DEC. 25

RAVol. 10, No. 14

15 CENTS

America's First and OnlyNat tonal Radio Wcrkly Illustrated

NEW COUPLING METHODVARIES THE SELECTIVITY

HOW TO MEASURE OUTPUTOF ALL B ELIMINATORSFADING EASILY CHARTEDBY HOME EXPERIMENTERS

FOREWORD on DE LUXE SET

EYES TO RECEIVE BROADCAST SCENESTurn to Page 20

RADIO WORLD December 25, 1926

NATIONAL Tuning Units' made good RadioSets because of their NATIONAL BROWN-

ING -DRAKE Coils and Spacewound R. F. Trans-formers with unique Slot -wound primary-NATIONAL Condensers and NATIONAL' Illu-minated Velvet -Vernier Dials Type C, theglareless, easily attached, illuminated Dials.

Price BD 1B $10.75(with C Dial)

NATIONAL products ore built toengineering standards of excellenceAnyone who ever built a set usingNATIONAL BROWNING - DRAKECoils and Transformers knows whatthat moans. Send for Bulletin 116-RW

Price BD -2B $14.25(with C Dial)

Nitional Co. Inc., Engineers andManufacturers. W. A. Ready, Pres..Cambridge, Mass. Makers ofNATIONAL BROWNING -DRAKECoils and R.F. Transformers, Im-pedaformera, Condensers, PowerTransformers, etc., for Radio.

The BRETWOODVariable Grid Leak

IS A REMEDY FOR DISTORTION

iiil

ai

Precision Range, 3/4 to 10 1Vlegohms

Much of the distortion present in radio receivers is dueto an overloaded detector tube. Too much power for thatlone tube to handle with fidelity. The Bretwood VariableGrid Leak permits control of the grid circuit so that themaximum efficiency without distortion is achieved. Puta Bretwood Variable Grid Leak in your set and marvel atthe difference!- - - - - - - - - - - - - - -NORTH AMERICAN BRETWOOD CO.,

143 West 95th Street, N. Y. CityEnclosed find $1.50, for which send me one Bretwood Vaiiable Grid Leak-.

(or $2.00 for leak with grid condenser attached) on five-day, money -backguarantee.

NAME

STREET ADDRESS

CITY and STATE(Inquiries Invited from the Trade)

Good Back Numbers of

RADIO WORLDThe following illustrated articles have ap-peared in recent Issues of RADIO WORLDs1926:Mar. 27-An Economical 4 -Tube Set, by Edger

T. Collins A Practical B Battery, by Capt.P. V. O'Rourke. Tectron Trouble Shooting,by Lewis Winner.

April 3-How to Get DX, by Capt. P. V.O'Rourke, A Compact B SuPply, LewIsWinner.

April 17-The New 1 -Dial Powertone, by Capt.P. V. O'Rourke. The Action of Transform-ers. by Lewis Winner.

May 8-To Wind a Loop on a Cardboard Frame.How to Reflex Resistance AF, by Theo. Kerr.

May 15-Super-Heterodyne Results Brought Upto Maximum, by Herman Bernard. The TruttAbout Coll Fields, by J. E. Anderson.

May 22-A Bullt-in Speaker Set, by HerbertE. Hayden. The Powertone In Operation, byCapt. P. V. O'Rourke.

June 5-Five-Tube Compact Receiver, by I, E.Anderson. A Tester for Tube Circuits, bySpencer Hood. Problems of Portables, byHugo Gerneback.

June 19-Selectivity's Amazing Toil. by 3. E.Anderson. The Light 5 -Tube Portable Set,by Herman Bernard

July 3-Set with a 1 -Turn Primary, by HermanBernard. Part 2 of the Victoreen Portable, byIL Bernard. Trouble Shooting Article for TheLight 5 -Tube Portable.

July 10-A Run in Single Control, by HermanBernard. A DX Double Regenerator, byCapt. P. V. O'Rourke. A 2 -Tube Dry CellReceiver, by Samuel Schmalz.

July 17-A Double Duty Loop Aerial, by 7 E.Anderson. How to Measure Coupling, byJohn Rider. A 1 -Control Crystal Set, bySmedly Lyons.

July 24-Why the Super -Heterodyne Is the BeetSet, by Herman Bernard. A 1 -Tube RoderReceiver, by IL A. Reed.

July 31-What's Beet in an AP Amplifier, byHerman Bernard. A 6 -Tube Reversed Feed-back Set, by K. B. Humphrey.

Aug. 7-The 5 -Tube Tabloid, by A. Irving Wits.The Wiring of Double Jack, by Samuel Lager.

Aug. 14-The Improved Browning -Drake, by Her-man Bernard (Part 1). Storage Batteries,by John A. White.

Aug. 21-A New Stabilized Circuit, by E. H.Loftin and S. Y. White (Part 1). The Brown-ing -Drake, by Herman Bernard (Part 2).

Aug. 28-The Constant Coupling, by N. H. Loftinand S. Y. White (Part 2). The Browning -Drake, by Herman Bernard (Part 3)

Sept. 4-The Four Rectifier Types, by H. B.Humphrey. A, Simple Battery Charger, byJ. El Anderson.

Sept. 11-The Beacon (3 -tubes), by James ELCarroll. The 1927 Model Victoreen, by Her-man Bernard.

Sept. I8-The 1927 Victoreen, by Arthur H.Lynch. Eliminator In a Cash Box, by PaulR. Fernald.

Sept. 25-The Lynch Lamp Socket Amplifier, byArthur H. Lynch. W;ring UP the Victoreen,by Herman Bernard.

Oct. 2-The Victoreen (Continued), by HermanBernard. New Eauemetie System, by Capt.P. V. O'Rourke.

Oct 9-A Practical "A" Eliminator, by ArthurH. Lynch. Building the Eguamatic, by Capt.P. V. O'Rourke.

Oct. 16-The Bernard, by Herman Bernard, Howto Box an "A" Supply. by Herbert E.Hayden.

Oct. 23 --The 6 -tube P. C. Samson, by CartP. V. O'Rourke. Getting DX on the Ber-nard, by Lewis Winner.

Oat. 30-The Singletrol Receiver, by Herbert E.Hayden How to Get Rid of Squeals, byHerman Bernard.

Nov. 6-Reduction of Interference, by 'A. N.Goldsmith Variations of Impedances, by J.E. Anderson.

Nov. 13-The 4 -tube Hi -Power Set, by HerbertE. Hayden. A Study of Eliminators. byHerman Bernard.

Nov. 20-Vital Pointers About Tubes, by Cold.P. V. O'Rourke. The 4 -tube Diamond ofthe Air, by Herman Bernard.

Nov, 27 --The Antennaless Receiver, by Dr.Louis B. Illan (Part 1). Short Waves YieldSecrets, by NI. L. Prescott.

Dec. 4-The Regenerative 5 -Tube Set, by Capt.P. V. O'Rourke. The 8 -tube Lincoln Super.by Sidney Stuck. The Antennaless Receiver,by Dr. Louis B. Bien (Part 21. Winner'sDC Eliminator, by Lewis Winner.

Dee. 11-The Universal Victoreen, by Ralph G.Hurd. Some Common Fallacies, by J. E.Anderson.

A nY COPY, 15e. Any 7 copies, $1.NO. All these32 copies for $4.00, or start subscription withany Issue. RADIO WORLD, 145 West 45thStreet, New York CitY.

Vol. XNo. 14

Whole No. 248DECEMBER 25, 192615c Per Copy. 56.00 a Year

PAREG. U.S. PAT. OF F.

won[Entered as second-class matter, March, 1922, at the post office t New

A Weekly Paper Published by Hen-nessy Radio Publications Corporationfrom Publication Office, 145 W. 45th

Street, New York, N. Y.Phones: BRYant 0558 and 0559

York, N. Y., under Act of March 3, 1897]

A New Coupling DeviceAffords Variable Selectivity and Volume

FIG.The novel feature of J. E. Anderson's circuit is the flexibility of the coupling between the first RF tube and the second. It may be

impedance, resistance on a combination of both, at will. This affot ds selectivity variation, due to regeneration control.

By J. E. AndersonConsulting. Engineer

THE object of building the receiver.1- which is about to be described was toget a set worthy of a cone speaker. Qual-ity of reproduction was the paramountobject; selectivity and sensitivity weresecondary. It was built for the writer'spersonal use for listening in on the betterclass of broadcast stations in the NewYork area. The receiver performs satis-factorily.

A desirable feature of a receiver inwhich quality of tonal reproduction isparamount is that it should have no selec-tivity at all. But that characteristic ceasedto be a practical possibility the day thatMarconi built his second transmitter.Even since then it has been necessary totune receivers. Selectivity has had a ris-ing mar'.: et. At the present time whenthere is a band of wave pirates at .largeit is imperative to increase selectivity toa point where quality of reproduction ofthe broadcast music suffers appreciably.But this must be tolerated if the jabber-ings of the pirates are to be excludedfrom the rotund precincts of the cone.It is necessary to compromise betweenquality and exclusiveness until such atime that these ethereal interlopers shallhave been banished from space.

Choice of SelectivitySince the necessity for rather sharp

tuning exists, there is nothing to do butmake the best of the situation. It is pos-sible to make the circuit moderately selec-tive and so arrange it that the selectivitymay be increased as occasion demands.For instance, when receiving a powerfulstation located nearby it is not necessaryto have as great selectivity as when re-ceiving a weak station located at somedistance. Also, there are times when cer-tain interfering stations are not on theair, when the desired station may be re-ceived satisfactorily with a moderately

selective circuit. The solution to theproblem, then, is to have a receiver withvariable selectivity with which the pointof compromise between quality and ex-clusiveness may be moved as required.That has been done in this .receiver.

There are three tuned circuits in thereceiver, each one having such a selectiv-ity that the combined selectivity is notexcessive for good quality. That is, thesuppression of the higher audible soundsis not great enough to be perceptibleto the keenest ear.

Versatile CouplingThere is still another feature in the cir-

cuit which makes it possible to use onlytwo of the tuned circuits in the case thereis negligible interference, and when thedesired station is strong. This feature isthe peculiar type of coupling between thefirst and the second tube. The coup-ling device is a parellel tuned cir-cuit in series with a variable high resist-ance. The coupler may be used either asa straight resistance coupling, as astraight tuned impedance coupler, or as acombined resistance and tuned impedancecoupler.

In the parallel tuned circuit case the

Anderson)FIG. 2

How to mount a coil on the backvariable condenser.

of a

tuned circuit is detuned and the resistanceis set at maximum, or at any value thatgives the volume desired. In the resistancecoupled case the resistance is set at zero,or minimum, and the tuned circuit is ad-justed to resonance. In the circuit dia-gram the tuned crcuit in question is LaCaand the coupling resistance is

When Rib is set at maximum, the tunedcircuit may be adjusted to resonancewithout starting oscillation in the re-ceiver at any frequency within the tun-ing range. When Rho is set at minimumthe circuit will oscillate at all frequenciescovered by the tuner provided all threecircuits are accurately adjusted to re-sonance. To stop oscillations it is onlynecessary to increase the value of Rho.

Choice of SensitivityWhile the resistance is increased the

tuned impedance should be kept at orvery slightly below resonance. It is pos-sible to operate the set as near the oscil-lating point as is desired, and thereforeboth the selectivity and the sensitivitymay be varied 'at will as conditions de-mand.

The, three tuning coils L. and Laare wound on bakelite tubing 1.5" in di-ameter and 2.5" long. The wire used isNo. 28 double silk covered. This wire isused for compactness of receiver as-sembly as well as to limit the selectivitysomewhat. A heavier size wire is not ne-cessary to get satisfactory selectivity. Theexact number of turns to be used in anygiven circuit cannot be stated definitelybecause it depends on the condensers usedand on the placing of the coils. However,-80 turns should be wound on all -three,and then if the three, dials do not tunetogether turns may be removed from oneor two of the coils (to give higher read-ings) until dial settings are as nearly thesame fol all as possible. The number ofturns may vary. between 80 and 76.

The antenna coil Lt has only one wind-ing, (80 turns), but a tap is brought out

4 RADIO WORLD December 25, 1926

Tone Quality Put FirstIn Anderson's Personal Receiver

(Anderson)FIGS. 3, 4 AND 5

The panel view shows the balance of the respective parts. The bottom view of thesub -panel depicts placement of parts and wiring. The top view shows general dispo-

sition of other parts.

15 turns from the grounded side, and thistap is connected to the antenna bindingpost A. Coil L. (80 turns), has a singlewinding without any tap. The couplingcoil between the second and the thirdtubes has two windings, L. and Lo. Loconsists of 15 turns of No. 32 double silkcovered wire, but it may well be woundwith the same number of turns of No. 28,which is used in L..

Two Volume ControlsThe tuning condensers used were Bruno

straight line frequency, bakelite shaft,.0005 mfd. The tuning coils are mounteddirectly on the condensers in the mannershown in Fig. 2.

Besides the volume control afforded bythe variable resistance Rho and the im-pedance coupler, there is the rheostat Rho.This controls the filament current in thetwo radio frequency amplifier tubes. Its

resistance is 10 ohms, and therefore thefilament current in each of these tubesis variable from .3 to .15 ampere when thevoltage applied is six ohms. This givesadequate control of volume. It may bepointed out that controlling volume bymeans of the filament current may bedone to good advantage in the radio fre-quency stages. It saves the B batteryby limiting the plate current and it doesnot affect the quality of reproduction ofthe set. But controlling the volume in asimilar way in the audio frequency ampli-fier cannot be done without seriously dis-torting the signal.

The variable resistance Rho has a valueof 100,000 ohms. Its minimum value is verynearly equal to zero. Therefore when re-sistance coupling is used between the firstand the second tube, the coupling may bevaried from almost nothing up to theusual value employed in audio frequency

LIST OF PARTSC', Co C.-Three .0005 mfd. straight line

frequency condensers.Co-One mica .001 mfd. fixecVeondenser.Co-One mica .00025 mfd. fixed condenser.Co-One mica .0005 mfd. fixed condenser.Co Co-Two by-pass condensers, .25 mfd.Col-One by-pass condenser, 2 mfd. Two

additional by-pass condensers, 1 mfd. orhigher, optional.

Rhi-One Carter 10 ohm rheostat.Rho-One 100,000 ohm variable resistance.

'Ro, Ro-Three 1 megohm grid leaks.

Ro-One megohm leak.Ro-One 1/4 megohm leak, or a 100 henry

choke coil.Ro, Ro, Ro-Three 100,000 ohm coupling

resistors.Eight pairs of mounting clips for these

resistors.R., R.1. R., Roo-Amperites to suit tubes

used.:S-One Carter filament switch-Lo, Lo, Lo, L.-Tuning coils as described.Six push type sockets.12 binding posts.Two 7x18" hard rtibber panels.Three vernier dials.Two lengths of brass angle 3/s" by 3/a"

by 6".Two lengths of brass strip Ya" by W

by 12".A cabinet at least 9" deep.

resistance coupled circuits. This affordsa wide range of volume control. Thisrange is considerably widened by thetuned impedance.

Values of ConstantsThe filament currents in the detector

and audio frequency tubes are controlledby Amperites. There is no need for vary-ing any of these currents and consequentlyit is best to use fixed or self-adjusting re-sistors to limit the currents to normalvalues.

The grid leak resistors R., R. and RS are1 megohm units. IV is a megohm leak,while R. is Y4 megohm. Larger valuesmay sometimes be used for R., but whenthe signal is very loud, blocking of the lastgrid is likely if the resistor has a valuewhich is too high. In some cases it isnecessary to substitute a large valuechoke coil for Rs, particularly when veryloud volume is desired. A choke coil ismuch more effective in preventing block-ing of the grid but it has the disadvantageof cutting down the low notes in the_signal.

Each of the coupling resistors R., R.and 12.' has a value of 100,000 ohms.

The stopping condenser in the grid cir-cuit of the second tube, namely, Ca hasa value of .001 mfd. The next stoppingcondenser, Co is a .00025 mfd. unit, becausethis serves as the detecting condenser.CO and Co each has a value of 25 micro -farad, while C9 has a value of 2 anfd.

Need of Large CondenserThe larger value is necessary in the

last stage to prevent too great a reductionin the volume of the low notes when lowvalues of grid leak resistance are used inthat stage. For any given amount ofdistortion, or transmission, the product ofthe capacity of the stopping condenserand the resistance of the grid leak shouldbe constant.

The by-pass condenser Co in the platecircuit of the detector has a capacity of.0005 microfarad. Two more by-pass con-densers may be used to advantage in this

(Concluded on page 30)

Det.Filiber-25, -1920 RADIO WORLD 5

Voltages of EliminatorsMeasured By Inexpensive Means

By Brunsten BrunnConsulting Engineer

THE output voltage of a B batteryeliminator cannot be accurately

measured with an ordinary voltmeter suchas is commonly used in radio receivers.The reason is that inexpensive voltmetersrequire a considerable current for theiroperation. For example, one very com-mon voltmeter has a resistance of 50

ohms per volt. If the range of this meteris 150 volts the total resistance is 7,500ohms, and the current required for fulldeflection is 20 milliamperes. This isabout the same as the plate current in a171 power tube.

As long as the voltage source does notcontain appreciable resistance this metermay be used to get the correct voltage,but a B battery eliminator contains ahigh resistance, which is distributed be-tween the rectifier and the filter coils, andthe ordinary voltmeter when connectedacross the output of the filter will notgive the correct voltage at all. What isneeded to get the correct voltage is avoltmeter which has a very high resist--ance per ohm, say a thousand ohms pervolt. But such meters are expensive. '

It is important to know the correctoutput voltage of a B battery eliminatorif the receiver is to be adjusted for opti-mum results. There is a simple solutionto the difficulty.

The Choice of Meters

An ordinary voltmeter is simply a-milliammeter with a resistance in serieswith and the combination calibrated involts instead of milliamperes. The firstthing that is needed to make a voltmeterthat is capable of measuring the outputvoltage of B battery eliminator is a sen-sitive milliammeter, one which has a max-imum deflection of 10 milliamperes, orstill better one which has a maximum de-flection for 1 milliampere. The latter-costs a little more, but a great deal moremay be done with it. The addition of a-milliammeter to the stock in trade of theradio experimeter or broadcast fan is wellworth while and should not be regarded-as adding to the cost of the high resist-ance voltmeter.

In favor of purchasing a 0-1 milliam-meter it should be stated that its rangemay be extended to 0-10 or 0-100 bymerely putting a resistance of appropriatevalue across it, such as a small filamentrheostat, while the sensitivity of the 0-10meter cannot be increased to 0-1.

Supposing then, that we have a 0-1milliammeter to start with. If we connecta 100,000 ohm grid leak in series with thisinstrument 100 volts will give full scaledeflection, and we have a 1,000 ohm pervolt voltmeter. (Fig. 1.) If such a meterbe used to measure the output voltage ofa B battery eliminator, a very close ap-proximation to the correct value wouldbe obtained. In fact, if the resistance of-the eliminator is as high as 1,000 ohms,the error in the indicated voltage wouldbe only 1%, the reading being low.

Increase of Resistance

If higher voltages are to be measuredwith this meter it is only necessary to usea high value of series resistance. If 200

--volts is the highest voltage to be measured,-the resistance should:be 200,000 ohms, or if300 volts is to be measured the series re-sistance should he 500,000 ohms. In each

R=100000 -a fdr 100 yob'sR-200000 u2 /or200 I,R,.,5 -0000_r). to- SOO

To B WiniNa-

millinZeter0-1

To Cali 4ralc ,ninter-`,connect Ta lolovitsource '

s I

0-1 Mi?114171717e-

2

02D01-4#er

111111

A B111111 1.

c.FIGS. 1, 2 AND 3

case the meter would have 1,000 ohms pervolt and the accuracy of the meter wouldbe the same for all ranges.

The choice of series resistance is im-portant. If a grid leak rated at a certainvalue be taken at random, the probabilitythat it has exactly rated value is rathersmall. If the resistance is not correct themeter will not be accurate. A number ofgrid leaks should be tried out on a knownvoltage, and one which has the correctvalue should be selected for use. If afixed resistance cannot be found whichhas the correct value, a variable resist-ance of adequate maximum value may beused, and the resistance varied until themeter reads correctly. Again, if neithera variable resistance nor a fixed grid leakof the correct value is available, then anyhigh resistance of approximately correctvalue may be employed provided themeter be calibrated against a known volt-age.

Using Known Sources

The known voltage source used incalibrating the meter should have negli-gible internal resistance. Perhaps the bestavailable source is a high voltage storagebattery of the lead plate type. Anothergood source is an ordinary battery of drycells provided this battery is absolutelyfresh. (Fig. 2.) A DC power line may alsobe used. In all of these cases the voltageof the source should be measured withthe best available voltmeter, then thesource should be put across the high re-sistance and the milliammeter and thecurrent in the meter noted. Then again

the source should be checked up to makecertain that it did not change during theoperation.

When one reading of the milliammeterused as a voltmeter has been obtained fora known voltage, any other voltage with-in the range of the meter may be obtain-ed by simple proportion. T6 obtain otherranges of the high resistance voltmeterit is only necessary to calibrate the mil-liammeter against other resistances, usingthe same known source of voltage, orsome higher source of known voltage.

The above method of measuring theoutput of a B eliminator is perhaps thesimplest, but there are other methodswhich will give correct readings of thevoltage.

The Vacuum Tube Voltmeter

One is the vacuum tube voltmeter.When using this meter the plate currentin the tube is measured with a milliam-meter, and the voltage which gives thiscurrent is read from the plate voltage,plate current curve of the tube. Beforethis method is available, therefore, thetube used in the meter must be calibrated(Fig. 3). To do this the plate current givenby the tube for various known voltageson the plate must be obtained, using adefinite filament current and grid bias onthe tube. Then the curve is plotted oncross section paper. This curve may thenbe used to measure any unknown voltage.

When using this meter to measure anunknown voltage care must be taken tosee that exactly the same filament cur-rent and the same grid bias be used onthe tubes as were used during the cali-bration. The output terminals of the Beliminator are connected in the plate cir-cuit of the tube in the usual way, theplate current is noted, and the corres-ponding voltage is read off the curve.This is an accurate method and it givesthe output voltage under actual condi-tions, that is, it gives the voltage actuallyapplied to the plate of the tube.

The tube 'In this case may he one of thetubes in the receiver. In fact all of thetubes may be used in turn to get the ac-tual plate voltage applied to them fromthe eliminator. The voltage thus obtainedis the effective plate voltage and is thevoltage to be considered when the gridbias is to be adjusted. Of course eachtube must be calibrated when all theother tubes in the receiver are working,otherwise the voltage obtained will notbe the correct applied voltage.

Measurement Important

In most cases when a vacuum tube volt-meter is used the plate current will begreater than the 0-1 milliammeter willcarry. Therefore it will be necessary touse a meter of higher range or else put ashunt across it as wassuggested above.

The, importance of measuring the volt-age under actual working conditions can-not be over -emphasized. The importantthing is the voltage applied to each tubein the circuit when all of the tubes inthat circuit are working, and when theyare working normally with proper fila-ment and grid potentials. It is possibleto measure the output voltage of aneliminator with a vacuum tube voltmeterand actually get the emf of the eliminator.This voltage would not mean a thing un-less every resistance in the circuit is ac-curately known. The output voltage varies

(Concluded an page 6)

6 RADIO WORLD December 25, 1926

Functions of EliminatorsAnd the Adaptation to Receivers

VA /A BCE RES/Sr04BET

.760

13-1-91HP

By-LE'r- or, eArrzey

13C-PowERTv

SECONO /TRYOF POWER

7- RA evs FoRmSRI

111+RIIR

EttRi

51-0 Er

(C.-)R3 (rso ohms.)

(c--)

--o

FIG. 1The output of an eliminator, represented at left by the completed eliminator and atright by a schematic diagram. The resistor, pictorially at left, is likely to be about750 ohms for most AC eliminators. The B minus lead becomes C minus, too, while A

minus is at the other end of the resistor (R3).

By Herman BernardAssociate Institute of Radio EngineersBATTERY elimination is the subject

uppermost in the minds of the radiobuying public today. It is the outstandingquestion because it applies to all receiv-ers, whether home constructed or factorybuilt, whether already installed or mere-ly contemplated, and because the publicwants electrification. It is seeking knowl-edge, so as to acquire as much familiaritywith battery elimination as it now haswith receivers themselves.

While it is generally true that a re-ceiver is made for utility in any and alllocations, it is not true that all batteryeliminators are applicable to all receiv-ers. In some instances some wiringchanges must be made in the set, in

others particular care must be given tofiltering, because the receiver is extreme-ly sensitive and a residual hum may pre-vail, while in some locations total batteryelimination is an impracticality with cer-tain types of sets.

Considering total powcrizing or batteryelimination, the first question to be con-sidered is the type of current availablefrom the lamp socket or lighting main.It is either alternating current (AC) ordirect current (DC). With alternatingcurrent almost anything is possible. Withdirect current the useful voltage cannever be anything except less than theoriginal supply, unless a motor generatoror equivalent is used, and that is not com-mercially practical at this time. The orig-inal voltage is usually 110, and in somefew special instances 220 for DC. If youdo not know what type of current you

Meters That Measure Rectifiers(Concluded from page 5)

greatly with the current that the elimina-tor delivers, but the emf remains con-stant. The output voltage is the differ-ence between the emf of the eliminatorand the voltage drop in the internal re-sistance. The drop is quite great whenthe current drain is heavy, and the netoutput voltage is correspondingly small.

The working output of an eliminatordelivering a considerable current may bemeasured quite accurately with an ordin-ary voltmeter provided the total currentis adjusted to have the same value thatit has when the circuit is operating; andthis includes the current that is requiredto operate the voltmeter.

Suppose that the circuit takes a totalof 35 milliamperes when all the tubes areworking normally, and further' supposethat the meter requires about 20 milliam-peres to cause the necessary deflection ofthe needle. A high resistance rheostatshould then be connected, across themeter or across the output of the elim-inator so that the total is 35 milliamperes,that is the rheostat should be of suchresistance that 15 milliamperes flowthrough it at the voltage in question.This method of measuring the voltage isnot of wide application and is not recom-mended if accurate values are desired.

A method of extending accurately therange of a sensitive milliammeter to be

used in the plate circuits of tubes draw-ing a heavy current will be of use whenmeasuring the output of a tube. An or-dinary rheostat such as is used in thefilament circuits of tubes may be used.The range of this rheostat depends onthe meter and the range to be employed.A twenty-five ohm unit should proveabout right for the 0-1 milliammeter.

Suppose it is desired to double therange of the meter, that is, to make. it a0-2 milliampere instrument. First adjustthe current in the meter to maximumdeflection when no shunt resistance isused. This may be done with an externalseries resistance or with a potentiometerfor adjusting the applied voltage.

When the deflection is exactly 1 milli-ampere connect the variable shunt re-sistance and adjust this until the readingon the meter is exactly .5 milliampere.Full deflection now indicates a current of2 milliamperes. In the same way therange of the meter may be made 0-4, 0-5,0-10, or any other desired range.Care must be taken to see that theshunt across the meter is connected atall times, or the meter is in danger ofdamage. If the shunt resistance shouldbreak or become disconnected while oneof the higher ranges is used, all of thecurrent would go through the meter, andin all- probability the meter would burnout, or the needle would become bent.

have, ask the lighting company. Also in-quire as to the voltage. Only in specialcommercial instances will the voltageprove to be 220.

90 Volts from 110 DC.Due to the obstruction to current flow

offered by the resistors necessary in theDC eliminator, the actual maximum volt-age delivered by the rectifier is around90. So if you have a receiver equippedwith a power tube that requires high

and.large

voltage, heavy current drainlarge C bias for efficient operation, youcan not apply to it the resultant outputof a DC eliminator and expect good re-sults. Likewise, if you have a resistancecoupled audio amplifier you can not counton full volume with a maximum platevoltage of only 90. Also with such lowvoltage a last stage power tube offersno advantage. Current you have aplenty,so that even 5 -volt, .25 ampere filamenttubes maybe heated from the eliminator.A 5 -tube receiver, consisting of four typeA tubes, at .25 ampere each, and a type12 power tube, at .5 ampere, draws 1.5ampere, but the eliminator can be so con-structed as to take care of this currentdrain very nicely, and the plate currentdrain of say 20 milliamperes to boot, atotal of 1.52 amperes.

It is apparent, therefore, that you cannot step up DC, but you can insert re-sistors to reduce the voltage and to carrythe required current. These resistors, ofwhatever form, used solely for voltagereduction purposes, are bound to heatup, even if they are lamps. Hence theconsole or table in which the eliminatoris housed should have holes drilled in therear for ventilation. About 1 inch in

is suggested.The Choke Coils

If the eliminator uses choke coils, espe-cially if high. A current is passed, onebuilding such a device should make dou-bly sure that the choke coils will passthe heavy current. Perceptible heatshould not be tolerated in them.

While DC eliminators must operatewithout power transformers, because thecurrent does not reverse its polarity and,a transformer would not function, all ACeliminators require a power transformer.This consists of at least a two -windingcoil. One inductance is the primary and,the other is the secondary. The voltagedeveloped in the secondary may be almostanything, and depends directly on theratio between the number of turns on thesecondary and the number on the pri-mary, granting the same diameters and'same kind of wire. A third winding isbecoming more and more popular, sothat the final audio tube, or the rectify-ing tube, or both, may be heated by ACfrom this tertiary coil.

The RectifierNo rectifier is needed or possible for

DC, for that kind of current flows in onedirection only, and is not a wave, whereasAC changes its direction of flow, AC isusually 110 volt 60 cycle, which meansthat the voltage remains the same, butthat the direction of current flow changesonce every one -sixtieth of a second. Thisis an audible frequency, as only too manyknow to their disappointment, becauseit is familiar as the hum that makes itspresence loudly known in some unfortu-nate attempts to cope with the eliminatorproblem. But there need be no real hum.With AC not only is a power trans-

December 25, 192ti RAI) 1 0 \V 0 1: I, I) 7

C Bias Through ResistorObtainable from Any B Eliminator

former needed, to step up the voltagefrom the original 110 to say 200 or evenmuch more, as well as down to 5 or 7volts, but some system of converting thealternating current to direct current isnecessary, most particularly because onlydirect current is useful on the plates ofthe tubes, the familiar B plus leads. Alsothe detector tube can not readily be heat-ed by AC, because that tube is so sen-sitive to picking up the hum, in otherwords is microphonic. Its elements makeit a miniature microphone on account ofthe characteristic on which the detectortube is necessarily operated, wherebysmall grid variations become extraor-dinarily large variations in plate current.

The rectifier most commonly used is atube, one containing special gas, andoperating on the principle that the gaswill pass only direct current, where thevoltage differences set up in twin ele-ments force the current across the gas.Examples of gas conduction tubes arethe Raytheon, which has no filament, andthe 213, which has a filament. Besidestubes, electrolytes are used for rectifica-tion. An electrolyte requires attention,and this may account for the greaterpopularity of tube rectifiers, since batteryelimination is something made attractiveby its convenience, and anything savoringof inconvenience is not within the spirit-of the general objective.

The Current CapacityThe tube has limitations, and these af-

fect principally the amperage. It is notpossible to draw any more current fromthe entire unit than the tube itself willpass. One may overload the tube, as issometimes done in A, P., and C eliminator-design for use in conjunction with the 71type power tube in the final audio socket.The newest Raytheon tube, type BH, forinstance, easily passes 85 milliamperes,the rated maximum, at full voltage, andif series connected 99 type tubes are usedahead of the final audio tube, a 71 type,then the filaments of the 99s draw 60milliamperes (.06 ampere), the plates ofsay four tubes 16 milliamperes, and theplate of the 71 tube 16 milliam-peres, a total of 92. The filament of thepower tube need not be considered, as itis heated by AC from the tertiary wind-ing. By suitable biasing of RF tubes thisdrain may be cut to 88 or so milliam-peres, an allowable overload of 3 or somilliamperes.

Hence one may say, broadly speaking,that there is amperage aplenty in the DCeliminator, with a scarcity of voltage,while in the AC eliminator there is volt-age aplenty, and a limitation rather onthe amperage or current, although there-is plenty of current available. Assumingthe power transformer to be wound withstrong enough wire, the amperage limit-ation is introduced principally by the rec-tifying tube, and augmented by the chokecoils, which consist of a large number ofturns, hence have an appreciable DC re-sistance. It is advisable to have this re-sistance as low as possible.

The choke coils, in point of position,electrically follow the tube, and theirpurpose is really to serve as wave traps,to filter out the hum. In this object theyare aided by large filter condensers. For.an A, B and C eliminator the conventionalcondenser triplets would be 2, 2 and 4mfd., while for a B eliminator or a Band C eliminator they would be 4, 4, and

-99 -99 -99

A-1- I.e tGO w A

H 4

FIG. 2Series connected -99 tubes, with two grids negatively biased about 3 volts by takingadvantage in each case of the voltage drop in the filament. S is the secondary of

each RF transformer. The audio tubes may be similarly biased.

6, although these values are not adamant.The filter condensers must be able towithstand not only the maximum voltageof the secondary, but much higher volt-ages, so that a 600 volt duration test isnecessary.

The Line SurgesOccasional surges take place in the line

and are communicated to the eliminator,and the condensers should be able towithstand these surges, and should beguaranteed by the manufacturer to doso, as determined not simply by flashtests, but by duration tests.

The other condensers used in an ACeliminator are connected between themidtap of the secondary and the ends ofthe winding. There are two such buffercondenser, and they should stand 1,000volt shocks. The value is .1 mfd. Natur-ally here the surges are felt the worst.

Now, the eliminator has been traced tothe output, where we have two bindingposts, let us say, with a voltage drop of180 between them. One extreme is the Bminus lead, representing zero voltage, andthe other is the B plus amplifier, wirerepresenting 180. From this we caneasily get intermediate voltages by in-troducing high resistors, fixed or varia-ble. The smaller the resistance the lessthe voltage drop, hence the higher thevoltage. It is customary to have a re-sistor to give an intermediate voltage forradio frequency tube plates and also an-other resistor to bring the voltage -stilllower, i. e., to detector plate values. R1and R2 represent these resistors in Fig. 1.

If there is no provision for C batteryelimination, and you want to use a 71power tube, for instance, that requires40% volts negative on the grid for a platevoltage of 180, this may he done by in-troducing a fixed resistor.

Introducing C BiasAt left in Fig. 1 is a pictorial represent-

ation of a B battery eliminator. To makeit also a C battery eliminator, to avoidthe necessity of putting in a large B bat-tery (used as C) and perhaps an extrainversely poled small C battery to get thedesired bias, connect the fixed resistorbetween the B minus lead of the elimi-nator and A minus (or A plus) on the Abattery. All the B current must flowthrough this resistor, since the current isflowing through the A battery and theB eliminator. Where current flows volt-age drops. Hence the 40% volts or there-abouts may be taken from the eliminator.This, to be sure, leaves you just that muchless voltage for the plates, but the prob-lem is simply solved by having a totaloutput of around 200 volts or more, leav-ing about 160, the necessary bias in that

case being about 35. How this resistor isconnected is shown pictorially and dia-grammatically in Figure 1. You will notethat the B minus lead front the elimi-nator-so marked on the wire or identi-fied by coloration and reference to a codeon the container-is used as C minus,while the free end of the resistor goes toA minus or A plus. All the current of theeliminator flows through this resistor,R3, hence B minus is made negative inrespect to the A battery, the value ofthis voltage for biasing depending on thedrop in the resistor. What the value ofthis resistor should be may be determinedby calculation. But you do not know theactual total voltage output of the elimi-nator, because you have not the expen-sive high -resistance voltmeter necessaryto determine this. Ordinary voltmeterswill not do, because they have so low aresistance, compared with the resistanceof the eliminator, that too much currentflows through the meter to enable any-thing like an accurate reading. The meterhas a modified short-circuiting effectupon the eliminator and likely will drawmore current itself than the total safecurrent capacity of the rectifying tube.

As an alternative you may measure thetotal current flow in the plate circuit ofthe last tube, using a milliammeter ofsay 50 full-scale deflection, connected inseries with one of the speaker leads. Ifa minus zero reading is obtained, reversethe connections to the meter. Insert theresistor as shown and watch the needleof the meter. If the needle kicks up, thatis, toward higher readings, increase thevalue of the resistor R3. If it kicksdown, decrease the value of the resistor.For such an operation an assortment offixed resistors would be necessary. Hencea variable one may be used and the armmoved until the needle stands still, evenon strong notes. That is the goal ineither instance. You still do not knowwhat the plate voltage is, nor the bias,but you do know what the current is.You do know that you are "all set," andthat counts more than the missing con-siderations.

Under this system no other C bias isreadily accessible, unless two series con-nected resistors are used, and the jointemployed for the lesser bias. However,the other C biases could be taken withinthe receiver itself, clue either to connec-tion of the grid return to A minus, thusnegatively biasing the grid to the extentof the voltage drop in the rheostat or bal-last in the negative filament circuit, orby a more elaborate system of grid re-turn connections where series filarnenthookup is used. (Fig. 2).

Tubes are connected with filaments inseries for no other reason than the desire

RADIO WORLD December 25, 1926

Motor -Boating Remedies

FIG. 3(A), a large bypass condenser across the eliminator output helps cure motorboating.(B), the detector plate may be brought to A plus, if B minus and A minus are inter-connected, to stop detector tube self -oscillation. (C), an audio choke coil in the finalAF grid circuit subdues extraneous noises; a similar choke is used for the filtered

output. (D), how an output transformer is hooked up.to limit the current drain of all tubes soconnected to the total drain of any oneof the tubes. It is imperative that eachtube have the same filament current re-quirements.

Use of 99 Type Tubes.The 99 type tubes are commonly em-

ployed in this fashion, because 60 milliam-peres, their filament drain, is within thescope of adapting a B eliminator circuitfor A battery elimination. With say atotal of 85 milliamperes to play with, and60 extracted by the filaments of the seriesconnected tubes, you have 25 left forfeeding all the plates, including the plateof the last tube, so if you desire to avoidoverloading the rectifier tube of theeliminator, you may use a power tubewith more modest plate current drain atthe available maximum voltage, e. g., a 112tube.

It can be seen, therefore, that the Bbattery can be eliminated and the A bat-tery as well, in an AC eliminator no lessthan in a DC eliminator. The sacrifice isthe necessity of using tubes that on thewhole will accomplish just a little lessthan the 5 -volt variety.

For total battery elimination it is wellto use an A battery eliminator (AC) as aseparate unit, to supply 6 volts, as woulda storage battery, and with a safety mar-gin of say 2 amperes or more. While sucheliminators have not been very abundant-ly described in the radio press, and arefraught with problems well left to thelaboratory at this time, there are a fewvery excellent factory made A elimina-tors on the market, and more in the off-ering. They are just as humless as thegood B eliminators which happen to bemore plentiful just now than their highercurrented but lower voltaged brethren.

In all instances it is advisable to keepthe speaker several feet from the installa-tion, and this is particularly true if a sep-arate A eliminator is used. The speakercords and magnet windings will pick upa hum otherwise not present, and thehum may be made to disappear graduallyif you will slowly walk away from the setwith the speaker in your hand. Also itsuggests the inadvisability of attemptingto use self-contained speakers in con-junction with batteryless sets. Standingthe speaker on the cabinet of the electri-fied set is particularly bad practice.

The Trickle ChargerSo far we have taken up only the actual

batteryless condition-complete elimina-tion, without qualification. If it was a Beliminator it completely eliminated the Bbattery. If it was a B and C eliminator,or an A, B and C, it completely elimi-nated each such battery. In the categoryof other than eliminators, yet somethingthat achieves a desired goal, is the tricklecharger and A battery combination. Thisconsists of any suitable storage battery,and it need not be of more than 25 am-pere hours or so, used in conjunction with

a slow charger. When the set is on, thebattery is off charge. When the set is offthe battery is being charged all the while.The charging rate is so slow, say :1 am-pere, that the process is inexpensive. Itis a good method of serving convenience,since it dispenses with the necessity ofbattery removal, or replenishment at reg-ular intervals.

Normally it would be necessary to turnoff the set and turn on the trickle charg-er, or turn on the set and turn off thecharger, but this detail is safely left to -the good offices of the relay, which takescare of this automatically and permits thebattery switch of the receiver to be thesole custodian of these duties. However,the B eliminator must be turned off sepa-rately.

An example of where the switch on theset controls everything is in the case ofthe separate 6 -volt A battery eliminator,which is connected to the receiver at oneend and to the lamp socket at the other.A relay in the A eliminator takes care ofswitching the A eliminator on and off bymeans of the A switch on the receiver.A plug is provided on the receiver sideof the A eliminator relay so that the Beliminator lamp cord is simply plugged inat the A eliminator plug, and not directlyat the lamp socket, the one relay thusserving a double purpose. In any othercase it is important separately to turnoff the current from the main that isfeeding the P. eliminator.

Troubles CuredEliminators are not wholly free from

trouble, nor are any other things in thislife. However, the present season hasseen the development of the eliminator,particularly the B eliminator, to a veryfine point. The outstanding trouble isput -putting, like the chugging of thekicker on a motorboat, hence the name"motorboating" as applied to this viceascribed to eliminators. Its cause is con-sidered to be the common impedance ofthe circuits, it being well known that thisneed not reach any very high level beforeoscillation sets in and distortion appears.Suitable ameliorating agencies are largebypass condensers, particularly a ratherpreposterously large one across the out-put, let us say 25 mfd. or thereabouts.(Fig. 3A). Dismissing that inaccessibleremedy, let us examine the type of re-ceiver and audio amplifier employed. If

,the set is of the sort that self -oscillatesat radio frequencies, much trouble maybe expected, so the best thing to do is toneutralize the set.

If the detector tube is of the specialdetector type it may be drawing 6 mil-liamperes and likewise may be oscillat-ing in a fashion not easy to stop withoutchanging the wiring or connections,hence consider the possibility of usingonly the A battery voltage on the plateof the detector tube. B minus must bejoined to A minus, and not to A plus, insuch a case, or signals will be noticeablyabsent. B plus detector connects to A

plus. (Fig. 3B) While this suggestion ismade as a remedial one, and often re-sults in greatly improved reception, itcures one vice at the expense of cuttingdown the plate current in the detectortube to a point where it may not be quitesufficient to avoid a little distortion, dueto the inability of the plate variations toduplicate, on the greater scalp, the gridvariations. It is well to note that the Apositive connection to detector plate re-moves the detector circuit entirely fromthe impedance of the B eliminator, hencethere is no common impedance as to this..

Even Works on ResistorsThe connection, strange as it may

sound to relate it, is satisfactory evenwith resistance coupled audio frequencyamplification immediately following thedetector, although the usual .1 meg. plateresistor had better be supplanted withone of the .5 meg. variety, as this con-siderably increases volume. The voltagedrop across the resistor determines thedegree of input to the next stage, and thelarger value of resistance makes forgreater volume, up to the point wherethe resistances cuts down the plate cur-rent to a descending volume.

The motor -boating nuisance, when en-countered in conjunction with receiversutilizing resistance coupling, may bewholly cured in many instances by sup-planting the final audio stage grid leakwith a choke coil of about 60 henrys,(Ch 1 in Fig. 3C), the same sort of chokecoil as is used in the eliminator. Thesechokes are large and heavy and are notto be confused radio frequencychokes, which are small and light. Theaudio choke in the final grid circuit offersa high impedance but much lower directcurrent resistance, and is most effectivein the region of the low notes, where themotor -boating nuisance resides. Theo-retically this choke, Chl, might be sup-posed to injure qutility a little, but ingetting rid of a distorting and awfullyannoying vice it actually improves qual-ity. The secondary of an audio trans-former may be pressed into service as amakeshift.

Filtered OutputIt is common practice nowadays to use

a filtered output from the receiver,either an audio choke coil and fixed con-denser combination, Ch2-4 mfd. in Fig.3C) or an output transformer (or), usual-ly of l -to -1 ratio. The choke coil should.have an inductance of 60 henrys or more,even up to 100 henrys, if you can getone, while the larger the fixed condenser,the better. The most popular value ofthe condenser is 4 mfd.

More Anecdotes, LessMusic, Depew's PleaChauncey M. Depew, once dean of

after dinner speakers, formerly railroadpresident, attorney and United StatesSenator, announced he is a radio fan.He expressed great confidence inradio's future. He said that it was agreat help to the tired person, who aftera hard day's work could come home andrest himself comfortably, listening to thebest music an talks one can desire. Hesaid, however, that too much music wasbeing broadcast. He prefers more anec-dotes. If it was not for this, his opinionswould be much higher.

Mr. Depew is 92 years old.

December 25, 1926 RADIO WORLD

How to Use B ueprin s

(Hayden)CONSTRUCTIONAL BLUEPRINTS are not difficult to follow or use, if the proper care is exercised. The panel print requires theutmost attention, since all holes must be accurately placed and drilled. A hole drilled a 1-16" out of the way disarranges the wholepanel. The first thing that should be done is to cut off the panel print portion, (upper left.) Then paste the print on the panel, mak-ing sure that the surface is absolutely even. This can be done with the aid of a flat iron or some other heavy object. For holding thepanel down, a small vise should be clamped on both sides of the panel to the table (upper left). If you haven't a punch or scriber, apair of shears can be used to make the proper marks for the various holes, through the dots on the print (lower left). If you havecondensers, having different hole drillings than those specified, paste the template of this condenser over the other condenser mark-ings, making proper dots. After all the marks have been made and the holes drilled, wash the print off the panel with some hot

water. Hard rubber or Bakelite will not be affected by the water.

FADING REDUCEDBY DOUBLE LOOP

WASHINGTON.Scientists are putting forth greater ef-

forts than ever before to overcome fad-ing.

Occasionally they are discouraged thy-slow progress. At other times it seemsas if the solution is just around the corner.They believe it will be possible to coun-teract fading but don't know how long itwill take to bring it within the means ofthe average set owner.

For four years the Radio Laboratory ofthe Bureau of Standards has been inves-tigating the culprit. His habits, night andday, winter and summer have been plot-ted charted and studied. Out of it allhave come -a few theories which are, gen-erally accepted.

The most important is that there is aclose relationship between fading and theHeaviside layer. It is not believed thereis any connection between fading and theweather. Curiously, fading is worse rela-tively close to a station that at great dis-tances.

Investigations reveal two dips in thevolume of reception. Maximum fadingoccurs at about 100 kilometers -from thestation. Reception then gets better up

to 300 kilometers where fading is againvery bad. From there on it is not sopronounced.

Dr. C. B. Jolliffe, of the Bureau ofStandards, is optimistic about the future.

"The status of our knowledge of fad-ing," says he, "is considerably better thanever before. We are now able to predictwith some accuracy what will happen onthe various frequencies. I have no doubtthat sometime we will be able to counter-act it."

Fading is different on almost everywavelength, but the general rule is thatthe higher the frequency, the more rapidthe fading.

Dr. A. Hoyt Taylor, Chief of the NavalResearch Laboratory, at Bellevue, is anauthority on high frequency fading.

"Lots of persons must wonder how weare able to use the high frequencies at allif fading is so bad on them," says he."The fact is that fading is so rapid thatit doesn't make much difference in codework. We have records of as many as100 clips during the transmission of onedash. Telephony, of course, would. beimpossible with such rapid fading.

"Fading on the high frequencies de-

pends on the distance from the sendingstation. It doesn't look to me that we'llbe able to use the high frequencies forshort distance telephonic purposes. Onthe other hand, it apears as if the highfrequencies will 'be fine for telephoninghalf way around the world. The reason issimple. At great distances- the fadingsmoothes itself out and is not noticeable.

"By using a combination of loop an-tennas I am able to reduce fading to someextent. I have found that by setting theloop at one angle, fading is differentthan from another angle. The secret isto use two loops set at different anglesand have them both feed into a differen-tial. Sometimes there is fading on oneloop and reception is good on the other.By combining the two I manage to getmore of the program,"

Dr. Taylor's theory is that fading existseven as close as a mile from a hroadcast-ing station, but that, it is not noticeableto the ear at such close distances.

Acceptability of the theory that changesin the Heaviside layer are responsible forfading, would seem to make the solutioneasy for scientists. All they would haveto do would be to find some way to com-pel the layer to' remain stationary.

"It's a natural law that we're facing,"says Dr. Taylor, "I know that sometimewe'll be 'able to counteract it. At first wethought we might be able to do it withimprovements in transmission. But it be-gins to look as`if well also have to workon it from the reception -end."

Fans are much interested in this.

10 RADIO WORLD December 25, 1926

How to Be a Signal SleuthAnd Test Wave Intensity

FIG. 1The circuit diagram of the 2 -stage radio frequency amplifier and specially hooked up

detector for use in testing.

Received Impulses Measured By the Effect on theOutput-Simple Apparatus Used-Most ExistingReceivers Can Be Accommodated to the InterestingTesting System

By John F. RiderMember, Institute of Radio Engineers

THE increased interest displayed bymany of the large radio broadcasting

institutions in the subject of received sig-nal intensity opens up to the averageradio fan an extremely interesting fieldof experimentation, with very little ex-penditure of money required for thenecessary equipment.

The subject of received signal intensityis gradually becoming of great import-ance in the study of the enigmatical artof radio transmission and reception, andfrequent requests are broadcast by sta-tions who desire information relative tothe constancy of their transmitted sig-nal, as received at various points.

Records showing variations and fluc-tuations of the received signal intensityduring different hours of the day, suchas several minutes prior to sunset, duringsunset and after sunset, bring to lightdata which are of great interest and aidto the persons interested in the better-ment of the art. Observations of re-ceived signal intensity during the transi-tion period from day to night in variouscities; the effect of a sudden shower,high humidity, etc., are all interestingpoints of great significance, Perhaps asisolated examples they are not of im-mediate value, but records of nightly testsmade over a period of a month or so willbring to light many peculiar facts andreactions very seldom considered. Bearing

Phone's -FIG. 2

The diagram of the testing unit.

in mind all facts, this work constitutes avery worthwhile field of experimentation.

Simple EquipmentAt first glance it would seem as if the

equipment necessary for this work is quiteelaborate. In fact the major portion ofthe complete equipment can be found inthe home of many experimenters, and whatis not on hand can be very easily con-structed. In the regular course of thiswork, as carried out by large institutions,photographic records are made, by caus-ing the electric impulses to actuate ap-paratus which when utilized in conjunc-tion with other equipment, results in avisible record upon a photographic plate.But for all purposes to which the inter-ested fan can apply these data, photo-graphic records can be dispensed with,and very excellent data obtained withmuch simpler equipment.

The carrying out of these tests is notdifficult work, nor does it require muchtechnical knowledge. To be exact, it isentirely within the powers of the averagefan whose radio experience has been theconstruction and operation of radio re-ceivers. A sample layout of the apparatusused in these tests is given in Fig. 1.Reading from left to right we have a twostage radio frequency amplifier, and thecrystal microammeter combination. Anexamination of the circuit used in thetuned radio frequency amplifier will showthat it does not differ from the conven-tional.

The RF AmplifierIt employs the regular methods as

found in practically all radio frequencyamplifiers. Insofar as this portion of theunit is concerned, any and all types ofradio frequency amplifiers can be used,the more stages the better, since greatersensitivity and selectivity are thus madeavailable.

There is, however, one paramount con-sideration relative to the choice of theseamplifiers, and this is stability. The stab-ility of the entire amplifier unit, inclusiveof the tubes, A and B batteries, must beas nearly perfect as it is possible to makethem. The reason for this is very ob-vious. We are to make records of the

Variationsvariation in the input signal as evidencedby fluctuations of the output. If the re-ceiving system is unstable we have nodefinite proof that a fluctuation in theoutput, whether it be a decrease or in-crease, is caused by a variation of theinput. But if we are assured of the stab-ility of the amplifying system, it is safeto assume that the output fluctuation wascaused by a variation of the input signal.Hence the reason for the filament andplate voltmeters.

Now, a further study of the radio fre-quency system shows that the connec-tions to it, -that is, the filament and platevoltages do not differ from the conven-tional.

Hence it is possible to utilize the radiofrequency portion of a receiver on hand,if accessible. If the various radio fre-quency stages are shielded, by being en-closed in individual containers, thus ren-dering the leads and contacts inaccessible,a separate RF unit will be necessary. Ifaccess is possible, none of the internalwiring is tampered with or changed inthe slightest. The leads from the crys-tal-microammeter combination are con-nected to the rotor and stator plates ofthe variable condenser, connected in thegrid -filament circuit of the detector tube.This places the indicating device in shuntwith the tuned circuit feeding the regulardetector tube of the receiver, since theconnection is made to the condenser sideof the grid condenser. This is illustratedin Fig. 3.

The Indicating SystemThis drawing shows how connection is

made to a conventional five tube tunedradio frequency receiver, consisting oftwo stages of tuned radio frequency am-plification, detector and two stages oftransformer coupled audio fre-quency amplification. When the re-ceiver is to be used for the entertainmentof the family or guests, the crystal' mi-croammeter circuit is disconnected, andthe receiver operated in the normal man-ner. When the field intensity tests areto be made, the receiver is left connectedas used for normal operation, the crystalindicating circuit is placed in shunt tothe tuning condenser as shown, the de-tector and two stages of audio frequencyamplifying tubes removed from theirsockets, and the receiver operated in thenormal manner. This means that the twostages of radio frequency amplificationare being utilized to feed the energy intothe crystal microammeter circuit.

Therefore by proceeding as outlinedyou can utilize the regular family re-ceiver for this work without fear of dam-aging or dismembering the system.

Having disposed of the amplifying sys-tem, we now arrive at the indicating sys-tem. This consists as shown, of a crystaland a microammeter or a galvanometer.Much need not be said of the crystal,other than stating that stability and de-pendability are preferable to sensitivity.For this reason a fixed carborundum crys-tal detector, without the voltage varyingdevice, is suggested. This detector hasbeen found to maintain its adjustmentfor very long periods, with very littlechange in sensitivity, and excellent re-sults can be obtained with it. As to themicroammeter or the galvanometer, thechoice is dependent upon the purse, sinceeither type of instrument can be ob-tained at different prices.

The requisites for these instruments are

December 25, 1926 RADIO WORLD 11

Intensity Changes ChartedBy Meter Placed at Detector Output

Fading Recorded a n dPlotted on Curves-In-sensitivity of the Hu-man Ear Is Proved ByVisually DeterminedFluctuations That MakeNo Aural Impression

not many, but it is essential that it bea low reading unit and the divisionsequivalent to small values of current. Themicroammeter should have a maximumreading of 500 microamperes with 100 di-visions, each division being equal to 5

microamperes. If a lower reading in-strument is available, such as a microam-meter with a full scale deflection of 200microameters and 100 divisions, each di-vision being equal to 2 microammeters, itis much preferred. This is the type ofinstrument I used. As to the galvano-meter, the string type is preferable to thestudent's galvanometer, because of itsgreater sensitivity, and smaller currentvalues per division.

A Worthwhile SearchUnfortunately this unit is not obtain-

able as easily as the regular microam-meter, although essentally the galvano-meter is a microammeter. Search through -some second hand storetrical equipment will usually result in thediscovery of one of these units, witheverything intact. I had occasion tosearch and found one in perfect condi-tion and at a very reasonabe price.

The operation of the complete systemis very simple. This is so although thetopic pretends a technical discussion. The.receiver system is operated in the con-ventional manner, and record is made ofthe deflections shown on the microam-meter needle. And since these deflectionsare independent of the modulation fre-quency, the fluctuations of the microam-meter needle indicates variations in fieldintensity at the point of receptiOn.

A variation in field intensity at thepoint of reception, does not necessarilysignify a variation in transmission, but ifall other local stations are received withconstant field intensity at any one point,and fluctuations are noted for one localstation, it is quite safe to assume that thefluctuations are due to unsteady transmis-sion. However, the item of prime importis not 'the quick conclusion of what the

Q 4o

30

CI 0T ME- IN / 7-L.5`

FIG. 4Graph showing results of local station

tests.

-r

FIG. 3The circuit diagram of the standard 5 -tube tuned RF receiver, with a makeshift con-

nection of the testing unit.cause may be, but rather a record of theKDKA, however, were of radical nature,reception under different conditions. Do as is shown by the curve, and thenot arrive at conclusions. Wait until a changes in the signal intensity as recordedfull week or a month of records has beencompleted. The records may surpriseyou. You may even find that rainy nightsresult in greater field intensity at the re-ceiver than clear nights.

The Recording WorkThe matter of records and tabulations

is entirely up to the person conductingthe work. If he desires precise data hewill record the deflection each 15 sec-onds. If the record is to be short, say,of 5 to 10 minutes duration, observationseach 10 seconds are not difficult by anymeans. It would seem that this manualobservation and recording during suchsmall intervals is tedious. But it is in-finitely simple. Just try it. A few mo-ments, and one is an experienced checker.If, however, the record is to be of greaterduration, say 30 minutes, the deflectioneach. 30 seconds would be sufficient.

Herewith are given some curves show-ing reception from several local stationsin New York City, and reception fromKDKA, made after observations of thelocal stations were completed. Theserecords are 5 minutes long. It is evidentthat station number 3 did not afford con-stant reception, insofar as the recordingdevices were concerned. But unsteadyreception as indicated by small fluctua-tions does not mean that there would benoted any changes in the signal inten-sity perceptible to the ear. The lack ofsensitivity of the human ear and the con-sequent danger of making aural observa-tions are very emphatically illustratedwhen making these tests, if one connectsa pair of phones into the crystal microam-meter circuit, and compares aural obser-vations, with the readings obtained fromthe meter. The ear is a poor second, theresults will show conclusively.

Sidelight on Super PowerIt will be observed that unless the field

intensity undergoes an appreciable changeno variance in signal intensity will benoted. Bearing this demonstration inmind one can very easily realize why theuse of super power does not necessaryresult in easily heard increase in receivedintensity.

The fluctuations of the sig sal from

a

FIG 5Graph showing results of KDKA tests.

by the ear were very easily noted. Butcomparing the, ield intensity variationsof locals with that of the diStant station(e. g., KDKA), it is obvious that thelocals are sufficiently steady for sat-isfactory reception. As a matter of ob-servation, it was found that variationsof fully 20 per cent were necessary be-fore they were noticed by the ear. Thisfigure, of course, does not apply to allobservers, since the sensitivity of thehuman ear differs with individuals.

Referring again to the curve for sta-tion KDKA, the fading effect is veryevident, being continuous. Yet to theear, it would seem intermittent, since thes:nall variations would go entirely un-noticed.

One does not appreciate the fun in thiswork unless he experiences the sensationof making records of various stations.

English Is HeldSuitable Tongue

For the UniverseBy GIDEON WALRUS

With the rapid improvement of bothreceivers and transmitters, which haveincreased the mileage range to such anextent that it is as simple to get in touchwith all portions of the world by code asit is to call up your friend, via the tele-phone, the topic of what language shouldbe universally employed comes into thelimelight.

Esperanto has been and is still beingtried. However this so-called universallanguage presents difficulties in that fewpeople already speak it and it may bedifficult to learn. English, however,which so many people can talk, and whichmany more are learning, is becoming thetongue, which broadcasters" say, will beuniversal. During the last half centuryEnglish speech has become so widely dis-tributed, that it is with much difficultythat one can enter a community and beunable to find a person who cannot speakEnglish.

Up to the present, however, the growthand spread of languages have been com-paratively slow clue to the difficultiespresented by transportation and com-munication. Even the telephone has nothelped very much. However, the radio,has cut through all the obstacles, andnow signals can be sent through withease, with little expense and over greatdistances. The English language hasbenefitted by these improvements, andit seems it will in a very short while ex-tend to every portion of the universe.

12 RADIO WORLD December 25, 1926

A 1.1

adio Receiver De 11 xecal Qu ilty Design y Noted Engineers

THE TWO -TUBE DE LUXE RECEIVER is shown in a table model cabinetThis is the set to be described next week. The amplifier is inside the table, atleft, and this will be discussed the ensuing week. Adaptation of the outfit to

lamp socket operation will be the subject of subsequent articles.

By Herman BernardAssociate, Institute of Radio EngineersTHERE was a time not so very long

ago when tone quality meant nothing.The more a set squawked, squealed, hissedand yapped the more highly it was prized,so long as it was "plenty loud." In factit was termed "powerful" and thought tobe capable of dragging in the elusivesignals from a small broadcaster acrossthe continent. Miles and volume, nottone quality, were then the criterion ofradio reception.

But the intelligence of the broadcastlistener has improved with the age andscientific developments of the industry.Mr. Radio Listener is now beginning torealize that it's how good not how farthat really counts. In other words, thenovelty stage has passed and the radioindustry is now established as an import-ant public utility. The broadcast stationsof today are disseminating programs ofirreproachable artistic and electrical per-fection. There remains only the necessityfor the education of the public so thatfull advantage of the present-day engin-eering knowledge concerning well-nighperfect reception may be realized.

The essentials for such reception arebut few and easily met. First, a sethaving such an RF amplifier must be used

that distortion due to "cutting" of sidebands is not introduced. Some multi-stage RF amplifiers tune so sharply thatthe side bands of the broadcast stationcarrier wave are cut off and so neverreach the detector. Without side bandsthe high notes are lost and the set soundsdeep toned and unnatural.

Then the detector tube must not beoverloaded. A single stage of RF amplifi-cation seldom will overload a detectorunless the reception is from a powerfullocal station. The prevention of detectoroverloading is one of the several goodreasons for using an RF amplifier gaincontrol as a general volume control forthe set as a whole.

With good quality detector output, itis necessary only to use a real good audioamplifier to build up the volume to sucha value as to give satisfactory loudspeakeroperation. To complete the chain, ofcourse, it is imperative that only the bestof cone speakers be employed. There islittle reason in supplying a high qualityinput to a poor speaker. Good qualitycannot result,

In subsequent issues of Ramo WORLDArthur H. Lynch one of the country'spioneer and best known radio engineers,will describe the construction and opera-tion of a lamp socket operated setdesigned with reliability, service, ease of

operation and construction, and last butmost important, the best of tone qualityirl mind.

Mr. Lynch is an outstanding engineerin the radio field and has spent manymonths in developing the B -D, resistance -coupled amplifiers, resistance -coupledpower amplifiers, etc. Seldom is it possiblefor two such engineers to get togetherso as to develop a product that is rightboth from a radio, electrical, mechanical,and assembly point pf view. This newNational -Lynch Amplifier marks a realstep forward in the progress of the radioindustry along the line.

The author has spent a great deal oftime on the development of this lampsocket operated receiver.and has collabor-ated with and received the valuable assist-ance of the best known engineers in theirindividual fields. For instance, the RFamplifier employs the B -D circuit devel-oped by Fred Drake and G. H. Brown-ing and tuning units developed by theengineers of the National Company in aspecial improved Lynch arrangement-separating of the RF and AF circuits.

The circuit used in the lamp socketpower amplifier was also designed by Mr.Lynch. The units were made for it bythe National Company. The entiremechanical layout and assembly are thework of James Millen, who, although arecent graduate of Stevens Institute ofTechnology, already has come to be rec-ognized as a radio engineer of great merit.Mr. Millen has contributed many articlesto radio and other scientific magazinesand was on the staff of "Radio Broadcast"when Mr. Lynch was its editor.

Resistance -coupled amplification haslong been known as a positive road toquality when high grade resistors andcoupling condensers were used in its con-struction. Until recently, however, it hasbeen difficult for the home constructor toobtain satisfactory resistors. The impreg-nated paper variety formerly so muchused were far from satisfactory. In fact,not only were they noisy in operation, butthey also rapidly changed in resistancevalue with age, so that after a few monthsuse distortion and even failure to operateat all frequently resulted. With the newmetallized filament resistors, however,both of these objections are entirely over-come, as the units are both silent andpermanent.

One of the most common causes of dis-tortion in the average amplifier, otherthan that due to frequency characteristics,is tube overloading. For the best of re-sults it is essential that the proper powertube be used in the last stage. It takesreal energy to operate a cone speakerproperly and a 201A, and even an UX112for that matter, is not capable of supply-ing this power. For the home radioset the UX171 is the ideal tube as it cansupply plenty of energy to operate aspeaker with as much volume as will everbe required, unless, of course, the purposeof the set is to keep all the neighborsawake at night. The UX171 tube doesnot require the dangerously high platevoltage and the expensive filter con-densers needed for the UX210 tubes.

With an amplifier built into the set,many leads, several being of rather highpotential, must be run between the setand the power unit. To eliminate suchunnecessary leads, the amplifier andpower supply are combined Into one unitwhich, as it requires no adjustments afteronce being put into operation, may beplaced out of the way in the battery com-partment of a console or table. Such ar-rangement not only simplifies construc-tion, but also makes it easy to use the

December 25, 1926 RADIO WORLD 13

Result of 11 ngineers' ChoiceIs Ikx uisite Lamp Socket Operated Console

IF a radioist had as many dials on his set as the members of a regiment have feet, he would want those dials to keep "in step,"station for station, just as do the marchers. The De Luxe receiver has only two dials. How these are made to tune in step will be

told next week.

amplifier with different sets and with ex-isting sets of the factory -made type. Ifhe so desires, a fan may have severalsets, say one, such as the VictoreenSuper -Heterodyne, for distance, and an-other, such as the BD for ordinary use,without the necessity of duplicating anexpensive -audio -amplifier and powersupply.

Perhaps a few words about the develop-ment of high quality lamp socket ampli-fiers in general may be of interest. Inthe spring of 1925, as a result of thelaboratory work in connection with thedevelopment of the electric phonographor panatrope and the R. C. A. 104 speaker.Messrs. Rice and Kellogg delivered apaper before the American Institute ofElectrical Engineers on high quality lampsocket operated audio -amplifiers. Realiz-ing the value to the public of the theor-etical data presented in this paper, theengineers of the American TransformerCompany, particularly George C. Crom,Jr., developed a line of practical partsso that the advanced home constructorcould enjoy a "real" radio program. Atthe instigation of Mr. Lynch, then editorof "Radio took theparts developed by the American Trans-former Company and in collaboration withMessrs. Crom and Lynch, developed ahigh quality broadcast receiver. In theNovember issue of "Radio Broadcast,"Mr. Millen described this set, making

available to the radio public for the firsttime a truly fine receiver. This set usedan UX210 tube as a power amplifier.Realizing the disadvantages of the 210 andthe possibilities of the new 171 in con-junction with the ,Raytheon BH rectifier,Mr. Lynch originated the idea of makinga safe and economical amplifier in oneunit so that it might be connected to anyexisting set.

Further realizing that the parts avail-able on the market at that time were notsuitable for the construction of amplifierswhich could duplicate'the results obtain-able with the laboratory models that hehad developed in conjunction with Mr.Millen, Mr. Lynch looked around to finda reliable radio manufacturer that had thefacilities for manufacturing the necessarychokes, transformers and condenserblocks so that any one purchasing a kitof the parts would have no difficulty inconstructing an_ amplifier which wouldperform with the same high degree of ex-cellence as the laboratory models.

The National Company was selectedbecause of their long experience in themanufacture of power transformers, scien--

-tific equipment and high grade radio pro-ducts.

An entire floor of the new Nationalfactory, -which takes in a whole block, isnow devoted to the manufacture of allthe necessary parts according to the exactideas and specification of Messrs. Lynch

and Millen, for the construction of oneof the finest amplifiers that it has so farbeen my privilege to examine and listento.

By taking the best in radio frequencyamplification and combining it with thebest in audio -frequency amplification Mr.Lynch has produced a truly remarkablecombination. Not only is lamp socketpowerization obtained with this receiver,but also au -somatic power control bymeans of an automatic line supply relay.

The set proper is also most easily oper-ated, as the only tuning controls are twoilluminated National variable ratio vernierdials and a volume control. The adjus-table ratio feature on the dials permitseither a fine or coarse vernier adjust-ment, within the limits of six to one totwenty to one, at the will of the operator.Provision is made for directly recordingthe call letters of the different stationson the dials.

Next week the first of the three articlesby Mr. Lynch will appear in Ramo WORLDon the construction of the two tubeBrowning -Drake receiver. In the secondarticle Mr. Lynch will describe the con-struction of his new high quality poweramplifier and in subsequent articles hewill tell how to combine the various unitsinto the complete Lynch Browning -Drakelamp socket operated receiver and how toadapt it to commercial devices that con-cern powerizing the installation.

(Herbert Photo) (Hayden)

THE GENERAL TREND is toward making receiver installations larger. Note batteryless 5 -tube set at left. The rectifyingtube is at right. The other photos show a "nut" crystal set and a front collar button used as a tip jack.

14 RADIO WORLD December 25, 1926

Radio UniversityWhen writing for information give your

A FREE Question wad An-swer Department con-

ducted by RADIO WORLDfor its yearly subscribersonly, by its staff of Experts.Address Radio University,RADIO WORLD, 145 West45th St., New York City.

Radio University subscription number.

OThe circuitup a double

FIG. 484

B -I-

diagrams illustrating the correct and incorrect methods of connectingcircuit jack to a detector output, A being the wrong away and B the

right way.I HOOKED up a double circuit jack at

the output of my detector tube as perdiagram and cannot get signals, when theplug is inserted, although I can hear themthrough the output of the last tube. Whatcould be the trouble?-Dave Greenberg,Bx., N. Y. City.

Your method of connection is wrong.The correct way of connecting up thejack at this point is shown in Fig. 484B.In the same figure, A, the wrong way,which you have followed, is shown. Youwill note in A, that the plate and B plusterminals of the transformer are con-nected to the outer terminals of the jack,instead of to the inner terminals, as perB. Therefore when you place the plug inthe jack, the two outer prongs are sep-arated, there is no contact to the outputterminals, as per B, the contact beingmade to the transformer. In B, whenthe plug is inserted, contact is made tothe plate of the tube and the B plus post,the transformer being shunted completelyout of the circuit.

* * *

I CONTEMPLATE building the 1 -tubereceiver (bottom diagram), used in illus-trating the short wave article in the Nov.27 issue of Radio World, page 5, forbroadcast waves. (1)-Can a 10 turnpriinary and a 70 turn secondary coilwound on a 2R" diameter tubing, usingNo. 22 double cotton covered wire, beused as Ll and L2 respectively?' (2)-What capacity condenser should shunt thesecondary winding? (3)-How manyturns should the plate coil consist ofand what capacity condenser should beused?-Harry Morton, Atlantic City, N. J.

(1)-Yes. (2)-Use a .00035 mfd. vari-able condenser. (3)-This coil consists of35 turns wound on a 3" diameter tubing,with No. 22 double cotton covered wire.It should be shunted by a .00035 mfd.variable condenser.

* * *

I HAVE built a 1 -tube receiver, usinga 3 -circuit tuner, hooked up in the stand-ard fashion. In series with the antennaI connected a 33 turn coil, wound on a 3"diameter tubing, and shunted by a .001mfd. variable condenser. This, I used asa tuned antenna system. I used a 20 ohm.rheostat for controlling the filament cir-cuit of the detector tube. I would liketo know if it is possible to add two stagesof transformer coupled audio frequencyamplification to this set. I have two 3 to 1type AFT. (2)-Are the P and B outputposts connected to the P and B posts ofthe AFT respectively. I have the circuitdiagram of a standard two stage amplifier.C battery provision for each AF tube andautomatic filament controls for each tube

is made. Is this 0. K.?-Wesley Lyter,N. Y.

(I)-Yes. (2)-Yes. Check it up againstthe audio frequency amplification unit ad-dition, in the Selective 1 -tube set describedin the Dec. 18 issue of Radio World.

* * *

I HAVE built the crystal set, describedin the May 15 issue of Radio World,Radio University columns, and have ob-tained good results. Now I would liketo add transformer coupled audio fre-quency amplification. To what terminalsare the P and B posts of the first audiotransformer connected to? (2)-Howmany stages should be added for bestresults? (3)-I have several all stageratio transformers. Can they be used?(4)-Should I use an output transformer?I have a cone speaker. I desire to use apower stage in the last audio stage.-Leonard Pacifico, Portland, Me.

(1)-The P post is connected to therotor plates of the variable condenser.The B post is connected to the poten-tiometer arm. (2)-Two. (3)-Yes. (4)-Yes.

* * *

IS IT possible to use fixed Vitrohmresistors in the output of the B elimi-nator described in the June 26 issue ofthe Radio World, so that I may obtainmany fixed voltage values? (2)-Fromeach B plus to B minus lead, should a 1

mfd. fixed condenser be shunted? (3)-Ihave a 2 mfd., a 4 mfd., and an 8 mfd. fixedcondenser. Can they be used? How shouldthey be installed?-Willard Mork, Hous-ton, Tex.

(1)-Yes. Be sure to insert the correctvalues as per data on the carton. (2) -Yes, this is absolutely necessary. (3)-Yes. Place the 2 mfd. first, the 4 mfd.next, and the 8 mfd. last.

* * *

I HAVE constructed a 4 -tube reflex,designed exactly as per diagram on thebottom of page 8, in the Dec. 4 issue ofRadio World, under the Big Five article.Although the set operates satisfactorily,there is a tendency for it to howl. Canthis be prevented by inserting radio fre-quency chokes in series with the gridreturns of the two RF tubes? I havetwo such coils containing 150 turns, woundon a 1" diameter, using No. 30 enameledwire.-Robert Harris, Bar Harbor, Me.

Yes, this is a good stunt. Also try re-ducing the number of turns on the pri-maries in the plate circuits of the RFand detector circuits. Try reducing theplate voltage on these tubes, also.

* * *

PLEASE SHOW how to connect upa separate B battery in the detector platecircuit, so that there is no feedback

FIG. 483The diagram illustrating how to use a

separate B battery for plate voltage.through the batteries. At present, I amusing a 6 -volt storage battery to lightthe filaments of 5 tubes, with three 45volt batteries supplying a single platevoltage.-John Carston, Atlantic City,N. J.

Fig. 483 shows the circuit diagram il-lustrating this stunt. The individual bat-tery connection to the set is indicated atpoint D.

* * *

1 READ with interest the descriptionof the radio frequency unit using vari-ometers and shown diagrammaticallyunder Fig. 482, in the Radio Universitycolumns of the Dec. 18 issue of RadioWorld. I am going to build this receiverwith two stages of transformer coupledaudio frequency amplification. Could Iplace the parts in a 7x18" cabinet with apanel to fit, using the panel outline shownin Radio University columns of the Nov.13 issue?-Gregory Halstead, Altoona,Pa.

Yes. However, there are several pre-cautions which you will have to take. Asmall copper or other good conductivematerial must be placed between eachvariometer for shielding. This shieldshould be grounded. The resistance in theplate circuit controlling B voltage shouldbe placed on the inside of the receiveron a subpanel. Automatic filament con-trols should be used in the amplifier fila-ment circuits.

* * *

IN REFERENCE to the 4 -tube receivershown under Fig. 479, Radio Universitycolumns, Dec. 4, issue of Radio World.(1)-Can a separate 10 turn primary and44 turn secondary RFT, wound on a 3"diameter tubing using No. 22 double cot-ton covered wire, be used to couple theRF tube to the detector tube? The 33turn coil wound on a 3" diameter form isto be used as a plate coil, for regenera-tive control of the RF tube. That is, thisplate winding is to be connected in serieswith the primary winding of the RFT.(2)-Can the double circuit jack, at thefirst amplifier audio amplifier output, beleft out, direct connections being madeto the transformer and tube respectively?-Godfrey Luce, White Plains, N. Y.

(1)-Yes. (2)-Yes.* * *

CAN 20 -ohm rheostats be used to con-trol the filaments of the radio frequencyamplifier and detector tubes in the 4 -tubeset, shown in the July 24 issue of RadioWorld on page 9? (2)-I am going touse a 50 turn coil tapped at the 8th turnfor L1L2, and a 3 -circuit tuner with a10 turn primary, 42 turn secondary and35 turn tickler. The primary and sec-ondary windings are each wound on a3" diameter t Ming with No. 24 doublecotton covered wire, with no spacing. Thetickler is wound with No. 26 single silkcovered wire, on a 13/4" diameter tubing.Can these be used? (3)-1 am goingto use -0IA tubes throughout. Are they0.K?-Laurence Anderson, Los Angeles,Cal.

(1)-Yes. (2)-Yes. (3)-Yes.* * *

I AM going to build the Tectron Beliminator, described in the April 3 issueof Radio World. (1)-Will I get better

December 25, 1926 RADIO WORLD 15

0

55"

AA

FIG. 485The circuit diagram of the 3 -tube regenerative receiver requested by Maxwell Phillips.

results if I place a .5 mfd. fixed con-denser across the B plus Amp. 90 post andthe B minus post? (2)-Can R1 be avariable resistance, such as the Claro-stat?-Joseph Murps, Louisville, Ky.

(1)-No. (2)-Yes.* * *

CAN A tube be successfully substitutedfor the crystal in the 4 -tube Toroid set,shown in the Radio University coluThnsof the Feb. 27 issue of Radio World?(2)-Can ballast resistors supplant therheostat in the AF filament circuit?-James Hartford, Bridgeport, Conn.

(1)-Yes. The grid is connected to thestationary plate post of the third vari-able condenser and to G post on third

- coil. The rotary plate post of this con-denser is brought to the A plus post andto the F post on third coil. The platepost is brought to the P post on theaudio frequency transformer. The Fminus post is brought to the resistanceterminal of a 20 -ohm rheostat. The armof this rheostat is brought to the A minuspost. The F plus post is brought to aterminal of the filament switch. (2)-Yes.

* * *

I AM going to build the one stagetransformer and two stage resistancecoupled audio frequency amplifier, shownon page 19 of the July 24 issue of RadioWorld. Please state the values. Also giveany improvements to be made.-WilliamThompson, Boundbrook, N. J.

The transformer is a 3 to 1 type. Thecoupling condensers in the resistancestages are of the .25 mfd. type. The lastoutput condenser is a 4 mfd. one. Theplate resistors are of the .1 megohm type.The first grid resistor is of the 1 megohmtype, while the second one is of the .5megohm type. Don't use a resistor forpreventing DC from entering the speaker,as shown. Instead use a choke coil. Theconnections are the same as for the re-sistor. Connect the filaments of the firsttwo AF tubes to a single rheostat, 10 ohmtype. Connect a rheostat or ballast in thefilament circuit of the last tube. Returnthe plate leads of the first and secondtubes to a separate B post connecting theplate of the last tube to a separate B post.Also connect a filament switch in serieswith the A plus, B minus lead. C batteryconnections to the first and second tubesand to the last tubes, should be madethrough the grid resistors and secondarywinding of the AFT.

* * *

IN THE November 6 issue of RadioWorld, Radio University columns, thereappeared a circuit diagram of a 6 -tubeset, using double impedance coupling,which interested me. (1)-Could I useseparate ballast resistors to control thefilaments of the two AF tubes at onetime and the filament of the last AF tube?That is, a 112 Amperite on the first twoAF filaments and another 112 Amperiteon the filament of the last AF tube. The-01A tubes will he used the first twostages, while a 171 will be used in thelast AF stage. (2)-What type rheostatcould I use in the filament circuit of thedetector tube? (3)-Using the' -01A tube

as a detector, is the grid leak connectedacross the grid condenser? (4)-Using aB eliminator, would it be a good idea torun the detector plate to the plus postof the 6 volt A battery, to prevent feed-back?'-Henry Williamson, Butte, Mont.

(1)-Yes. (2)-20 ohm type. (3)-Yes.(4)-Yes. A separate B battery can alsobe used.

* *

I HAVE a tuned radio frequency trans-former, containing a 15 turn primary anda 50 turn secondary wound on a 3" dia-meter tubing; a variometer with a 58turn rotary section, wound on a 24"diameter tubing and a 74 turn stationarysection wound on a 3" diameter, and a.0005 mfd. variable condenser. The radiofrequency windings consist of No. 24double cotton covered wire, while the vari-ometer windings consist of No. 26 doublecotton covered wire. Can I have the cir-cuit diagram of a 3 -tube receiver usingthese parts. I wish to use transformersin the audio stages. Please state the type.-Maxwell Phillips, Hollywood, Cal.

The windings on the radio frequencytransformer will have to be changed.That is, the number of turns on the sec-ondary winding will have to be reducedto 44 turns. It is also advisable to reducethe number of turns on the primary wind-ing to 10. The circuit diagram of a re-ceiver using these parts is shown in Fig.485. It employs a regenerative detectorand two stages of transformer coupledaudio frequency amplification. Both thesetransformers should be of the low ratioorall stage type. The tuned radio fre-quency transformer is used in the antennaand grid circuits, while the variometer isused to control the oscillatory action ofthe tube, it being in the plate circuit.Across the secondary winding of the tunedRFT, the .0005 mfd, variable condenseris shunted. A 20 ohm rheostat is used tocontrol the filament temperature of thedetector tube, which is of the -01A type.A .00025 mfd. fixed condenser is used incombination with a 2 megohm leak in the

grid circuit. C3 is a .001 mfd. fixed con-denser used for bypassing. A ballast re-sistor is used to control the filament tem-perature of both AF tubes, which are alsoof the -01A type, SCJ is a single circuitjack, S is a filament switch. A single 13voltage is used for the detector plate anda single B voltage is used for the am-plifier plates. If you use the 15 turnprimary, you are liable to experiencetrouble with uncontrollable oscillations onthe low waves and also broad tuning.

* * *HOW MANY Canadian broadcasting

stations are there at present? (2)-Howmany of these stations are owned by theCanadian National Railways? (3)-Howmany Cuban broadcasting stations arethere? (4)-Has WRW, of Tarrytown,N. Y., discontinued operation ?-SamuelLessens, Port Jervis, Conn.

(1)-There are 53 stations (2)-Ten areowned by them. (3)-Ten stations. (4)-Yes.

* * *

CAN RESISTANCE coupled AF am-plification be used instead of the trans-former coupled audio frequency amplifica-tion, in the 9 -tube Super-Pliodyne, de-scribed in the Aug 14 issue of RadioWorld, Radio University columns? (2)-Can ampere ballast resistors be usedto control the filaments of the RF tubes,one for two tubes at a time? (3)-Cana power tube be used in the last stageof resistance coupled AF amplification?-Warren Howard, Pittsburgh, Pa.

(1)-Yes. Higher plate voltage will haveto be applied. The exact voltage will bedependent upon the tubes. (2)-Yes. (3)-Yes. Apply the proper B and C volt-ages.

* * *

IF I reduce the number of turns on theprimary windings of the radio frequencytransformers, in my 5 -tube tuned RF set,will the tendency of the tubes to oscillatedecrease? (2)-Do run down B batterieshave a tendency to cause the tubes tooscillate? (3)-If I space the primarywinding further away from the secondarywinding, will the tubes decrease theiroscillatory action on the lower waves?(4)-If I place the coils further awayfrom each other, will it aid keeping theoscillatory condition of the tube down.At present they are angles, but about 2"from each other. (5)-Will shieldingbetween the radio frequency coils aid indecreasing the oscillatory action of thetubes?-Morgan Fitzgerald, East Pitts-burgh. Pa.

(1)-Yes. (2)-Yes. (3)-Yes. Sug-gest you see the Dec. 18 issue, in the ex-planation of the operation of the Equa-matic coil in the special one and threetube. (4)-Yes, at least 4". (5)-Yes.the shields should be grounded.

Join RADIO WORLD'S University ClubAnd Get Free Question and Answer Service for the Coming 52 Weeks

This Service for Yearly Subscribers Only

Have your name entered on our subscription and University lists by special number.Put this number on the outside if the forwarding envelope (not the enclosed return)envelope) and also put at the head of your queries. If already a subscriber, send $6for renewal from close of present subscription and your name will be entered in RadioUniversity. No other premium given with this offer.

[In sending in your queries to the University Department please paragraph them so thatthe "reply can be written under or alongside of each query, Write an one side of sheetonly. Always give your university number.]RADIO WORLD, 145 West 45th Street, New York City.

Enclosed find $C00 for RADIO WORLD GI,- one year (52 nos.) and also enter myname on the list of members of RADIO WORLD'S University Club, which gives mefree information in your Radio University Department for 52 ensuing weeks, and send

me my number indicating membership.

Name

Street

City and State

16 RADIO WORLD December 25, 1926

Atlanta's SchoolsTeach With Radio

ATLANTA, GA.In the Atlanta educational system, the "three Rs" no more

exist. There are now four and the fourth is Radio.Daily classroom instruction by radio is being given in each

of the 70 public schools.On the basis of more than two months' experience with

radio as an adjunct to teacher instruction, Willis Sutton,superintendent of schools, is not only convinced that radiowill be retained as a permanent instrumentality of educationin Atlanta, but that its adoption by school systems generallyis inevitable. Both as a factor in education and as an aidin school administration, he declares the value of radio hasbeen proven unmistakeably by the Atlanta experiment.

But a value even beyond these, Superintendent Sutton be-lieves, is established by radio in the schools. It widens theeducational horizon and fires the imagination of the studentsas no other agency of instruction ever has done. The stimu-lated interest and broadened scope of work has thus madepossible, promise to give our schools new efficiency and toplace the American educational system on a level neverbefore approached. National educators, particularly the ex-perts of the United States bureau of education, in Washington,and leaders in the National Educational association, are watch-ing the Atlanta experiment with great interest.

Must Adopt Modern Devices"Any school system that does not recognize and adopt the

latest and most modern devices," says Superintendent Sutton,"is out of date. And any school system that does not lookat least 13 years ahead cannot serve its students with thegreatest degree of usefulness.

"The public schools demand and take 13 years of a child'slife. At the end of that time he is supposed to be ready toenter into the usual activities of life. If equipment and ap-pliances and modern devices as now used are not includedin the teaching material, then the child will enter life handi-capped. If: I

"So marvelous a discovery as radio must be shaped into amedium for broader education. It must be utilized both as ameans of stimulating the interest of the pupil and for provid.ing more effective teaching. The amount of knowledge thatmay be communicated by radio, the time saved for schooladministrators in disseminating this information, the intensityof the child's attention, and the certainty that the same mes-sage is delivered to all-all these give to radio distinct educa-tional value."

Experts Make the' InstallationIn developing the necessary radio plant for the Atlanta

school hookup, Dr. N. R. Eubanks, president of the board ofeducation, and Superintendent Sutton obtained the co-opera-tion of radio experts. The result is a uniform high-gradeinstallation that insures maximum reception under all condi-tions. Each of the 70 schools in the city-white and coloredalike-is equipped with a modern five -tube receiving set andloudspeaker. A microphone in the office of the superintendentof schools carries the broadcasts to station WSB, where theyare put on the air.

One daily 30 -minute radio period suffices to give each gradeone radio lesson each week. On Mondays there is a programfor the kindergarten and the first grades. Tuesdays, the juniorand senior high schools have the radio hour. On Wednesdaysthe program is shaped for the third and fourth grades, onThUrsdays for the high schools again, and on Fridays the fifthand sixth grades are the lucky ones.

"Thus every child in Atlanta," Superintendent Sutton pointsout, "has the opportunity to listen to at least one radio lessoneach week.

Faculty Meetings Use Radio"In addition the radio is used for weekly faculty meetings

of the entire force. Another decided advantage is the factthat the superintendent and supervisors can speak instantly tothe entire teaching force, without the difficulty and expenseof assembling at some -central point. There is a unifyingpower in this method of procedure that is giving solidarity tothe entire system.

"The Parent-Teacher Association also is addressed over theradici. Messages concerning the health of the children, adviceas to how the children should be taught to i.tudy and informa-tion concerning the public schools in general constitute a partof the material for these talks.

"At 6 p. m. each day a program for both parents and chil-dren is put on. Prominent educators, entertainers and musi-oians are employed."

FORMER EMPRESS

ide World)

THE FORMER EMPRESS ZITA of Austria, with her sonhome in Lequeito, Spai

AID TO BEAUTY

(Hayden)

A CONE SPEAKER can be made moredecorative with the aid of designs andother illustrations cut out of magazines.These designs may be pasted on the pa-per of the cone. The lower photo showshow a cut out parrot is being prepared

for pasting,

HI

(Herbert PhotIT SEEMS TOplay, "Adele Disreaders of theBrows loses a IJ

December 25, 1926 RADIO WORLD 17

'ND FAMILY ENJOY SET

and his brothers and sisters, spending a quiet evening at theirtuning to a radio concert.

WOOD BROUN KEEN. FOR DX

that Heywood Broun, who gained all deserved renown for his," gets just as big a kick out of tuning in distant stations as

"World" get out of his masterful daily column. When Mr.ation, due to fading, he wreaks his vengeance on the punching

bag, or lights a cigarette.

McCormack-PonselleNew Year Program

Radio programs for the New Year have a most pretentiousbeginning with the presentation of four operatic and concertartists of world-wide reputation in a two-hour program to begiven by the Victor Talking Machine Company on the'eveningof New Year's Day. The artists are: John McCormack,tenor; Rosa Ponselle, soprano; Afischa Elman, violinist, andAlfred Cortot, pianist. With them will be heard the VictorSalon Orchestra, under the direction of Nathaniel Shilkret.

The program begins at 9 p. m. Eastern Standard Time andwill be broadcast simultaneously through practically all of theNational Broadcasting Company's "Red Network," withWEAF as the "key" station, in addition to its newly formed"Blue Network" emanating from WJZ.

Red and Blue TogetherThe "Blue Network" is broadcasting its first simultaneous

program this evening under the new arrangement which en-ables the distribution of WJZ features to WBZ, Springfieldand Boston, KDKA, Pittsburgh, and KYW, Chicago, duringcertain hours throughout the week. The stations of the "RedNetwork" participating will be: WEAF, New York; WEEI,Boston; WJAR, Providence; WT/1G, Worcester; WFI,Philadelphia; WCAE, Pittsburgh; WTIC, Hartford; WGR,Buffalo; WRC, Washington (D. C.); WGN, Chicago; KSD,St. Louis; WOC, Davenport; WCCC, Minneapolis -St. Paul;WCSH, Portland (Me.); WDAF, Kansas City (Mo.);WTAM, Cleveland; WWJ, Detroit, and WHAD, Milwaukee.It is quite possible that others will be added to the latter listbefore the evening the program is presented.

Of the four artists on the program, three of them are beingheard over the air for, the first time. John McCormack hasbeen heard on each of the two previous Victor New Yearprograms. The 1927 New Year program marks the radiodebut of Rosa Ponselle, Elman and Cortot.

Remainder of SeriesElman is being heard in concert this season with these Elman

String -Quartette and the January 1 broadcast is not only hisfirst appearance before the microphone, but is also his firstsolo concert of the season. He sails for Europe a few daysafter his appearance during the coming Victor presentation.

Cortot will also sail for Europe shortly after the Victor.concert. He is now on a concert tour which is announced ashis last American tour for two years. --

Following the New Year's night program, the remainingconcerts in the Victor series will be heard on alternate Fridayevenings from 9:00 to 10:00 o'clock, Eastern Standard Time,throughp the National Broadcasting Company's "Blue Net-work."

WGY to Be ChristmasGift Jesting Station

WGY will be the Christmas broadcast testing station.The Schenectady transmitter will go on the air at 6:30

Christmas morning, enabling recipients of radio sets fromSanta Claus to test the outfits for distance and quality. Mostof the country will be in darkness at that hour and the rangeof station should be very nearly that of night.

So far as the technical operators of WGY are concernedChristmas is just another day for service to radio listeners.The day's schedule calls for operation morning and evening.

The day's broadcasting will start at 6:30 a. m. with theCandle Service of the First Lutheran Church of Albany, N.Y. This is the oldest Lutheran Church in America and theCandle Service has been a Christmas feature for many years.A large vested choir will lead the congregation in singing offamiliar Christmas carols and the sermon will be by the pastor,the Rev. Charles E. Frontz.

At 11 a. m. the service of St. Peter's Episcopal Church ofAlbany will be put on the air. The Rev. Charles C. Harrimanwill give the Christmas message and the choir, under thedirection of Dr. Frank Sill Rogers, will offer a special pro-gram of music,

From 6 o'clock until midnight WGY will be continuously o' -the air beginning with dance music by the Original BayState Aces. A program_ of dinner music will be furnished bythe Hotel Onondaga Orchestra, following which Shea'sBuffalo Theatre will send down a half hour variety program.

A feature of the evening will be another program in theexceptional series presented by the Boston Symphony Orches-tra. WBZ and WJZ will also broadcast this program.

18 RADIO WORLD December 25, 1926

A THOUGHT FOR THE WEEK

Perhaps the 1926 Santa Claus will dis-play a new get-up on Christmas Eve.Earphones, spaghetti wiring for whiskers,a cone speaker for a hat and a tube forthe jolly red nose-who can tell? SantaClaus is so real, even to grown-ups, thatany change in standard equipment willbe met with mixed feelings by an aston-ished world.

PAREG.US PAT. OFF

The First and Only National Rad.o 14'eeklyRadio World's Slogan: "A radio set for every home."

TELEPHONE BRYANT 0558, 0559P UBLI SUED EVERY WEDNESDAY

(Dated Saturday of same ek)FROM PUBLICATION OFFICE

EIENTNESSY RADIO PUBLICATION CORPORATION145 WEST 45th STREET, NEW YORK, N. Y.

(Just East of Broadway)ROLAND BURKE HENNESSY. President

NI. B. HENNESSY, Vice -PresidentFRED S. CLARK, Secretary and Manager

European Representatives: The International News Co.Breams Bldgs.. Chancery Lane, London, Eng.

Paris, France: Brentano's, 8 Avenue de l'OperaChicago: Willitm A. Diehl, 30 North Dearborn St.

Los Angeles: Lloyd B. Chappell, 611 S. Coronado -St.

EDITOR, Roland Burke HennessyMANAGING EDITOR, Herman BernardTECHNICAL EDITOR, Lewis WinnerART DIRECTOR, .I. Gerard Sheedy

CONTRIBUTING EDITOR, James H. Carroll

SUBSCRIPTION RATESFifteen cents a copy. $6.00 a year. $3.00 for six

months. $1.50 for three months Add $1.00 a yearextra for foreign postage. Canada. 50 cents.

Receipt by new subscribers of the first COPY of RADIOWORLD mailed to them after sending In their order isautomatic acknowledgment of their subscription order.Changes of address should be received at this office twoweeks before date of publication. Always give old address;also state whether subscription is new or a renewal.

ADVERTISING RATESGeneral Advertising

1 Page, 7 % "xl 1" 462 lines $300.0004 Page, 7 %"x5 %" 231 lines

135000..0000

% Page, 814" D. C. 231 lines 150.00% Page. 404" D. C. 115 lines 75.001 Column. 204"x11" 154 lines 100.001 Inch 10.00

Per Agate Line .75Time Diseount

52 consecutive issues 20%26 times consecutively or E. 0. W. one year 15%

4 consecutive issues 10%VirEEKLY, dated each Saturday, published Wednesday:

Advertising forms close Tuesday. eleven days in advanceof date of issue.

CLASSIFIED ADVERTISEMENTSTen cents per word. Minimum 10 words. Cash with

order. 13usinese Opportunities ten cents per word, $1.00minimum.

Entered as second -claws matter March 23, 1922, atthe Post Office at Nets York, N. Y., under the Act ofMarch 3. 1879.

KJR USING 20 KWKJR, Seattle, Wash., has increased

its power to 20,000 watts, becoming oneof the four super -power stations in theUnited States.

CLOSING OF MANYSTATIONS URGED

Air Committee of American Bar Association Sees Shutdown of Hundreds as Only Solution to Congested

Ether-Reimbursement Recommended

The recommendation that several hun-dred stations be closed and put out ofbusiness, the Federal Government to re-imburse these stations and to devise sometax plan for the remaining ones to defraythe actual expense, was made in a reportof the Air Law Committee of the Amer-ican Bar Association. Chester W. Cut-,hell, chairman, gave out the report inNew York City, and said that the prin-ciples set forth in the report were ap-proved by fellow members, includingGeorge C. Bigert of Chicago, formerlydean of the Cornell Law School; W. Jef-ferson Davis of San Diego, Cal.; John C.Cooper Jr., of Jacksonville, Fla., and Rob-ert T. Swaine of New York.

The relief plan offered by the commit-tee is intended as a safeguard to the list-

oening public, so that inter -station inter-ference, and peanut whistles, so prevalentnow, will be avoided. The report setsforth that there are 615 broadcasting sta-tions existing in the United States, 70under construction and 110 others con-templated, all on wavelengths between200 and 600 meters, while there are only89 channels which can be used by allthese stations at the same time withoutinterference with one another.

Congressional action is necessary, thereport states, so that the recommenda-tions can be carried out.

Suspension of New LicensesIn a discussion of opinions and court

decisions which have held that the pres-ent radio regulatory law gives the Secre-tary of Commerce no discretion in issuinglicenses, the report advises that theissuance of any new licenses be suspendeduntil new legislation is enacted to pre-vent the increase of broadcasting stations.The report cites the decision of Chancel-lor Francis S. Wilson of Chicago in anaction brought by The Chicago Tribune(WGN) against the Oak Leaves Broad-casting Station (WGES) as important. Inthis decision, the Court held that the "pri-ority of time created a priority of right,"in the. possession of a wavelength andthat WGN was entitled to the posses-sion of the wavelength it had held forseveral years before WGES undertookto operate on it.

"It seems obvious to our committee thatthere are already too many broadcastingstations and that it is already impossibleto avoid interference if all the stationsare to be permitted to operate at thesame time," the report adds.

Expected to Get Worse"The probabilities are, according to the

Department of Commerce that the situa-tion-bad as it is-will get steadily worseby reason of the fact that the broadcastersare steadily increasing their power. Fivehundred watts was formerly consideredample, but now the stations are usingmany thousands of watts and the ten-dency is constantly upward.

"We understand also that there areproblems other than this one of inter-ference between broadcasters, such as the

possibility that pictures and even motionpictures will be transmitted by radio.within the next few years; that powertransmission by radio is also being ex-perimented with, and that some provisionwill have to be made so as to permit radio.communication for the guidance of air-planes."

The report discusses' the two bills in-troduced in Congress, that in the Senateby Dill and that in the House by White.It expresses a preference for placing theadministration of any new radio regula-tory law in the hands of the Secretaryof Commerce, as proposed by the Whitebill, instead of in the hands of a newlycreated commission, as proposed by Sen-ator Dill.

Opposes Separate Commission

"The opinion of our committee, whichwe believe is shared by a very large per-centage of the bar, is that the creationof more and more commissions, whichare merely appointed by the Presidentand which thereafter do not report tothe President, is not the form of organ-.ization that tends to the greatest ef-ficiency," the report continues. "There isa constant tendency on the part of com-missions to enlarge their own powers.They rarely work harmoniously becausetheir members are chosen from differentparties. They are slower to act and slowerto deal with new problems than an in-dividual Cabinet officer.

"Senator Dill stated to your commit-tee that he believes that this commis-sion would be merely the beginning of acommunications commission. If that beso, then it would be our thought to addanother member to the President'sCabinet and make him Secretary of Com-munications. It seems to us that theframers of the Constitution did not con-template attrition of the Executive'spower by the creation of a series of com-missions, reporting to the legislativerather than to the Executive branch ofthe Government."

In discussing proposed anti -monopolyprovisions of radio legislation, the reportsays:

"The committee believes that it is notthe best legislative policy to incorporatein a radio regulatory measure provisionsthat either parallel or duplicate the Sher-man and Clayton laws with respect tomonopoly or limitation of .competition.

"Those laws have been on the books fora good many years. They have beenlitigated perhaps more fully than anyother group of statutes, and they seemto us adequate to deal with any tendencytoward monopoly. In the Senate bill,however, we think that the provision forrevocation of a license, if the licensee orany subsidiary is found guilty of a re-straint of trade (even though such a re-straint of trade might have been in somebusiness other than radio), is in effect anadditional penalty for tile enforcement ofthe Sherman and Clayton laws. It there -

(Concluded on page 19)

December 25, 1926 RADIO WORLD 19

The Leading Points ROGERS OFFICIATES

Of Lawyers' ReportThe outstanding recommendations of

the Air Law Committee of the AmericanBar Association for clearing the chaosout of the air follow:

That the Secretary of Commerce begiven authority by Congress to closedown several hundred stations.

That the Federal Government reim-burse the stations thus closed.

That the remaining stations be madeto bear the expense by a tax on theirprofits.

That any new legislation vest fullauthority in the Secretary of Commerce,instead of in the hands of any new ex-ecutive commission.

That, if need be, another cabinet port-folio be created, that of Secretary of Com-munications, rather than creation of anexecutive board.

(Concluded from page 18)fore, in our judgment, has no place in aradio regulatory act.

"The provision in the Senate bill, wethink, is improper in that it confers uponthe commission a purely judicial func-tion. The language, 'the commission ishereby directed to refuse a station licenseto any corporation or any subsidiarythereof which has been found guilty byany Federal court of unlawful monopoliesor attempting unlawfully to monopolize,'is more drastic than is necessary.

"Close Several Hundred""It seems to be the consensus of opinion

that to bring about a situation whereinterference will not be possible severalhundred stations now existing will haveto be closed if the remaining stationsare to operate on full time and if poweris to be increased so as to bring aboutthe best conditions for reception. To closestations in which large sums of moneyhave already been invested is obviouslya drastic provision. We do not believethat the courts would hold constitutionallegislation which permitted such closing,either directly or indirectly by way of de-clining to issue new licenses, unless justcompensation were paid.

"We have therefore urged on SenatoiDill and Congressman White that theyincorporate provisions permitting eitherthe commission or the Secretary of Com-merce to close stations entirely and topay compensation. We appreciate thelegislative situation-that such provisionscannot be put in the present bills withoutunanimous consent. Nevertheless, wethink it would be wiser to bring in newbills in order to cover this vital pointThe companies securing the new licenseswhen thus limited will benefit very largely.by the closing of many of the old sta-tion. They will make much larger profitsthan they are now making.

Profits Tax ProposedTherefore they are the companies whose

profits should be taxed in order to providethe funds to pay the compensation tothe stations which have been closed.

"In summary permit us to state thatwe believe that either of the bills wouldbe an improvement over the existing sit-uation, but only in respect to future li-censes. On the other hand we thinkneither bill deals, except by indirection,with the present condition, which the Sec-retary of Commerce says is chaotic.

"The committee believes that if its sug-gestions are followed there will be agreater justification for more- completeregulation of the broadcasters and thatthe situation from the point of view ofthe listeners will be .greatly improved."

(Fotograms)AT THE laying of the cornerstone ofthe Ziegfeld Theatre, Fifty-fourth Streetand Sixth Avenue, New York City, WillRogers acted as master of ceremonies. Atright is Patricia Ziegfeld, daughter of

Florenz Ziegfeld and Billie Burke.

Stations WaiveRight to Wave

Under New ActWASHINGTON

President Coolidge is expected to signthe emergency measure- passed by theHouse and Senate last session providingthat all stations applying for licenses orrenewals must sign a waiver to any vestedright in a wavelength as against theUnited States Government. The resolu-tion, which also limits broadcast licensesto ninety day periods, will be put intoforce immediately by the Department ofCommerce upon enactment.

According to officials of the Departmentof Commerce, the emergency measure willin no way affect present policies otherthan requiring signature of a waiver.

Congress Is ExpectedTo Pass Relief Bill

WASHINGTON.Meetings of the Conference Committee

of the House and Senate on the Whiteand Dill radio bills were delayed due tothe ill health of Senator James E. Wat-son, (Indiana), chairman of the Senateconferees. Senator Watson was ill sincehis arrival in Washington. Meantime Con-gress continued to mark time so far asradio is concerned.

Reactions in the House and Senate onthe President's message are interpreted asfavoring the White bill which providesfor Department of Commerce regulationof radio, and the general opinion is thata regulatory measure of some kind willbe enacted early in the session.

50,000 WATTS FOR NICEWASHINGTON

A 5 kilowatt broadcasting station is tobe constructed at Nice, France, accordingto a report to the Department of Com-,coerce.

16 New StationsJoin Merry Throng

WASHINGTON.Sixteen new stations have been licensed

by the Department of Commerce, four ofwhich are of 500 watts power. Sevenstations reported having changed theirwavelengths, and one station discontinuedoperation.

NEW STATIONSWKBU-Harry K. Armstrong, New

Castle, Pa., 238 in., 1260 kc., 50 watts.WFKD-Foulkrod Radio Engrg. Co.,

Phila., Pa., 249.9 in., 1,200 kc,, 10 watts. -

KFQX-A. M. Hubbard, Seattle, Wash.,210 m., 1,428 kc., 15 watts.

KVOS-L. L. Jackson, Seattle, Wash.,333.1 m., 900 kc., 500 watts.

WLBH-J. J. Lombardi, Farmingdale,N. Y., 230 m., 1,304 kc., 30 watts.

WMVM-E. J. Malone, Jr., Newark,N. J., 475.9 m., 630 kc., 500 watts.

KGCU-Mandan Radio Ass'n. Mandan,N. D., 285 nt., 1,052 kc., 100 watts.

WABF-Markle Broadcast Corp., Prin-gleboro, Pa., 410.7 m., 730 kc., 500 watts.

WPEP-Maurice Mayer, Waukegan,Ill., 212.6 m., 141( kc., 500 watts.

KGDP-Boy Scouts, Pueblo, Colo., 260.7m., 1150 kc., 10 watts.

KGEA-Puget Sound Broadcast Co.,Seattle, Wash., 345 m., 869 kc., 15 watts.

WRRS-Racine Radio Co., Racine, Wis.,360 m., 832.8 kc., 10 watts.

WPAB-Radio Corp. of Va., Norfolk,Va., 319 m., 940 kc., 100 watts.

KGDR-Radio Engineers, San Antonio,Texas, 240 m., 1249 kc., 15 watts.

WWVA-J. C. Stroebel, Wheeling, W.Va., 348.6 m., 860 kc., 100 watts. .

WLBI-A. Yarc, East Wenona, Ill.,296.9 m., 1010 kc., 250 watts.

The following stations changed theirwavelengths: WKBO, Newark, N. J., from309.1 m., 970 kc., to 303.9 m., 980 kc.;WCOA, Pensacola, Fla., froth 222.1 m.,1350 kc., to 252 nt, 1190 kc.; WSAR, FallRiver, Mass., from 254.1 m., 1180 kc., to322 m., 931.1 kc.; WKBM, New Yorc,from 215.7 m., 1390 kc., to 285.5 m., 1050kc.; KFVD, Los Angeles, from 205.41460 kc., to 208 m., 1441 kc.' WOAN,Lawrenceburg, Term., from 282.8 m., 1060kc., to 356.4 m., 841.2 kc., and KGCL,Seattle, Wash., from 230.6 m., 1300 kc., to238 m., 1260 kc.

The calls of the following stations havebeen changed: WABC, Ashville, N. C.,changed to WWNC; KGCM, San An-tonio, changed to KTAP, and WJAF,Ferndale, Mich., changed to WTHO.

KGBW, a 250 watter at Jon1; Mo., isreported as having discontinued operation.

Her Visit to WEAFLeads to the Altar

BROOKLINE, Mass.Little did Violet E. S. Stewart realize

that the writing of words of appreciationto WEAF, would result in a ro-mance. However, recently, Mr. and Mrs.Charles E. Stewart announced the mar-riage of their daughter, Violet, to Har-old M. Schaffer, the assistant programdirector of the station.

When a letter of thanks from MissStewart for complying. with requests toplay certain numbers was received at thestation several members of the orchestrasand their wives sent her an invitation tovisit the station for inspection and seehow the broadcasting is actually carriedon. She accepted and it was during thisvisit that she met Mr. Schaffer.

GRID WIRING CRITICALIf a detector tube squeals when you put

your hand near it, inspect the grid wiring.

20 RADIO WORLD December 25, 1926

EYES TO WATCHSCENES BY RADIO

(Fotograms)DR. E. F. W. ALEXANDERSON, chief consulting engineer of the GeneralElectric Company, testing out one of his experimental television projectors. Thisis the first public announcement that the noted genius is experimenting with

television.

Scientists Encouraged by Advance in Televison Experi-ments-Alexanderson Is Revealed as Inventor

of One Machine

By Conrad NugentExpert on Television

Many scientists say that television iscoming, but few will undertake to statethe approximate time when it will arrive,because at the present time no sure wayof accomplishment has been revealed. Yetthey state that it is coming because suchencouraging advance has been made.

Many experimenters have attacked theproblem. A few have had a certainamount of success. Noteworthy amongthose who have made progress are JohnBaird of Scotland; C. F. Jenkins in Wash-ington, D. C., and E. F. W. Alexander -son. Baird employs .a large number oflights, Jenkins a revolving disc containinga large number of prisms, and Alexander -son employs a revolving cylinder contain-ing a large number of mirrors.

The problem of television may be stated

briefly in terms of transmission of pic-tures by wire or radio. Pictures may nowbe sent successfully but it takes from 10to 20 minutes to send a complete picture5x7" in size. Say that it takes ten min-utes to send an average picture. A motionpicture must contain at least 16 separatepictures every second to give the illusionof continuous motion. In television thesame number of pictures must be sentper second. But how much time is therein which to send each picture? A motionpicture is on the screen one -fifth of thetime and off four -fifths. That means thateach picture is only on the screen one -fifth of one -sixteenth of a second, or inone -eightieth of a second. In televisioneach picture must be sent in the sameshort time. Since it takes 10 minutes nowto transmit a complete picture it is obvi-ous that the solution of the- televisionProblem lies in increasing the speed oftransmission of ordinary pictures in the

Expectation ofTelevision Good,Says Alexanderson.

ST. LOUIS.A television projector which he believes

will result in a realization of the dream ofa direct vision of moving objects bymeans of radio, was explained by Dr. E.F. W. Alexanderson, consulting engineerof the General Electric Co. and the RadioCorporation of America, in the course ofan address before the members of $t.Louis section of the American Instituteof Electrical Engineers.

Many internationally known scientistsand experimenters have declared thattelevision is impossible, but Dr. Alexan-derson, who has devoted a great deal oftime to telephotography and television,declared that "our work has alreadyproved that the expectation of televisionis not unreasonable and it may be accom-plished with means that are in our pos-session at the present day. How long -itwill take us to attain practical televisionI do not venture to say."

Radio transmission of a single photo-graph has been accomplished by Alex-anderson in two minutes in the researchlaboratories of the General Electric Com-pany. Television will require the trans-mission reception and reproduction of asingle picture in one -sixteenth of a sec-ond. One of the fundamental difficultiesin the way of a speed of sixteen picturesper second is the development of a pro-jector which will enable anyone to see ona screen the movement of objects milesaway,

Dr. Alexanderson explained the tele-vision projector which he now has in ceration in his laboratory and by means ofwhich he is hopeful of getting the 300,-000 brush strokes per second that arenecessary for producing motion pictures.

"It is easy enough to design a tele-vision system with something like 40,000picture units per second," stated Dr.Alexanderson, "but the images so ob-tained are so crude that they would haveno practical value.

ratio of 1/80, to 600, or they must betransmitted 48,000 times faster than theyare now. There may be a simpler way outof the difficulty, but it is not now on thescientific horizon.

The question may now be raised whythe picture could not be reduced in sizeand thus increase the speed of transmis-sion somewhat. The answer is that lackof definition of the picture. If the sizeis decreased, it must be enlarged afterreception, and the enlarged picture wouldlack detail. It would be like a pen andink drawing with very heavy lines.

In the photo herewith is shown Dr.Alexanderson and his machine. The largebright spot in the background is an arclight. Then there are three lenses in arow, and finally is the large wheel con-taining the mirrors. Note the seven brightspots on the screen to which Dr. Alex-anderson is pointing. When the wheelcontaining the mirrors rotates at a highrate of speed, the seven spots cover theentire screen in rapid succession. If theintensity of the spots varies from black towhite in accordance with the gradationsof a picture a person viewing the screenwill see the picture reproduced on thescreen provided that the picture is tracedout rapidly enough. If a complete pictureis traced out once in every sixteenth ofa second' a moving picture may be seen.

Some striking demonstrations of thevarious methods, in their present state ofincompletion, have been given beforelearned spectators, who patted the demon-strators on the back and said that someday men will focus their eyes on a re-ceiver and see by radio what is being en-acted at the studio.

December 25, 1926 RADIO WORLD 21

WAVE REFLECTEDBY IMPEDIMENTS

Loop Is Used to Determine from What Direction theEnergy Comes, as Contrasted with the

Geographical or Compassed Direction

By Hood AstrakanTheoretically the radio wave front is

a perfect sphere; actually it has a shapewidely divergent from that. The wavefront is distorted by all obstacles in itspath. What happens to the radio wavemay be compared with the conditions metby a water wave. Suppose a stone isthrown into a still body of water. A seriesof circular waves starts from the pointand advances in the shape of ever-increas-ing circles. The wave front is circularin this case. But if there is an obstaclein the water the circular front of the wavewill be distorted. There will be a smallwave starting back again, that is, it willbe reflected. Behind the obstacle therewill be a certain area"of still water, orthere will be a "shadow." If the wavestrikes a very large obstacle like ashoreline, most of the wave will be reflectedand part of them will be -absorbed. Simi-lar phenomena take place in radio, onlythey are much more complex becausethere are many more obstacles.

Antennas, used for receiving, walls,chimneys, rivers, storm areas, shore lines,are all obstacles to a radio wave. Someof them affect the wave front just a little,others a great deal. An antenna is a sinkhole into which radio energy disappears,that is, the antenna is an absorber. Struc-tures such as walls and chimneys are ob-stacles which absorb, bend and reflect thewave. Near them the apparent directionof the origin of the wave is not the truedirection. If they reflect the greater partof the wave, the apparent direction oforigin may be exactly reverse from thetrue origin. If these objects bend thewave the apparent direction is changedto a smaller degree. An analogy may becited from optics. A straight rod insertedpartly into water will appear bent. Ifone should sight along the immersed por-tion one would not look in the directionin which the other end of the rod actuallyis.

Storm areas are obstacles because thereis a difference in the velocity of the radiowave, which is due to the difference inthe barometric pressure. A river or otherwater course is an obstacle for a similarreason.

The direction of the wave front at anypoint may be determined very easily byan ordinary loop and a receiver, and thusthe distorting effect of various objectsmay be found. The. loop is set in thedirection in which the signal from a cer-taM station comes in loudest. The planeof the loop then points in the apparentdirection of the broadcast station. Thisis compared with the actual direction inwhich the station lies as determined froma map or with a compass.

In the photograph the man with theloop is engaged in determining the dis-torting effect on the wave front of thechimney to his left. Where more ac-curate work is desired the operator him-self should remove himself from the fieldof influence of the chimney or he willintroduce additional distortion. Carefuloperators turn the loop by means of longstrings and a couple of levers attached tothe loop.

90 -Day License

Confirmed By LawJoint Resolution (S. J. R. 125) signed

by President Coolidge, which providesa limitation of time from which radiobroadcasting licenses are effective, merelyconfirms the present practice of the De-partment of Commerce, said SecretaryHoover.

The Department, Secretary Hooversaid, had always held broadcastinglicenses to 90 days, and this practice offive years standing has not been in-volved in recent judicial decisions.

Efficiency RuinedBy Stray Leakage

In Direct CouplingBy SPENCER BURROUGHS

One of the most frequent causes offailure of direct coupled amplifiers is thecoupling condenser which is used to iso-late the grid from the plate of the pre-ceding tube. The trouble is that it doesnot isolate. At times it is leaky, and whenit is it is useless for isolation purposes.It is then impossible to maintan the gridof the tube negative no matter what rea-sonable value of grid -leak is employed.This trouble is often attributed to block-ing -of the grid when it is in reality due toa reverse condition, that is, to a too muchpositive grid.

As a proof of this a tube was calibratedunder actual working conditions in a re-sistance coupled amplifier, that is, a gridvoltage plate current curve was takenfrom zero plate current to saturation.Such a curve may be used to determinethe actual grid potential by measuringthe plate cu -rent. When no potentialwas applied to the plate of the precedingtube the calibrated tube behaved nor-mally when the grid bias was varied, evenwhen fairly high grid leak resistance wasused. But when the voltage was appliedto the plate of the first tube the platecurrent in the second tube would not re-spond to changes in the applied gridvoltage. The plate current indicated ahighly positive grid even when the ap-plied grid voltage was so much negativethat it should have reduced the platecurrent to zero. Removing the platevoltage from the preceding tube immedi-ately restored.the second tube to normal.The rate of leakage through the con-denser was much greater than the leak-age through the grid leak, even when theleak resistance was reduced to very lowvalues.

Some condensers are better in this re-spect than others, even condensers of thesame make and capacity.

This trouble may arise also from leak-age through the insulation other thanthat of the condenser. For instance, cer-tain sockets are leaky, particularly onthe surface. Again, the sub -panel orbaseboard may be at fault. One frequentcause of the trouble is the mounting unitfor the coupling resistor and the gridleak. Some materials are very leaky andare wholly unsuitable for this purpose.

Dr. Taylor RecallsAid to Explorers

WASHINGTON.Dr. A. Hoyt Taylor, Chief of the Naval

Research Laboratory, at Bellevue, is fondof telling of unusual experiences is con-nection with his work.

One night two years ago the operatoron late duty at NKF, the Laboratory sta-tion, heard a weak call by a station sign-ing itself GNB. The operator knew ofno such station and in curiosity he tunedin and asked who it was. It was theRoosevelt Expedition in Brazil 6,000 milesaway. The expedition was being attackedby brigands and wanted help immediately.The operator called the Brazilian Lega-tion on the telephone and a cable was dis-patched to that government.

The Laboratory kept in constant com-munication with the Expedition through-out that night and the next day. The ex-pedition had a gasoline engine and, whenrunning it sounded like a machine gun.This kept the brigands off for a shorttime but the engine ran out of gas. Thebrigands then closed in and robbed theparty of its transportation facilities.

9? RADIO WORLD December 25, 1926

THE RADIO TRADE

PROSECUTOR PUTON GRE ES CASE

Defendant's Alleged Model of Neutralization InventionVanishes in Action Brought by Hazeltine-Court

Orders Inquiry by District Attorney

Federal Judge Moscovvitz in Brooklynrecently ordered that the minutes of someof the testimony in the suit for $100,000,-000, brought by the Hazeltine Corpora-tion against the A. H. Grebe Companyfor infringement of certain radio patents,be turned over to the District Attorneyfor investigation.

The Hazeltine Company charged thatthe process of plate neutralization, orneutrodyne, patented by Professor LouisA. Hazeltine December 5, 1922, had beenimproperly used by the Grebe Company.Mr. Grebe admitted that the sets hiscompany manufactured employed a sim-ilar process of neutralization, but said itwas for the use of tuned and untunedcircuits, while the Hazeltine patents cov-ered untuned circuits alone.

Their process, Mr. Brebe said, had beenpatented November 2, 1926. The patenthad been issued to Carl 0. Weber, of 412East Fifty-first Street, and was ownedby the Electric Service Engineering Com-pany, whose laboratories are at 105 WestForty-seventh Street.

The Hazeltine Company denied this dif-ference between the use of circuits andobtained a subpoena for a model built byWeber, which the Grebe Company saidproved their right to the patent.

This model was never produced incourt. Mr. Weber testified it had beenstolen. He said he had got the modelto bring it to court, when he noticed thatit seemed to have been tampered withand would not work. He passed most ofa night, he said, in repairing it and leftthe laboratories of the Electric ServiceCompany.

On his return in the morning, he said,

he found the model had been stolen.Isaac Gottlieb, of Cedarhurst, L. I.,

secretary -treasurer of the Electric Serv-ice Company corroborated him.

Judge Moscowitz reserved decision onthe 'question of admitting this testimonyas evidence and turned it over to theDistrict Attorney, should the latter findground to use it as the basis of a criminalaction.

The final decision in the suit will de-termine whether the Hazeltine Companyhas a monopoly of the manufacture ofplate neutralization sets. At the presentthere are more than 500 independent com-panies manufacturing such sets.

The outcome is eagerly awaited.

ALBANY INTERFERENCE CUREDALBANY, N. Y.

Albany's radio interference noises, firstcalled to the attention of power andtraction officials in a story which recentlyappeared in this city's papers, were fasttraced down and the cause removed, un-der the direction of radio engineers.

C. C. Harris, radio engineer in the em-ploy of the Radio Corporation of America,sent to Albany to lend his aid and thebenefit of his training and experience inrunning down radio interfereces, reportedmuch progress. He was receivig full co-operation of the Municipal Gas Companyand the United Traction Company in hiswork. Mr. Harris was assigned to Al-bany at the request of Sidney J. Laneof the Havens Electric Company.

Other investigating parties were mak-ing progress in bringing about the elim-ination of the annoyances.

Hazeltine teginsThird Kent Suit

NEWARK, N. J.An action alleging infringement of the

Hazeltine neutrodyne patent has beenfiled against E. B. Latham & Co., a dis-tributor of radio receiving apparatus inNew York City by the Hazeltine Corpora-tion and Independent Radio Manufactur-ers, Inc., in the United States SouthernDistrict court of New York.

The action just filed is the third ofa series alleging infringement of the Haz-eltine patents through the manufactureand sale of the same radio receivers. Oneaction was filed recently in the courts ofPennsylvania against Atwater Kent Man-ufacturing company, and a second in theEastern district Federal court, of Brook-lyn against E. A. Wildermuth, another dis-tributor of the Atwater Kent Manufac-turing company.

$2,000,000 FOR HIGH FREAKSOne Michigan concern alone spent $2,-

000,000 last year on research in the field'of short waves.

Home Builder Knows,Says Veteran Dealer

SAN FRANCISCO.Parts of home -built radio sets are in

large demand, according to Conrad Rich-ter, manager of a radio store at 1284Market Street. Experimenters, both oldand young, are making sets of their ownwith the same fervor and enthusiasm thatattended the first two years of broadcast-ing.

The home -set builder of the presentday, says Richter, demands parts of high-class manufacture, whereas the earlierexperimenters were satisfied with almostanything. "He knows a great deal aboutradio today and you can't fool him withparts of inferior construction."

Richter -started in the radio businessnearly twenty years ago, long beforebroadcasting was ever dreamed of.

NEW SHOP IN IOWAMONTICELLO, Ia.

A new radio shop has been opened hereby Messrs. Harms and Zimmerman. Inaddition to selling radios they will repairoutfits.

Dealer Tries StuntTo Bring a Crowd

To Set on WheelsHUTCHINSON, Kans.

A. R. Cogswell, a radio dealer at Kir-win, Phillips county, has adopted an in-teresting method of attracting the at-tention of prospective radio buyers.

He tells how he- did it in this letter :"I put a five tube set in the rear seat

of my car and hook up dry B and C bat-teries. Then I hook the set ter- the carbattery for A current. A piece of wireabout ten feet long is hooked to the Apost and a battery clip to the outer end.A loud speaker is set on the trunk onthe rear of the car and attached to theset.

"I drive up in the street where therewere a few people and get out of the carwith a screwdriver, take hold of the, wireconnected to the A post of the set andstick the screwdriVer in the ground andclip the wire to it. Before starting, theset is tuned to KFKX and as I get outof the car I connect the positive A. Asquick as I touch the wire to the screw-driver the speaker begins giving the doperight out. I do not get any very greatdistance during the day time but at nightI get nearly anything.

"The action -is that of a big condenser,as the negative post of the car battery isgrounded to the frame and the entire carbecomes one side of the condenser withthe ground forming the other. It hap-pens that I have disc wheels on my carand the same thing tried in a coach withwooden wheels was even more success-ful."

Swindlers DecampWith Sets On Trial

LAWRENCEVILLE, Ill.Merchants throughout the State- are

being warned of a new type of swindle, aradio swindle, that has been worked suc-cessfully in Rockford. The warning wasissued by the Illinois Chamber of Com-merce. The two swindlers went to Rock-ford recently and rented apartments indifferent parts of the city. Then each ofthem ordered a radio, on trial, from eachof the twenty-two radio dealers in Rock-ford. They got away with about $3,000worth of radios.

Another radio graft has also been foundin Rockford. One man there kept him-self in radios for forty-four weeks by"trying out" various radios for two weekseach at the expense of each of the twenty-two dealers there. From now on theRockford radio dealers are to reportevery radio sale and each machine putout on trial to the local chamber of com-merce for a checkup.

FIRE IN HURON SHOPHURON, S. D.

The Brand Brothers Tire & Radio Shopwas damaged by fire with a loss of $3,000.

NEW CORPORATIONSHygrade Radio Products, Newark, N. J., 500

shares, no par; Gale Harrison, Bloomfield, N. J.;Vernon W. Bennett, Alice M. Bennett, Newark,N. J. (Atty., Michael Breitkopf, Newark, N. J.)

Transcontinental Coil, Inc., Newark, N. J., coilsfor radios, 500 shares, no par; Gale Harrison,Bloomfield, N. J.; Vernon W. 'Bennett, Alice M.Bennett, Newark, N. J. (Atty., Michael Breit-kopf, Newark, N. J.)

Bernice Radio Electric Shop, 9816 Dexter Boule-vard, Detroit, Mich., wholesale and retail radioand electrical supplies, $1.0,000. (Incorporated un-der the laws of Michigan.)

Altitude Radio Manufacturing & Supply Co.,Denver, Col., $15,000. E. A. Morassey, C. H.Alexander, R. F. Whitmore. (Incorporated tinderthe laws of Colorado.)

December .5. 1926 RADIO WORLD

Field Studies HeldA Boon to Business

LINCOLN, Neb.The comforts of the modern midwest

homes have made radio problems in thissection that differ widely from the inter-

. ference encountered in the east, accord-ing to J. B. Ferguson, president of J, B.Ferguson, Inc., of New York City. Mr.Ferguson was the guest fora few days ofDonald Chaplin of the Chaplin ElectricCo. Mr. Ferguson made a trip over themidwest territory to investigate radioproblems in this part of the country.

"You have considerable man-madestatic in this section caused by arc lights,electric refrigeration and other modernappliances in the homes," said he.

Mr. Ferguson feels that radio manu-facturers must make separate study ofradio problems in the mid -west.

"I feel that the trip should be madetwice a year by the head of every radiomanufacturer, because the problems hereare so different from those of the east,"stated Mr Ferguson.

"You have far more possibilities outhere. Reception is made difficult in theeast because there are so many stationsoperating in the big cities and because somuch steel is used in the big buildings. Ihave gathered some very important dataon conditions which have made it possiblefor me to develop in this territory a de-cided improvement. It is somethin , whichmakes possible the simplifying cf'opera-tion of high powered radio receivers, mak-ing the receiver of today as simplz andeasy to operate as the original crystalreceiver of years ago."

Mr. Ferguson has been engaged inradio engineering work since 1907.

Pioneer OrganizesDrumright Company

KANSAS CITY, Mo.The Drumright Radio Company has

been organized in this city by Jack Por-ter, one of the pioneers in the radio in-dustry, and associates for the purpose ofselling radio outfits and accessories. Mr.Porter was one of the original radio menwho. became interested in the industrywhen its possibilities became known eightor nine years ago and has since continuedhis interests in radio. He began experi-mental work in radio when the firstbroadcasting station was put on the airand has been instrumental in developingthe industry in Oklahoma to a consider-able degree.

The Drumright Radio Company is at136 East Broadway.

KRAFT VISITS ST. LOUISST. LOUIS, Mo.

Vincent Kraft, president of the North-west Radio Company of Seattle, nowerecting a super -broadcasting stationhere, was a visitor in St. Louis recently.He mentioned as his only worry the loca-tion of a suitable downtown studio. Thenew plant will cost nearly $100,000.

Radio Mailing Lists27428-Radio Dealers, Retail, Per M $ 7.502660-Radio Mfrs., Per List 20.002857-Radio Jobbers, Per Lit 22.501847-Radio Jobber rated $5,000 and

up. Per List 15.001060-Radio Mfrs. Complete Sets, Per

List 10.00and any other Radio List you want. Askfor detailed price ILsts all guaranteed as%correct.

Trade Circular Co., Inc.W, Adams Street Chicago

Basement SidelineBecomes Big Factor

ST. 1.(0 ls, Mo.

The Star Square Auto Siliqdv Com-pany, which recently estalihslied itseighth store in St. Louis at the cornerof Cherokee Street and Iowa avenue, 11;1utilized the whole basement of the estab-lishment to accommodate the radio trade,which now constitutes a major portionthe company's winter business. WillianLisak, formerly of the sales force at th,Locust Street store, is manager of theCherokee Street store, and Edward Weis -endanger, who was in charge of the serv-ice department at the Grand and Shanandoah avenue store, is now managing t

radio department."Radio has become an important factor

in the everyday life of every one now,and our sales departments all over thecity are busy," J. A. StitTelman, generalmanager of The chain of stores, said.

Bensons CombineTheir Two Stores

ST. LOUIS, M.o.The Benson Radio Company, which

formerly operated a wholesale establish-ment at 1003 Pine Street and a retail storeat 920 Pine Street, has combined thestores and now is located at 808 Pine.The Benson company. of which L. A.Benson is president and C. W. Benson.secretary and treasurer, was organizedfour years ago.

L. A. Benson and William Woods, bothradio operators with commercial licenses.opened the first radio house in St. Louis.at the southwest corner of Thirteenthand Olive streets in 1919 under the firmname of Benwood Radio Company. Thisfirm later was combined with the LinzeElectric Company.

GREAT GROWTH IN SOUTHATLANTA, Ga.

The demand for radio this season ac-cording to M. 0. Hutchinson, of th Ful-ton Electric Company, prominent localdistributors. is far greater than normallyexpected. Of course, with the rapid im-provement and developments, certain num-bers outsell other styles, but the growthand development of the industry is verygratifying, especially in the South.

OPERATOR OPENS STORENEW ORLEANS, La.

Guy S. Craig -has quit radio work atsea to open a radio service station at3702 Loyola Street, this city, where hehas installed a shop for the repair andequipment of radio sets.

FINE RADIO CABINETSWE BUILD THEM

esistiet. Rm.. built of hardwood flee ply built upstock solid walnut and genuine mahogany. Size 7018:10 to 7:30:10. Priced from $3.25 to $12.00 Wespecialize on odd sizes. send sketch or blue prints forestimates on single or in quantities. write Inc ratalneue.

HICKORY TABLE AND NOVELTY CO.Hickory, North Carolina.

RADIOCATA.

LOGAND HOOK-UPS FREE

atT great new 1927 catalog fresh from the 'Hess, con-tains the very newest In complete sets, parts and acrws-sories--hundrods of amazing bargains. 250.000 customerstestify to our wonderful values and reliability. CompleteInformation, 164 pages on the newest circuits aryl mostPractical popular seta FREE. SEND QUICK for sourcopy. (Please Include name of friend who is interestedIn Radio.)

THE BA RAWI K CO., 580 Monroe Street, CHICAGO

Literature WantedrUi' ,same, of readers o1 RADIO WORLD

who desire tram radio ob.hero and are abllaised la RAOIOWORLD on requeat of the reader. Theblank below stay be awl, or * poet ealdor letter will do Warm",RADIO WORLD,145 West 45th St., N. Y. City.

I desire to receive radio literature

Name

Address

City or town

State

.i922 t rawtord , Cerdwl,Montreal, °lichee, Canada.

A. S Metal, 1358 Lyman Place, N. Y.City, N. V.

Frank Zowada, 82 Alden St., Wel Wal-lington, Passaic, N. J.

W. F. Holtz, 1726 Mandeville St., NewOrleans, La.

P. S. McComb, 79 Mamaroneck Ave.,White Plaini, N. V.

Donald F. Jones, 3660 S. W. 24 Terrace,Miami, Ha.

O. T. Hodson, Jr., 50 Dartmouth St.,Portland, Me.

HOLD AN OPENINGBINGHAMPTON, N. Y.

B. W. Livingston 8A Sons, wholesalersand retailers of radio receiving sets anda variety of radio and other electrical ac-cessories, recently held a formal openingof both their wholesale and retail storesat 289-291 Main Street, Johnson City.

JAYNXON TONE BRIDGENO TUBES

NO BATTERIESattaene nntantly

le say Mi.PREVE NTS 1 0SPEAKER

DESTRUCTION.

Your grenteat RadioNeed. Order NOW.

JAYNXON LABORATORIES57 DEY STREET NEW YORK CITY

atiorovro by RADIO WORLD Littrarator

FREENEW RADIO CATALOG1927

Write Today i.

Chicago Salvage Stock Store509 S. Slat+, Dept. R.W.. CHICAGO, U.S.A.

3/10aliltbent

-al I the lawtto te,lid them --

at pricer that mean tilt laTirtgA for son. And allthe latest Darla and acre swartea as advertised In

PUTTefit radiomairosines. Theleered. to to i

mplete andcoop. to.daso re'din stock In

the wend.Tonsshoots fromin this

mt,v1.4.Wr,

P.4ki

24 RADIO WORLD December 25, 1926

VICTOREEN HASHIGH SELECTIVITY

(Part 1 of the article on 'How to Buildthe Victoreen Universal," was published inthe Dec. 11 issue. Hints on constructionwere given in last week's issue, datedDec. 18.)

By Ralph HurdOne of the difficulties met with in

many Super -Heterodynes is what mightbe called secondary interference. By thisis meant crosstalk between two broad-casting stations which are so far removedin frequency that they should not or-dinarily cause any trouble. Yet they doin some Super -Heterodynes which havenot been properly designed. The inter-ference is caused by the beating of theintermediate frequency with anotherbeat current produced in the detector bythe two interfering stations. For instance,suppose that the intermediate frequencyof the super is 50,000 cycles, and supposefurther that there are three broadcaststations operating on 600,700 and 800 kc.Now if it is desired to receive the 700kc station, the loop is tuned to this fre-quency and the oscillator is either tunedto 750 or 650 kc. So far so good. Butsuppose one should desire the 600 kc sta-tion. That would require a setting ofthe oscillator for 650 or 550 kc. But oneof these 650 is the same setting as thelower setting of the oscillator for the 600

220 and 221

The proof of the pudding is in eating, that'swhy S -M audios-sold on a satisfaction ormoney back guarantee, are the choice of theexperts the country over-that's why they areoutselling all other makes --that's why everyimportant magazine has recommended them.

Do you know that the largest telephonemanufacturing company has unofficially setalp the S -M 220s as the finest they have evertested 3-that custom set manufacturers, news-paper editors, testing laboratories, manufac-turers of phonograph records have endorsedthe S -M as the very finest?

Can you think of any better recommendationfor your audio transformers?

S..M type 220 audio transformer is designedfor all stage use in ordinary or power ampli-fiers, with all standard tubes. S -M 221 is anoutput transformer' to be used between yourpower tube and loud speaker. It is guaranteedto improve quality and handling, power un-conditionally with any set or speaker. Bothtypes are priced at $6.00.

Ask your, nearest dealer for a coiy of "TheSecret of Quality." It boils clown in under-standable language every practical phrase ofquality amplification. It's free/

Prices 10% higher west of/the Rockies.

SILVER -MARSHALL, Inc.878 West Jackson Blvd.

Chicago, U. S. A.

kc station. It is obvious therefore thatboth the desired 700 kc station and the600 kc station would be received whenthe oscillator is set at 650 kc. The rela-tive strengths of the two signals would belargely a matter of loop tuning. Sincethe loop is tuned to a 700 kc station theinterfering station is reduced. But it isvery difficult to tune out the interferenceunless special precautions have been takenin designing the receiver, particularly thesqueals which are very annoying even ifthey are not strong enough to spoil com-pletely the reception.

Well there is another possibility. Theoscillator may be set at 750 kc to get the700 kc station. But then the 800 kc stationalso may be received when the oscillatoris set at this point. Hence that stationwill interfere just as badly as the 600 kcstation. In an ordinary Super -Heterodyne,then, it would not be possible to receivethe 700 kc station without interferenceunless one of the other stations is offthe air.

The case looks bad for the Super -Heterodyne, that is, for the hap-hazardlythrown together Super. But Supers-haveso many attractive features that muchtime and effort have been spent to rem-edy this one minor defect. It has beenattacked in two different ways with suc-cess. One is to increase the selectivityof the loop or pick-up circuit to such apoint that the interfering station maybe rendered innocuous as far as produc-ing squeals is concerned. The other isto choose the sothat secondary interference cannot takeplace, or at least is rendered negligible.Both of these methods have beenthoroughly considered in designing theVictoreen Super -Heterodyne.

The main method is that of designingthe intermediate frequency transformersor the filter. system, which here are ofthe best grade.

LET US SHOW YOU HOWTO GET A COMPLETE

TUBE FREE4 5 or4U KIT

Send Postal for ParticularsB. C. L. RADIO SERVICE CO., Inc.

221 Fulton Street Dept. R. W. N. Y. C.

LOOK up DOWNSUPERHETERODYNE SPECIALIST

SETS-TUBES-BATTERIES-SERVICE,RE, Heathers° Leatherette Log end Date Beek.......- 8end Ten Cents to Cover Melling Cost.CHAS. W. DOWN, M. E.

2050 Broadway. N. Y. C.. Phone: Trafalgar 5979

STATION IS SOUGHT

BY ASHEVILLE AS

PART OF BIG CHAINASHEVILLE, N. C.

An attempt to make some definite plansto obtain a $25,000 municipal radio broad-casting station for Asheville was madeat a special meeting of the fadio commit-tee of the Asheville Chamber of Com-merce.

-The meeting was called by F. A. Bar-ber, chairman of the radio committee. Ifthe committee is successful in its attemptsto establish a station here, Mr. Barbersays, reception of outside programs willbe materially facilitated in addition toAsheville's own programs furnishing addi-tional publicity for Asheville and WesternNorth Carolina.

Supporting the broadcasting stationplan the Battery Park Investment Com-pany has offered to build a radio studioon top of the Flatiron building and give itto the city rent-free for two years. Acheck for $1,000 as a contribution towardthe station has also been offered.

According' to Mr. Barber the city ispractically assured of being placed on theNational Broadcasting Co. program if itgets a standard type broadcasting sta-tion. He has the assurance of H. A.Aylesworth, general manager of the com-pany that Asheville will receive favorableconsideration.

This would mean that Asheville wouldbe connected by a direct telephone wirewith the New York studios and other largestations of the company which would al-low it to relay programs. This wouldenable fans here to get as good resultswith cheap sets as they now get with themost expensive apparatus made.

-It HARD RUBBER L.SHEET - ROD - TUBING

Special Hard Rubber Parts Made to OrderRADION and HARD RUBBER

PANELS, ANY SIZESend for Price List

WHOLESALE RETAILNEW YORK HARD RUBBER TURNING CO.212 Centre Street New York

DIAMOND NAMEPLATESOUT

Our supply of nameplates for theDiamond of the Air has been ex-hausted. We can, however, con-tinue to send a booklet and blueprint for the 5 -tube Diamond of theAir on receipt of 50c, and a bookletand blue print for the 4 -tube Dia-mond of the Air on receipt of $1.00.Radio World, 145 W. 45th St.,N. Y. C.

DX p°0NLEE ANTENNAPatent Pending

More distance, louder signals, less interference. The one polecan be put up most anywhere. This DX ANTENNA has twicethe antenna input of any other type-delivers same volume onone-half the current normally used. Saves half the batterycurrent. Is 100% self -directional. Separates stations more easily.Simply installed, rugged construction, takes practically no room.

DX Antenna Kit Complete, $13.50 rox,West of Rockies, $14.00 Canada, 614.50Dealers -Jobbers, Write for Trade Terms

Manufactured by theDX LABORATORIES

39 Soper Ave., Oceanside, Rockville Center, N. Y.Tested and Approved by Radio World Laboratories

December 25, 1926 RADIO WORLD 25,

BIG DRIVE IS ONFOR MORE POWER

WASHINGTON.Eighty-two new broadcasting stations

are under construction in the UnitedStates, according to reports received bythe Department of Commerce from Ra-dio Supervisors throughout the country.This is an increase of twelve over thelast reports by Supervisors on November1.

The reports indicate that present con-gestion of stations has not in any waydiscouraged 'Would-be broadcasters. Thelast reports showed 110 stations beingplanned. The more recent reports showan increase to 130.

One of the outstanding features of thereport is the general increase in power.Fifty-six stations are preparing to in-crease their power, while 100 stations in-creased power since July 1. There havebeen 88 new stations licensed since July1, the reports show, of which thirty-nineuse more than 500 watts power.

Only five stations changed their wavelengths between November 1 and 15, thereports show.

The reports by districts follow:First, Boston, District: Eight new sta-

stations, five with increased power, twelvehave changed wavelengths, seven are un-der construction and seven new stationsare planned.

Second, New York, District: Fifteennew stations, seven with increased power,nine have changed wavelengths, two areunder construction, fourteen are prepar-ing to increase power, and twenty-threenew stations are planned.

Third, Baltimore, District: Two haveincreased power, two have changed wave-lengths, and five are preparing to in-crease power.

Fourth, Atlanta, District: Seven haveincreased power, five are under construc-tion, and five are preparing to increasepower.

Fifth, New Orleans, District: Ten newstations, six have increased power, fivehave changed wavelengths, ten are underconstruction, eleven are preparing to in-crease power, and thirteen new stationsare planned.

Sixth, San Francisco, District: Threenew stations, six with increased power,fifteen have changed wavelengths, seven

NA-ALOUX POWER TUBES mstalled m any setwithout rewiring oy Na-Aid Acaoters andConnectoralds. For toil anormanon writeAlden Manufacturing Co., Dept. S-21,SPringfield. Mass.

are under construction, and eleven newstations are planned.

Seventh, Seattle, District: Nine newstations, nine with increased power, eighthave changed wavelengths, ten arc underconstruction, three are preparing to in-crease power, and thirteen new stationsare planned.

Eighth, Detroit, District: Thirteen newstations, seventeen have increased power.three have changed wavelengths, sevenare under construction, one is preparingto increase power, and forty new stationsare planned.

Ninth, Chicago, District: Thirty newstations, forty-one have increased power,twenty-five have changed wavelengths,thirty-four are under construction, seven-teen are preparing to increase power andtwenty-three new stations arc planned.

Thoriated FilamentsIs it as harmful to operate a tungsten

filament (thoriated) below the rated volt-age as it is above the rated voltage?Is any material gain in amplification ef-fected with a tube, if the filament bril-liancy is maintained above the ratedvalue? The answers to these questionscannot but be of interest to the entireradio fraternity, since they constitute fac-tors encountered in everyday receptionA series of experiments conducted in the.A.mperite laboratory, has cast a great dealof light upon these problems, and observa-tions modus operandi of great re-search organizations, with respect to thefilament circuit design of their receivers,have substantiated the findings in the la-boratory. It is generally conceded thatthe grid is the most important elementin the three element thermionic vacuumtube. But to the average fan, the gridis not the paramount item. His personalexperiences have forced upon him theconclusion that the filament, the sourceof electrons in the most important factor

CARTER"Midget" Rheostat

The better known Circuitssuch as Hammarlubd-RobertHI -Q; L. C.-27 (PopularRadio); lororoved BrownhueDrake; Silver MarshallSl-ielded; etc.MI use this rheostat. Madein at resistances.

Any dealer can supply

CARTERRADIO CO.

CHICAGO MEMBERS

R M A

Half Sire

LION OLETwo -Tone Panel Chosenfor Universal Victoreen

After a thorough canvass of the field for a front panel that combinedthe highest electrical efficiency with beauty unsurpassed two-toneLignole was chosen for the Universal Victoreen. The most dis-criminating radio engineers and designers regularly choose Lignole, the,NEW specially treated wood that meets all panel requirements.

in the tube ,q,eimi,m. fully awarethat the grid uruliii t a kdwdul,,tnsIluence upon lite utility f Ire,- lulu-. Huthe also realizes that who the Mammabecomes inactive for solii,. otherthe function of the other tv..,the grid and plate Is of no avail. \V henthe tube filament is dead, the tube is dead.

The fact that the overh,.0.1 safety factoris approximately 6 per cent. should there-fore be of great interest. Increasing thevoltage above 5.3 in the case of 01A typetubes for instance materially reduces (hroperating life of the filament by greatlyaccelerating the electronic emissions fromthe filament. Needlessly increasing therate of electronic emission, rapidly dis-sipates the supply of thorium in the fila-ment. When this supply of thorium is ex-hausted, the filament is dead. It was.furthermore found in the Amperite ex-periments, that the increased rate ofelectronic emission from the filamentbrought about no material gain in ampli-fication with the tube, with a definite ap-plied plate voltage. rhereforc operatingthe tube filament above the rated voltageis a total loss from every angle. Thenecessity for recharging of the "A" bat-tery is hastened, the operating life ofthe tube is reduced and the time for tubareplacement licrried.

Make any Good ReceiverBETTER

C.E.rIFG.00Prey:thence

R -l.

AX

USE KARAS HAR-

MONIKS IN YOUR

NEW VICTOREENFor your new Victoreen, featured by Mr.Ralph G. Hurd in this issue of Radio World,by all means use Karas liarmonik AudioTransformers, which are specially recommend-ed by Mr. Hurd for this circuit. Br doingthis you will tieCtire the superb quality aridthe tremendous volume of which the Victoreenis capable when equipped with Kara, Har-moniks.These famous train...for/nem amplify Merl toil,-firer] elude of Lene--every vital harmonic-veryovertone--svith remarkable fidelity and torpassincvolume. DIU maximum Cie./Una-C,. Karel Barmoniksnet all liege roes trassronssrs of extremely lootMee type. They have high impedance and minimumdtstributed mrsicity and ere an extremely hien are-ollitration of low frequency fundamental harmonics.They are sclentillcally shielded and pertmily matched.itereated test, by leading radio experts have provedthat they will outperform any other audio crane -formers ever made. Their cue In your now Vie-torem will bring nut ,eery partkle of its mtendidDerfOrmanee and more than any other tutor willInsure the matchless tone finality and volume ofwtich this receiver ls capable.Your dealer carries Kama Ilarmoints la some orcan set thens for you promptly. Boo him bids;and order a set of these marvelous transformers foryour Yietereen. Why be satiated with leas thanthe best audio amplificutfun fur this aulendiri rt

LIGNOLE CORPORATION OF AMERICA508 SOUTH DEARBORN STREET CHICAGO, ILL.

KARAS ELECTRIC CO.1145-S ASSOCIATION BLDG., CHICAGO

26 RADIO WORLD December 25, 1926

LYNCH'S ANONYMITY PENETRATED

A DRUMMER of no mean ability is Arthur H. Lynch, shown doing a remote controljob at his home on Long island. He usually performs anonymously before the micro-

phone.

SETS SO PROFUSE,WAVES BROADEN

The More Receivers Tuned to a Station, ParticularlyNear It, the Greater the Radiation Resistance,

Expert Contends

By Knollys SatterwhiteA broadcasting station projects into

space a certain number of watts. Any-body within range may tune in on thewave and get a portion of the energy

eocingaiaisimASTERPIEck

AT AUTHORIZEDFRESHMAN DEALERS ONLY

As the number of receivers increases, theamount of energy for each one is de-creased. Those receivers which are near-est to the transmitter have the first chanceat it and they can take much more thanthose far away. The greater the num-ber of stations within a certain radiusof the transmitter the less of the trans-mitted wattage is left for those receiversoutside that radius. It is not surprisingtherefore that at present, when theremay be hundreds of thousands of receiv-ers tuned in on a certain station, that thatstation does not carry as far as it did afew years ago when there were only a fewreceivers tuned in on it. Even with theincrease of power of the station fivefoldor more it is now harder to receive that

FILL OUT AND MAIL NOWSUBSCRIPTION BLANK

RADIO WORLDRADIO WORLD 145 West 451/1 Street, New York Cif,

(Just East of Broadway)

Please send me RADIO WORLD for months, for whicA

Olease find enclosed

SUBSCRIPTION RATES:Single Copy 3 .15Three Months 1.50Six Months 3.00One Year, 52 Issues 6.00Add $1.00 a Year for ForeignPostage; 50c for Canadian Post -sge.

station at some distance away from itthan it used to be with the lower power.

Using the same reasoning, the moreunpopular or less well known stationsshould carry to greater distances becausenot so much of the energy transmitted bythem is picked up by receivers. This isundoubtedly a fact. This may also ac-count to a certain extent for the factthat DX is easier in the late hours of theevening when many of the local receivershave signed off for the night and whilethe broadcast station is still stirring upthe ether.

If everybody at present uses a largeoutdoor antenna and a simple Erystal setas of old, much more of the transmittedenergy would be absorbed by the re-civers, and distant reception of the sta-tion would be much more difficult. Per-haps it is only because' of the greatersensitivity of present receivers that re-ceivers at remote points will get anythingat all. The modern receiver picks up avery small portion of power as comparedwith the old time crystal set and thesingle tube single circuit receivers. ASuper -Heterodyne picks up the least ofall. Next come the various regenerativeradio frequency sets. They cannot beaccused of hogging the transmittedpower. They take just a tiny bit and makethe best of it.

it has been said that the selectivity ofa broadcasting- station is dependent onthe number of receivers tuned in on it.That is, as the number of stations tunedin on the wave of the station increases, theselectivity of the tuned circuit controllingthe frequency is reduced because eachreceiver introduces just a little bit of re-sistance into the transmitter. It was re-ported that the selectivity of the trans-mitter of station WEAF was measur-ably lower during evening broadcastinghours than during transmission periodswhen the general public did not know ofit, as during test periods.

If there is a large number of receivingstations tuned in on a transmitter withina very short distance, say one wavelengthor less, then the receivers should reacton the transmitter just as one coil reactson another. But when the receivers arelocated farther away, the connection be-tween transmitter and receivers is totallydifferent, and there seems to be no reasonwhy the receiver should react on thetransmitter.

Receivers very close to the station arewithin the practical induction field of thetransmitter, but stations farther away arewithin the radiated field only. The energyin the induction field returns to the sta-tion without loss, unless there are sec-ondary tuned circuits very close by. Theradiated field is thrown out by the sta-tion for good. It does not return evenif there is no receiver to pick it up. Ifit is not picked up by receiving antennasit is absorbed by various obstacles in itspath, or else it goes on and on forever.The radiated field is the load on the trans-mitter, and is a type of friction; the in-duction field is a reaction only and is -analternating magnetic field of the samekind that exist around any coil carryingalternating current.

Gives wonderfultone quality atlow cost. Con-nects like trans-former.

fSamson Elec.Co. CANTON,City and State

Decemher 25. 1.020 RADIO VV()I I I) 27

TESTING THE Hi -[The construction of the Hammartund-Roberts High -Q

three preceding issues.]

Connect the plus terminal of the A bat-tery to the binding post marked A Bat.plus. Then touch the wire from the minusside of the A battery to the metal partof the A Bat. binding post (the tubes arenot yet in the set). If a spark occurs itindicates an error in the filament wiring,entire filament circuit should be checkeduntil the mistake is found and corrected.

If no spark occurs make the connectionto the A Bat. bidding post and turn thecombination volume control -filamentswitch in a counter-lockwise direction asfar as it will go. The switch is now off.All five tubes should be placed in theirsockets but not one should light.

With the volume control full on andwith all the tubes in their sockets, removethe wire from the A Bat. binding post andconnect it to the plus terminal of a volt-meter. Connect one end of another wireto the minus terminal of the voltmeter andtouch the other end of this wire to eachof the two C Bat. posts and the 45 V, 67 V,90 V, and 135 V posts. In no case shouldthere be any movement of the voltmeterneedle. If any movement should occurthe circuit on which it occurs should betraced and the error corrected.

After completing the above tests replacethe plus A wire on the A Bat. plus bind-ing post and turn the volume control tothe "off" position.

You are now ready to connect the "B"and "C" batteries. First connect the "C"batteries and then the "B" batteries.

Final Adjustment and OperationAfter completing the connections to all

batteries the antenna should be attachedto the middle post of the antenna switchand the ground wire should be connecteddirectly to the minus terminal of the "A"battery. Yaw plug in the loud speakerand the receiver is ready to operate.

Turn the volume control in a clockwisedirection as far as it will go and slowlyturn the two tuning dials simultaneously,keeping both at approximately the samesettings. As soon as a station is heard,turn back the volume control until thesignal becomes barely audible. Then ad-just each tuning dial separately for loud-est signal and set the volume control sothat the output from the loud speaker isquite soft. Now adjust the Midget con-denser (on the left side of the detectorstage shield) to the point where the signalis loudest. Then carefully retune the sec-ond tuning dial for loudest signal and thenmake a final adjustment of the midget.Once set, this midget compensating con-denser should need no further attention.

We are now ready to adjust the equaliz-ing condensers. First tune in a loud signalat about 30 on the dials. Then disconnectthe wire running to the "minus" post ofthe first socket, leaving the tube in thesocket however. Now, with a woodenstick sharpened like a screw driver, turn

SHORETRANSFORMERS A N DCHOKES FOR EVERYRADIO POWER NEED

Special Transformers Made to OrderWrite for Prices-Also See ^

Dec. 4 Issue

SHORE ELECTRIC CO., Inc.124 Cypress Avenue, New York City

Receiver was described in the

the screw in the center of the first equal-izer until the signal is at a minimum ordisappears entirely. Now replace the wireon the mist of the first socket. This com-pletes the balancing of the first R. F.stage and the same procedure should nowbe following with the second R. F. stage,

The antenna "short" "long" switch en-ables the receiver to be adapted to differ-ent types of antennae and should be ex-perimented with until the operator be-comes familiar with the best position ofthe switch for the different wavelengths.

In general, the two tuning dials will readmore nearly alike with this switch in the"long" position and this position will alsoafford the greatest selectivity. Whenthrowing this switch from one position toanother it will be necessary to slightlyreadjust the first tuning dial.

Batteries and Tubes

For the operation of the receiver thebatteries and amperites required dependon the type of tube used. It may be notedthat the new detector tube CX200A orCX300A may be used in any of the com-binations of storage battery tubes whichare listed herein. It is recommended thatthis type of tube be used if great sensi-tivity is desirable or if reception over ex-treme distances is an object of special im-portance. No change in either batteryvoltages or amperites is required.

Although either dry cell or storage bat-tery tubes will prove entirely satisfactory,it should be noted that in general, storagebattery tubes are more satisfactory thanthe dry cell type and should therefore beused where possible.

1 he new power tubes which have re-cently become so popular well deservetheir popularity. For maximum operatingefficiency they call for somewhat higherplate voltages and consume a little moreA and B current than 'the 201A type oftube, but this is more than repaid in theform of greater volume and greater free-dom from distortion caused by overload-ing. Therefore, it is recommended thattype 112 or 171 tubes be used in the lastaudio stage of storage battery tube corn-

1.inations,*and the 120 type in (Iry celltube combinations.

A tube combination which is highly re-commended for the average installation,is shown below. It may be used withoutmaking any changes in the receiver andcall be depended on for stability, volumeand tone quality.

UX201A or CX301A in sockets Nos, 1,2, 3 and 4.

UX112 or e\312 in socket No. 5.6 volt storage A Battery.Three 45 volt B batteries.Two 4i volt C batteries.To secure in full the advantages of the

171 type of tube, four 45 volt 13 batteriesshould be, used, and a 40 volt C batteryshould be connected to the C Bat, andaudio) binding post. With these voltagesthe plate current drawn under normalconditions is 18 or 20 milliamperes, whichis too much to safely pass through thewindings of the average loud speaker.

This difficulty can be easily overcomeby connecting a choke coil (such as usedin B eliminator filters), directly across theterminals of the loud speaker jack. Asthe resistance of the average loud speakerwindings it considerably higher than thedirect curre it resistance of such a choke,most of the 18 or 20 milliamperes of platecurrent will pass through the choke coiland so prevent the burning out of thespeaker windings. At the same time thealternating current impedance of thechoke coil is so high that practically allof the voice currents will go through theloud speaker and no loss of volume willbe noticed.

It the method suggested herewith isused the choke coil may be placed in therear portion of the left side of the cabinet.two wires run from the terminals of thechoke through the space between thefront and rear shields, and then solderedto the terminals of the jack.

CAPITAL INCREASESBrandt Radio Pau er ia t,41..

fIC1,15C,1 its capital from 1,9r) 411a rrii of nn tarvalue to 1 Pro shares no par v $20,c03preferred stock.

AAA,;;, Blackburn Crcuncl ClampsTelephone companks t1.41.14

xi LLION8. Adjartablit-fltaany sirs Pip,. it8,14 !A. TYR

pipe alcanIng--aerrr, trarchrari2h rwt and min. Saul12 rents far is told. and 1.1,see.

SoealsIty coops.),1550 E. 613th St.. Chrreload. 0.

il00)

'Ne

NO THE SOLUTION OF THE PERFECT]DISTORTION LOUD -SPEAKER PROBLEM FIDELITY

. 9 -its Choice eReodingEngineersCOMPLETE parts furnished in kit form. the only direct -drive, distortionless unit for

We guarantee this speaker the equal of large cones; Alhambra Fonotex for big cone,any manufactured cone speaker at any price.With this THREE-FOOT CONE SPEAKERyou hear all the tones. It brings out thetrue depth and beauty of orchestral and in-strumental music. Can be operated stifflyfor living room music or full volume fordancing, and without trace of distortion.Kit includes famous rENSCO" cone unit,

MAKE YOUR OWNTHREE FOOT CONE SPEAKER

IN LESS THAN AN HOUR'WORLD'S FINEST LOUD SPEAKER,

GENUINE -"ENSCO" 3`2CONIE KIT

ONLY ab be If

07:1

with brass apex, two septa prints showingcabinet or simple stand construction. Allnecessary instructions.Buy this wonderful speaker under our abso-lute guarantee. Your money back if you arenot convinced that it is the finest reproducingmedium obtainable at any price. It works onany set, with ordinary Tubes or with PowerOutput.

SEND Write your name plainly as indicated below, then mail and complete kitwill be forwarded to you. Just pay postman $10.00 upon delivery.

NO NameAddress

MONEY1 City and StateENGINEERS SERVICE CO., 25 Church Street (Desk WI, Now York City

28 RADIO WORLD December 25, 1926

THE THREE TUBE

SELECTIVE SET[The theory and operation of both the one

and three tube receivers using the .Equamaticcoil were described in last week's tssue,December 18. The following gives the con-structional data.]

By Edgar SpeareThe photos on this page illustrate very

clearly how to lay out the parts for the3 -tube set. The center point of the shaftof each variable condenser is 51/4." fromeach side and 3%2" from the top andbottom, using a 7x21" panel. The con-denser to the right controls the antennacoupling coil, while the one to the leftcontrols the regeneration. The 20 -ohmYaxley rheostat, which is used to controlthe filament of the detector tube, is placedin the left hand center, while the 20 -ohmYaxley rheostat used for the filamentcontrol of the first AF tube is placedin the opposite center. Ti.e filamentswitch is in the center of the panel.

As to the layout of the subpanel, whichis held up by Karas subpanel brackets,placed underneath this panel. The socketfor the detector tube is placed near thecoil terminals, e.g., 2%" from the lefthand edge and 3" from the back. Thetwo audio sockets are 3" from the backand 5" from each other. The first audiosocket is 6,A" from the detector socket.They are all in the same line, measuringfrom the back, though. The two audiotransformers are placed near the audiosockets, toward the back, the respectiveterminals being placed opposite the postson the sockets, so that short leads can bemade. Either a phone jack or a pair ofphone tip jacks can be used at the out-put. In the model shown, the tip jackswere used. There will be no differencein the results, though. The grid con-denser is placed undei-neath the subpanelclose to the detector socket, while thegrid leak cis placed across this condenser.The plate coil, as stated, last week, isplaced underneath the subpanel, with itsaxis vertical or in the same line as thelarger coil on top of the subpanel, whichis also vertical. Either a cable or bindingposts can be used for battery connection.

The above data are for the 3 -tube

RADIO WORLD'SQUICK - ACTIONCLASSIFIEDADS.

10 CENTS A WORD10 WORDS MINIMUM.

CASH WITH ORDER.

SEND FOR PAMPHLETS OP THE GOOD-MAN TUNER-In use for years and still good.Tested and approved by many technical labor-atories. L. W. Goodman, Drexel Hill, Penna.

BUILD YOUR OWN "B" RUMINATOR our easyway. Total cost approximately $5.00. Clear recep-tion guaranteed. Complete drawings and instruc-itions, $1.00. Radio Equipment Co., 621 Main Street,Mitchell, S. D.

FINE RADIO CABINETS. WE BUILDTHEM. Hardwood-Mahogany-Walnut. Writefor catalogue. Hickory Table and Novelty Co.,Hickory, North Carolina.

PATENTS-Write for free Guide Books and"Record of Invention Blank" before disclosinginventions. Send model or sketch of your in-vention far our Inspection and Instructions Free.'Terms reasonable. Radio, Chemical, Mechanical'Electrical and Trademark experts. Victor J.Evans Co., 924 Ninth, Washington, D. C.

The panel, top and rear views of the selective 3 -tube speaker receiver. The AF trans-formers are Silver -Marshall No. 220. Karas condensers, coil and dial are used.

model. Now as for the 1 -tube model, a7x14" panel can be used. The shafts ofboth condensers should be 3" from eachside and 3%" from the top and bottom.The rheostat can be placed betweenthe condensers. Nothing else appears onthe panel. The detector can be placed inthe center of the subpanel, being sure to

Replaces -B -Batteries

S12.50FERBEND

13' ELIMINATORComplete. Operates direct from socket on110-120 'volt A. C. lighting circuit. Deliversup to 100 volts. Second successful year.Amazingly low in price-high in value.Equal or superior to any "B" Eliminator,regardless of price. The FERBEND "B"Eliminator is approved and passed by therigid laboratory tests of Radio News andPopular Radio.

Ask Your Dealer-or Send DirectShipment made direct on -receipt of price, orC. 0. D. if preferred. Use for 10 days toconvince yourself-if-unsatisfactory write uswithin that time and purchase price will berefunded. Write for Literature.

FERBEND ELECTRIC CO.424 W. Superior St. Chicago, Ill.

place the G and F terminals, so that theyare close to these terminal connectionson the secondary winding of the coil. Thegrid leak and condenser are placed un-derneath the subpanel. Only two sub -panel brackets are used to hold the sub -panel up. Phone tip jacks or a singlecircuit jack is used in the output. Sincethere are only three battery connections.binding posts are used. No filamentswitch is used or necessary.

A few tips on how to get the best re-sults from the set. Use the variablecondensers having the capacity specifiedonly. Use the -01A type tubes in thedetector and first AF sockets. A powertube_can be used in the last stage. Takecare to use the proper ballast resistorin this filament circuit of the last tube.

RADIO SHOP OPENEDIN ORLANDO, FLA.

ORLANDO, Fla."The Radio Shop," 141 Court street,

Orlando, recently opened. They are ex-clusive retailers of the Bosch radio.

A full line of accessories and parts isavailable, also parts for the home builder.In addition, they have a fully equippedlaboratory and repair shop on hand, anda service department.

Chas. E. Haywood has resided in Or-lando for 17 years and has had severalyears' experience in radio.

December 25, 1926 RADIO WORLD 29

Microphone Exacting But True Friend,Says Rosaline Greene

"The microphone makes certain uniquedemands on one's voice," declares Rosa -line Greene, possessor of "the perfectradio voice" and winner of a cup emble-matic of that distinction at the Radio.World's Fair.

"Resonance is perhaps the first re-quirement," asserts the former leadinglady of the WGY players. "This calls forplacing the voice where it receives the ut-most re -enforcement. My unusual lungcapacity, with an unladylike chest expan-sion of four inches, I am told, aids mehere. The next, I think, is richness dueto overtones in the voice. This I possess,at the sacrifice of song for as a child, ,Ihad a lovely singing voice, while now itseems all the music has entered my speak-ing voice and left me unable to sing atall."

Miss Greene, . radio fans will recall,played several, hundred parts in thedramas staged each week in the studioof WGY at Schenectady, when she wonthe honor of being the first, and, later, themost prominent leading lady of the air.

"I've had to adopt various kinds ofvoices for the many diversified roles I'veplayed in the radio dramas," Miss Greenestated, in an interview with Eric H. Pal-rner.

"These characters included the lowmodulated voice of the cultured- woman,the whiskey voice of a suffering MadameX, the joyous treble- of an enthusiasticschoolgirl, and even the nasal coarsenessof another type of woman. No costumenor makeup could help me make thesecharacters live for my audience-only theflexibility of voice with its almost astound-ing propensity for &eating a living charac-ter.

",Agatha's Aunt' was a severe test forthe voice. In it I --had to portray an edu-cated young girl disguising herself beforea suitor as her own great aunt, and againas an uncouth servant girl. I could notrely on any makeup, wrinkles or whitehair, abetted by a cane and faltering steps.Only by my thin quavering voice, couldI suggest age, as by my slouchy nasalspeech, could I suggest Hepzibah-and ina flash, shift back to an amused fullnessof tone.

"I wonder if you realize how all im-portant the voice becomes when one isdoing radio work. Cheering at a foot-ball game one afternoon robbed me ofall speech for six days. A big play wasscheduled for that Friday night which hadhad columns of advance publicity-mywhole radio world was anticipating thewell-known role of Ophelia, and I couldn'tspeak above a whisper I My gallant mike,however, came to the rescue. It seemsto possess a certain magic which alwaysrestored my voice, for at play time, thetones actually came out, clearer andsweeter than ever, it seemed.

"Sometimes, unforeseen things occur atthe studio which make unusual demandson one's voice. One of the women ofthe company may be unable to speak herlines. In a flash, I've had to disguisemine, make it sound just like hers, saythe lines and then go on again with myown part-while the radio audience re-mains blissfully unaware of any holdup:Many a time I've blessed this flexibilityof voice for saving a play.

"My fan mail? That is among my mostcherished possessions. From old andyoung, from educated and unlettered,come unsolicited the most touchingtributes to my voice and acting. Invalidswrite of the soul quieting peace I bringthem; isolated farmers of the sunshine "Icarry into their lives, young folks of the

romance. I wish I could shbw you theexpressions of love received from peoplewho know me through my voice-even amarriage proposal. And there was onecrippled man who used to travel milesevery week to bring me a gift at thestudio-he has never seen me.

"The most touching tribute I have everreceived is the Ace's wings which awounded aviator cut from his uniform tosend me as the thing he prized most high-ly on earth to show his appreciation. Ifeel that I have never been more greatlyhonored."

Congressional AidAsked by Pittsburgh

PITTSBURGH.On presentation by W. Y. English, the

city council recently adopted a resolu-tion calling on the congressional delega-tion of Allegheny county to urge promptpassage by Congress of a bill to regulateradio broadcasting. The resolution alsois to be called- to the attention of theUnited States senators from this state,with a letter from the president of coun-cil stating that it is the belief that the res-olution expresses the sentiment of manythousands in Western Pennsylvania.

When the resolution was offered somecouncilmen said that the matter was notone for councilmanic consideration. How-ever, when it was explained that the ques-tion was one affecting many, and thatthere had been published requests thatindividuals write their congressman to thesame effect, the resolution was adoptedunanimously.

THREE FROM MAMARONECK INBUSINESS AT PORT CHESTER

PORT CHESTER, N. Y.Fully equipped with an expansive sup-

ply of radios and parts three local youngmen opened "The Radio Shop" at 110Westchester Avenue, recently.

Charles Lilling, Leo Margoluis, andMortimer Levy, who have conducted asuccessful radio business in Mamaroneckfor the past months, are the proprietorsof this new establishment here. Atwater -Kent, Garod, Bosch, Crosley, Ferguson,Fada and many other popular -makeradios will be sold at this shop.

r "1"1"AMETALLIZE D

J.WARRANTED FIXED RESISTORS

THE vital importance of a silent,accurate resistor cannot be over-

estimated. Comprising a concentratedmetallized deposit one -thousandth of aninch thick, upon a glass core and sealedforever within the tube, each LynchResistor is warranted absolutely noiseless,permanently accurate, dependable! Guar-anteed accuracy -10%; in production theyaverage 5%. .25: .5; 1: 2; 3; 4; 5; 6;7; 8; 9; 10 Meg., 50c. .025; .09; .1Meg., 75c, Single mounting 35c; Double,50c. If your dealer cannot supply you,send stamps, check or money. order. Weship postpaid same day order is received.Dealers-Qet on one Mailing lift: we keep you posted on

new CIMMIOPMMLL Write us WdaYI 426-WARTHUR H. n''IV 250 W. 57th St.LYNCH, INC. NewYork,N.Y.

SINGER AT WMSG

(White)HELEN GLEASON, of the San CarlosOpera Company, sang before the micro-phone of WMSG, New Madison Square

Garden, New York City.

FREEI SEND

FFOR IT TO -DAY

B.C.L. RADIO SERVICE CO.INC221 FULTON ST. DEPT. R.W. N.Y.C.

RADaoBOOKLET

World RadioStorage "B" Battery

12 Cell -24 VoltProved value. Thousands of users find reception ahnostmagical. Clear, true power-instantly and unenoingly. Wiseeconomy. Sturdy construction-SOlid Rubber Cass protec-tion. Recharged for almost nothing. Endorsed and listed asstandard by famous Radio institutions including P.P. EMI.Laboratories, Pop. Sci. Inst. Standards, Radio News Lab.,Lefax, Inc., and other Radio authoriti.. What more needbe said? Extra Offer: b Batteriee in series (96 voile) 01040.Send No Money ;a": Tut* mrdl w.vranelva.nd tart ahip

C. 0.D. Pay expressman after exegining Latrtnr7es cf?.;=for cash with order. Remember-von save 50q, on Worl Batteries.

1219 So. Wabash Ave. Dept. 82 Chicago, Ill.Makoro.of the Famous World Rad. "A"A.' Stomps BottomsPriossi Us.oll.1,5=104th.l.aadmAJI:fa Amp. VAC?.

,-set mar radio dials .52882 meters fee theWerld gto,r,ase Dot.511WV"MiP-915gr,!frtntrntt;11

HOW TO BUILD THE BERNARD, the beau-tiful 6 -tube thumb -tuning set, fully described andillustrated in the Oct. 16 issue. Send 1Sc for acopy. Namepieces for affixing to front panel freeto all on special request. Radio World, 145 W. 45thSt., N. Y. City.

30 RADIO WORLD December 25, 1926

CONSTRUCTION INSET IS FLEXED(Concluded from page 4)

circuit, though these are not shown in thecircuit diagram. One is from B' to minusside of the filament battery, and the otheris from Ba to the same point on the bat-tery. isoth of these should be large, pre-ferably more than 1 mfd. If large con-densers are not used they might as wellbe omitted altogether.

The set is primarily designed for lAtype of tubes in all sockets except thelast, which should house a power tube.However, if it is desired to increase thesensitivity of the set on weak signals CeCo high mu tubes may be used in thefirst radio frequency stage and in thefirst two audio stages.

Voltage AdviceThe applied 'plate voltage at B. should

be 45 volts or slightly more. The voltageat B. should be 135 volts or more, pre-ferably more. It will be observed thatthe plate return from the detector tubeis connected to the 45 volt line through

the 100,000 Ohm resistance Re. Since thevoltage drop in this resistance is con-siderable the effective voltage on the plateis quite small. Voltage is increased bydecreasing the coupling resistance toabout 50,000 ohms or by connecting theplate return of the detector to the highervoltage line. It may also be increasedby using a high mu tube for detector.

A small grid bias is provided for theradio frequency tubes by the voltage dropin the rheostat Rh.. The grid bias forthe audio tubes is provided by a smallbattery, and three separate binding postsare used for this purpose. The grid re-turns from the first two first audio tubesare connected to one of these, and thegrid return from the last to a second.The third is used for the positive andthis, of course, connected to the negativefilament line. Since the first two audiotubes have both the same grid and platevoltages, these tubes should always be ofthe same type.

The first step in the building of the re -

'40iA0.0:4A406**OCO.47.6?/.

RADIO WORLD

eijrigtMa5 ift Rate $6 a year. Two or more annual

subscriptions, $5.00 each.

for which which please. send I*:

(Please check here if you wish Christmas card

':A?M5M-0.00..MOMO:01003MOVICWinent

RADIO WORLD,145 West 45th Street, New York City

Enclosed find $RADIO WORLD for one year to-

Name

Address

Name

iii Address

Ai Name

Address

My Name is

My Address is

bearing your name sent to recipient)

ceiver should be winding and mountingthe coils (Fig. 2). Then the panel layoutshould be attended to. A suitable ar-rangement for the panel with Bruno dialsis shown in Fig. 3. The panel is reinforcedby the bras§ angle strips, which are fas-tened by the four screws shown in thecorners of Fig. 3. The next step shouldbe mounting the parts on the panel andwiring these as far as possible at thistime. The parts that go on the panelare the three tuned circuits, the three ver-nier dials, the filament switch, the fila-ment rheostat, and the variable resistanceRhg.

Now comes the sub -panel layout. (Figs.4 and 5). It should be pointed out thatthe circuit is not laid out as is the cus-tom. It is mechanically flexed. That is,the radio frequency imput is on the rightend of the set, as is also the audio fre-quency output. Thus the extreme righthand condenser and coil form the antennainput tuner. The middle is the tunedimpedance, and the coil and condenserat the left hand end form the detectorinput tuner. The two front tubes are theradio frequency tubes. The detector tubeis the first in the back row and the poweroutput tube is the last in the same row.This arrangement makes for the shortestpossible leads throughout the set.

Sub -panel DataThe sub -panel is set back 1.5" from thepanel, or just sufficient to clear the con-denser rotors as they are opened up wide.The sub -panel is also raised up so thatthere will be plenty of room for the sub -

panel wiring and the various fixed con-densers. The method of mounting thesub -panel to the front panel is shown inFig. 5.

Strips of soft rubber are placed be-tween the mounting brackets and the sub -panel in order to minimize tube noisesarising from jars. These are quite effec-tive although they are very thin.

As much of the Wiring as possible onthe sub -panel should be done before put-ting it on the mounting brackets. If thisis done, only a few wires need be put inplace after the mounting. This simplifiesthe work and it also protects the panelfrom injury while working.

RESULTS

Results Editor:Please give my best regards to HermanBernard for his wonderful contribution,the 4 tube model Diamond of the Air,to the radio public. I have built the setand rejoice over the fact. Many distantstations were received on the loud speakerwith great volume.

WILLIAM STIEMAN,16 Passaic St.,

Trenton, N. J.* * *

Results Editor:I have built the 4 and 5 tube Diamond

of the Air receivers, and have had ex-ceptionally good results from them. Ihave received about 114 distant stations.

RAYMOND THOMPSON,Kingfisher, Okla.

* * *Results Editor:

About six months ago I constructed the4 tube model Diamond of the Air. Theresults have been beyond my expectation.Throughout the summer, stations up to1,000 miles away, came in with goodspeaker volume.

JOHN H. WEIGHELL,R.F.D. 2, Holyoke, Mass.

* * *Results Editor:

I have constructed the 4 tube modelDiamond of the Air and have had wonder-ful results. I have built several othersets, but the Diamond beats them all.

EDWARD BISHOP,Gauauoque, Ontario,

Canada.

December 25, 1926 RADIO WORLD

KITS FOR XMAS GIFTSTHE NEW, IMPROVED

DIAMOND THE AIR

7.50

9 -Tube DIAMOND Kit $30.00Filtrex Intermediate Power Pack $42.50Bruno Regenatrol $60.00Hammerlund-Roberts Hi -Q $63.05New Karas Equamatic $88.70S -M Shielded Six $95.00

AND KITS FOR ALL CIRCUITSBERNARD. BRUNO PRODUCTS IN STOCK

B. C. L. RADIO SERVICE, INC., Dept. R.W., sera for Booklet

Itifd by the Clapp-Eastham Co. Licensed underArmstrong Patent No. 1,113,149 for BrunoRod's Coot,

Blueprint, ready to wire, asComplete Kit of Parts, with

Specified by HERMAN

6 -Tube Wonder Circuit. Corn-plete Kit of Parts with Blue-print, ready to wire.

KT

o.221 Fulton St., New York City

PERFECT FILAMENT CONTROLin the

"DIAMOND OF THE AIR"Is Assured with AMPERITE

Eliminates hand rheostats. Simplifies set wiring. M-ooted as the only perfect filament control In every Penalarconstruction set.

Z di all ---1--InpatlyDept. R.W.24, 50 Franklin St., N. Y. City

Write for"RADIALL

BOOK"

TEThe "SELF-ADJUSTING"Rheostat

BLUE PRINT and Book, DIAMOND OF THEAIR sent on receipt of 50c. Guaranty Radio GoodsCo., 145 West 45th Street, New York City.

How to Build

THE DIAMONDHerman Bernard, designer of this wonder cir-cuit, has wrttten an illustrated booklet on"How to Build Rnnio Wosco's Improved Dia-mond of the Air." Send 50c and get thisbooklet, including a full-sized wiring blueprintSend $6 for year's subscription and get book-let, and blueprint FREE.tNewsdealers or radio dealers, order the bookLets with blueprints included, in quantity, directfrom American News C5. or branches.]

RADIO WORLD145 WEST 45th ST. NEW YORK CITY

THE BROWNING -DRAKE CIRCUIT-Text andillustrations covering this famous circuit startingwith our issue of Aug. 14. The 3 numbers senton receipt of 45c. RADIO WORLD, 145 W. 45thSt., N. Y. C.

A 6 -TUBE CIRCUITBEAUTIFULTO EAR AND EYE

How to Build the

This Nameplate Free to All!Fully described in the October 16 issue ofRADIO WORLD by Herman Bernard.Schematic and picture diagrams of thewiring, textual wiring directions, step bystep; striking photographs of the com-pleted receiver, all treated so that theveriest novice in radio can build theBernard.

THE SET YOU TUNEWITH YOUR THUMB!Send 15c for October 16 issue

Blueprint of panel, subpanel andwiring (complete), with Bernard'sconstructional article $1.00Or send $6 NOW for one year's subscriptionto Radio World (52 numbers) and get theblueprint FREE; also the October II issueFREE, and panel nameplate FREEI KeepInformed on this fine circuit by readingRadio World.

RADIO WORLD145 West 45th St. N. Y. City

ANY SET DESCRIBED IN

RADIO WORLDBUILT TO YOUR ORDER. WRITE

M. LERNER1498 Remsen Ave. Brooklyn, N. Y.

"Built Better"Fixed Condensers and ResistorsSpecified by HERMAN BERNARD

in theFOUR AND FIVE TUBE

"DIAMOND OF THE AIR"and in his newest marvel, the

Registered U. S. Patent OfficeThe S -Tube Receiver of Exquisite Tone

BERNARD BATTERYLESS, HAYDEN'SSINGLETROL, BLAN'S ANTENNALESS,RIDER -SAMSON 100% EFFICIENT SET

AEROVOX products are also used inover thirty leading circuits and "B"ELIMINATORS.

-THERE'S A REASON!

Aerovox Wireless Corp.489-411-493 Broome St., New York City

THE BRETWOOD

Variable Grid LeakCertified for

The Diamond

The Diamond of the Air Owes Some of Its Efficiency to This Leak

THE BRETWOODImproves Any Set!

Price, $1.50

SPECIAL PREMIUM SUBSCRIPTION OFFERFor NEW RADIO WORLD Subscribers Ordering NOW

Radio World has made arrangements-To offer a year's subscription FREE for anyone of the following publications with one year'ssubscription for RADIO WORLD

-BOYS'or-RADIO NEWS or LIFE-RADIO DEALER or-POPULAR RADIO or -RADIO (San Francisco) er

-SCIENCE AND INVENTION or -RADIO AGE.

This is the way to-for the price of one:-Send S5.00 today for RADIO WORLD-foe one year (regular price-far 52 numbers)-and select any one of the other-nine publications for twelve months.

get two publications-Add 11.56 a year extra for

or Foreign Postage.-Present RADIO WORLD aubsconhore-can take advantage of this offer by-extending subscriptions ono year-If they send renewals NOWI

RADIO WORLD'S SPECIAL TWO -FOR -PRICE -OF -ONE SUBSCRIPTION BLANKRADIO WORLD, 145 West 45th Street, New York City.Enclosed find $6.00 for which send me RADIO WORLD for twelve months (52 numbers, beginning..and also without additional cost, Popular Radio, or Radio News, or Science and Invention, or Radio Dealer, or Radio (San Francisco), or Radio Age,or Boys' Life (or $10.00 for two yearly subscriptions). (No other premium with this offer.)

Indicate if renewal. Name

Offer Good Until Street AddressJanuary 15, 1927. City and State

30 RADIO WORLD December 25, 1926

CONSTRUCTION INSET IS FLEXED

(Concluded from page 4)circuit, though these are not shown in thecircuit diagram. One is from B. to minusside of the filament battery, and the otheris from 133 to the same point on the bat-tery. both of these should be large, pre-ferably more than 1 mfd. If large con-densers are not used they might as wellbe omitted altogether.

The set is primarily designed for IAtype of tubes in all sockets except thelast, which should house a power tube.However, if it is desired to increase thesensitivity of the set on weak signals CeCo high mu tubes may be used in thefirst radio frequency stage and in thefirst two audio stages.

Voltage AdviceThe applied 'plate voltage at B. should

be 45 volts or slightly more. The voltageat Ba should be 135 volts or more, pre-ferably more. It will be observed thatthe plate return from the detector tubeis connected to the 45 volt line through

the 100,000 ohm resistance Re. Since thevoltage drop in this resistance is con-siderable the effective voltage on the plateis quite small. Voltage is increased bydecreasing the coupling resistance toabout 50,000 ohms or by connecting theplate return of the detector to the highervoltage line. It may also be increasedby using a high mu tube for detector.

A small grid bias is provided for theradio frequency tubes by the voltage dropin the rheostat Rh'. The grid bias forthe audio tubes is provided by a smallbattery, and three separate binding postsare used for this purpose. The grid re-turns from the first two first audio tubesare connected to one of these, and thegrid return from the last to a second.The third is used for the positive andthis, of course, connected to the negativefilament line. Since the first two audiotubes have both the same grid and platevoltages, these tubes should always be ofthe same type.

The first step in the building of the re-

10 WORLD

ebrigttna t iaate5$6 a year. Two or more annual

subscriptions, $5.00 each.

RADIO WORLD,145 West 45th Street, New York City

Enclosed find $RADIO WORLD for one year to-

for which which please send

Name

Address

Name

Address

Name

Address

My Name is

My Address is

(Please check here if you wish Christmas cardbearing your name sent to recipient)

0:

A

3MMOMO:M14910tOMMAkt......MIAM

ceiver should be winding and mountingthe coils (Fig. 2). Then the panel layoutshould be attended to. A suitable ar-rangement for the panel with Bruno dialsis shown in Fig. 3. The panel is reinforcedby the bras§ angle strips, which are fas-tened by the four screws shown in thecorners of Fig. 3. The next step shouldbe mounting the parts on the panel andwiring these as far as possible at thistime. The parts that go on the panelare the three tuned circuits, the three ver-nier dials, the filament switch, the fila-ment rheostat, and the variable resistanceRha.

Now comes the sub -panel layout. (Figs.4 and 5). It should be pointed out thatthe circuit is not laid out as is the cus-tom. It is mechanically flexed. That is,the radio frequency itnput is on the rightend of the set, as is also the audio fre-quency output. Thus the extreme righthand condenser and coil form the antennainput tuner. The middle is the tunedimpedance, and the coil and condenserat the left hand end form the detectorinput tuner. The two front tubes are theradio frequency tubes. The detector tubeis the first in the back row and the poweroutput tube is the last in the same row.This arrangement makes for the shortestpossible leads throughout the set.

Sub -panel DataThe sub -panel is set back 1.5" from thepanel, or just sufficient to clear the con-denser rotors as they are opened up wide.The sub -panel is also raised up so that

there will be plenty of room for the sub -panel wiring and the various fixed con-densers. The method of mounting thesub -panel to the front panel is shown inFig. 5.

Strips of soft rubber are placed be-tween the mounting brackets and the sub -panel in order to minimize tube noisesarising from jars. These are quite effec-tive although they are very thin.

As much of the hiring as possible onthe sub -panel should be done before put-ting it on the mounting brackets. If thisis done, only a few wires need be put inplace after the mounting. This simplifiesthe work and it also protects the panelfrom injury while working.

RESULTS

Results Editor:Please give my best regards to HermanBernard for his wonderful contribution,

the 4 tube model Diamond of the Air,to the radio public. I have built the setand rejoice over the fact. Many distantstations were received on the loud speakerwith great volume.

WILLIAM STIEMAN,16 Passaic St.,

Trenton, N. J.* * *

Results Editor:I have built the 4 and 5 tube Diamond

of the Air receivers, and have had ex-ceptionally good results from them. Ihave received about 114 distant stations.

RAYMOND THOMPSON,Kingfisher, Okla.

* * *Results Editor:

About six months ago I constructed the4 tube model Diamond of the Air. Theresults have been beyond my expectation.Throughout the summer, stations up to1,000 miles away, came in with goodspeaker volume.

JOHN H. WEIGHELL,R.F.D. 2, Holyoke, Mass.

* * *Results Editor:

I have constructed the 4 tube modelDiamond of the Air and have had wonder-ful results. I have built several othersets, but the Diamond beats them all.

EDWARD BISHOP,Gauauoque, Ontario,

Canada.

December 25, 1926 RADIO WORLD

KITS FOR XMAS GIFTSTHE NEW, IMPROVED

DIAMOND THE AIRAffd by the Clapp-Eastham Co. Licensed underArmstrong Patent No. 1,113.149 for BrunoRadio Corp.Complete Kit of Parts,. withBlueprint, ready to wire, as $3 7e50Specified by HERMANBERNARD.

4 -Tube DIAMOND Kit $30.00Filtrex Intermediate Power Pack $42.50Bruno Regenatrol $60.00Hammerlund-Roberts Hi -Q $63.05New Karas Equamatic $88.70S -M Shielded Six $95.00

AND KITS FOR ALL CIRCUITSBRUNO PRODUCTS IN STOCK

B. C. L. RADIO SERVICE, INC., Dept. R.W., Send for Booklet

6 -Tube Wonder Circuit. Com- e.plete Kit of Parts with Blue- .10print, ready to wire.

KT

o.221 Fulton St., New York City

PERFECT FILAMENT CONTROLin the

"DIAMOND OF THE AIR"Is Assured with AMPERITE

Eliminates bend rheostats. Simplifies set wiring. At.opted as the only perfect filament control In every populartonstructlen set.

,--1<f-Ldiall Company -Dept. R.W.24, 50 Franklin St., N. Y. City

Write for"RADIALL

BOOK"

TEghe "SELF-ADJUSTING"Rbeartat

BLUE PRINT and Book, DIAMOND OF THEAIR sent on receipt of 50c. Guaranty Radio GoodsCo., 145 West 45th Street, New York City.

How to Build

THE DIAMONDHerman Bernard, designer of this wonder cir-cuit, has written an illustrated booklet on"How to Build RADIO WORLD'S Improved Dia-mond of the Air." Send 50c and get thisbooklet, including a full-sized wiring blueprintSend $6 for year's subscription and get book-let, and blueprint FREE.flgewsdealers or radio dealers, order the book-lets with blueprints included, in quantity, directfrom American News Co. or branches.]

RADIO WORLD145 WEST 45th ST. NEW YORK CITY

THE BROWNING -DRAKE CIRCUIT-Text andillustrations covering this famous circuit startingwith our issue of Aug. 14. The 3 numbers senton receipt of 45c. RADIO WORLD, 145 W. 45thSt., N. Y. C.

A 6 -TUBE CIRCUITBEAUTIFULTO EAR AND EYE

How to Build the

This Nameplate Free to All!Fully described in the October 16 issue ofRADIO WORLD by Herman Bernard.Schematic and picture diagrams of thewiring, textual wiring directions, step bystep; striking photographs of the com-pleted receiver, all treated so that theveriest novice in radio can build theBernard.

THE SET YOU TUNEWITH YOUR THUMB!Send 15c for October 16 issue

Blueprint of panel, subpanel andwiring (complete), with Bernard'sconstructional article $1.00Or send 56 NOW for one year's subscriptionto Radio World (52 numbers) and get theblueprint FREE; also the October 16 issueFREE, and panel nameplate FREE! KeepInformed on this fine circuit by readingRadio World.

RADIO WORLD145 West 45th St. N. Y. City

ANY SET DESCRIBED IN

RADIO WORLDBUILT TO YOUR ORDER. WRITE

M. LERNER1498 Remsen Ave. Brooklyn, N. Y.

"Built Better"Fixed Condensers and ResistorsSpecified by HERMAN BERNARD

in theFOUR AND FIVE TUBE

"DIAMOND OF THE AIR"and in his newest marvel, the

Registered U. S. Patent OfficeThe 6 -Tube Receiver of Exquisite Ton.

BERNARD BATTERYLESS, HAYDEN'SSINGLETROL, BLAN'S ANTENNALESS,RIDER -SAMSON 100% EFFICIENT SET

AEROVOX products are also used inover thirty leading circuits and "B"ELIMINATORS.

-THERE'S A REASON!

Aerovox Wireless Corp.4811-4111-493 Broome St., New York City

THE BRETWOOD

Variable Grid LeakCertified forThe Diamond

The Diamond of the Air Owes Some of Its Efficiency to This Leak

THE BRETWOODImproves Any Set!

Price, $1.50

SPECIAL PREMIUM SUBSCRIPTION OFFERFor NEW RADIO WORLD Subscribers Ordering NOW

Radio World has made arrangements way to get two publications-To offer a year's subscription FREE for anyene of the following publications with one year'ssubscription for RADIO WORLD --RADIO NEWS or BOYS' LIFE or

-RADIO DEALER or-POPULAR RADIO or -RADIO (San Francisco)-SCIENCE AND INVENTION or -RADIO AGE.

or

This is the-for the price of one:-Send Has today for RADIO WORLD-for one year (regular price-for 52 numbers)-and select any one of the other-nine publications for twelve months.

-Add SIM a year extra ter-Canadian or Foreign Postage.-Present RADIO WORLD subscribers-can take advantage of this offer by-extending subscriptions one year--11 they send renewals NOWT

RADIO WORLD'S SPECIAL TWO -FOR -PRICE -OF -ONE SUBSCRIPTION BLANKRADIO WORLD, 140 West 45th Street, New York City.Enclosed find $6.00 for which send me RADIO WORLD for twelve months (52 numbers, beginningand also without additional cost, Popular Radio, or Radio News, or Science and Invention, or Radio Dealer, or Radio (San Francisco), or Radio Age,or Boy.' Life (or $10.00 for two yearly subscriptions). (No other premium with this offer.)

Indicate if renewal.Offer Good UntilJanuary 15, 1927.

Name

Street Address

City and State

RADIO WORLD December 25, 1926

VICTOREENcA Super Set

'Without an 6quallBuild it with

VICTOREEN Parts

VICTOREENMASTER CONTROL UNITS

A completely assembled unit with one dialreading controlled by a compensator on theVernier dial which compensates for any differ-ence in the capacities of your condensers within20 points on the dial. Used in circuits em-ploying two or more condensers of the samecapacity. Easy to mount-no change of wiringnecessary.

Victorcen Master ControlUnit, 2 Condenser type,

$19.50. Extracondenser,

$4.50

Pioneer Builders ofSuper Set Radio Parts

Send for Folder)he GEO.W.WALKER CO.6528 Carnegie Ave. Cleveland,Ohio

Merchandise ofPictoreen Radio Parts

Best Christmas GiftThis Marvelous B. T. 5 at $40 willbring as much joy and happiness in ahome as the most expensive set.

Send your order to -day so as to insureChristmas delivery.

RADIO NEWS RADIO WORLD

GIVE BST -5 CERTIFICATE OF MERITA $75 Set Direct from Factory at $40

GUARANTEEI received my B. S. T. radio set two

weeks ago and I am very well pleasedwith it.

I had the set working in fifteenminutes and at the end of two hoursand a half I had twenty-nine stationslogged. The set brings in new stationsalmost every night.

The cabinet is very well constructedand the people that have seen it saythat it is a very beautiful set.

G. C. PARRISH, Dallas, Oregon.

IMMEDIATEDELIVERY

New model cabinet, Du Pont Duco finish; base 21" long by 0"wide, height 91/2", top 21" by 6". Five-ply walnut veneer

piano finish.

Satisfaction or Money BackEach receiver is tested andretested, boxed and inspectedbefore leaving factory, andguaranteed to reach youdirect in perfect condition.Workmanship throughoutguaranteed the best. As-sembled by experts.

RenaissanceModel Console

With built-in Utah UnitLoud Speaker and commo-dious compartment in whichthere is ample room for bat-teries, charger, eliminators,etc.

COMPLETERECEIVER

BST -5Loud Speakerand Console

$57.00As Illustrated

Send Check orP. 0. Money Order

'T HIS highly sensitive, powerful and selective BST -5 radio receiver has all up-to-the-minuteimprovements. Heavy aluminum automobile type chassis, shielded against stray currents

and distortion. Flexible grip, Universal type sockets, eliminating microphonic noises. Hasprovision for battery eliminator and any power tube. Fahnestock clips on sub -panel foradjusting C battery, has voltages for power tube. Efficient on either long or short aerial,including indoor aerial. This BST -5 sets a new standard for true tone values and selectivity.This BST -5 gives greater volume than many six -tube sets and consumes less current.

GUARANTY RADIO GOODS CO.145 West 45th Street New York, N. Y.

RADIO WORLD Guarantees the Responsibility of This Advertiser