi and his assistants for this remarkable discovery. It was something that no one had pre- dicted, and I have been informed by one of Mr. Marconi's assistants that Mr. Mar- coni himself was as surprised as the rest of us at the results of the 32 -meter tests.

Another indication that this discovery was a surprise to the Marconi people was the following incident: In the autumn of 1921, I was in England. Mr. C. S. Franklin showed me his experimental 15-meter tele- phone station at Hendon, just outside of London, which communicated with Bir- mingham some 97 miles distant. A pecu- liar type of distortion was encountered on this circuit at times for which there was no reasonable explanation. We know now that this distortion was probably caused by transmission of the 15 -meter signal completely around the earth, so that it came in on the directive antenna and interfered with the direct signal. Certainly, such an explanation in 1921 would have been considered completely fantastic.

(Continued on page 42)

FM AND TELEVISION

FIG. 7. Bottom view of the complete Dispatcher transmitter- receiver shows how compactly the circuit components are arranged

COMPACT UNIVERSAL MOBILE UNIT CIRCUIT DETAILS OF MOTOROLA'S DISPATCHER EQUIPMENT, FOR SINGLE- OR DUAL -

FREQUENCY USE, WITH OPTIONAL SELECTIVE CALLING: PART 2 -By L. P. MORRIS*

4. Receiver Section: The circuit diagram for the receiver sec- tion is shown in Fig. 7. This is a double super -heterodyne, producing a high degree of stability, with sensitivity requiring less than 1 microvolt to produce N db quieting of inherent noise. Crystal controlled with temperature regulation maintains the fre- quency within limits better than one -half the conventional standards.

Selectivity gives 85 to 100 db protec- tion against alternate channels. It is pos- sible to reject a signal of 20 milli -volts or more while receiving a 1- microvolt signal on the desired frequency. With this selec- tivity, the mobile unit can drive around the block where a 250 -watt station is

operated on the alternate channel, and experience no interference. This same de- gree of protection against spurious re- sponses is provided by 85- to 100 -db rejection.

4.1 RF and IF Circuits:

Section 7 of Fig. 7 shows the RF section of the receiver. The input circuit of the 6BH6 first RF tube is impedance coupled

* Communications & Electronics Division, Motor- ola, Inc., 4545 Augusta Blvd., Chicago, 51.

through condenser C -1. L -101 is a permea- bility- tuned tank circuit with a 50 -ohm input across condenser C -3 of the resonant circuit. The impedance stepup from the 50 -ohm transmission line connector to the grid coupling condenser C -1 is provided by the impedance ratios of the two tank condensers C -2 and C -3. The resonant coupling unit L-102 and L -103, between the first and second RF tubes, is double - tuned and coupled for maximum rejection of undesired signals. The coupling be- tween L-10e and L -103 is obtained by capacity inherent in the wiring. This RF coupling unit is impedance coupled to the second RF tube through the condenser C -5. Maximum low -signal sensitivity is obtained by the use of 3.3- megohm resis- tors R -2 and R -5 in the grid circuits of the. 1st and 2nd RF tubes, respectively. Additional RF selectivity and rejection is obtained in the double -tuned circuits, L -104 and L -105, between the second RF tube and the first mixer. Mixing in the first mixer is accomplished by signal injection on the first grid through C -10, and beating frequency injection through C -14.

The high beat -frequency injection to the first mixer is obtained by multiplica-

August 19.48 - formerly FM, and FM RADIO -ELECTRONICS

tion from the temperature -controlled crystal shown at the left of Section 9. The crystal oscillator tube also serves as a first quadrupler for the oscillator fre- quency, delivering 4 times the crystal frequency to the resonant circuit L -109 and condenser C-20.

All the circuits are permeability tuned and the inductances are separated and completely shielded in independent cans to assure high stability and low spurious response. The secondary of this circuit is L -108 and C -19.

To facilitate alignment and to check the operation of the oscillator, the grid cur- rent to the second quadrupler is measured across the grid resistor R -11, by- passed by the condenser C-21. Resistor R -10 within this first quadrupler provides isolation, to give the correct meter reading at the terminal of this first quadrupler coupling transformer connected to re- sistor R -10. The values of the resistors and multipliers have been worked out so that correct readings are obtained when using a 50- microampere test meter, having p2,000 ohms resistance.

Double tuning and the correct coupling between the crystal oscillator and multi- plier units are essential for maximum re-

19

1

lr r CI

152-182 MC r

C3

L110 r-

IT

L101

C2

6BH8 1ST RF

R2

L102 152-182 MC.

U L_

6BH6 'CS 2ND RF

1

L103

RS

., INDICATES

. COUPLING

L104 152-182 MC. L105

101

8BJ8 I

1ST MIXER I -IT

L08

L_

8BJ8 2 ND QUAD

R10

C19

C21

I --:r 7.3-8.0 MC.

I

8,1136 1 ST IF-1

Tl

r sr f17.3-8,0 MC.

_J

8JB8 -

1ST IF-2 L114 7.3-8.0 MC.

-J L_

8BH8 2ND MIXER

I

I L118 r-

L_

6BJ6 2 ND IF

L 1 18

L

L_

- L - _ _ _ - - -_ _ _ _

C70

6BH8 8AL5 NOISE AMP. NOISE REGT. a

C73

12AÚ7 1ST AF

8 SQUELCH

I I R49

I NYV

RSO

178 I

- C80

FIG. 8. .Schematic wiring diagram of the Dispatcher receiver section. Note that the remarkably compact design of this It; -tube receiver

jection of harmonics of the oscillator be- fore the first mixer grid, in order to keep spurious responses of the receiver to a minimum.

Section 10 shows the first IF frequency arrangement, using double -tuned coupled units at all interstage points. The plate of the first mixer tube couples to the grid of the first IF amplifier tube through L -110 and L -111. They are tunable from 7.3 to 8 mc. The second tube of the first IF amplifier is coupled to the second mixer tube grid L -114 and L -115. The injection frequency of the second mixer tube is obtained from condenser C -25, Section 9, to the second mixer tube. The second IF frequency from L -115 and the injection voltage from the crystal oscillator are combined on the first grid of the second mixer through the 330 -ohm resistor R -25.

The second IF produced in the plate circuit of the second mixer tube is coupled to the first tube of the second IF ampli- fier across IF transformer L -116 and L -117. The coupling between the primary and secondary of this permeability -tuned unit is obtained through the small cou- pling condenser C-45. The second IF

20

amplifier tube feeds the first limiter across another second IF transformer. This unit, L -118 and L -119, operating at approxi- mately 1.7 mc. is coupled in the same man- ner as the preceding units. The first limiter feeds the second limiter across a double -tuned second IF transformer unit L -120 and L -121. Meter reading points are provided at 3 points in this second IF amplifier : in the grid circuit of the first IF amplifier tube, the grid circuit of the first limiter tube, and the grid circuit of the second limiter tube, through 1- megohm isolation resistors. Second limiter grid potential is fed to the squelch system via L -121. The second limiter tube of this circuit feeds the frequency discriminator diodes through the discriminator trans- former L -122 and L -123, also double - tuned. Discriminator voltage for measur- ing and alignment purposes is taken off through R-4e across condenser C-69 at the meter connector. The parallel dis- criminator diode voltages are fed to the diode through condenser C-62, direct from the plate of the second limiter.

The phase displacement voltage for the discriminator diodes, normally obtained

in the conventional discriminator by in- ductive coupling between the primary and secondary coils, is obtained in this par- ticular discriminator across the small un- balancing condenser C -68 between the 6AL5 discriminator tube and ground. This method of obtaining the phase displace- ment voltage permits better control of discriminator characteristics than is gen- erally possible where it is necessary to depend upon the inductive coupling be- tween the primary and secondary coils for the equivalent discriminator compo- nents. With the method used here, primary and secondary circuits can be isolated magnetically. The circuit con- stants can be much better controlled since it is not necessary to depend upon varying degrees of magnetic coupling due to physical irregularity of the circuits. The discriminator metering balance is ob- tained for the metering connector through the isolation resistor R -4e and by -pass condenser C -69 from the discriminator cathode. For correct alignment and on- frequency signal, the - voltage drop across the resistor .R-40 and the resistor R-41 are opposed and equal.

FM AND TELEVISION

6BJ6 1 ST QUAD.8. 05C.

XTAL HEATER\

- - - e13J6 - - - - - - - - -

1V

53

1ST LIM L120

6A05 POWER AMP.

L_

IIIr OUTPUT TRANS.

- 6BJ8 2ND LIM. I

1.7 MC. L121 L122

L__ -

L

L123

¡R40

6ALS - DISC.

IC 67

VA

I I METER CONNECTOR I

POWER CONNECTOR

TO ALL FILAMENTS E XTAL HEATER SQUELCH

CONTROL IN CONTROL L.

HEAD

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R63 VOL.

il

chassis is made possible by the use of miniature tubes and components throughout

Great care was exercised to assure the physical and electrical isolation of the components to prevent stray coupling, regeneration, and unsymmetrical selectiv- ity, at the same time maintaining accessi- bility for servicing despite the small size

and compactness of this unit. The chassis is only 3 ins. wide, and for this reason it was necessary to use miniature tubes throughout. Primary and secondary cir- cuits of the IF and RF coupling units have been positioned and shielded care - fully to prevent stray coupling and permit the highest LC ratios possible, consistent with the tolerances of the components. LC ratios have been maintained below the points where manufacturing and physical tolerances might cause variations in coupling to the extent that adjacent- and alternate -channel rejection values might not be uniform. The top of the selectivity curve is narrow and AVC is not used, so

that out near the fringe areas of operation the signal -to -noise ratio is somewhat improved. As a result of this careful de- sign, component by component; this com- pact receiver, requiring less than 6 am- peres drain from a 6 volt storage battery,

has a sensitivity varying between .5 and 1

microvolt for 20 db quieting.

4.2 Squelch and Control Circuits: The squelch system of the Dispatcher re- ceiver gives very stable and sensitive quieting operation. The circuit can be seen in Section 14 of Fig. 7.

Noise from the grid circuit of the second limiter is applied to the No. 1 grid of the noise amplifier tube through condenser C-70. The noise is applied to the 6AL5 voltage- doubler, noise -rectifier through the condenser C -73. The triode squelch section, the left half of the 12AU7, is

controlled by the DC potential on its grid through a resistor filter combination R -50 and C -78. The DC input from this filter to the squelch tube is obtained as a re- sultant of the DC output of the voltage - doubler, noise -rectifier tube and DC grid voltage from the second limiter. The DC noise voltage is developed across R-49 and its polarity is such that the audio amplifier is turned on or made operative by a drop in noise.

This drop or reduction in noise always accompanies a signal in FM equipment of

August 1948 - formerly FM, and FM RADIO -ELECTRONICS

this type, so that this characteristic alone is in the proper direction. The negative DC bias from the grid of the second limiter increases with a very small amount of signal at the antenna, and the connec- tions are such that this increase in voltage also tends to make the amplifier circuit operative. The ratios of these voltages have been determined so that an increase of noise tends to squelch the receiver audio system a little more than before the noise was introduced, to the extent that noise does not make the audio system operative but instead tends to squelch the set a little tighter. Thus the audio system never becomes operative due to noise. This is an extremely important factor, when com- bined with the voltage of the second limiter, producing an extremely sensitive, sharp, and positive squelch action. The polarity and values have been determined so as to cause a sort of double -levering operation here, with part of the control coming from the second limiter and part from the noise -amplifier and rectifier combination.

This double leverage operation acts on the grid of the left section of the first audio and squelch tube. The amount of noise and the squelch control is deter- mined by the cathode resistance to ground of the noise amplifier tube. This cathode circuit is connected to the power connector on the receiver unit, and permits external control of squelch, as shown at the lower right hand corner of Fig. 7. The right half of the 12AU7 is the first audio ampli- fier, controlled by the DC bias and the plate circuit of the squelch tube through resistor R -52. The left half of this tube operates as a DC amplifier of the squelch - controlled DC voltage from resistor R -50 across C -78, explained above.

The audio voltage from the discrimina- tor, appearing across C -67 and cathode pin No. 1 of the 12AU7, is fed to grid pin No. 2 of the audio section through resistor R -53 and condenser C -82, comprising the audio discriminating network. This network reduces the audio response to the higher audio frequencies at a rate of 6

db per octave for a part of the audio spectrum. The audio voltage is fed through C -8 to the grid pin No. 2 of the 12AU7, the grid of the first audio amplifier tube. Audio output from the audio section of the tube, pin No. 1, is fed through cou- pling condenser C -80 to the volume control R -63 and also to the power connector, where it can be used externally for volume control purposes. Audio to the grid of the audio power amplifier tube, section 15 of Fig. 7, is taken from the center tap to the volume control R -63 and also from the connector socket. This permits volume to be controlled from an external adjustment or from a volume control on the receiver chassis. The plate circuit of the power amplifier tube is bypassed to ground with C -83 to reduce the high frequency re- sponse and accompanying noise. This improves the signal -to -noise ratio of the

21

CONTROL CABLE

MICROPHONE

CONTROL HEAD

ANTENNA

GROUND BRAID

- CABLE CLAMPS

MOTOROLA DISPATCHER oi,,,,a, GROUND BRAID

TO CAR FRAME 1,11/11111,,

mik Nwirfr'lz%

o POWER CABLE

U ANTENNA CABLE

FIG. 10. Plan of conventional mobile installation. Sometimes the radio unit is put in front of the driver's seat, on the floor

receiver. The audio fidelity of the receiver is matched to the characteristics of the transmitter in order to deliver the best signal -to -noise ratio at extreme ranges.

4.3 Receiver Crystal Frequency: Knowing the assigned frequency at which a radio system is to operate, the crystal and first IF frequencies of the Dispatcher receiver can be determined readily.

A. The carrier frequency fe, plus the second IF frequency f2 (1.7 me. in this case), divided by 17, equals the crystal frequency f. That is,

f + f2 - f 17

If the assigned carrier frequency is 155.0 mc., then

155.0 + 1.7

17

156.7 or = f = 9.217 mc.

B. Having found the frequency re- quired for the crystal, the proper fre quency for the first IF amplifiers can be determined. The crystal frequency f minus the second IF frequency f2, equals the first IF frequency f1. That is,

f -f2 =fl In the case above 9.217 - 1.7 = 7.517 mc.

Test and Operating Data: The transmitter and receiver can be com- pletely checked by a meter test kit which plugs into the metering sockets. The meter test kit contains a loudspeaker, a 50- microampere meter, a transmitter start button that can be used independently from the microphone, a socket to plug in a standard microphone so that the trans- mitter can be operated from the rear of the car, and test circuit switches. There are provisions for housing a Simpson Model 260 volt -ohmeter, either the old or

22

new type, and additional space for a small, battery- operated test oscillator. A re- mote RF test probe is available for testing the system through the antenna. The meter multipliers within the receiver and transmitter unit have been determined to give useable readings on a 50- microampere meter having 2,000 ohms resistance. A simple antenna load can be made from a 32 -volt, 15 -watt lamp, with the connec- tions soldered to a coaxial connector. A 3 -mmf. Erie Ceramicon should be con-

0613J6 2ND LIM.

6AL5 DISC.

NOISE RECT. 6AL5

613/16

NOISE AMP,

1ST LIM.

12AU7 AF a SQ.

BAGS AF OUT.

06BJa 2NDIF

OBBJa 2ND MIX.

0 0 6BJB 6BJ6

1ST IF OSC.

OBST IF

69J6 OMgULT.

BST MIX.

2NDRF 6BJ6 1ST RF

O6AK5 OSC.

00 6E1E6 MOD.

O 6UA5 QAKS,

VIBO

O TR TRIP IP

OBAKS DOUG.

2E26 DOUB.-

DRIVER

CK-1003 RECT.

0 2E26 POWER AMP,

RECEIVER TRANSMITTER TOP OF CHASSIS

FIG. 9. Layout of the tubes as seen from the top of the transmitter and receiver

netted in series with the center contact. The frequency stability of the trans-

mitter is x.0025% with ambient temper- atures of -30 to +60 °C., or .005% at -20 to +80 °C. Stability of the re- ceiver is better than *.002% over an ambient temperature range of - 25° to +125 °F.

Power output to the antenna is 7 to 10 watts. Battery consumption of the re- ceiver is 6 amperes at 6 volts. The total transmitter -receiver drain is 9M amperes at standby, and 19 amperes during trans- mission. The low- voltage syn chronous vibrator B supply for the receiver and part of the transmitter delivers 175 volts at 45 milliamperes, while the high -voltage non -synchronous vibrator delivers 280 volts at 135 milliamperes for the trans- mitter output tubes.

Fig. 9 shows the arrangement of the tubes as they appear on the top of the transmitter and receiver chassis.

Notes on Installation: The case for the combined transmitter and receiver sections measures 17% ins. deep, 5% ins. high, and 8% ins. wide. The complete .unit weighs 27 lbs.

Fig. 10 illustrates a typical car installa- tion. The cables and connections have been so simplified that the equipment can be installed quickly.

It is customary to use a fixed mounting for the transmitter -receiver unit. How- ever, shock mountings are available, so designed as to suit a variety of mounting methods. If necessary, to save space, the case can be fastened without the use of the regular feet. Bosses are supplied on the bottom of the case, just high enough to permit the front panel to be withdrawn.

Under some circumstances, there are advantages in having the volume and squelch controls accessible at the front panel. These controls can be fitted with shaft extensions for external adjustment.

FM AND TELEVISION

FCC PREPARES FOR UPPER-BAND TV FCC LISTS ISSUES TO BE CONSIDERED AT HEARING WHICH STARTS SEPTEMBER 20,

TO INITIATE PLANS AND STANDARDS FOR TV BROADCASTING ON 475 TO 890 MC.

ON September 20, the FCC will start a hearing in preparation for opening

the upper television band to commercial broadcasting. This is not a new idea. How- ever, it seems to be news to a great many members of the industry, probably be- cause the ground work was laid during the war period.

Origin of Upper -Band Plans:

In the FCC's Report of Proposed Alloca- tions from 25,000 Kilocycles to 30,000,000 Kilocycles, dated January 16, 1945, it was stated: "The Commission is fully con- vinced that by virtue of the recent devel- opments in the electronic art, a wide -

channel television broadcasting system, utilizing frequencies above 400 mc., can be developed, and the transmission of higher -definition monochrome pic- tures and high -definition color pictures achieved.

"The Commission is also convinced that all of the improvements that have been made possible in the transmission and reception of monochrome pictures by recent developments in the electronic art cannot be utilized in the 6 -mc. television channel. However, the Commission does not believe that broadcast service to the public through the use of a 6 -mc. channel, with the improvements presently avail- able over pre -war developments, should he abandoned and commercial television held in abeyance until a wide -channel system in the ultra -high frequencies can be developed and proven. Therefore, we

have endeavored to assign to television broadcast as many 6 -mc. channels below 300 mc. as possible in the light of the needs of other services for frequency space in the same part of the spectrum. ... The importance of an adequate pro- gram of experimentation in this portion of the spectrum cannot be over- empha- sized, for it is obvious from the allocations which the Commission is making for tele- vision below 300 mc. that in the present state of the art the development of the upper portion of the spectrum is necessary for the establishment of a truly nation- wide and competitive television system."

This proposal was confirmed in the final FCC report on allocations, dated May 25,

1945. On January 15, 1945, at a press con-

ference the day before the January 16

proposal was made public, then -Com- missioner E. K. Jett explained FCC think- ing on the new FM and TV frequency as- signments in these words: "However, FM is to be started [postwar] . and devel- oped as a permanent broadcasting service for the future. Television may or may not

be a permanent service in the bands be- low 225 me. because we are encouraging the development of television above 480 mc. We fully expect after a number of

years that the truly competitive opera- tions in this Country will be in the bands above 480 mc. Therefore, of the two services, when you consider that we must select between one and the other, the 6 -mc. television service will be of a tempo- rary character. I admit, of course, that the temporary character may extend for some years. Therefore, the service that is tem- porary in character should take the inter- ference, not the one that will be with the public throughout the entire future."

The Present Situation

Considerable experimental work has been done in the upper TV band, but no plans for scheduled broadcasting and receiver production can be initiated until trans- mission standards have been agreed upon by the manufacturers and approved by the Commission. One of the first and most interesting reports on propagation at upper -band TV frequencies appeared recently in the RCA Retrieve 1 This paper describes tests of reception at Denville and Princeton, N. J., from transmitters set up on the Empire State Building, New York City.

Since 1945, the FCC has not put any real pressure on the industry to prepare for upper -band operation. Meanwhile, with the postwar availability of 2 -way FM phone equipment and the provision of additional channels, mobile communi- cations has expanded at a rate undreamed of when the present allocations were set up. Even the latest changes proposed, which the FCC will probably confirm shortly, amount to nothing more than stop -gap measures.

But with television a demonstrated suc- cess as a public service, the FCC cannot formulate plans for giving any more TV channels to mobile communications until the stage can be set for upper -band oper- ation. Also necessary is a long -range time- table, acceptable to the industry, for moving into the upper band. That is re- quired to protect the public and the man- ufacturers against a condition of chaos which could throw a monkey -wrench into the wheels of current TV progress.

JTAC Will Advise FCC:

In appraising the status of present upper - band TV, establishing new standards, and

1 "Comparative Propagation Measurements; Tele- vision Transmitters at 67.25, 288, 510, and 910 Mega- cycles" by G. H. Brown, J. Epstein, and D. W. Peter- son, RCA Review, June, 1948. Obtainable from RCA Laboratories Division, Princeton, N. J. Price 75e.

August 1948 - formerly FM, and FM RADIO- ELECTRONICS

making effective plans for the future, the FCC will have the assistance of the new

Joint Technical Advisory Committee. JTAC was organized recently, at the sug-

gestion of FCC Chairman Coy, by the Institute of Radio Engineers and the Radio Manufacturers Association. This group succeeds the Radio Technical Plan- ning Board and, it is expected, will func- tion in a more objective manner than did

RTPB. The members are: Dr. Ralph Bown, Melville Eastham, D. G. Fink, John Hogan, E. K. Jett, Haraden Pratt and D. B. Smith, with P. F. Siling as

chairman and L. G. Cummings, secretary. JTAC is already gathering data for

consideration at the upper -band hearing. Accordingly we have been asked to pub- lish the following list of issues involved, and the list of detailed questions pre- pared by the FCC staff. JTAC requests that our readers send any information related to these questions to L. G. Cum- mings, Secretary, Joint Technical Ad-

visory Committee, 1 East 79th Street, New York 21.

Upper Band Considerations:

The purpose of the FCC's upper -band hearing, which opens September 20, is:

1. To obtain full information concern- ing interference to the reception of tele- vision stations operating on channels 2

through 13 resulting from adjacent chan- nel operation of other services, from har- monic radiations, and from man -made noise.

2. To receive such additional data as

may be available since the close of pre- vious hearings (Dockets 6651 and 7896)

concerning the propagation characteris- tics of the band 475 to 890 mc.

3. To obtain full information concern- ing the state of development of transmit- ting and receiving equipment for either monochrome or color television broad- casting, or both, capable of operating in

the band 475 to 890 mc. 4. To obtain full information concern-

ing any proposals for the utilization of the band 475 to 890 mc. or any part thereof, for television broadcasting and the stand- ards to be proposed therefor.

The specific questions prepared by the FCC at the request of JTAC are :

1. What is the present state of develop- ment of equipment in the band 470 to 890 mc., in regard to

A. transmitters, tubes and components B. receivers and components C. antennas, transmission lines and

related equipment for transmission and reception?

(Concluded on page 45)

23

RCA EQUIPMENT CABINETS for small rack- mounting units, such as monoscope camera, studio line amplifiers for sound and picture, microwave relay receiver, test equipment, power supplies, etc.

RCA DUMMY LOAD. For testing and measuring power output. This unit con- sists of a coaxial line, the inner conductor of which is a water -cooled resistor.

L -F ANTENNA DIPLEXER (left) AND THE VESTIGIAL SIDE -BAND FILTER (right). Diplexer makes it practical to use one antenna for picture- and -sound signals. Side -band filter partially suppresses one sideband. No adjustments required.

You see here the transmitter room that is being delivered to more than thirty television stations ... complete, and RCA throughout.

As practical, we believe, as an AM station transmitter room, this layout has the proper equipment you need to put high -quality picture -and -sound signals on the air - reliably, and with surpris- ingly little supervision. It includes: a combined 5 -kw picture and 2.5 -kw FM sound transmitter; a complete transmitter control con- sole; a vestigial side -band filter; a dummy load; an antenna coup- ling network; sound- and -picture input antenna coupling network; sound- and -picture input amplifiers; and frequency and modula- tion monitors.

Why the overwhelming acceptance for this transmitter room . and all other RCA television equipment? It's the thoroughness with which RCA TV equipment is de-

signed. It's the practical engineering experience behind it -more of it than any other television equipment manufacturer. It's the completeness of the line ... with one equipment source for every- thing you need in your station. It's the undivided responsibility RCA assumes for all equipment you buy. It's the unbroken record of past performance and service to the industry.

Nothing to planning a television station -when you let an RCA Television Specialist help you. Call him in. Or write Dept. 38 -H, RCA Engineering Products Division, Camden, N. J.

ge one Source for EVerything

in TV-4 q

RCA CONTROL CONSOLE for "push- button" control of your transmitter room. Handles both picture and sound transmitters, a turntable, and an announce microphone. Includes power switches, picture and sound monitors, switching circuits, antenna cur- rent meters -and an oscilloscope.

THE RCA 5 -KW TV TRANSMITTER (plus 2.5 kw for FM sound). Full picture- and -sound power on your channel. High -level modulation. Meter -tuned, nar- row -band drivers. Only one class B stage to adjust. No neutralizing of PA. Built for "walk -in." De- livery being made to more than 30 stations.

...entire transmitter rooms, 4;16

,4

COMPLETE TRANSMITTER ROOM - by RCA

More than 30 rooms like this one are going to television stations. The entire layout is designed to be used adjacent to your TV studio control room...or at a remote control location.

TELEVISION BROADCAST EQUIPMENT RADIO CORPORATION of AMER /CA ENGINEER /NG PRODUCTS DEPARTMENT CAMDEN, N.J.

o In Canada: RCA VICTOR Company Limited, Montreal

SPOT NEWS NOTES FM Transit Radio:

Although several test installations of FM receivers in street cars and buses are now in operation, the first wide -scale service has just been completed in Covington, Ky. Cooperating in this project are Tran- sit Radio, Inc., Union Trust Bldg., Cin- cinnati, the Cincinnati, Newport & Covington Railway, Dixie Traction Com- pany and station WCTS. Already 100 receivers are in operation, and 300 more will be in service by the end of August. This will add 380,000 to the audience of WCTS.

Easy Money: Financing of new TV set manufacturers reminds us of similar promotions of radio concerns back in the early 20's. Only trouble is that we can't remember a single radio company financed by brokers in the old days that is still in business.

TV in France: The Eiffel Tower station is on the air again. Their standards are set at 840 lines per inch. Program schedules is one hour on week days, three on Sunday.

Servicemen's Meetings: Series of Town Meetings of Radio Tech- nicians, initiated in Philadelphia last January, has been set up by the Radio Parts Industry Coordinating Committee. New York meetings will be at Hotel As- tor, September 27 -29. The next will be at Hotel Bradford, Boston, November 15 -17, followed by others at Atlanta in January, Los Angeles in March, and Chi- cago in April. Chairman Harry A. Ehle has appointed Walter W. Jablon to assist in preparations for the New York meet- ings, and W. A. Ready to serve in connec- tion with the Boston meetings.

TV Studios Remodeled: WABD New York is spending over $125,000 on studio improvements which include redecorating and the addition of new equipment. The latter includes a Fearless hydraulic camera dolly and a dual Iconoscope film pickup chain.

Max H. Bice: Former chief engineer of KMO Tacoma has been appointed to similar post at FM station KTNT, now under construction by the Tacoma News Tribune.

FM -TV Score: At the end of August, FM stations on the air passed the 600 mark. In 1949, the number will equal the AM stations at the end of the war. The FM -TV score is now:

26

ITEMS AND COMMENTS, PERSONAL AND OTHER- WISE, ABOUT MANUFACTURING, BROADCASTING, COMMUNICATIONS, AND TELEVISION ACTIVITIES

TV FM On the air 30 601 Authorized 81 441 Pending 299 95

Total 410 1137

The FM figure includes 22 educational stations.

Indiana FM Net: Comprised of WSRK Shelbyville, WCTW New Castle, WCNB Connersville, and WFML Washington, is now in regular operation. Stations WFMU Crawfords- ville, WMRI Marion, and WBCR War- saw will join the net as soon as their facilities are completed.

Armstrong Medal Award: Formal presentation, in recognition of contributions to the radio art by the late Stuart Ballantine, was made to Mrs. Bal - lantine at her home in Boonton, N. J., on June 26. Prof. Hazeltine, Lawrence Horle and Harry Houck represented the Radio Club of America. On this occasion, Major Armstrong recalled that Stuart Ballan- tine's work included the development of the direction -finder for anti -submarine work in World War I and, later, the prin- ciples of negative feedback and AVC, mathematical theory of the vertical an- tenna, and inventions in acoustics which included the throat microphone.

Important IRE Publications: Just issued are: "Standards on Television: Methods of testing receivers for mono- chrome, 6 -mc. channel service," price $1.00, and " Standards on Antennas, Modulation Systems, Transmitters: Defi- nitions of terms," price 75¢. Copies can be obtained from the Institute of Radio Engineers, 11 E. 79th St., New York 21.

Last Word in AM Receivers: New York manufacturer offers the tops in functional design. It's a statue of a horse, presumably in bronze, mounted on what looks like a marble base. But it's de- scribed as a 4 -tube AC -DC set, with built -in antenna. From the picture we judge that: the set is tuned by twisting the horse's tail; the music comes out of his mouth; he hangs his head for com- mercials; and static makes him buck.

AES Elections: San Francisco chapter of the Audio En- gineering Society has elected I. R. Ganic, chairman; Walter Selsted, vice chairman; Don Lincoln, secretary, and Frank Len - nert, treasurer.

WSB -FM Atlanta: Atlanta Journal will soon have a 10 -kw. Westinghouse FM transmitter on the air, replacing the present low -power installa- tion. A 600 -ft. tower for the FM antenna is designed to take a TV antenna later. Chief engineer of WSB is C. F. Dougherty.

Ignition Interference: Tests made by RMA and the Society of Automotive Engineers, under the chair- manship of K. A. Chittick, show that recommended changes in ignition systems reduced tolerable interference with TV reception from a distance of 200 ft. from the antenna to a distance of 70 ft. Average tolerable interference was found to be approximately 33 microvolts. The sound channel was immune to impulses that interfered with picture reception.

WMBI -FM Chicago: New call letters for Moody Bible Institute station, formerly identified as WDLM. Present power of 5 kw. will be increased to 50 kw. early this fall.

ABC's TV Center: American Broadcasting Company has taken over a building which runs from 66th to 67th Streets, New York City. The structure, just west of Central Park, was formerly used as an arena for the N. Y. Riding Club. This will be ABC's TV studios when alterations are com- pleted early next year. WJZ -TV New York is already transmitting test patterns on channel 7.

New Company: Raymond Rosen Engineering Products, Inc., 32nd and Walnut Ftreets, Philadel- phia, has been formed to handle what was the commercial sound, communications, and development department of Ray- mond Rosen & Company. One of the big jobs done by the new concern was the installation of the sound systems for the recent political. conventions. Vice presi- dent and general manager is Louis P. Clark.

Straight FM Table Model: Emerson Radio has announced a table model, priced at $30, with FM tuning only. If it has good sensitivity and limit- ing action, it's big news to dealers and broadcasters. Today, in all important trading areas, a good FM set can bring in enjoyable reception from more FM sta- tions than AM stations. So the advent of a straight FM set is amply justified. However, to be successful, the Emerson model must equal the FM performance of Zenith's new $49.95 FM -AM receiver.

FM AND TELEVISION

NEWS PICTURES 1. To protect the WWJ -TV cameras which televise baseball games at Briggs Stadium, home of the Detroit Tigers, Rohm & Haas produced a % -in. sheet of

Plexiglas 7 by 8 ft. The material does not interfere with the cameras, and affords ample protection against a 9 -oz. ball.

. RCA recently staged another week- long course in television for sixty -four broadcast engineers at Camden. The group included a Canadian contingent. In this photograph are, from left to right: Walter J. Blackburn, president of CFPL, CFPL -FM London, Ont. ; Aurele Bois - vert, chief engineer of CHUM Toronto; Frank M. Foison, executive V.P. of

RCA; W. W. Watts, V.P. in charge of

RCA engineering products department; Percy Fields, chief engineer of CFPL, CFPL -FM; and RCA representative Ken Chisholm.

3. A tape recorder, designed to meet the requirements of FM broadcast studios, has been developed by Ampex Electric Corporation, 129 Howard Avenue, San Carlos, Cal. Response is rated at = 1 db from 30 to 15,000 cycles; overall distor- tion is 4% intermodulation at peak meter reading.

4. Latest addition to FM and TV test instruments is the Raytheon -Belmont signal generator for RF alignment. Used in conjunction with an oscilloscope FM sets can be checked accurately and quickly. For TV, a video generator is

needed.

5. York, Pa., Fred Link's home town, is

also distinguished by having a unique broadcast antenna installed for WNOW and WNOW -FM. The top 54 -ft. section is a 4 -bay Pylon antenna, mounted on a 154 -ft. Wind Turbine tower. The entire structure serves as an AM radiator.

6. FM transit radio service from WCTS Cincinnati was formally inaugurated on July 10. Taking part were, left to right, Guy C. Hecker, manager of the American Transit Association and Harry Reid, president; P. G. Vondersmith, president of the Green Line; Richard C. Crisler, vice president of Transit Radio and Hul- bert Taft, Jr., president.

7. At the new Terrace Plaza Hotel in Cincinnati, a Crosley television ,receiver is fitted permanently into one wall of the garden restaurant, and connections are provided for three more sets to be used on special occasions.

8. To facilitate the use of test equip- ment, and to protect the instruments from damage on the service bench, RCA is

providing this rack mounting. Of alumi- num trimmed in blue -gray, it holds six standard -size RCA instruments. Size is 4 ft. wide, 3 ft. high, and 1 ft. deep.

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MERCHANDISING TV RECEIVERS RECOMMENDATIONS BASED ON THE RESULTS OF A SURVEY OF TV OWNERS AND NON -OWNERS IN NEW YORK AND PHILADELPHIA AREAS-By STANLEY H. MANSON*

ELEVISION is a rapidly growing industry. It has moved ahead so fast

during recent months that manufac- turers, broadcasters, distributors, and dealers have all made serious blunders in selling this new and exciting form of home entertainment. This confusion in the ranks is a natural outcome when everyone tries to get into the business in a hurry. However, progress in the right direction has been made since the first of this year by broadcasters who are now offering better programs, manufacturers who are producing better receivers at more attrac- tive prices, and by dealers who have im- proved their demonstration facilities and s -fling techniques. The public has been given a better understanding of what it can and cannot expect from television by more informative advertising sponsored by manufacturers and dealers, plus a wide distribution of literature and booklets on the subject which have recently been made available.

In markets where television has been a factor for many months, the fans and those individuals who always are among the first to buy something new have made their purchases, and business for the dealers is settling down to the application of merchandising techniques that have proved successful in the past. In other words, television, like any other product, must be thoroughly sold in order to guarantee the dealer a satisfied owner list. The radio business is now entering a tremendous era of expansion with the advent of television, and competition will be greater than ever between manufac- turers and within the ranks of the re- tailers. Therefore, it is only logical that those who are adequately prepared in every way to enter this new field will gain the greatest amount of volume and profit from it during the years ahead. There has been confusion in the ranks as in- dividual manufacturers attempt to ap- proach the problem of merchandising and promoting their television products in a manner which differs from their com- petitors, but this is a healthy condition and probably one of the main reasons why the radio industry is fast reaching a billion -dollar annual sales peak. Sales methods employed by individual dealers in any given community also differ, but these varying approaches to the problem of moving merchandise usually result in profitable operations for the majority.

There are, however, certain fundamen-

* Manager of Advertising and Public Relations, Stromberg- Carlson Co., Rochester, N. Y. Complete text of an address before the National Association of Music Merchants, Chicago, June 17, 1948.

28

tal merchandising techniques which have been exploited already and proved suc- cessful in the promotion and sale of tele- vision instruments. In these cases, the progressive dealer usually knows what the prospect wants in his new television re- ceiver, what he is willing to pay, why he will make his purchase at a particular store, and what he can say in his local advertising which will make the prospect want to buy now. This same knowledge must be obtained by the manufacturer

THE CHANGING SCENE

IN the days before FM and TV, most radio dis- plays were cubby -hole affairs, with little table

models (top price $29.95) set in each opening. Con- soles, if shown, were pathetic affairs, with a minia- ture chassis reposing in an almost -empty shell of borax woodwork.

The display of 1948 FM and TV models on the page opposite, in amazing contrast, emphasize the new merchandising problems which now confront manufacturers and dealers. From left to right, and by rows from top to bottom are models produced by Westinghouse, Magnavox, Freed -Eisemann, Hoffman, RCA, Du Mont, Pilot, Philco, TCA, Farns- worth, Zenith, and Crosley.

New sets and added services are multiplying the profit -possibilities of radio sales, but they call for a more profound technical knowledge and a broader understanding of markets and merchandis- ing methods. Over -the -counter, cash- and -carry sales are becoming fewer and farther between for the simple reason that while production of shelf merchandise is dropping off, there is an enormous increase in sets too heavy to pass over the counter, or to carry out under one's arm.

and applied to his planning of future products and merchandising campaigns.

Early this year, our Company dele- gated its advertising agency to make a pilot survey among owners of all makes of television receivers and also non - owners, or prospects, in the New York City and Philadelphia areas. This form of market research will be continued in other cities during the fall months, for we antici- pate many changes in the buying habits and desires of the public as television be- comes more and more an essential part of home entertainment.

From both groups, owners and non - owners, we took a complete history of their exposure to television, what in- fluence this exposure had on their en- thusiasm for television, and what con- siderations would be regarded as the most important if they were investing in tele- vision today. In allocating both owner and non -owner interviews, representation was secured from all important sections, both city and suburban, as well as a cross section by income and age groups in the New York and Philadelphia areas. Here are the highlights of the survey:

1. We found that the man of the house made the purchase decision in 75% of the cases. This is a high percentage compared to the sale of radio and radio -phonograph

combinations, for in the past women have had great influence in the selection.

2. 30% of the owners made a decision to buy and bought immediately. 24% took 2 to 4 weeks to shop around. Another 24% took 2 to 6 months before placing their order.

3. 73% of the owners purchased table models, against 27% who selected eon - soles or combinations. Price or availability were the chief factors in table model sales, although many indicated that because of the television programming available at the time of purchase, it was desirable for them to retain their radio -phonograph combination in the living room for the entertainment of members of their family and friends who were not interested in television programs. In such cases, the television table model was 'placed in a den or game room for the entertainment of Dad and the boys.

4. In the homes visited by interviewers, 75% of the receivers contained 10 -in. tubes and 11 %, 7 -in. tubes. The remainder were using larger tubes. When asked for preference in considering the next pur- chase, the majority indicated that they would buy a receiver with a larger tube, with the 12 and 15 -in. sizes most popular.

5. In considering the extent of shop- ping comparisons before purchase, it must be remembered that the limited avail- ability of television during 1947, and even in early 1948, undoubtedly upset the normal shopping habits of buyers. It is noteworthy that almost half of the owners (49 %) did not consider any makes other than the particular one purchased. The present shopphg habits are becoming more normal, as many more makes and models are being introduced and effec- tively advertised, resulting in the pros- pect's desire to see and compare before making his choice.

6. Here is an interesting observation which must be given consideration in planning your merchandising program. Although the man of the house made the selection of the television receiver (in 75% of the cases), a tremendous amount of influence on him to buy was exerted by other members of the family, especially the children. In fact, children are the most enthusiastic audience for television programs, and it is common for youngsters in the neighborhood to gather as a group in a television home and quietly watch afternoon and evening programs by the hour, no matter what type of entertain- ment is being broadcast. This may be a good thing for those of us who occasionally look for a little peace and quiet at home.

FM AND TELEVISION

~

Nearly three- fourths of the respondents claim that members of their families had developed new interests as a result of television ownership. This pertains par- ticularly to sporting events.

7. Although many owners took several months to make up their minds regarding their television purchase, they were upset because of the period of time which elapsed between purchase and installa- tion. No doubt many of these complaints could be eliminated if the dealers' sales- men would explain the delivery and installation problems at the time of purchase.

8. Under the heading of service, we were pleased to find that 84% of the own- ers reported that their installation was completely satisfactory. This indicates that dealer and special installation service organizations are well trained and are doing a thorough job.

9. Another encouraging report is that the large majority found their television receivers easy to operate. Wives receive more instruction on operation than hus- bands, probably because more women than men are home at the time of installa- tion. Generally speaking, buyers have learned to operate their sets quickly and easily, with only 6% admitting difficulty.

10. More than two -thirds of the re- ceivers (68 %) required service of one form or another. As to the nature of the trouble, the majority of complaints were not serious and necessary service calls were reported to be satisfactory with little time involved in making adjust- ments. It should be pointed out that poor signals from the broadcast transmitter or inferior programs have resulted in many calls to the dealer's service department. Stations are overcoming this by announc- ing during the broadcast that their diffi- culties are temporary. Dealers should also be alert to any period of unsatisfactory broadcasting service in order to explain to the customer that the fault does not lie in the receiver.

11. Viewed in relation to standards of reception anticipated prior to purchase, set owners evidenced a high degree of satisfaction with their television receivers. 82% judged the pictures "very good "; 16% regarded them "fairly good "; and only 2% had experienced real disappoint- ment and considered the images "poor." Evaluation of sound or tone quality was identical with the evaluation of the image. Difficulty in picking up channels or sta- tions was reported by 22 %. This will naturally vary by cities because of signal strength and location of transmitter.

N. Important to all of us in the tele- vision business is the influence of this new communication service on the family life and interests. The greatest source of satis- faction, cited by 45% of the owners, was that for the first time they were able to enjoy a variety of entertainment visually in their own homes. As natural corollaries, such responses were received as " brings

30

family closer together " and " provides means of entertaining friends." The edu- cational advantages of television, par- ticularly for children, were mentioned by nearly 25% of the respondents.

13. 60% of the owners experienced some disappointment in their television set ownership. The entertainment now offered on television was the principal ground for criticism, 19% citing poor programming and an additional 15% specifically naming old, poor movies. Lack of variety was also pointed out by 9 %, and 6% expressed this same thought "no good programs except sports." This problem is fast being overcome by stations and networks broadcasting better pro- grams, including musical shows, now that the ban has been lifted.

14. In regard to the weekly viewing time spent by individuals and families before their television receiver, 31% re- ported 25 hours or more per week, while 22% use their set 20 to 25 hours. This means that more than one -half of the television owners interviewed were ac- tually viewing on an average of 3 hours per night. Only 11% limited the use of their sets to less than 10 hours per week. Another interesting observation is that 69% of the leisure time now given to view- ing television was previously spent lis- tening to radio. When owners were asked to indicate their favorite radio program and their favorite television show and then decide which they would tune in if both were on the air simultaneously, 89% favored the television broadcast. This is something for all of us to think about, especially those who are in the broadcast- ing business.

15. A strikingly strong endorsement of television was evidenced when 99% of the owners answered that they would buy a television set if they had the decision to make again. As further testimony of satis- faction, 35% are interested in acquiring a second television receiver.

16. With a background, of experience with their present television receivers, owners in entering the market today would look first for a larger screen, as indicated by 48% of the respondents. Somewhat related, and of almost equal importance, would be clarity of image, 40 %. Better cabinet designs and finishes would be expected by 24 %. 18% would require improved sound or tone quality. Simplification of controls and fewer knobs would be an advantage in reselling 15% of the owners. The hope for color tele- vision was expressed by 17 %. With the exception of the last mentioned require- ment, the radio manufacturers are meet- ing the future wants and specifications of those who have television sets in their homes today.

17. 51% of these owners would want a console type receiver with all services - television, AM, FM, short wave, and automatic record player. In contrasting preference with the present ownership

(27% console and 73% table model) the apparent shift must be considered in the light of the limited availability of tele- vision during the period in which many of the present sets in operation were pur- chased. Also, the respondents have had both an introduction to television and gratifying experience with it, which makes them less resistant to higher -priced con- sole models. Interesting information re- garding furniture styling, finishes, desired height of screen from the floor (which happened to be 38 ins. as indicated by the majority), improvement of controls, and size of screen was also secured from this survey.

18. Our survey among non -owners showed that 96% had been exposed to television programs. 84% desired to own television sets, representing all income groups. It is interesting to note that the non -owners' requirements are almost identical to owners' specifications, 51% desiring a console model and 49% a table model for the same reasons expressed by owners. Large picture, clarity, fine cab- inetry are also expected by non -owners. The general level of prices which non - owners would be willing to pay for tele- vision receivers was considerably lower than the prices the owners would expect to pay. 35% indicated that they would invest up to $400 for a television set. Another 35% of non -owners would be willing to pay $400 to $600 and 30% over $600. In the majority of cases,. these prospects were not fully informed on the costs involved in producing receivers to meet their requirements.

These are the high lights of our survey as they pertain to the problems faced by manufacturers and dealers in merchandis- ing television effectively during the months ahead. Our contacts with dealers in television areas indicate that they are genuinely enthusiastic about this new and wonderful broadcasting service, many realizing that television is the answer to a much needed impetus to greater volume and profits in the radio business. Sales in television territories have been made to all income classes, although it was not many months ago that television was looked upon as a rich man's toy.

Dealers are now beginning to report that all prospects interested in television are not buying. Objections to price, char- acter, and quality of programs being broadcast, and the desire to hold off for revolutionary developments and improve- ments are influencing factors. As stated above, manufacturers, broadcasters, and dealers are now finding the way to satisfy the millions of television prospects who will buy during the next few years.

With a thorough knowledge of what television is and how it is playing so im- portant a part in offering complete home entertainment to owners, those of you who are already selling television receivers, and others who may soon be, must enter

(Continued on page 46)

FM AND TELEVISION

y Mallory Midgetrol

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popular small sets where ordinary controls will not fit. manufactured. Pushes on -stays on -and works.

NEW

THE DESIGN IS NEW THE ELEMENT IS More accurate over -all resistance, smoother tapers, ample power dissipation.

NEW Brand new shaft style saves valuable time in installation - reduces inventory since one shaft fits all knobs.

THE CONSTRUCTION IS . . NEW Extra quiet -no metal -to -metal contact between shaft and cover or bushing. Special Mallory contact material.

THE SHAFT IS NEW Unique -two simple fittings -for all type knobs. No need

for extra controls for different knobs.

THE EXTENSION IS NEW Easy to apply with self- tapping screws. Supplementary shafts available for installations which require them.

Side snips neatly eat shaft to length desired.

THE CONTACT IS . . NEW Laboratory tests prove that the Mallory Midgetrol is the quietest control on the market.

THE TERMINAL IS . . . . NEW Won't break -twist 'em all you want in close working space. Away from panel to avoid shorting.

THE SUSPENSION IS NEW Two -point- insures even contact pressure at all points of rotation. Larger bushing area -added support -no wobble.

U-clip furnished to slide over end of shaft -holds set -screw knobs.

Use half the U-clip to hold push -on type knobs.

Spring steel clip in- cluded for use with knurled knobs.

Extension shafts with two self -tapping screws available when needed.

It's the NEW Standard in Carbon Controls. See your Mallory distributor.

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CAPACITORS CONTROLS VIBRATORS SWITCHES RESISTORS

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D PRECISION PRODUCTS P. R. MALLORY & CO., Inc., INDIANAPOLIS 6, INDIANA

August 1948 - formerly FM, and FM¡.RADIO- ELECTRONICS .31

/( //J radio installations on the tugs can be identified by the cartwheel antenna

HOW N. Y. TUGS USE FM LACKAWANNA RAILROAD SAYS: "DON'T SHOUT! OUR TUGS HAVE HEARING AIDS

FEW people, not connected with the railroads, realize that their marine

extensions in harbors and on waterways perform an important function in moving freight between inland areas and coastwise and foreign vessels. Also, transit time is saved by moving freight cars on floats.

." - By JOHN M. SITTON

Motive power for these operations is supplied by tug boats. Their movements are necessarily slow because the loads are heavy and ponderous, and their speed is limited by harbor traffic, tides, winds, and weather. There has been a further limitation to tug boat operations, namely,

Use of the 2-way radio does not interrupt tugboat Capt. Torcic's trick at the wheel

32

the lack of communications between the captains and their respective dispatchers. Until the advent of the 2 -way FM tele- phone, orders and changes could be de- livered to a tug over a distance limited by the carrying power of the human voice, augmented by the use of a mega- phone!

It is easy to see that, under such cir- cumstances, considerable time is lost 1) when conditions change and a tug con- tinues unnecessarily to a destination be- cause it was impossible to countermand the original order, or 2) when a tug, returning to its pier, passes an assignment because new orders cannot be transmitted to the captain en route.

In contrast, Captain Doran, assistant superintendent of the Lackawanna Rail- road's marine department, described the effect of equipping ten of their fourteen tugs with radio in these words: "Two - way radio has made it possible for us to coordinate our whole New York Harbor operation of moving freight into a co- hesive, efficient organization."

Two -Way FM Performance: To get first -hand information on the use of radio in tug boat service, the author spent a day with Capt. Torcic on the Fulton, one of the Lackawanna's New York Harbor tugs now equipped with 2 -way FM.

The headquarters antenna, 250 ft. above the water, is mounted on the Lacka- wanna tower, Hoboken. The transmitter, a Bendix installation operating on 160.29 mc., is about 75 ft. down the tower, remotely controlled from the dispatcher's office on Pier 6.

Similar Bendix equipment is used on each tug, with the addition of a dyna- motor power supply. The remote control unit and hangup for the handset are mounted directly forward of the wheel, as shown in one of the accompanying illus- trations.

The loudspeaker is normally connected to the radio receiver, but when the hand- set is removed from its hook, the speaker is silenced, and the incoming voice is heard on the receiver in the handset. This is the same arrangement as is used on land mobile installations.

According to John de Silva, who handles the maintenance of all the radio equipment, radio coverage of New York Harbor is virtually solid except at a few spots in the East River, close to the Man- hattan shore. That is due to strong shadow effects from certain groups of tall build- ings, since the main transmitter is across the Hudson River on the opposite side of Manhattan. In the middle of the East River, and on to the Brooklyn side, no trouble is experienced at all, as would be expected.

The noise level in New York Harbor is

* Bendix Radió Division, Bendix Aviation Corpora- tion, Towson, Md.

FM AND TELEVISIQN

very high, with the source apparently in the direction of Manhattan Island. Initial trouble caused by the high level of inter- ference was overcome, however, by chang- ing the squelch from carrier operation to noise operation.

Typical Daily Schedule: Normally, each crew on the Lackawanna tugs stands an 8 -hour watch. Each tug is out of service for 1% hours in 24, when the ashes are blown out by a steam injec- tor into a gondola car at the pier. Then new fuel is taken on.

The day starts at 5:00 a.m. when the Captain and his crew go aboard. By radio, the Captain reports to the dispatcher that he is ready for orders. Up to this point, there is no change in routine over pre - radio procedure. But when the tug leaves its pier, there are radical departures. On the occasion of the writer's trip with Capt. Torcic of the Fulton, we had just pulled in at Emigrant Slip, Hoboken, when a call came with instructions to tow the tug Madison to the ash car. Before that as- signment was completed, the next order came:

"Pier No. 6 to Fulton, over." Capt. Torcic replied:

"Fulton to Pier No. 6, OK." "Take barge 507 from Pier 4, D.L. &

W. Terminal to 7th Street, Hoboken. Also, shift lighter 448, Pier No. 1 Army Hoboken to Pier No. 60, North River."

A few minutes later there was another call, the routine acknowledgment, and then:

"Pick up barge 571 from Hoboken Pier No. 3 Army and take it along with 507, over."

"Fulton to Pier No. 6, OK, over and out."

Capt. Doran explained: "The old method was to send a deck hand ashore whenever a tug docked so he could tele- phone the dispatcher for orders. It took about 15 minutes for each call. If 10 calls were made during a watch, that meant tying up the tug for em hours! If the dis- patcher wanted to reach the tug, he had to wait until it showed up, and hove to within hailing distance. He couldn't catch it en route. Now he can give a tug a string of change orders, no matter where it's working. Radio has done that."

By 1:00 p.m. the Fulton had completed six jobs. On our way to the next one, we

heard: " Tug Newark to Pier 6, over." "OK, Newark, go ahead." " Tug Newark reporting a fire ashore at

Roosevelt Street, East River. Fire boats are on the way. No need for us to stand by. Over and out."

"Pier 6 to Newark, OK, out." The Captain explained that the fire was

under Brooklyn Bridge. "If it had been necessary, the Newark would have helped fight the fire. Each tug has a fire tower and extra hose. It can throw a stream about 60 ft. to fight a fire aboard a vessel

To dispatcher Joseph Strohscheim., the old megaphone is

or ashore. During the famous Weekauken fire, the tug Bath operating as a central station, transmitted messages to two Lackawanna tugs which passed them to non -radio tugs working in the area."

As we plowed along, Capt. Doran de- scribed events on that day- after -last- Christmas, when winds of hurricane force lashed harbor traffic with blinding snow. "With radio aboard," he said, "our tugs never lost a minute's time, for they were in constant contact with the dispatcher. At one time, damage was threatened to equipment at the Bush Docks in lower Brooklyn. where it was exposed to the full sweep of the wind from the upper bay.

a //( of pre -radio days

But it was saved by the crew from one of our tugs. The dispatcher knew the loca- tion of each tug, and sent the nearest one to do the job. Not a minute's time was wasted.

"Some carfloats were being towed around the Erie Basin breakwater that day. The wind was so strong that a second tug was needed. As soon as the difficulty was reported by radio, the dispatcher called another tug and rerouted it."

Capt. Torcic, the Fulton's skipper, re- called that the snow on that day was the heaviest he had ever seen, and he has been on the Harbor for nearly fifty years.

(Concluded on page 40)

Main transmitter installation at Lackawanna tower is remotely controlled from Pier G

August 1948 - formerly FM, and FM RADIO- ELECTRONICS 33

TELEVISION HANDBOOK CHAPTER 3: PRIMARY COMPONENTS OF EQUIPMENT - PART 5: DISCUSSION OF THE THEORY & OPERATION OF RELAXATION OSCILLATORS - 'By MADISON CAWEIN

(5.2) Current Relaxations: The type of relaxation oscillator which was discussed in the last section is used to generate sawtooth potential waves. This type is generally referred to as the capacitance- resistance (CR) type of relax- ation oscillator, of which the multivi- brator, the van der Pol, the blocking oscillator, and the Potter oscillator are examples. Figs. 62 and 63 illustrate the two latter circuits. The time -determining circuits are defined by the magnitude of C and R, and the output waveform is defined by the magnitude of C' and R'. R" may be introduced to include a pulse component. in the output sawtooth wave.

Another type of relaxation oscillator can be used to generate sawtooth- current waves, in which the time -determining cir- cuit may consist of L and R. Then the oscillation is referred to as an L/R re- laxation.

(5.21) The Beam Relaxor: One form of sawtooth -current relaxation oscillator Nvhiclr has been referred to as the Beam Relaxor will supply 2,500 volts DC for excitation of the 2nd anode of magnetic -focus camera tubes, in addition to supplying the deflection current. Thè circuit shown in Fig. 63. The theory of this circuit will be described in some detail from a physical standpoint, to help the student to visualize the operation of the circuit.

This circuit is known as an L/R type of relaxation oscillator, in which the fre- quency and waveform control are depend- ent entirely on the ratio of plate- circuit inductance to dynamic plate- circuit re- sistance, as opposed to the capacitance and resistance in the more generally used CR -type relaxation oscillators.

The effective load of the plate circuit is the determining L, and the effective plate resistance of the tube is the deter- mining R of the circuit. The actual im- pedances of the primary and secondary are non -critical. The impedance and po- tential of the screen electrode is the most critical element in the circuit, there being an optimum value of screen resistor for every design, which optimum controls the amount of high- voltage obtained, the synchronizing susceptibility, the speed of the wave, and the tendency to parasitic oscillations.

The equivalent circuit is shown in Fig. 64. The potential waveforms at various points of the circuit are shown in Fig. 65. The following physical description of a single cycle is suggested :

34

Consider that a linear, sawtooth elec- tron- current flows into the plate of the beam -power tube from the cathode. during the trace portion of the sawtooth cycle. The load is purely inductive. The electrons leave the plate, flowing into the load inductance at a lower rate than that

YNC INPUT

OUTPUT WAVE FORM

IT

FIG. 61. CR relaxation oscillator, in which the low frequency blocking -osillator type of

circuit is employed

at which they arrive from the cathode, due to the inertia effect of the inductive circuit. There is a linear, negative po- tential- gradient along the plate induc- tance, the plate being the most negative point, due to the steady difference be- tween the number of arriving and depart- ing electrons at any point of the circuit. This difference exists even though the number of electrons arriving from the cathode is steadily increasing with time, as the cycle progresses, because the num-

FIG. 62. Another CR relaxation oscil- lator, employing the high. frequency Potter

oscillator type of circuit

ber which leaves the plate and flows away through the inductance is also steadily increasing with time. It may also be con- sidered that the uniform potential in- duced across the inductance due to this steady change in current keeps the plate potential at a lower- than -normal value during this pa rt of the cycle.

Suppose now that the steadily increas- ing electron stream from cathode to plate slows down, or is cut off. If the current change through the inductance is inter- rupted slightly, for any reason, then elec- trons pile up at ground due to inertia,

which keeps them flowing through the in- ductive load away from the plate. This leaves a great deficiency of electrons at the plate, and a consequent high value of positive potential on this element. The positive potential at the plate slows down the rate -of -flow of electrons away from the plate until this rate becomes less than the decreased rate -of -flow from the cath- ode. The two rates become equal at a point midway along the retrace, or fly- back of the sawtooth cycle, indicated by dots in the diagrams of Fig. 65. The plate potential reaches its maximum negative level again as current -flow from the cathode starts in again. The starting cur- rent represents at least the maximum rate -of -rise at any point of the cycle.

In this type of relaxation, as the cathode - current interruption starts, there is an instantaneous pile -up of electrons at the grid due to the transfer of kinetic energy of motion from electrons in the plate cir- cuit to those in the grid circuit, by way of the radiation field of the coupling trans- former. This is perhaps another manner of saying that the mechanics of any physical process is not completely understood or explainable in the final analysis. A nega- tive, impulsive potential is produced at the grid, and this accelerates the inter- ruption of the cathode current. We say that the circuit is regenerative, any small change becoming greatly augmented to its physical limit in a small interval of time, limited by the transit time of electrons and the time constants of the circuit elements.

The screen potential, as the cathode current starts to rise, is at its lowest value, because a large number of electrons are deflected toward the screen just at the inception of the cathode current. This can be seen by reference to the potential waveform of the screen, Fig. 65. The po- tential waveform of the cathode is such that absolute current cut -off occurs during the retrace. The beam -forming electrode, which is connected to the cathode inter- nally, must follow the cathode potential. One explanation of the performance of this oscillator is that, as the beam -forming electrode potential increases linearly with the cathode potential, the screen is robbed of electrons at a linearly increasing rate until the screen potential reaches a value where part of the beam strikes the beam -forming electrode, and current interruption starts.

(5.22] Magnetic Deflection Circuit: The analysis of the output circuit in Fig. 63 is typical of magnetic deflection

FM AND TELEVISION

circuits in general, whether of the current - relaxation type under discussion in the previous section, or whether the grid of the power tube (utilized as an amplifier) is driven by a waveform similar to either of the output waves shown in Fig. N as generated by a CR -type of relaxation oscillator.

oscillations. With deflection coils having an inductance equal to 2.0 mh., the turns ratio of the transformer should be ap- proximately 6:1.

The optimum value of screen resistor increases with the turns ratio, having a value of approximately 5,000 ohms for n = 6, and for a 300 -volt B supply. De-

H. SY- N- C PULSES

BEAM POWER 1/2 0SN7GT TUBE

S00T.

H.V.

RECT.

DEF. YOKE 9.000 V.

H.COILS TO C.R.TUBE

5K 10W

ti CONTROL CENTER CONTROL

.300V.4

Lp 100 2W.

ZA4 30-30 I, : 700T. 2W

85T.' 500 = 500 .UF .(LF

Ls 3.5 M.H.

1000 r ,ow.

LINEAR ZING CIRCUIT

f50- 500

Z

FIG. 63. L/ R Beam Relaxor, in which frequency and waveform depend on the ratio of

plate- circuit inductance to dynamic plate -circuit 9esistance. FIG. 64. Equivalent diagram of the Beam Relaxor, showing the circuit elements

The effective impedance of the equiva- lent plate circuit in Fig. 64 is:

LPL8(1 = k2) + LPL Z

= L + LB (neglecting r) (10)

which reduces, at substantially unity coupling (k = 1), to:

LPL Z =L,

The ratio of LP:L1 is approximately equal to n2, where n is the turns ratio of

(10.1)

PLATE WAVE

--------f -- -- -- -- 300V.

GRID WAVE

ZERO I POTENTIAL

J

SCREEN J -- -4140 V.

CATHODE

ZERO POTENTIAL

FIG. 65. Potential wareforms as they ap- pear at various points of the Beam Relaxor

circuit shown in Fig. 63

the transformer, so that when L. is large with respect to L

Z =n2L This impedance is the frequency-

determining inductance. It should be of

the order of 80 mh. for tubes of the 6L6 type, which have a plate resistance of the order of 500 to 1,000 ohms during the positive -grid portion of the cycle. This gives an L:R ratio between 1/6;000 and 1/12,000 second, and is approximately the correct lime- constant for 16,000 -cycle

August 1948 - formerly FM, and FM

parture from this optimum value will result in some loss of deflection -current amplitude, and may decrease the im- pulsive high -voltage at the plate.

As might be expected, the linearity of

current rise can be controlled by the use of an L + R damping circuit across the coils, instead of a C + R circuit, or a damping diode. The damping circuit absorbs a considerable amount of power, which loss can be avoided by the use of a damping tube when reduction in the number of tubes is not important. A correction of the curvature of the power- tube characteristics would eliminate the necessity for this non -useful power drain. Almost any efficient horizontal deflection transformer will give satisfactory opera- tion in this circuit.

Control of deflection amplitude can be obtained in several ways. The easiest and cheapest method is to vary the 2nd -anode potential of the camera tube or cathode - ray tube. This method has the dis- advantage that brilliance and focus must be adjusted as the size is changed.

Small universal coils with iron plungers and screw adjustments make satisfactory variable inductances for size control. This variable inductance can be placed in series (coil L' in Fig. 63) or parallel with the deflection coils, so that its adjustment changes the current flowing therethrough. When the deflection frequency is in proper step with the synchronizing signal, approximately 1 in. of deflection-ampli - tude variation can be obtained before the sync control needs readjustment.

(5.23} Kick -Back High -Voltage: The high- voltage AC pulse, Fig. 65, exist- ing at the plate of the horizontal- deflec- tion tube (6L6, 807, or 6BG6G) can be rectified as shown, and used to supply the high voltage for the camera tube. This is

usually of the order of 1,500 to .2,000

RADIO -ELECTRONICS

volts. This is usually not considered good practice for studio equipment, however, in spite of the fact that it is common usage to employ 8,000 to 10,000 volts for television receivers. It is more usual at the camera to use an RF high -voltage supply, or to use a brute -force supply by the rectification of high -voltage, 60 -cycle power in the conventional manner.

Generally, it may be said that in the kick -back or fly -back type of high- voltage transformer, the magnitude of the high voltage pulse is directly proportional to the effective plate- circuit inductive im- pedance Z, and inversely proportional to the effective capacitance across the plate winding. It is necessary to keep this capacitance at a low value in order to obtain high- voltage pulses, and fast return of the sawtooth wave.

{5.24} The Deflection Transformer: In Fig. 66 there is shown the essential output circuit of a deflection amplifier, together with the equivalent circuit, for purposes of analysis. Referring to the figure, the driving EMF in the secondary, for each component of the deflection wave having an angular velocity CO is :

es = -jwMi (10.3)

which, by Kirchoff's Law is also:

e8 = jw(L8 + L)I -F- rI (10.4)

Let L' = L8 + L. The power factor (which is the reciprocal of Q) in the secondary circuit is

p = r/L'w (10.5)

DEFL. AMP. BEAM POWER TUBE

R 1

¡-- LP rIIIrLs

e.

K

f a Lp

DEFL. COILS

FIG. 66. Essential output circuit of ade- flection amplifier, together with the equiva-

lent circuit elements

and therefore the driving electro- motive force for each component of the sawtooth wave in the secondary circuit is

es = L'wI(j + p) (10.6)

From (10.3) and (10.6) the magnitude of the secondary deflection current can be obtained:

I = L,(j + p)

(10.7)

From this equation it is clear that the magnitude of the deflection current is dependent upon the ratio of mutual in- ductance to total secondary-circui t in-

(Continued on page 40)

35

FIG. 1. Visual TV alignment calls for .11 ego- .Marke,, Mega -Marker Sr., and Mega-Su 7, p

TV TEST TECHNIQUES HOW AND WHY FAST VISUAL METHODS HAVE REPLACED SLOW POINT -BY -POINT TESTING -%3y FRANK G. MARBLE*

TELEVISION receivers are, in many respects, similar to conventional audio

receivers. For instance, they have RF sections, local oscillators, mixers, IF am- plifiers, second detectors, low- frequency amplifiers, and energy converters. There are many differences in the specifications of these sections, but their primary func- tions are the same.

Testing Audio Receivers: In the earlier days of audio receiver manu- facturing, much of the testing was done simply by tuning receivers to the local transmitters that happened to be on the air. Adjustments were then made for satisfactory tone and volume. As long as the number of sets to be tested was small, and signals from these transmitters were available, this was a satisfactory method. But the transmitting schedules were lim- ited in those days, and it was necessary to make adjustments for stations other than those available. So, as set production in- creased, that method of testing receivers was soon abandoned.

It became necessary to devise equip- ment and techniques that would make it possible to test both components and assembled receivers on signals generated in the factory. Signal generators and oscillators tuned to different single fre- quencies were devised for use with output meters. Techniques which came into use then included tests which, when completed satisfactorily, showed that the receivers would operate perfectly on all channels.

Television Receiver Testing: The passbands of RF and IF amplifiers in a television set are very much broader than those in an audio receiver. In addi-

* Kay Electric Co., 14 Maple Ave., Pine Brook, N. J.

36

tion, the shapes of these passbands are more critical, and must be maintained within narrow limits. Response of a tele- vision receiver can be determined by the same point -by -point methods used in audio sets. However, since the band is so broad, the mechanical operations involved require more man -hours than can be spared in these busy days. Also, the job is complicated by the fact that an adjust- ment at one point in the band is liable to have considerable effect at other parts of the response curve. For these reasons, the adjustment of an IF amplifier by the point -by -point method becomes a tedious, cut -and -try process.

In the initial stages of television re- ceiver development, that method was em- ployed because there was no equipment to accomplish the work more rapidly. Under pressure of necessity, however, a new technique was evolved for checking sets both in the laboratory and in the factory test cages. Now, a constant -amplitude, frequency -modulated signal is used in place of the adjustable, single- frequency signal generator and, instead of measur- ing the receiver output on a meter, the output amplitude is observed on an oscil- loscope deflected horizontally by a voltage related to the sweep -signal voltage. This allows a continuous view of the shape and width of the response while adjustments are being made.

Since television receivers operate at higher frequencies and over broader band- widths than audio receivers, the need of matching the antenna, transmission line, and RF section input is more critical. To take care of this requirement, it is necessary to test the input impedance of these three elements over the frequency range in which they are to be used. Again,

frequency -sweeping equipment can be used to display the impedance match over a wide frequency -band on the screen of an oscilloscope. This method takes minutes, compared to the hours spent on point -by- point measurements.

In order to indicate specific frequency points on the oscilloscope when using the frequency- sweeping technique for ampli- tude response and impedance -matching observations, instruments have been de- signed to put marker birdies or pips at corresponding points on the trace.

Also required for television work is the observation of the sideband and carrier en- ergy propagated by the transmitters, and the measurement of field strength. This need has been met by the development of spectrum analyzers and field strength devices for the new frequency range.

Newly- Developed Instruments: Some of the new instruments developed for these purposes by Kay Electric are shown in the accompanying illustrations. The three setups are arranged for typical TV measurements.

Fig. 1 shows the equipment used for RF and IF alignment. At the top left is the Mega- Marker, then the Mega- Marker Sr., and the Mega -Sweep, with a DuMont oscilloscope at the right.

Instruments for measuring the input of a TV tuner are illustrated in Fig. 2. A Mega -Pipper is set on a Mega -Match at the left.

In Fig. 3, a Mega -Pulser is pulsing a Mega- Sweep, at the left. Thus the tran- sient response of the TV set can be deter- mined on the Magalyzer, at the right. These three typical arrangements will be described in detail.

Visual Alignment: In Fig. 1, a frequency- modulated oscilla- tor, the Mega- Sweep, is used to provide a constant -amplitude, variable- frequency signal. The output of the sweeping oscil- lator produces up to approximately 100 millivolts at a 50 -ohm impedance level: The signal is swept by a linear, sawtooth waveform at rates between 50 and 100 cycles per second over a bandwidth up to 30 kc. The amplitude modulation is very small, and the sweeping signal can be used anywhere between 50 kc. and 500 mc. Thus, in conjunction with any standard oscilloscope, the shape and bandwidth of video, RF, and IF response can be ob- served, except for the very low frequen- cies in the video amplifier. The sawtooth voltage which sweeps the frequency is also made available for deflecting the oscillo- scope trace in a horizontal direction. The frequency range of the Mega -Sweep can be extended, by a simple internal adjust- ment, to 1,000 mc. This feature makes it applicable to work in the upper television band, between 400 and 900 mc.

In order to determine the frequency in the horizontal direction on the oscillo- scope, a wavemeter is included in the

FM AND TELEVISION

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Angv8t 1948 formerly FM, and FM RADIO- ELECTRONICS 3 '

Mega- Sweep, accurate to about 1 mc. To tune the various traps in a receiver, and to determine accurately the shape of a curve, more precise frequency indications are necessary. The Mega -Marker and the Mega -Pipper were developed for this pur- pose. The Mega- Marker, Fig. 1, is a pre- cise variable oscillator which can be tuned to any frequency in the IF band. When used in conjunction with the Mega -Sweep, it produces a narrow birdie on the response curve at a point corresponding to the fre- quency indicated on the dial of the Mega - Marker. It is accurate to ±.25 %. Provi- sions are included for adjusting the ampli- tude of the birdie, and for mixing the out- put of the Mega -Marker with that of the Mega- Sweep. A crystal- controlled oscilla- tor, included for periodic calibration of the variable oscillator, produces an accurate birdie in the center of the FM IF charac- teristic.

The Mega -Pipper, Fig. 2, when used with the Mega -Sweep, provides four accu- rate, crystal- positioned pips which are introduced directly at the oscilloscope, rather than going through the television receiver. These pips occur simultaneously at the audio and video IF carriers and at the adjacent -channel IF carriers. Because they do not go through the television re- ceiver, their amplitude is not diminished when they are tuned into the center of the traps. This allows more accurate trap adjustments. Provisions are made for inter -connecting the sweep output and the Mega -Pipper and receiver inputs. By

racy of .01 %. Internal provisions are made for tone modulation, so that adjustments can be made aurally. The tone amplitude modulates the crystal oscillator stage, and can be switched on or off by a front -panel control. When the local oscillator of the receiver is correctly tuned, the level of the tone is at a minimum. At this adjustment,

This new technique allows very rapid adjustment of antennas or RF input im- pedances, and indicates all the changes which occur over a wide frequency -band as a result of the adjustments.

Voltmeter & Spectrum Analyzer: The Megalyzer, Fig. 3, has a built -in oscil-

FIG. 3. Measuring transient response visually with a Mega- Pulser and Mega -Sweep

the signal is at the center of the IF dis- criminator characteristic.

Visual Impedance Measurements: A mismatch between the transmission line from the antenna and the input to the RF section results in overall loss of sensitivity, since energy is reflected away from the input. The television spectrum covers a wide range of frequencies, and determina- tion in the laboratory of the,correctness of the impedance match over this range by

7 -11.101

FIG. .2. TV tuner input impedance measurements employ Mega -Pipper and Mega -Match

,140,

' to

changing one plug -in crystal, the four pips can be positioned properly for any I.F fre- quency within the standard RMA band.

To adjust a TV receiver, it is necessary to trim the local oscillator for each chan- nel, so that it can then be tuned for maxi- mum audio output by a vernier control on the front panel. The Mega- Marker Sr., Fig. 1, provides 12 sound IF carriers - one for each channel - for this operation. The signal for each channel is controlled by a separate quartz crystal to an accu-

38

point -by -point methods is not only tedi- ous but wasteful. However, the Mega - Match, Fig. 2, provides a means for observing the correctness of the impe- dance match. This instrument, used with a standard oscilloscope, indicates the amount of reflected energy from a trans- mission -line termination over a band- width up to 30 mc. The center of the swept frequency band can be set anywhere be- tween 10 and 250 mc. Standing -wave ratios as low as 1.02 can be observed.

loscope to indicate the frequency and rela- tive amplitude of the signals present over a band up to 30 inc. wide. This swept - frequency band can be set anywhere be- tween 30 and 300 mc. by tuning the Mega - Sweep, which forms part of the equipment. By adjusting the sweep to a suitable band width, the relative energy in the side bands and the carrier can be observed. Using a calibrated, single- frequency signal generator as an accessory, the microvolts present at the antenna from each of the signals displayed can be measured by comparison methods. The CW sensitivity of the instrument is approximately '200 microvolts for a % -in. deflection at full gain, and the resolution is approximately 100 kc. The instrument will, therefore, dis- play signals separated by about 100 kc. anywhere in the frequency band defined.

Pulse Equipment: In testing video amplifiers, one technique which has been employed is to introduce at the input of the amplifier a test signal consisting of very narrow pulses, repeated at audio rates. The quality of the repro- duction of the pulses on an oscilloscope at the output of the amplifier is a direct indication of the bandwidth, phase char- acteristic, and transient response of the circuit. Broader bandwidths will correctly reproduce narrower pulses. For these tests, the Mega- Pulser has been devel- oped. This instrument, Fig. 3, produces pulses of .0'25 to .25 microsecond in width, at repetition rates between 100 and 2,000 per second. This range covers video ampli- fiers up to bandwidths of 50 mc.

The Mega- Pulser has been used success- fully to pulse the Mega-Sweep. By this method, a pulse- modulated, high -fre- quency carrier is made available for test- ing the transient response of wide -band RF and IF systems. The frequency of the carrier can be adjusted by simply chang- ing the frequency of the Mega-Sweep.

FM AND TELEVISION

Type 910 -C Dynamic Noise Suppressor the only noise suppressor suitable for use with broadcast stations.

No. 2 of a series on the reproduction of music from FM and phonograph records

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BROADCASTING can be no better than its programs. In earlier days, the microphone was often merely placed in front of a me- chanical phonograph. Because of limitations in the primitive radio equipment, the listener could notice little quality difference be- tween live and recorded programs.

Radio improvements soon eclipsed recorded music until, first,

electrical recordings, and, later, transcriptions (which are merely high -grade records) provided sufficient improvement in quality to make recordings compare favorably with contemporary live

AM programs. Then came FM.

Now, recorded music spans the entire audible frequency range, and the only remaining disadvantage of records as program ma-

terial is the surface noise which seems inherent in all types of recordings.

Manufacturing refinements can reduce record noise, but always at a higher price for the finished product. Furthermore, even the finest records become more noisy with wear or as a result of dust or handling. With the present demand for high -fidelity programs, the earlier method of filtering out the high frequencies to mini-

mize noise is inacceptable.

In the past two years, a new technical development has made

recorded programs again comparable with live talent. When the

Dynamic Noise Suppressor * was first announced, it met with

considerable understandable skepticism on the part of many

broadcast station owners. The continuous and profitable use of even the earliest models for over two years has completely reversed this attitude. Instead of a scientific mystery bordering on per- petual motion, it is now regarded as an indispensable part of any

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The Dynamic Noise Suppressor * more than pays for itself by

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39 August 1948 - formerly FM, and FM RADIO- ELECTRONICS

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TELEVISION HANDBOOK (Continued from page 35)

ductance, and upon the primary current, as is to be expected. It is apparent, also, that the power factor of the deflection yoke and transformer should be mini- mized. For practical purposes, the primary current will be optimum if the primary impedance matches the output impedance of the deflection amplifier.

The secondary reactance which is re- flected into the primary (labeled Z' in the figure) adds to the primary reactance to produce a total primary impedance of

M2W2 Z = jwLp +

L0)0 p) (10.8)

The primary current, then, is

i = E /(Z + R) (10.9)

() summarize the theory, briefly, let: \ I " magnetomotive deflection force

= number of turns in the deflection yoke

I . " = effective load inductance I. = deflection yoke inductance SO2 = transformer impedance ratio i = primary current w = angular velocity of deflection E = B + potential

Then: (a) L is proportional to n2 (b) M' is proportional to nI (c) L" is proportional to ç2L

from which the defining proportionalities for any unknown parameter can be de- termined from the known. For Beam - Relaxor operation :

(d) w is proportional to E /Sa2Li or L is proportional to E /r02iw

The ways in which the various para- meters affect deflection are determined from these relationships:

(1) The DC power requirement is pro- portional to the product of frequency and the square of the deflection force.

(2) The power requirement is inde- pendent of the impedance ratio (neglect- ing transformer losses).

(3) The current requirement is pro- portional to the product of frequency and the square of the deflection force for a given B supply.

(4) Independently of other parameters, the turns ratio is inversely proportional to the inductance of the deflection yoke. This ratio should be chosen to reflect as low a capacitance as possible from the cable connecting the yoke to the trans- former.

From experiment the following facts have been ascertained:

(1) The number of oscillating tubes in parallel which supply the current is im- material to the design except as it affects capacitance across the primary. Too many tubes will increase the return time. Adding tubes in. parallel merely divides the total load per tube.

(2) A value of L' = 60 mh. is approxi- mately optimum for horizontal deflection.

(3) A magnetomotive force of approxi-

mately 50 RMS ampere -turns is sufficient for deflection of the dissesector under average conditions.

(To be continued)

HOW N. Y. TUGS USE FM (Continued from page 33)

"Visibility," he said, "was cut down to 150 ft. What a comfort it was to have the radio to keep us in constant contact with the dispatcher. Did you ever try to holler through a megaphone against a gale ?"

While we were talking, another call came in: "Get that long spile out of the ferry slip at Barclay Street, New York. before one of the ferry boats breaks a wheel on it."

It's All Different Now: Finally, we got back to Pier 6 just as dispatcher Joe Strohscheim was coming on duty for the night watch. He has been in the employ of the Lackawanna for forty - two years, and has dispatched tugs for thirty -one. He knows his business! An- swering the $64 question, he explained:

"Sure I like to use the radio. It's a great time -saver for the shippers, and makes my job easier, too. I used to holler into a megaphone ,all day long." - he produced it from under the table. "The tugs had to come right up here under the office win- dow so we could yell to each other. Now I just talk natural -like, and they can hear me past Governor's Island!" He con- tinued: "I had a hard time to keep from hollerin' in the radio at first. They say I'm pretty good at it now, though. Yoii know, I was thinking of retiring, but this radio gave me a new lease on life."

The conversation shifted to special uses of radio on the tugs. For example, there are inquiries made by steamship operators concerning the arrival time of floats with cars bearing freight consigned to their vessels. Before radio was installed, the tug boat dispatcher's answers were pure guess- work. Without knowledge as to the where- abouts of the tug and the floats, or condi- tions prevailing at their location, he was often wide of the mark by hours. Such errors are costly when they affect the departure -time of a big ship.

Now, when such an inquiry is received, the dispatcher simply says: "Hold the wire! Then he calls the tug in question by radio, asks the Captain where he is and when he expects to dock, and relays the information over the land telephone to the steamship company. The dispatcher's an- swer is exact, and it takes him less than a minute to give it. That is an extremely valuable by- product service of the Lacka- wanna's 2 -way communications system.

Capt. Doran summed up the value of the radio system in this way: "We don't think about the time we save with radio any more. It's a standard facility for us. We could figure out how much time we'd lose in a week's operations if they took the radio away. But there's no danger of that. The radio is much too valuable!"

NEXT MONTH, READ:

Pattern for FM Profits NEXT MONTH, FM and TELEVISION will carry what we believe to be the

greatest scoop published by any radio magazine in recent years.

Under the title "Pattern for FM Profits ", we shall present a complete, one -

package plan that will have a profound influence on the entire radio industry,

from broadcasters and manufacturers to dealers and servicemen.

You say you've been hearing enough fancy theories lately? You're only inter-

ested in down -to -earth ideas that have already paid off in hard cash?

Brother, you are going to get exactly what you've asked for in the September

issue of FM and TELEVISION.

` `Pattern for FM Profits" is a detailed account of the most comprehensive FM

setup in the United States, one that is unique, complete, and successful. This is

not a special case, however, built around unusual circumstances. On the con-

trary, you can set this pattern down in any area of the Country and put it to

work without changes other than minor modifications.

Who conceived the idea? Who's behind it? Well, this job was planned and

executed by a group of practical businessmen, assisted by smart engineering

brains. Working with them was an old -time broadcaster whom many people

consider the outstanding genius among broadcast executives. He, by the way,

has written the introduction to the special section devoted to "Pattern for FM

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If it's so important, why haven't you heard about this project before? You'll

find the explanation of that, too, in the five parts of the special section. Each

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"Pattern for FM Profits" contains profit -information for everyone in the radio

industry. Whatever your particular field, you'll find a wealth of practical ideas

that will make you exclaim : "This is just what I've been looking for.'" That's why

you must get and read the September issue of FM and TELEVISION.

. I iu¡ust 1948 - formerly FM, and FM RADIO -ELECTRONICS 41

THE MEGA -SWEEP WILL COVER ALL FUTURE NEEDS... Think that statement over before you spend even a few dollars for any sweeping oscillator ... With a Mega -Sweep you can cover any frequency.

. When any future channel, even above 500 mega- cycles, is added you will not have to fuss around with special adjustments or added equipment ... or buy new equipment ... The MEGA -SWEEP covers it with ease and accuracy ...

The News of Radio RCA Will Study Ultra -High Frequencies

in Search for Television Channels

Plans for the study of ultrahigh frequencies to determine whether they can accommodate the expan-

of television b d a ling weir announced yesterday by

broadcasting C. H. lfe, executive Mee pr..idrnt in

charge of RCA Lobaratotive. At the same time the Radio Corpora. lion of America applied to the Federal Communication. Commie- lion fora license to install an es- prrimental .tauon In Washington over which to conduct the tests. expected u led lo start about Rcpt. 1.

radio frequencies to be e x- Dored are

Jolllffr d. He explained that the spread between 471 and 800 megacycles. set aside by the PCC

already for future television de-

velopment. is the only part of the spectrum n.

channels television view can look

the reh more

additional view

byother services.

THE MEGA -SWEEP Wide Range Sweeping Oscillator ... DISPLAYS Pass BAND ... Features: Frequency Range -50 Kilocycles to 500 megacycles and up ... Frequency Sweep Adjustable from 30 megacycles to 30 kilo- cycles throughout the complete spectrum ... Con - tiiuously variable attenuator ... Low amplitud3

DISPLAYS

PASS

BAND

Modulation while sweeping -less than 0.1 DB per megacycles... Precision wovemoter. High and Low level output. Sweep voltage output for driving oscilloscope.

Price $395 f.o.b. factory

THE MEGA -MATCH Simultaneous Visual Display of Reflected Energy in a frequency band up to 30 me between 10 to 250 me and up. Completely electronic. No slotted lines, moving ports, bridges, or other frequency sensitive

devices. Precision frequency meter. Saves engi- neering time. Presents instantly data which would take hours to tabulate. Price $695 f.o.b. factory

KAY ELECTRIC CO., 25 MAPLE STREET, PINE BROOK, N. J.

Telephone Caldwell 6 -3710

HIGH FREQUENCIES (Continued from page 18)

'l'he Belfast tests were headed in the right direction to lead to the discovery that the short waves were effective during the daylight hours, but were quite over - shadowed by the results of the Poldhu tests. However, since RCA was privileged to cooperate with Mr. Marconi in the 32 -meter Poldhu tests, they were made aware of the possibilities of the short waves at the same time as was Mr. Mar- coni, and were greatly stimulated by this discovery to speed the development of equipment for making use of this dis- covery, and to make propagation studies

42

of the entire shortwave spectrum. At the time these tests were made in

1924, RCA was already on the air with a 10 -kw., 103 -meter transmitter at Tucker - ton, N. J., which was successfully handling traffic to South America under conditions which were impossible on the long waves because of the heavy static. In January, 1926 the world's first high power 15 -meter transmitter went into regular commercial service at Rocky Point, and was used with great success in handling traffic to Buenos Aires during the daylight hours.

In the early autumn of 1926, the period mentioned by Major Armstrong, RCA was operating a considerable number of shortwave circuits to various parts of the

world with reasonable success. Early in October, 1926 I accompanied Mr. W. A. Winterbottom and Mr. C. W. Hansell to Montreal to witness the Marconi beam tests to which Major Armstrong refers. I was greatly impressed by the results they were getting, which were brought about by the high gain of the beam antenna arrays supported by rows of 300 -foot towers spaced 650 feet apart. I know that Mr. Winterbottom was impressed and have no reason to doubt Major Arm- strong's statement that Mr. Winiterbot- tom was instrumental in having the Marconi beam system installed at River- head and Rocky Point during 1927 for communicating with London. I was in favor of this too because I felt that if we could equal or excel the Marconi beam system we were getting somewhere. An engineer always likes to have a standard with which to measure his results. As of the autumn of 1926, I think there is no doubt but what the Marconi beam system out -performed to a considerable degree anything that the RCA or, for that mat- ter, any other organization had in opera- tion. However, this situation did not last long. The RCA engineers felt that the Marconi beam system was too expensive for duplication to the extent necessary to serve the large number of worldwide cir- cuits they were operating. They had very early recognized the principle of diversity reception mad were working on the prob- lem of optimum spacing for the antennas, best methods for combining the outputs from the antennas, and developing the re- ceivers, antennas, transmission lines. and associated equipment and components. At the Transmission Laboratory, devel- opment was proceeding on transmitters and directive antennas, including the first directive antenna of the long -wire type. These developments made it possible for the RCA to outperform the Marconi beam system at a fraction of the cost. During 1928, or a little over a year after the period discussed by Major Armstrong, RCA installed diversity receivers and its own directive antennas on all of its major circuits. Shortly thereafter, the Marconi beam system at Riverhead and Rocky Point was dismantled, since the RCA de- velopments outperformed it.

I cannot agree with Major Armstrong's statement that " it is not true that the worldwide revolution in communication -

which brought about the obsolescence of the alternator was an ultimate result of anything that the Radio Corporation did." I feel that the RCA played a lead- ing role in this revolution and I am proud to have been privileged to have worked with RCA during this period. At the same time, I also appreciate the very great and outstanding contributions made by my old friends and co- workers, Senatore Mar- coni and C. S. Franklin. In addition, I would also like to mention Mr. G. A. Matthieu, who, as Marconi's assistant on

(Continued on page 44)

FM AND TELEVISION

Today's Outstanding Chassis Value

For Custom Set Builders

H ERE IS IMPORTANT NEWS if you build Or sell custom radio -phonograph installations where precise repro-

duction of musical values and absolute perfection of engineering detail is required: You can now obtain Freed - Eisemann chassis equipment for your custom -built jobs ... at prices that represent today's outstanding value by every valid standard of good engineering, sturdy construction, superb per- formance.

Here is the identical tuner and amplifier (plus high - fidelity co -axial speaker and Webster or Garrard inter - mixer record changers, if desired) which have given Freed -Eisemann Radio- Phonographs an acknowledged reputation among radio engineers, musical authorities, broadcasters and dealers as the finest instrument available any -where at any price. Now they can be built into special, personalized installations for those who demand something finer in radio -phonograph reproduction.

Furnished complete with 21 tubes *, the Freed -Eisemann No. 100 Tuner is a compact unit suitable for the most diverse cabinet applications. Connected by plug -in cable to the P.S. 1 Amplifier and any record changer and speaker system in your design, the actual installation of the equipment becomes simplicity itself.

Spanning the complete AM and FM tuning range, and with band -spread shortwave from 6.2 to 17.5 megacycles, the Freed -Eisemann No. 100 Tuner provides separate

*Two 6SK7, two 6SA7, two 6J5, three 6ÁG5, two 6L6 -G, two 5U4 -G,

two 6SG7, two 6SH7, one 6SL7 -GT, one 6H6, one 6J5 -GT, one 6U5.

August 1948 - formerly FM, and FM RADIO -ELECTRONICS

RF and IF circuits for both AM and FM sections. The FM section incorporates the Armstrong receiving system and employs a double superheterodyne to provide excel- lent stability and sensitivity, and dual limiters to give full limiting on 5 microvolts. Broadband IF circuits in the AM section offer maximum fidelity. Separate bass and treble controls, of course.

The Freed -Eisemann No. 1 Amplifier delivers an undis- torted output of 20 watts, with flat audio response from 30 to 15,000 cycles. All laboratory readings are carefully made ... and carefully maintained in production testing procedures.

For further information and for prices on this magnificent chassis equipment, write today to Freed Radio Corpora- tion, 200 Hudson Street, New York 13, New York.

ONE OF THE WORLD'S

GREAT RADIO -PHONOGRAPHS

43

WMRC -FM GREENVILLE, S. C.

STILL WIDER COVERAGE: 62% more power on the permanent frequency of 94.9 mc. now gives WMRC -FM listeners still finer entertainment service

With 79,000 watts of effective radiation on 94.9 mc., WMRC -FM has taken the lead in providing fine programs with powerful signals over the western and central Carolinas and east to Rocky Mount, Goldsboro, Fayette- ville, Myrtle Beach, and Charleston, and extending to Bristol and Danville, Virginia, Knoxville and Johnson City, Tennessee, and Atlanta and Athens, Georgia. Daily

schedule, Noon until Midnight - 12 Hours a day.

Textile Broadcasting Co. WMRC and WMRC -FM

FREQUENCY RANGE

54 to 216 MEGACYCLES

The model 202 -B is specifically designed to meet the needs of television and FM engineers working in the frequency range from 54 -216 mc. Following are some of the outstanding features of this instrument:

RF RANGES -54 -108, 108 -216 mc. t 0.5% ac- curacy.

VERNIER DIAL-24:1 gear ratio with main fre- quency dial.

FREQUENCY DEVIATION RANGES -0-80 kc; 0-240 kc.

AMPLITUDE MODULATION -Continuously vari- cble 0-50 %; calibrated at 30% and 50% points.

MODULATING OSCILLATOR -Eight internal mod- ulating frequencies from 50 cycles to 15 kc., available for FM or AM.

RF OUTPUT VOLTAGE -0.2 volt to 0.1 micro- volt. Output impedance 26.5 ohms.

FM DISTORTION -Less than 2' , at 75 kc deviation. SPURIOUS RF OUTPUT -All spurious RF voltages

30 dh or more below fundamental. Write for Catalog D

BOONTO BOONTON NJ U.S.A.

ADIO d--t190 La/(_

DESIGNERS AND MANUFACTURERS OF

THE O METER OX CHECKER

FREQUENCY MODULATED SIGNAL GENERATOR

BEAT FREQUENCY GENERATOR

AND OTHER DIRECT READING INSTRUMENTS

44

HIGH FREQUENCIES (Continued from page 4;21

his yacht "Electra '', did much of the pioneering propagation 'studies and, also, T believe, had a hand in the design of the curly beam receivers.

Perhaps the best proof that RCA made substantial contributions to the "short wave revolution" is the fact that RCA's diversity reception system, long -wire types of antennas, crystal -controlled and amplifier -multiplier transmitter arrange- ments and other developments, too num- erous to mention, are now widely used all over the world by many radio communi- cation organizations.

Very truly yours, H. H. BEVERAGE

CLASSIFIED ADVERTISEMENTS

Positions Wanted: No charge. Use either your own name and address or FM and TELEVISION box number.

Other Advertisements: 20c per word, minimum $2.00. One -inch advertisements in ruled box, $10.

Copy received up to the 20th of the month will be published on the 15th of the month following.

Address replies to box numbers: FM and TELEVISION, Savings Bank Building, Great Barrington, Mass.

PROGRAM DIRECTOR, announcer, newscaster, disc jockey. Ten years radio background (AM & FM) also includes production (drama and symphony), writing, acting, directing. Exten- sive theatrical experience as ,actor- director. Minimum $75. Veteran, single. Jack Stein- hardt, 390 Bergen Ave., Jersey City 4, N. J.

TELEVISION DIRECTOR, 15 years experience producing, directing, photographing motion pictures. Have thorough knowledge of stage- craft, television techniques and related arts. Salary open. Box 811, FM AND TELEVISION

CHIEF ENGINEER AM, FM, TV installation, maintenance, operation experience. At present head of radio school. 1st class telephone, tele- graph, amateur. College graduate, degree. Field strength measurements and FCC applica- tions experience. íZ years Bureau of Standards. Will also manage station, small city. Age 31, married, family. Prefer West Coast or New England. Salary $5000. Box 815, FM AND TELEVISION

ENGINEER, single, specialization transmitter installation, operation, maintenance. Broad- cast experience includes network nemos and control room operations. Also Navy electronics and amateur experience. Will travel anywhere in U. S. Available on two weeks notice. Excel- lent references. Box 830, FM AND TELEVISION

WANTED, by manufacturer entering mobile .

radio field, experienced engineer to head this new division. Excellent opportunity for a ca- pable man seeking recognition of hi, Ability. Knowledge of military communications de- sirable. Give resume of experience and state salary expected. Box 858, FM AND TELEVISION

WANTED, junior engineers experienced in the development of home television receivers. Pre- vious knowledge of this field is required: Im- mediate employment by one of the oldest receiver manufacturers in the New York area. Give full details in your first letter. Bóx, 875, FM AND TELEVISION

FM AND TELEVISION

UPPER -BAND TV (Coot; oar() from page 'f)

2, How much experimental work has been undertaken in television systems in

this band, with respect to field operation ?

3. What consideration has been given to the costs of television systems for this band, particularly to the reduction of re-

ceiver costs. and the transfer of cost bur- dens to the transmitter?

4. What areas of service might be ex-

pected in this band, based on the follow- ing assumptions:

A. a particular system, using one of the following typical bandwidths: 6 mc.. 13

nic., 20 mc. B. radiated power, available now and

expected to be available, say, 10 years in the future

C. receiver sensitivity D. at each of the following typical fre-

quencies : 475 mc., 600 mc., and 890 mc.? 5. What co- channel and adjacent -chan-

nel separations would be appropriate under the assumptions made in item 4, above?

6. How many channels would be avail- able in the band 475 -890 mc. on the as- sumptions of item 4, above, and how might they be allocated among the 140

metropolitan districts of the United States?

STRATOVISION (Continued from page 17)

ment, not only as a means of broadcasting. but of network operation by relaying programs from plane to plane, thus doing away with short -hop relay systems on the groun(I.

Statistics on Plane Operation: Since the Stratovision plan is built around airborne equipment, statistics on the Martin '202 are of interest. This is the type which is intended as the eventual carrier. The 202 can carry radio equip- ment and a 4 -man crew totaling 7,000

lbs., plus 1,250 gallons of fuel. That is

enough for climbing, 3 hours on station, descent, and, in case of bad weather, flying 200 miles to another field and circling for 1 hour. This plane can reach transmitting altitude in 32 minutes. Dur- ing transmission, it would circle at 180

MPH in a radius of 3% miles, with a maximum bank of 10 to 20 °.

Summary: From observation of Stratovision in opera- tion on the low band, and such data as has been released by Westinghouse and Martin, it appears that the system has been developed to the point of being tech- nically practical, except for the fact that frequencies required for cross -country operation are not available. However, it may well be that, on the upper band, Stratovision can render such an important service that there will be justification for providing the number of channels required for its operation.

LINE OF FM & TNTE AS

(44tollBMC) by

MASS PRODUCERS OF ANTENNAS''

SINCE THE START OF BROADCASTING

Be assured of maximum reception and trouble free operation with Brach FM & TV antennas. They are

recommended for their simplicity, ease of installation

and durability by service -men, installation engineers

and dealers. Brach features a complete line, engi-

neered for maximum performance and 'o meet all

individual problems and requirements.

All antenna kits are complete, containing a five

foot steel mast, non- corrosive aluminum elements,

ample down -lead, all necessary hardware and the

Brach Universal Base Mount which permits a 360' rotation of the mast to any position on any type of

building after the mount has been secured. Guy wires

are also included and give complete protection and

stability to the installation.

Brach antennas feature a low standing wave

ratio for peak reception and can be obtained to cover

all chanrels from 44 to 216 MC. Each type of antenna

has been tested to give a uniform pattern over the

frequency range specified.

ATTENTION, USERS OF PRIVATE BRANDS

L. S. Brach Mfg. Corp., experienced in the de

velopment and manufacture of all types of receiving

antennas, offers engineering and mass production facilities for the design and production of antennas

to individual specifications.

SEND FOR CATALOG SHEETS DEPT F

BRACH MULTI BAND

FOR FM & TV #344 44408 MC 174-216 MC

/Accessory Reflector Bit *344.R os Illustrated)

BRACH BROAD BAND

FOR FM 8 TV #338 44 -108 MC

174.216 MC

BRACH STRAIGHT DIPOLE

FOR FM #334 88.108 MC FOR TV #333 44.88 MC

Accessory Reflector KIt- For FM #J34.R

Accessory Reflector Kit - For TV 71333 -R

BRACH STRAIGHT DIPOLE

SHOWN WITH REFLECTOR

BRACH FOLDED DIPOLE

FOR FM #335 88.108 MC

FOR TV #337 44.88 MC Accessory Reflector Kit-

For FM #335.1 Accessory Reflector 1(11-

For TV #337R

BRACH CROSS DIPOLE

FOR FM #346 88.108 MC

BRACH

UNIVERSAL

BASE MOUNT

L. S. BRACH MFG. CORP. 200 CENTRAL AVE., NEWARK 4, N. J.

WORLD'S OLDEST AND

August 1948 - formerly FM , and FM RADIO -ELECTRONICS

LARGEST MANUFACTURERS OF RADIO ANTENNAS AND ACCESSORIES

KNOW ACTUAL RF POWER FED TO

FM ANTENNA -WITH

Glancing at Micro - Match Model MM -200 indicator unit at WTHT's new FM trans- mitter is Charles S. Masini, Chief Engi- neer of station. Above, coupler unit is stand- ard 1%" dia. coaxial line.

Micro -Match gives you direct, continuous accurate reading in kilowatts. Also gives precise, continuous reading of SWR of antenna system. Thus at a glance you are assured of the proper functioning of the complete RF portion of your trans- mitter and of your antenna system and transmission line. MICRO -MATCH models available for operation at 500 KC to 250 MCS, and power levels of 2 to 50,000 watts.

Write for complete descriptive literature

M. C. JONES ELECTRONICS COMPANY 96 North Main Street Bristol, Connecticut Distributed outside continental U. S. A. by R C A International Division Radio Corporation of America

Special Issues Coming: SEPTEMBER: The FMA Convention issue, presenting the new plans of broadcasters and

manufacturers, and a 3 -part analysis of the Rural Network's operation.

If you are a high -fidelity enthusiast, or if you are particularly interested in audio engineering developments, you will enjoy the special collection of articles to appear in this issue.

OCTOBER:

JANUARY: Containing the revised Communications Directory of systems operated by taxi- cabs, public utilities, trucks, buses, geophysical and all other special services.

IF YOU ARE NOT A SUBSCRIBER, MAIL THIS SUBSCRIPTION FORM TODAY

AND TELEVISION

A ,/ * * Ediledby Milton B Sleeper * *

d`OR the top -level bracket of those engaged in manufactur- ing, broadcasting, communica- tions, sales, and maintenance

Published at Great Barrington, Massachusetts

Enter my subscription: 1J 2 years $5.00 1 year $3.00 3 years $6.00 Remittance enclosed Remittance will be sent promptly on receipt of bill.

Name

Street

City

Official company connection:

Firm

State Title

SAVE $ 3 00 SEND $6 FOR THREE YEARS

Foreign Postage: Add $1.00 per yr. for foreign postage. For Canada, add 50c per yr.

Eli

MERCHANDISING TV (Continued from page 30)

t his great, new business with enthusiasm, knowledge, and proper facilities.

Many dealers have done very little advertising and merchandising of their television lines to date. They have been depending wholly on store traffic, leaving the promotion of their products up to the manufacturers. The exceptions to the rule have gone all out in their advertising and direct mail campaigns.

There is an old saying "You have to spend money to make money." I sin- cerely believe that there is no better time for you to invest in a business that is bound to succeed and pay real dividends than at the time television service comes to your city. Here are a few suggestions which may prove helpful in preparing for your future in television:

1. Enlarge your service department to handle installation of television receivers promptly, or arrange for this service to be provided by an experienced outside tele- vision service organization.

2. Construct comfortable, well -deco- rated demonstration rooms and invite the public to television shows whenever there are programs on the air.

3. Feature leading makes in attractive floor and window displays at all times.

4. Advertise your store regularly as headquarters for these leading nationally advertised brands.

5. Take advantage of the manufác- turers' literature and booklets on the subject of television by mailing this ma- terial out each month to your prospect list.

6. Let the prospects know that tele- vision provides entertainment for the entire family, that television receivers are available in many price classes, that they make the reception of a variety of pro- grams possible, and that your store offers the best in television service.

7. Invite manufacturers and distribu- tors to thoroughly train your sales and service personnel, not at just one meeting, but on a regular schedule.

8. The prewar success enjoyed by so many dealers in selling radios involved home demonstrations. Today radio-pho- nograph combinations and television receivers can be sold in the homes when store demonstrations have failed.

9. Attractive time- payment plans will also influence many television prospects to visit your store and make their ,pur- chases.

10. Enter the television business jwith enthusiasm and knowledge. This spirit will penetrate throughout your organiza- tion and be contagious as far as your customers are concerned.

You have a bright and prosperous fu- ture in television, and television itself will prosper as a result of the effective mer- chandising support the dealers can and will give it.

FM AND TELEVISION

i

WATCH FOR

COLLINS Custom

Components A complete high -fidelity radio re-

ceiving system, from antenna to

speaker, in one package:

1. FM -AM Tuner (19 tubes & squelch)

2. Amplifier (6 AS7G tube)

3. Record Changer (Webster 70 with G.E.

cartridge)

OPTIONAL: 4. Loudspeaker (12- or 15 -in.)

5. Antenna System

6. Transcription -type Record Player

COMPLETE DETAILS FOR

YOU NEXT MONTH

Collins Audio Products Co., Inc.

P.O. BOX 368 WESTFIELD, N. J. PHONE WE 2 -4390

Investigate A lden Facsimile

FM Stations use the Alden Facsimile system as a promotional means to increase their listening audience and call attention to their FM stations.

They choose Alden because:

1. The Alden Recorders produce the most beautiful pictures not only in black and white but in the pleasantly toned Alfax sepia papers.

2. The Alden system assures attention -getting programs by combining sound and the opera- tion of bulletin -size recorders in semi -public places, enlarging the same program that is sent to the home and other points.

3. The Alden system with its low frequency re- quirements simplifies the operation over ordi- nary telephone lines and with existing com- munication sets, making it capable of universal adoption. 4. The Alden system is designed and priced for the mass market; is not restricted as to particular FM sets and thus has the promo- tional interest of all set dealers in your area.

5. The Alden equipment has basic simplicity, minimizes service through interchangeable spare parts and is thoroughly suitable for use by non -technical people.

6. The Alden system has every factor, in- cluding program possibilities, that insure the largest saturation of recorders per area, opera- tion in marginal signal areas, and thus the greatest possible coverage for your station.

Investigate Alden Facsimile and Alfax Paper now

ALDEN PRODUCTS CO. Brockton 64F, Massachusetts

ADVERTISERS INDEX

Adair, George P. Alden Products Company Alford, Andrew Amy, Aceves & King, Inc Andrew Corporation

13

47 12 12

6,12

Barone, S. A., Company 13

Bell Telephone Labs 5, 14

Blaw -Knox 7

Boonton Radio Corp. 14

Brach Mfg. Corp., L. S. t5 Brociner Elec. Lab...... 10

Browning Laboratories, I II, . o

Collins Audio Products Commercial Radio Equip. Co I:i

Communications Research Corp. 13

Davis, George C. 13

Du Mont Labs., Inc., Allen B. 1

Eitel -McCullough, Inc. 48 Electronics Research!PublCo. 10

FM Association 3

Freed Radio Corp. 43

General Electric Co. 11

Graybar Electric Co. 5, 14

Hughey & Phillips Company 10

Jansky & Bailey 12

Jones Electronics Co. 46

Karp Metal Products Co.. Inside Back Cover Kay Electric Co. 10, 42

Kear and Kennedy 13

Knights, The James Co. 40

Lansing Sound, Inc

Mallory & Co., Inc., P. R May, Russell P. McCachren, Winfield Scott McIntosh, Frank H. McKey, Dixie B. & Assoc. McNary and Wrathall

National Co.

47

31 12 13 13 12 13

4

Philco Corp. Inside Front Cover Pollack, Dale 12

Radio Corp. of America 24, 25 RCA Communications, Inc. 12

Radio Engineering Labs. Inc.... Back Cover Ray, Garo W. 12

Raytheon Mfg. Co. 2

Sangamo Electric Co. Scott, Inc., H. H. Smeby, Lynne C.

Topflight Tape Co

U. S. Recording Co.

37 39 12

10

10

Weldon & Carr 13

Western Electric Co. 5,14 Williams, Nathan 12

Wilmotte, Raymond M 12

WMRC -FM 44 Workshop Associates, The 13

August 1948 - formerly FM, and FM RADIO -ELECTRONICS

These outstanding Loud Speakers are the result of more than a quarter century of development in the Sound reproduction field. They are de- signed to provide maximum dynamic range and frequenc\ response.

MODEL D -130

Compare

JIM LANSING

SIGNATURE SPEAKERS

Before YOU BUY-

MODEL D -1002

Two Way System

I he world s ftncst, modern styled two - way console Loud Speaker designed especially for FM monitoring and high quality home sound reproduction.

000

Write for descriptive catalog containing complete specifica- tions.

AVAILABLE THROUGH YOUR JOBBER

JAMES B. LANSING SOUND INC.

4221 SOUTH LINCOLN BLVD VENICE, CALIFORNIA

1.7

PROVEN

50 Kw, 100 -Mi.

FM BROADCAST

Follow the Leaders to

The Power for FM

THESE ARE IMPORTANT FACTORS of sound high -power FM operation . . . proven important in over one year of operation by station KSBR, Mt. Diablo, California, 100.5 -Mc., channel 263, effective radiated power 250,000 watts.

1) Overall power consumption is under 90 kw.

2) Equipment is of compact design.

3) Power tubes have highly efficient thoriated tungsten filaments. 4) Tube servicing is possible without special tools, equipment,

and training. 5) Vacuum tube components are capable of supplying sufficient

output without being run at maximum ratings. 6) 50 kw. final is driven directly by the IO kw. stage. 7) Air cooled. 3, 10, and 50 kw. stages only require the output

of a single blower driven by a I h. p. motor.

MODULATOR 50w

And they are made possible because of one component . the Eimac multiunit triode, type 3X12500A3. A pair of these tubes (as grounded grid amplifiers) are capable of providing over 50 kw. of useful output power with but 10 kw. watts of drive. The lineup of KSBR equipment and operational data, be- low, further illustrates advantages inherent to equipment de- signed around the 3XI2500A3.

Analyze the vacuum -tube components in the equipment you consider ... be sure their design presents the highest advantage to you. The Eimac sales department will gladly furnish names of equipment manufacturers and engineers using Eimac tubes. Phone, write or wire direct.

HERE'S THE KSBR LINE -UP

IPA EIMAC 4X500A's

3 kw stage -3kw

OVERALL EFFICIENCY: input from 50 watts to 50KW 65 %

OVERALL POWER CONSUMPTION - 85KW TOTAL FLOOR SPACE USED BY

EQUIPMENT - - - - - 22 sq. ft. TUBE REPLACEMENT COST

4X500A $97.50, 3X2500A3 $180.00, 3X12500A3 $875.00* *$115 credit for return of radiator and mechanical assembly in good condition. $35.00 credit for return of crate in good condition.

IPA EIMAC 3X2500A3's

10 kw stage

4000V

EITEL- McCULLOUGH, INC. 201 San Mateo Avenue, San Bruno, California

I0kw

PA EIMAC 3X12500A3's

50 kw stage

i

i

50kw

OPERATING CONDITIONS (Two Tubes)

D -C Plate Voltage 4000 volts D -C Plate Current - 14.4 amperes D -C Grid Voltage -620 volts D -C Grid Current 1.9 amperes Driving Power (Approx.) - 12 kilowatts Plate Dissipation (total) - 15.4 kilowatts Plate Power Input 57.6 kilowatts Useful Power Output - - - - 54.4 kilowatts Apparent Efficiency - - - - 94 per cent

'Actual power delivered to water -cooled load. Amplifier output estimated to be 3

kw higher, due to resistance and radiation losses between amplifier and load.

MULTI UNIT DESIGN IS ANOTHER EIMAC FIRST 48 FM AND TELEVISION

Our Hat Is Off to Television Engineers

Who Demand Superior Craftsmanship in Cabinets and Housings Building housings for television apparatus requires an ever -increasing degree of skilled workmanship and precision. Demands of design engineers are highly exacting.

Karp keeps pace with these higher standards by turning out racks, cabinets, consoles, chassis and other enclosures for telecasting equipment that bears the names of leading manufacturers in the field.

In a few months we will move into our new plant of 70,000 square feet -the last word in modern manufacturing quarters, equipped with newest and most efficient facilities, including up -to -date paint- ing and finishing department, scientifically air - conditioned. In this new home we can serve exacting needs better than ever.

For superior sheet metal cabinets, chassis and housings for television, radio or electronic apparatus of any kind, whether simple or elaborate, you will like our quality and service. Get our quotations.

WRITE FOR NEW CATALOG

KARP METAL PRODUCTS CO., INC. 126 - 30th STREET, BROOKLYN 32, NEW YORK

??u44mCep eSeit e et atard RUMFORD PRESS CONCORD, N. H.

1935

1939

1939

1940

1947

1947

1948

1948

1948

FIRST WITH AN FM RELAY!

FIRST WITH 50 KW FM!

REL manufactured the equipment used by Major Armstrong in the first public demonstrations of prac- tical FM transmission.

REL was the first manufacturer to produce and install commercial transmitter equipment for FM broadcasting.

REL established the first studio to transmitter FM relay ever installed. This equipment is still func- tioning between Boston and Paxton, Mass., 43 miles airline over two ranges of hills.

REL engineered and built the first commercial FM transmitter rated at 50 KW output.

FIRST WITH THE "QUADRILINE "!

FIRST WITH UHF STL!

The "Quadriline" circuit structure, at one stroke, eliminated a host of expensive RF and mechan- ical construction problems at the 10 KW level.

REL transmitting and receiving equipment was used exclusively to establish the first FM -all- radio -linked network. This net covered a total distance of 445 miles with total radiated power of approximately 450 KW.

With the introduction of REL Model 694 STL equip- ment, the art and practice of FM broadcasting took another great stride forward free from the handicap of inadequate wire line facilities.

FIRST WITH THE "SERRASOID" MODULATOR

CONTINUOUS ENGINEERING LEADERSHIP!

Simultaneously with the introduction of high performance STL equipment REL announced the amazingly efficient and economical "Ser- rasoid Modulator:'

Another REL first is in the making. We can't release information now but you'll hear about it soon. Just remember the "80 -80" -it's going to be big news for FM broadcasting.

RADIO ENGINEERING LABS INC 35 -54 36th STREET, LONG ISLAND CITY 1, N. Y.