i che balanced plan seven - americanradiohistory.com · 2019-07-17 · july 2 /q1,1 peg- u.s. pat....

JULY 2 /q1,1

PEG- U.S. PAT. OPE

15

CENTS

America's First and Only National Radio Weeklyt- H _7; I

NEW NEUTRALIZATION PLAN

IN FRESHMAN AC SET

The Six Different Typesof Units for Speakers

BEAUTIFUL APPEARANCE

IS RECEIVER DEMAND

CHE BALANCED "PLAN SEVEN"

The Top View of the Planofier Seven. See Article on Page 3

GET A TONE QUALITY SET By 0. H. CaldwellSINGLE CONTROL PROBLEMS -By C. T. Burke

RADIO WORLD July 2, 1927

There's 1000 HOURS of FUN!

r

50c THE COPY

hn

SAM LOYD'STRICKS and PUZZLES

HERE are more than one thousand hours of truly amazingfun and frolic-in Sam Loyd's "Tricks and Puzzles."

'here is only one Sam Loyd, the, Puzzle King, the incom-parable, a true master mind, and he has crowded in this newvolume, "Tricks and Puzzles," the best work of his life -time.

In this book are thousands of puzzles of every conceivable nature,games, tricks, conundrums. Hundreds of illustrations. Scqres of realbrain -teasing puzzles stories, dozens of humorous anecdotes.

With this inexhaustible gold mine of lively entertainment at hand youneed never be at loss for an evening's party program or a rainy day'sdelight.

It's a book for young and old folks alike-Riddles for the youngsters-Brain teasers for the grown-ups.

The kind of a book every home should have in its' book -rack. 116pages, 100 or more illustrations, large size, 9 x 12 inches with beautiful2 -color cover.

50c the Copy On All NewsstandsOr Use This Coupon

EXPERIMENTER PUB. CO., Inc.,230 Fifth Avenue, New York City.

Gentlemen :-1 enclose 50c for one copy of your book, "Tricks andPuzzles."

Name

Address

City State

Announcing-the first

AMAZING STORIES "ANNUAL"132 PAGES - - - 9 x 12 INCHES

featuring

The MASTER MIND of MARS

by EDGAR RICE BURROUGHSA Remarkable New Story by this fa-

mous author of the "TARZAN" series. Hasnever before been published.

Also a carefully selected group of themost important stories that have ap-peared in this magazine for the past year.

50c THE COPYIf your dealer cannot supply you, write direct

Experimenter Publishing Co., Inc., 230 Fifth Ave., New York, N. Y.

SIXTH YEAR

Vol. XINo. 15

Whole No. 275July 2, 1927

15c Per Copy. $6.00 Per Year

A Weekly Paper Published by Hee.nem- Radio Pnblicattions Corporatesfrom Publication Office, 145 W. 4g1at

Street, New York, N. Y.

Phones: BRYant 0558 and 0559

[Entered as second-class matter, March, 1922, at the post office at New York, N. Y., under Act of March, 1879)

The Planofier SevenEverything Is "Above Board" in the Set

By Robert F. Goodwin and Stuart Brunoa,

FIG. 2.One main tuning control, with an auxiliary control for DX, marks the station finder of the Planofier Seven, a set for dis-

criminating home -constructors. A three -section tuning condenser is used. There is only one rotor. This is brought out by thedash line. GD is a Goodwin Detector, with a .1 meg. plate resistor .0005 mfd. bypass condenser and .0005 blocking condenser.The audio circuit may be a factory -made amplifier. The three blocking condensers may be .006 mfd., the plate resistors .25 meg.

and the audio leaks 2 meg. The resistors and fixed condensors in the first two RF plate circuits are Phasatrols.SIMPLICITY of control is fast becom-

ing the watchword of set manufactur-ers. This does not apply only to themanufacturers, either, but also includesthe individual set constructor. There havebeen few radical changes made in circuitsbut there stein to have been a fewworthwhile kinks which have done muchto improve the operation characteristicsof the receiver. These have been in-corporated in Planofier Seven (Fig. 2).These improvements were found quitethe thing.

The method used to suppress oscillationdispenses with the use of an additionalcontrol for regeneration. The three stagesof radio frequency are tuned with a singretandem condensor. The detector portionof the set has an energy transfer systemthat excludes the use of tuning controlsfor that part of the set and safeguardsthe detector tube against overloading,while the audio frequency amplifier isresistance coupled.

Resistance and transformer coupledaudio seem to have been engaged in asort of tug-of-war, that is, as far as publicopinion is concerned. First the trans-former coupled amplifier would be in pub-lic favor, then the improvement of re-sistance coupled amplifier. This wouldhe an incentive for the manufacturers oftransformers to work overtime seekingimprovements. This has brought about thedevelopment of good audio frequencytransformers which amplify the signals

faithfully. The old type of resistancecoupled amplifier also amplified evenly.

20 Gain Per StageWith the coming of the B battery

eliminator, the owner of a set using theresistance coupled amplifier had his grief.Due to the tendency of this type of ampli-fier (particularly when using a B elimin-ator) to cause a noise in the loudspeakerresembling the put -put -put of a motor-boat engine, a blow was dealt to thistype of amplifier. Recently there hasbeen developed a resistance coupled am-plifier that eliminates this trouble andtoday we find the transformer and resist-ance coupled amplifiers about at a par.

With the old type of resistance coupledamplifier when using an -01A tube, anamplification of about 7 was all that couldpossibly be obtained from each stage,providing one used a resistance of about100,000 in the plate circuit of this tube.while the grid resistor was 2 meg. andthe blocking condenser was about .5 mfd.When using the new 30 mu tube, however,the plate resistance used is of 250,000ohms, and the gain per stage is about 20.The reason for using a high resistance inthe plate of the high mu tube is that theimpedance of this tube is so much higherthan the impedance of the -01A and toget a maximum transfer of energy theplate resistance used must be higher thanthe impedance of the tube.

For this reason the transformer coupledtype of amplification is not advisable

when using this tube, since it would re-quire an extremely high inductance for theprimary of such a transformer. If wewere to make a transformer with such ahigh inductance and use the new high mutube, the amplification would be so tre-mendous that violent distortion wouldoccur.

Power Tube in Last StageWe may get away from this condition

by using a very high plate potential andlarge grid bias, but this would not bepractical. Therefore the high mu tubeis used only in systems employing resist-ance and impedance coupling.

For the last stage we employ a powertube where the amplification constant ofthe tube is about 3 or 4, this tube beingused to handle this extra power withoutdistortion, rather than amplify to anygreat extent.

You will probably notice that the radiofrequency portion of the circuits employno method of shielding. While this isnecessary when we use such coils assolenoids, where the field is rather large,it is not necessary when using a coil witha constricted field. The toroid coil isnoted for this fact, but the resistance ofthis coil is rather large. Select a coil witha constricted field and low resistance, e.g.,the binocular type. While the field isnot as small as that of the toroid, the verylow resistance makes the binoculars de-sirable. This also keeps well up- theselectivity factor, which is necessary, since

R .D \\s RLL

A Great Deal for a Very Little!Ordinarily This Seems Too Good to Be True, But Here Is An Instance of Complete Verification

moanDe LazoIhreaseedWith Caochneett

Attached

in mechanicautility.

WHEN you are deciding on whatparts are to go into the receiv-er you are about to build, un-der no circumstances dismiss

the grid leak with only casual con-sideration. Respect the grid leak assomething well worthy of expertchoice.

The best course is to select a va-riable grid leak with an ample re-sistance range, one that may bemounted on baseboard, sub -panel orfront panel, as you prefer.

Such a leak is the BRETWOODVARIABLE GRID LEAK, which isnow on the market in new de luxemodel, representing improvements

I strength, electrical efficiency andHigher Efficiency

You should use a variable grid leak like theNorth American Bretwood Co.,

145 West 45th Street, New York City.Gentlemen: Enclosed find $1.75. Send me at once one

De Luxe Model Bretwood Variable Grid Leak on 5 -daymoney -back guarantee. (Or $2.25 for leak with grid con-denser attached.)NAMEADDRESSCITY STATE

BRETWOOD VARIABLE GRID LEAK in a setyou are about to build, or should put one in yourpresent receiver, because it will enable you to gethitxrhest operating efficiency from the detector tube.--,S'nearly all tubes used as detectors draw grid cur-rent, the resistance value of the leak is importantfor biasing and discharge purposes. Not only canexactly the right degree of flow be established todiscard excess electrons, but the grid -to -filamentimpedance is so affected as to afford, best selectivityunder the circumstances. Only a variable leakgives this precision choice.

You prevent overloading of the detector tube bycorrect leak setting. This improves tone qualityconsiderably. Often if your set sounds distortedthis is immediately and permanently reined:,Hence you reap greater volume. better selectand purer tone quality-all by the simple insci 11,of a BRETWOOD DE LUXE MODEL VARIABLEGRID LEAK.

Selected by BernardThis efficient instrument so struck Hermit,

Bernard that he prescribed it for his latest and mostpopular circuit, Radio World's Universal Four -TubaReceiver.

The BRETWOOD DE LUXE MODEL VARIABLE GRID LEAK costs $1.75-a small enoughprice for so much efficiency. If desired, a .0002'mfd. BRETWOOD BULLET CONDENSER is sup-plied, mounted on the leak, at 50 cents extra.

Note: The Bretwood Leak's range is .25 to 10 meg.Inquiries Solicited from the Trad, Dealers: Send in your orders direct!

B. S. T. CONE SPEAKERGuaranteed to give Satisfaction in

Tone, Volume and AppearanceAdjustable to Volume Desired

18 inches in diameter edged in GoldBraid, Art Metal Base can be placedon highly polished surface withoutdanger of scratching.

ImmediateDelivery $7.50 Shipped Direct

from Factory

Satisfaction Guaranteed or Money Baer

GUARANTY RADIO GOODS CO. 145 West 45th St., New York

JULY 2 Hz7

REG-U.S. PAT. OFF

15

CENTS

America's First and Only National Radio Weekly01-^11

NEW NEUTRALIZATION P

IN FRESHMAN AC SET

The Six Different Typesof Units for peakers

BEAUTIFUL APPEARANCE

IS RECEIVER DEMAND

CHE BALANCED LANOFIER SEVEN"

The Top View of the Planofier Seven. See Article on Page 3

GET A TONE QUALITY SET By O. H. CaldwellSINGLE CONTROL PROBLEMS -By C. T. Burke


There's 1000 HOURS of FUN!

50c THE COPY

in

SAM LOYD'STRICKS and PUZZLES

"THERE are more than one thousand hours of truly amazingfun and frolic-in Sam Loyd's "Tricks and Puzzles."

'here is only one Sam Loyd, the Puzzle King, the incom-parable, a true master mind, and he has crowded in this newvolume, "Tricks and Puzzles," the best work of his life -time.

In this book are thousands of puzzles of every conceivable nature,games, tricks, conundrums. Hundreds of illustrations. Scores of realbrain -teasing puzzles stories, dozens of humorous anecdotes.

With this inexhaustible gold mine of lively entertainment at hand youneed never be at loss for an evening', party program or a rainy day'sdelight.

It's a book for young and old folks alike-Riddles for the youngsters-Brain teasers for the grown-ups.

The kind of a book every home should have in its' book -rack. 116pages, 100 or more illustrations, large size, 9 x 12 inches with beautiful2 -color cover.

50c the Copy On All NewsstandsOr Use This Coupon

--EXPERIMENTER PUB. CO., Inc.,MO Fifth Avenue, New York City.

Gentlemen :-I enclose 50c for one copy of your book, "Tricks andPuzzles."

Name

I Address

, City State

Announcing-the first

AMAZING STORIES "ANNUAL"132 PAGES - - - 9 x 12 INCHES

featuring

The MASTER MIND of MARS

by EDGAR RICE BURROUGHSA Remarkable New Story by this fa- ti Also a carefully selected group of the

mous author of the "TARZAN" series. Has most important stories that have ap-never before been published. peared in this magazine for the past year.

50c THE COPYIf your dealer cannot supply you, write direct

Experimenter Publishing Co., Inc., 230 Fifth Ave., New York, N. Y.

SIXTH ,YEAR

Vol. XINo. 15

Whole Na 275July 2, 1927

15c Per Copy. $6.00 Per Year

A Weekly Paper Published by Hon:sassy Radio Publicattions Corporationfrom Publication Office, 145 W. 491k

Street, New York, N. Y.

Phones: BRYant 0558 and 0559

[Entered as second-class matter, March, 1922, at the post office at New York, N. Y., under Act of March, 1879]

The Planofier SevenEverything Is "Above Board" in the Set

By Robert F. Goodwin and Stuart BrunocA000

00

e-FIG. 2.

One main tuning control, with an auxiliary control for DX, marks the station finder of the Planofier Seven, a set for dis-criminating home -constructors. A three -section tuning condenser is used. There is only one rotor. This is brought out by thedash line. GD is a Goodwin Detector, with a .1 meg. plate resistor .0005 mfd. bypass condenser and .0005 blocking condenser.The audio circuit may be a factory -made amplifier. The three blocking condensers may be .006 mfd., the plate resistors 25 meg.

and the audio leaks 2 meg. The resistors and fixed condensors in the first two RF plate circuits are Phasatrols.SIMPLICITY of control is fast becom-

ing the watchword of set manufactur-ers. This does not apply only to themanufacturers, either, but also includesthe individual set constructor. There havebeen few radical changes made in circuitsbut there seem to have been a fewworthwhile kinks which have done muchto improve the operation characteristicsof the receiver. These have been in-corporated in Planofier Seven (Fig. 2).These improvements were found quitethe thing.

The method used to suppress oscillationdispenses with the use of an additionalcontrol for regeneration. The three stagesof radio frequency are tuned with a singletandem condensor. The detector portionof the set has an energy transfer systemthat excludes the use of tuning controlsfor that part of the set and safeguardsthe detector tube against overloading,while the audio frequency amplifier isresistance coupled.

Resistance and transformer coupledaudio seem to have been engaged in asort of tug-of-war, that is, as far as publicopinion is concerned. First the trans-former coupled amplifier would be in pub-lic favor, then the improvement of re-sistance coupled amplifier. This wouldbe an incentive for the manufacturers oftransformers to work overtime seekingimprovements. This has brought about thedevelopment of good audio frequencytransformers which amplify the signals

faithfully. The old type of resistancecoupled amplifier also amplified evenly.

20 Gain Per StageWith the coming of the B battery

eliminator, the owner of a set using theresistance coupled amplifier had his grief.Due to the tendency of this type of ampli-fier (particularly when using a B elimin-ator) to cause a noise in the loudspeakerresembling the put -put -put of a motor-boat engine, a blow was dealt to thistype of amplifier. Recently there hasbeen developed a resistance coupled am-plifier that eliminates this trouble andtoday we find the transformer and resist-ance coupled amplifiers about at a par.

With the old type of resistance coupledamplifier when using an -0IA tube, anamplification of about 7 was all that couldpossibly be obtained from each stage,providing one used a resistance of about100,000 in the plate circuit of this tube.while the grid resistor was 2 meg. andthe blocking condenser was about .5 mfd.When using the new 30 mu tube, however,the plate resistance used is of 250,000ohms, and the gain per stage is about 20.The reason for using a high resistance inthe plate of the high mu tube is that theimpedance of this tube is so much higherthan the impedance of the -01A and toget a maximum transfer of energy theplate resistance used must be higher thanthe impedance of the tube.

For this reason the transformer coupledtype of amplification is not advisable

when using this tube, since it would re-quire an extremely high inductance for theprimary of such a transformer. If wewere to make a transformer with such ahigh inductance and use the new high mutube, the amplification would be so tre-mendous that violent distortion wouldoccur.

Power Tube in Last StageWe may get away from this condition

by using a very high plate potential andlarge grid bias, but this would not bepractical. Therefore the high mu tubeis used only in systems employing resist-ance and impedance coupling.

For the last stage we employ a powertube where the amplification constant ofthe tube is about 3 or 4, this tube beingused to handle this extra power withoutdistortion, rather than amplify to anygreat extent.

You will probably notice that the radiofrequency portion of the circuits employno method of shielding. While this isnecessary when we use such coils assolenoids, where the field is rather large,it is not necessary when using a coil witha constricted field. The toroid coil isnoted for this fact, but the resistance ofthis coil is rather large. Select a coil witha constricted field and low resistance, e.g.,the binocular type. While the field isnot as small as that of the toroid, the verylow resistance makes the binoculars de-sirable. This also keeps well up theselectivity factor, which is necessary, since

4 RADIO WORLD July 2, 1927

FIG. 2The main tuning control of the Planofier Seven is the dial at center. At right isthe knob of the double midget condenser, MD, while at left is the volume control knob,

R2. The switch is beside it. Atop the set is a Vitalitone speaker.no shielding is used. The three circuitsare tuned with a triple gang condenser.

When building a single control set, tomake the set work satisfactorily all cir-cuits must be in resonance. First, a con-denser of high quality should be selected.Since the three condensers are made onone shaft, their capacity change must beequal. The coils selected must be equallyefficient and of equal inductance value.To overcome variations due to the lengthof leads and difference in capacity oftubes, etc., use a three -plate condenser tocompensate for the variations of the lasttwo circuits. In the first or antenna stage,use a single balancing condenser, called atrimmer. This is necessary, due to thevariations of antenna capacity effect. Thecompensating condenser is mounted on thefront panel and is tuned only when re-ceiving distant stations. The trimmingcondenser is placed inside the cabinet andpermanently set.

Phasatrol Balances SetIn controlling regeneration in radio fre-

quency amplifiers there are severalmethods to be used. Some employ a fixedresistance in the grid circuit, thus puttinga loss in that part of the circuit. Othersuse one of the numerous forms of neutral-izing schemes, while some use a variableresistance in the B battery circuit. Thishas been a very popular method for con-trolling regeneration. Recently there hasappeared on the market a novel devicethat fills the neutralizing bill quite well,by changing the current phase in the platecircuit by means of a variable resistor load.The device is the Electrad Phasatrol.

Regeneration in some cases is causedby an overload of the plate circuit ofthe radio frequency tubes, this excessvoltage being fed back to the grid, whereit strengthens the incoming signal inphase with the signal voltage. By the useof the condenser shown in the phaseshifting device, this back voltage is re-tarded so that it arrives at the grid justtoo late to strengthen the incoming signal,and cause oscillation. The phase is notshifted a complete 90 degrees, as this isnot desirable, since a little self -regenera-

tion greatly increases sensitivity. Thevariable resistance used to feed the plateof the tube is left set after it is onceadjusted to a satisfactory working point.

The energy transfer system used in thedetector portion of the circuit is untunedor aperiodic. Here we find that the selec-tivity factor of the RF stages is sufficientlyhigh not to warrant the use of any tuningcontrols in the detector portion of thecircuit. This allows us to keep the num-ber of tuning controls on the panel to aminimum and still obtain fine results.

Set Not Difficult to MakeSimplicity of construction as well as

simplicity of control are featured in thisset.

To make construction easy parts weremounted on a baseboard in plain view,instead of having some of the parts andwiring beneath the subpanel. The wiringis done with flexible covered wire. Thegrid and plate leads are brought shortand direct, while the filament or low ten-sion leads are bunched.

The audio frequency amplifier may bein one complete unit, with only a few leadsbrought to it.

The variable condenser is mounteddirectly in the center of the front panel.Then mount the three -plate compensatingcondenser (MD), which has two statorsinsulated from each other and one rotor.This condenser is to be mounted on theright-hand side of the front panel. Therotor is connected to A negative, and thetwo stators go respectively to the statorsof the second and third stage condensers.The trimming condenser (MS), ismounted directly on the frame of the tan-dem condenser. This can be fastenedwith a small bracket. The stator of thiscondenser is connected to the stator ofthe antenna stage condenser and the rotorto A negative. This is shown in Fig. 2.

The volume control (R2) is mounted onthe left-hand side of the front panel.The filament switch (S) is mounted onthe lower left hand side of the panel.One binocular coil is mounted on eachside of the condenser and one directlybehind. It will also be noticed that the

Phasatrols and by-pass condensers aremounted nearest the plate of their re-spective sockets.

After the parts are all mounted and theset is wired. Trace all leads and makesure that the set is correctly wired. Con-nect aerial and ground. Insert one tubeand pull the filament switch. If the tubelights insert the other tubes. Now turnC4 entirely to the right. Then turn thePhasatrols to the right. Tune in on a lowwave station. You will notice that thiswill come in with a squeal.

To eliminate this, adjust each Phasatrolby turning to the left until oscillations justdiminish. Now turn MS to a point whereyou get maximum power. Then adjustMD to maximum signal strength. Finallyturn C4 to the left this will Airing the an-tenna stage just below the level of thesucceeding RF stages, and will allow for abroad manipulation of the compensatingcondenser. These operations balance thereceiver roughly.

Fine TuningNow to tune the receiver to a fine point

on a weaker signal. Should oscillations bepresent, turn the Phasatrols to the leftbut if none is noticed turn to the rightuntil a little regeneration is noticed. Thiscan be eliminated by manipulating thevolume control. While doing this adjust(MS) to a final point. This condenser neednot be adjusted again unless the receiverbecomes unbalanced.

After all these adjustments are made. allthat will be necessary in tuning the set isto manipulate the regular tuning dial andadjust the .Compensating condenser (MS),also using the volume control for a finaladjustment.

The fan should not overlook the factthat the correct C bias should be used onthe power tube. The voltage on theaperiodic detector unit should be about67 when using B batteries and when usinga B eliminator should he varied from 22to 90 volts. Hence the B+ detector leadmay be the same for two plate circuits.In Fig. 2 this lead is marked B+D. Theother voltage values are 6 for A+, 90 forB+ RF and 135 for B+ (power). Thatis for a 112 power tube, with a bias of 9volts for C-. For a -71 tube use 180 voltsfor B+ and 40.5 for C-.

If high mu tubes (-40 type) are usedthey may be placed in the fifth and sixthsockets. The diagram is wired for aspecial detector, -00A. If any other typeis used here, connect grid return to A+not to F-. With high mu tubes 135 voltsmay be applied, even to the detector, ifthat too is high mu.

LIST OF PARTSCI-C2-Two Electrad mfd. condensers.C3-One Electrad .0005 mfd. fixed con-

densers.C4-One X -L Variodenser, .0005 mfd.L-Three Beniamin Lekeless coils.GD-One Goodwin Aperiodic detector, or

constants as given in caption of Fig. 1.Ch-One radio frequency choke, 5 milli -

henrys or less (Goodwin).R-Four 1-A Amperites.RI-One I -ampere Amperite.R2-One 100,000 -ohm Centralab variablehigh resistor.MD-One midget double condenser(Marco three plates).MS-One midget single condenser (Ham-

marlund .000035 mfd.).S-One DeJur switch.One' DeJur triple condenser, each section.0005 mfd.One DeJur resistance coupled amplifier.Four Benjamin X sockets.Two Electrad Phasatrols.Three binding posts (Glad.; Long. Ant.;Short Ant.).One 12x20 -inch baseboard.One 7x21 -inch front panel (or to matchcabinet).One National Velvet Vernier dial.One DeJur seven -lead battery cable.Flexatone wire.

juts 2, 1927 RADIO WORLD 5

A New Neutralization PlanEquaphase Embodied in Freshman Electric Set

By Robert Sagala

F I G. ICircuit diagram of the new Freshman Equaphase receiver, stabilized by means of balanced reactances. AC tubes are used.

Three different power transformer windings are required-one for the amplifier tubes, one for the detector, and a third for thepower tube.

ASIX -TUBE electric set is one of thelatest additions to the line of Chas.

Freshman Co., Inc. It uses the AC tubesof the R. C. A., from whom Freshmanrecently obtained a license. One of thefeatures of the electric set, called the Fresh-man Equaphase receiver is the method usedin stabilizing the radio frequency ampli-fier, and for which the set was named.

As is well known, one of the causes ofoscillation is feedback through the grid -plate capacity. It is also well known thatif the feedback through this route is tocause augmented amplification and oscilla-tion, the load impedance must be an induc-tance of rather high value. That is, theload on the tube must have a positive reac-tion of a high value.. If the load is capaci-tive or purely resistive oscillation cannottake place as a result of feedback throughthe grid -plate capacity. The ideal conditionis to have the load purely resistive overthe entire range of the tuner. This can beattained by the Equaphase stabilizer.

This device consists of a series inductancecoil and a resistance in parallel with aseries combination of a condenser and a re-sistance. The total effective resistance inthe condenser branch is made equal to thetotal effective resistance in the inductivebranch, and each is made equal to the squareroot of the L/C ratio.

Balanced ReactionsWhen these relations hold, the reactance

of the coil, which is the primary windingof. the RF transformer following the tube,is exactly neutralized by the reactance ofthe condenser which is connected across it,There is then no reactance on the plate andno feedback through the grid -plate capacity.Consequently there is no oscillation.

In selecting the resistors which are usedto establish this equality of reactances, ac-count must be taken of the resistance whichthe secondary circuit introduces into theprimary. This can be measured at a suitablefrequency and the adjustment made accord-ing to the measurement. Exact neutraliza-tion of reactances cannot be effective ex-cept at one frequency. But that does not mean that Icomplete stabilization of theset cannot be effected by the Equaphasecombination, So long as the reactance isnegative no oscillation can take place, aswas stated above, and so long as the posi-tive reactance is small in comparison withthe resistance in series with the coil, thecircuit will not oscillate. Hence it is pos-sible to select values of impedances in the

stabilizer which will stop oscillations at allsettings of the tuning condenser without atthe same time seriously cutting down am-plification.

The use of this type of stabilizer togetherwith tuning coils of small dimensions andfine wire makes it possible and practicableto employ four tuned stages. This arrange-ment also enables the use of a master con-trol for tuning the four stages. This is agreat convenience.

fine adjustment in the tuning whena common control is used, a vernier con-dener connected across the secondary of theantenna transformer is employed. Thisserves to sharpen the receiver and to clearup some interference.

The main volume control in the receiver

is a high resistance potentiometer across thesecondary of the first audio frequency trans-former. The volume can also be controlledto a degree by using the proper tap on theantenna coil.

The resistance in series with the condensershould be about 380 ohms and the resistancein series with the primary of the coup-ling transformer should be thirty ohms less,or 350 ohms. The difference is the resis-tance introduced into the primary by the

secondary. The condenser is shuntwith the primary should be variable, with acapacity about .00007 mfd. The correct ca-pacity can be found by trial and then itsadjustment can be left alone. The valueof the inductance of the primary is about20 microhenrys.

Voltmeter Is DeceptiveOn Storage A Battery

Distilled water should be added tothat already in a storage battery if theplates are not covered by the water, butthe water should be added only beforecharging, to give the acid a chance tomix thoroughly during the charging proc-ess. Too much water must not be added,either, since when charging, especially ata high rate, the solution starts to bubbleand consequently, if near the top, willflow over. Even with the slow chargers,if a charge is continued for too greattime, the same action will take place.About l/t inch above the plates is enoughcoverage.

In measuring the storage A battery,the hydrometer affords an accuratemethod, since this tells the condition ofthe acid, which is important. The volt-meter is not an accurate test, for even ifthe battery is discharged, after standinga length of time, it, will give a readingof full voltage. Upon connecting up toa set, it will be found, however, thatthe battery will' run down in a few min-utes. The battery, in this case, of course,acts like a huge reservoir of energy ora condenser, accumulating a charge. Theplates act as the conductors, while theacid acts as the dielectric medium.

A battery should be charged even whennot in use. Chemical action between the

acid and the plates causes the same ef-fect, e. g., clogging, when the battery isstanding idle.

The average battery when fully chargedwill give a reading of 1.300 on the hydro-meter, although on some batteries, areading of 1.280 will be obtained. Thisis dependent upon the strength of acidplaced into the cell by the manufactur-er. When a reading of 1210 is obtained,the battery should be recharged. Allow-ing it go lower will decrease the life ofthe battery. The charging of the bat-tery will also become more difficult, sincethe pores of the plates have becomeclogged up to such an extent that it willtake quite a heavy charge to remove thesulphate.

The connecting of the charger ter-minals should be done carefully. Thereis only one way to connect them andthat is the right way. Connecting themin the opposite way will buckle and over-heat the plates, as well probably destroythe entire cell.

Every now and then a coating of blu-ish substance will be noted on the posi-tive and sometimes negative post of thebattery. This is the sulphate. It is '1caused by the acid sprayed or spilled overthe top combining with lead. Always cleanit off.


The Six Types of UnitsUsed for Operation of Loudspeakers

By J. E. AndersonContributing Editor; Consulting Engineer; Associate, Institute of Radio Engineers

bSp

FIG 1

The balanced armature or"push-pull" type. (NOS) isa strong permanent magnet,the poles in two sections,(ss) and (nn.) A singlepiece of iron, the armature(AB), is suspended betweenthe four pole projections.

FIG. 2This illustrates the principle of the so-

called "bipolar" electromagnetic driverelement. (NOS) is the field magnet and(pp) are pole pieces around which the spoolsof wire (WW) are wound. (A) is thearmature to which the sound radiator isconnected. This type of speaker introducesa second harmonic frequency.

I NNUMERABLE loudspeaker unitshave been designed, some according to

scientific principles, others according toa total lack of principles, both moral andscientific.

The majority of speaker units, or asthey are now called, loudspeaker driverelements, work on the electromagneticprinciple. A few work on the electro-static, a few on the electrodynamic, andsome on the piezo electric principle.

In the electromagnetic units the vary-ing signal current changes the strengthof an electromagnet and this magnetexerts a correspondingly varying pull on apiece of iron called the armature. Inthe electrostatic speakers the varyingsignal potential exerts a correspondinglyvarying pull or mechanical force on anelectric conductor called the armature. Inthe electrodynamic the varying signal cur-rent passes through a small coil of wireplaced in a strong magnetic field and theinteraction of the permanent field and thevarying field of the armature coil causesthe coil to move.

The Response of a Crystal

The piezo electric units work on theprinciple that when a varying electricforce is impressed across the piezo crystalin a certain direction, the crystal vibratesin accordance with the varying electricforce.

As far as is known there are no driverson the American market operating on thepiezo electric or the electrostatic prin-ciples. But the electrostatic unit is com-ing soon. There are a few makes employ-ing the eletrodynamic and countless unitsworking on the electromagnetic principle.

There are two main types of driver ele-ments working on the electromagneticprinciple. One of the most efficient is thebalanced armature type, often called thepush-pull or floating armature type. Athird type is the one operating on thepolarized relay principle, which is alsobalanced.

FIG. 3This shows a

simplified form ofthe type of unit il-lustrated in Fig. 2.A single spool(W) is wound

around the polepiece (p), at upperright.

The balanced type of electromagneticunit is shown in principle in Fig. 1.

Analysis of Balanced ArmatureThe permanent magnetic field is ob-

tained from a strong magnet (SON). Eachof the poles of this magnet is split intotwo parts (ss) and (nn). The soft ironarmature (A) is mounted on a stiff spring(Sp) between the four pole projections.This armature is surrounded by a smallcoil of fine wire (shaded portion) whichis placed between the pole pieces. As acurrent is sent through the small coil thearmature becomes magnetized in onedirection or the other depending on thedirection in which the current is sentthrough. Suppose that it is sent throughso that the end near A becomes the northpole of the armature. The torque on thearmature becomes such as to cause acounter -clockwise rotation, because (na)repels (A) and (sa) attracts it, also (nb)attracts (B) and (sb) repels it. Thus thearmature is acted on in four differentplaces, all tending to turn the armaturein a counter -clockwise direction. Whenthe current through the coil is reversed(B) becomes the north pole and (A) thesouth pole of the armature and all theforces are reversed so that the motionbecomes clockwise.

Has Some Fine AdvantagesOne advantage of this type of con-

struction is that there is never any ten-dency to demagnetize the permanent mag-net by currents sent through the arma-ture coil, and therefore the unit holds itssensitivity much longer than other units.Another advantage is that the armatureis balanced both magnetically and mechan-ically, but the magnetic balance is un-stable so that a slight change in themagnetization of the armature will pro-duce a large effect.

One requirement of the armature isthat it be made of soft iron with highpermeability so that it can be readilymagnetized in either direction without anyhysteresis losses and with a small mag-

F FIG. 4The balanced or polarized

relax type of driver elements.(NS) is a permanent mag-net and (OA) is a soft ironarmature. One end of(OA) is connected to theneutral point (o) of thepermanent magnet. The cur-rent goes through WW.

netizing force. A requirement of thespring on which the armature is mountedis that it be stiff enough to pull thearmature away from the poles in case itshould touch. If it is not strong enoughthe armature will stick to one pair ofpole pieces and render the unit non -operative.

Rigidity Is Needed

Another requirement is that it berigidly attached to the armature and tothe spring supports. Lack of rigidity willrender the unit inefficient and is likely tocause rattling and buzzing noises. Stillanother requirement of the spring and thearmature is that they shall be unhamperedin their movement, or friction losses willcause loss of sensitivity. Rigidity of thewhole assembly is of extreme importance.

There are many structural modificationsof this type of driver. They differ mainlyin the size and shape of the magnet,direction in which the armature movesrelative to the plane of the fixed magnet,the method of mounting the armature.and the type of pole pieces used to ob-tain the split poles.

The other or "bipolar" type of elec-tromagnetic driver is shown in Fig. 2. Apermanent magnet (NOS) maintains astrong permanent magnetic field. Polepieces (pp), around which coils (WW) offine wire are placed, project from thepoles of the magnet. As a varying elec-tric current is passed through the spoolsthe permanent field is alternately weak-ened and strengthened and this producesa correspondingly varying pull to beexerted on the armature (A) placed nearthe pole pieces.

Extent of the PullThe pull depends on the strength of the

permanent field, on the intensity of thevarying current and on the distance be-tween the armature (A) and the polepieces. (A) is kept away from the polepieces by some kind of spring dependingon the particular construction. In virtu-

July 2, 1927 RADIO WORLD 7

ally, all cases this spring is the arma-ture itself, as in the' ordinary horseshoetype of unit with an iron diaphragm. Thistype of unit introduces a second harmonic

. movement into the motion of the speaker,which the balanced speaker does not do.But this distortion can be made as smallas desired by increasing the strength ofthe permanent magnet. This not only re-duces the distortion to a negligible quan-tity but it also greatly increases the sen-sitivity of the unit.

A variation of this type of driver isshown in Fig. 3. A single straight magnetsupplies the permanent field. A singlespool of wire (\V) is attached to one endof the magnet by means of a pole piece(p). The armature (A) is attached bymeans of a screw to the other end of thebar magnet and so adjusted that the freeend of the armature is directly over thepole piece. A varying current sentthrough the spool varies the strength ofthe magnet and thus the free end of thearmature is subjected to a varying pull.

This type of construction has no ad-vantages over the preceding type exceptsimplicity of manufacture. It costs lessto make and is equally efficient.

The Balanced RelayThe balanced relay type of construction

is shown in Fig. 4. The permanent mag-netic structure is (pNOSp), which sup-plies an intense field across the gap be-tween (p) and (p). The armature (A)is placed midway between the pole piecesand is lodged at the neutral point (0) ofthe magnet. The armature coil (W) iswound around the armature. When avarying current is sent through the wind-ing the upper end (A) of the armaturebecomes either a south or a north poleaccording to the direction of the current.Suppose it becomes north. The northpole of the magnet repels it and the southpole attracts it, and therefore the move-ment of the armature is toward the right.When the current reverses the movementof the armature also reverses. This con-struction is balanced and therefore it isfree from second harmonic distortion. Itis a sensitive unit but it is somewhat diffi-cult to construct. The armature shouldbe made of soft iron or silicon steel, andit should be sufficiently rigid to pull awayfrom either pole. As a means of decreas-ing the tendency of the armature to stickto the pole pieces, a thin layer of paintor varnish or non-magnetic metal can beapplied to the opposite surfaces of thearmature and the pole pieces.

A Coming PrincipleA unit working on the electrostatic

principle is shown in diagram in Fig. 5.(A) is the armature and can well be alarge metallic cone, or a paper cone towhich tin foil has been attached. (C) isanother conductor of electricity, placedclose to the armature. It should berigidly attached to the mountings so thatit cannot move. It is obvious that (A)and (C) form two plates of an electro-static condenser. A high steady polariz-ing voltage is applied between these twoplates by means of a battery (E). Inseries with this battery is a coil (L) inwhich a signal voltage is induced by theoutput of a receiver. The battery (E)causes plate (C) to exert a steady pull onplate (A). This pull is varied by the volt-age induced in (L), and the result is thata varying pull is exerted on plate (A). If(A) is free to vibrate, it will do so andradiate sound.

In Fig. 6 is shown a driver operating onthe electrodynamic principle. An electro-magnet (NNS) magnetized by a field wind-ing (FP) is employed instead of a per-manent magnet. This produces an intensemagnetic field across the ring shaped open-ing between the central round pole (S) andthe annular pole (N). In this opening isplaced a small coil of fine wire, shown by

FIG. 5This illustrates

the electro statictype of speaker,prophesied to be-come popular. Es-sentially it' consistsof two parallelconducting plates(C) and (A), oneof which is rigidand one which isable to vibrate. Apolarizing voltage(E) of from 200to 500 volts is im-pressed across thetwo plates. Thesignal voltage isinduced in serieswith this voltageby means of thecoil (L), whichcan be the second-ary of an audiotransformer. Plate(C) exerts a forceon plate (A) andwhen the force isvariable the (A)plate will vibrate.The effectivenessof this speaker de-pends on (E).

V

F

.5 IN

F

FIG. 6This illustrates

the electrodynamictype of loud speak-er driver element.A cup -shaped elec-tromagnet (NNS)is used to supplythe field. A directcurrent is sentthrough a coil(FF) woundaround the centralcore the end ofwhich is marked(S). The signalcurrent is sentthrough a smallmovable coil sus-pended between thepoles. This smallcoil is repPesentedby small dots.Lower view is thecross section ofthe unit and topview is the view ofthe unit lookingdown. The arma-ture coil is sus-pended in the an-nular opening be-tween (NNN) and(S).

dots to represent the cross section of thevarious turns.

Uses a Light CoilThis coil is made very light and it is

mounted so that there is a minimum of sep-aration between it and the pole faces. Whena current is sent through this small coil ittends to move just as the winding in anelectric motor tends to move when a cur-rent is sent through it. The direction ofthe motion depends on the direction of thefield across the pole faces and the directionof the current through the small coil. Whena varying or alternating current is sentthrough the smal coil the coil moves backand forth in accordance with the currentimpressed. If the coil is attached to thediaphragm of a speaker or a cone, soundwill be radiated.

One advantage of the type of construc-tion is that the armature coil can movethrough a wide amplitude without strikinganything, and without any change in thesensitivity of the unit. It is therefore par-ticularly adapted to reproducing low notes.

Task Is Too DifficultBut it has also disadvantages. It requires

a battery for the polarizing current, an ob-jectionable feature to many. But this reallyis not so objectionable when a battery orother direct current source is required inthe set anyway. Another thing that is re-garded as a disadvantage is that an outputtransformer is necessary to match the im-pedance of the speaker to that of the tubewhich feeds it.

A real disadvantage is that it is difficultto match the speaker to any tube. If the

impedance of the coil be .made high, thearmature will be heavy and then it will notrespond to the high notes. If the impedancebe made low and a transformer is relied onto match impedances, the secondary current,or the current through the armature coil,will he heavy, requiring a heavy wire. Againthe armature will be heavy.

The best material for permanent magnetsis cobalt steel, but this steel is expensiveand very difficult to handle. A very goodmaterial is tungsten steel, specially treated.It is not exceedingly difficult to work, ismoderately expensive, and has a highcoercive force, which means that it is noteasily demagnitized after it has been put inthe magnetic state. A good material ischrome steel. It is much cheaper than tung-sten steel and easier to work. If the chromesteel magnet be made about 10% larger thanthe tungsten steel magnet the, two will beabout equally efficient, but the tungsten mag-net will hold its magnetization much betterthan the chrome steel magnet. In some formsof construction it is very important to havea steel which will resist demagnetizationwhile in others it is not se important. Or-dinary tool steel is useless as permanentmagnet material. It will not hold its mag-netization.

Comparison of DemagnetizationThe balanced forms of driver elements

shown in Figs: 1 and 4 are not easily de-magnetized by Cm -rents flowing in the arma-ture windings. The unbalanced forms shownin Figs. 2 and 3 can easily become demag-netized by heavy direct currents flowing inthe armature windings, and for these formsit is important to have a steel which wiltresist demagnetization.

The best material for electromagnets andarmatures is silicon steels It has the high-est permeability and lowest hysteresis lossesof commonly available magnetic material.But this only comes in sheets, and sometimesarmatures cannot be made out of it. The nextbest material is pure Swedish iron or theequivalent American product, Armco iron.These products come in sheets, rods andvarious other forms. It has slightly lowerpermeability and higher hysteresis lossesthan silicon steel, but for many uses this isimmaterial.

When a permanent magnet used in a loudspeaker has lost its magnetism throughabuse, it can easily be restored. A verystrong electromagnet is needed for the pur-pose. The current is turned on the electro-magnet and the poles of the magnet to bereactivated is placed across the poles of theelectromagnet. After a few minutes themagnet has been restored, provided that theelectromagnet is much stronger than thepermanent magnet is to be. Of course di-rect current is necessary in the electromag-net.

WMSG and WGL Sueto Stop Radio Board

Two stations in the New York districtfiled injunction suits challenging thepower of the Federal Radio Commission.They were WGL, owned and operatedby the International Broadcasting Com-pany, which attack's the constitutionalityof the Radio Act, and WMSG, the Madi-son Square Garden station, which statesthat the limitations imposed by the com-mission amount to confiscation of prop-erty, without due process of law andwithout compensation.

In response to WMSG's statement,' thegovernment officials state, that the com-mission's regulation of radio does notactually deprive the broadcaster of anyproperty, but that it is simply a powerto regulate a commerce between theStates, derived from Congress and theConstitution. They state that it is properfor the Commission, in the lawful ex-ercise of regulatory power, to prescribea separation between stations, as ameans of avoiding radio congestion and ,interference.


The Woman Chooses the SetAnd That Accounts for Artistic Appearance

By Katrina Fleming.

L

ADIO is a modern development and itis technical. Comparatively fey,' people

understand its workings. For these reasonsa radio receiver is not considered decorativein the home no matter how attractive it maybe. It is not to be compared in decorativevalue with a huge green bottle, or with arusty shield dug up from an old battlefield,or with an old canvas with a few daubs ofmisplaced paint, or with an ancient worm-eaten chest without any paint. An oldgrandfather's clock is welcomed in any homefor its decorative value, and it matters notthat it keeps the wrong time. A radio setof similar proportions would not be toleratedin a barn. A cuckoo clock is consideredhighly appropriate on the wall but a loud-speaker any place where it is seen is anoffense to the eye. It matters not that it ismore in place than a cuckoo in a clock.

Radio is new and therefore it has not yetbeen endowed with any decorative norartistic value. The day will come when theradio monstrosities of 1922 will be highlyvalued for their exquisite craftsmanship andhuge amounts will be paid for their pos-session as antiques. In the year 2,422 or2,423 the superknobodyne of 1922 will havethe place of honor in the most exclusivehome, and the privileged visitors to thathome will exhale many an "ah !" in admira-tion of this rare and artistic contraption.

Must Be Dressed UpBut we are now too close to the incep-

tion of radio to tolerate a radio set in thehome as a radio set. It must be concealedand made to appear something else. It maybe piece of furniture, a clock, a treasurechest or something else to which we havebecome accustomed by long association.If the radio quality of reproduction can beretained when thus concealing the radio setall is well, but if quality cannot be retainedlet it be subdued by the camouflage.

Of course, a radio set is a desirable ad -

THE present-day trend is toward at-tractive appearance. At top is a consolemodel, at bottom a table model of the

treasure chest variety.

WBZA USES CAGE TYPE AERIAL

THE AERIAL MASTS and the cage antenna of Westinghouse station WBZA,atop the Hotel Statler in Boston. The masts are 160 feet high, while the antenna hasa span of 160 feet. The studios, offices, control and transmitting rooms are on the

second floor of the house, extreme left, 16 stories above the street.

dition to any home, in fact it is now almostindispensable. But 'few perons will admita radio receiver to the home unconcealed,lest it appear that they are condoning some-thing new. So radio has entered the furni-ture field, the antique field and the buildingfield.

Souse very attractive combinations ofradio and furniture have been brought out.The console type has been one of the mostpopular.

Some High, Some LowAlmost a life-long association with the

phonograph console has accustomed many tothis as a piece of decorative furniture andhence they admit the radio set in that form.Some prefer the highboy and others the low-boy type of console. The photograph here-with shows a corner of a room in which aconsole type of radio receiver forms thecentral motif. It is a decidedly attractivecorner, albeit a mixture of the old and thenew. Even the most rabid radio enthusiastwho would.prefer a receiver in the form ofcopper wire entanglements will have to ad-mit that the corner is inviting a pleasantradio evening by the fireside.

The treasure chest adVocate will find thearrangement shown in the second photographmore to his liking. Here the central objectis a radio set built into the form of a chestwith all the trimmings. Auxiliary objects inthe picture suggestive of treasure are thejewel box, the little strongbox, and not theleast the comfortable chair

Woman Does the ChoosingWhen the console type of receiver is used

the loudspeaker and the power supply unitscan be placed inside the console directly un-der the set. This method removes one of thecommon objections to radio in the home. Butthis idea cannot be well followed in thetreasure chest type of concealment, unlessthe table on which the chest stands forms aninseparable part of the receiving system.

The choice of type of radio set is nearlyalways up to the woman of the house. Thefactors which count in her mind are attrac-tiveness of the set, its harmony wills therest of the furnishings of the home, and dustcollecting nooks about the set. If there areany nooks and corners about the set in whichdust settle and defy removal the set sohandicapped is ruled out.

Technical excellence of the set seldom en-ters as a factor in her selection. Whethershe likes the tone quality of the receiveror not largely depends on how well the setmeasures up to her other points of judgment.It is up to the man of the house to seethat the tone quality is there as well. Whilethe woman makes the final decision, shemust give heed to the man's wishes on thepoint of quality, because if she does not, hemay refuse to listen to the set and spendhis evenings at the club, where "the boys"have a set which has been selected for tech-nical excellence, and which is still very goodlooking.

SOUTH AFRICA PLANS UNITYIn an attempt to unify control of

broadcasting in the Union of South Af-rica, Cape Town and Johannesburg maybe linked up by radio, according to re-ports received by the Department ofCommerce from Assistant Trade Com-missioner \Villiam L. Kilsein, Johannes-burg, South Africa.


The Hard Road to QualityThe Goal Is Reached, But Only 20% Know It

REAT improvement has been effectedCin broadcasting and reception during

toe past few years. In the early dayseven the best transmitting stations usedphonographs and player pianos promis-cuously before the microphone. Nowthese stations are using the highest typeof available artistic talent directly beforethe microphone. All "mechanical per-formers" are prohibited.

At first little thought was given to themodulation. Often it happened that thewave was badly overmodulated. Now theaverage percentage of modulation is solow that no overmodulation occurs oneven the loudest passages. Furthermore,the modulation is so low that the secondharmonic which is introduced into thesignal when the percentage of modulationis too high is negligible.

Not much thought was given previouslyto quality of modulation over the entireaudible scale. Now .the modulation isthe same for all essential frequencies with-in a very close margin.

At the receiving end the improvementin quality has been slower than at thetransmitting end, because many enteredthe receiver manufacturing field who hadno adequate knowledge of the fundamentalprinciples of radio in general and qualityin particular.

Accumulation of KnowledgeBut knowledge of these things was ac-

cumulated anu broadcast in technicalcircles and great improvement in the re-ceived programs was the result.

There was no one thing that camefirst in this general improvement of equip-ment. The realization that more powerwas required to operate loudspeakers sat-isfactorily brought larger tubes. The de-mand for the low notes in the signalbrought large transformers with high in-ductance primaries and it also broughtresistance coupled receivers with high mutubes The demand for the low as wellas the hjgh notes brought cone speakersof large dimensions.

The demand for convenience of opera-tion brought about simplified control inthe receivers. At first it was thoughtnecessary to have a variable for everycomponent part of the circuit. As a resultthere were receivers which had a rheostatfor every tube, one or more variable highresistances for oscillation control, oneseparately controlled condenser to everytuned circuit together with a vernier con-denser for each, potentiometers for vary-ing the grid bias, taps on the primariesto change the coupling, taps on the sec-ondaries for varying the tuning range,rotatable primaries for changing thecoupling, and other variables withoutnumber.

"Variomania" DisappearsAs a result of this mania for variables,

which has been called ''variomania," re-ceivers horrible in appearance and well-nigh impossible to operate appeared. Atpresent variables are used only for tuningand for volume control, and these arereduced to the smallest possible number.One or two controls for timing and onefor volume control are now popular. Manysets use a single control for tuning andanother for volume control. The resultis that the receiver is simple to operateand it is possible to build it so that it lookslike a piece of art.

The demand for convenience also

By Knute Petersen

MIGHTY POOR COIL PLACEMENT

UNCONTROLLABLE OSCILLATION will result if the coilsare placed parallel and fairly close to each other as shown.Place them at right angles, or at the popular Neutrodynu

angle, and keep them away from the variable condensers.

brought socket power devices. At firstthese were designed to eliminate the Bbattery only. Then they were built toinclude the C battery also. Finally at-tempts were made to build them so as toelminate the filament battery also. Fairresults have been obtained and the pros-pects for complete success along thisline are very bright. In fact, many re-ceivers of excellent performance charac-teristics are now in operation in which nobatteries whatsoever are used.

Competition FruitfulThe keen competition between the

phonograph and the radio was one ofthe greatest forces for improving thequality of both. But a few years ago thequality of phonographically reproducedmusic was atrocious. It was an ordeal tolisten to one of the instruments. Radiocame along. It was an improvement overthe phonograph, bad though it was atfirst. The phonograph manufacturers gotbusy and turned out instruments capableof reproducing recognizable music. Thatwas a challenge to the radio element.They accepted it and now the duel is be-ing fought. The best phonograph repro-duction is now on a par with the bestradio reproduction, and either is almostas good as the original.

In the competition between the phono-graph and the radio the phonograph hadthe early advantage of greater talent.Nearly all the great artists of voice andinstrument were bound by contract tothe phonograph makers. Radio had totake what was left. At first there wasnot much to take, but now practically allthe great artists are available to the radio.

Radio has one advantage over thephonograph, and that is that its pro-grams come to the listener right off thegriddle. Phonograph music is bought inthe store deliberately at so much perPackage. Radio music comes wafting^hrough snace so that he who listens mayhear by simply tuning in on it. A peachplucked off the tree is much more deliciousthat./ a peach fished out of a tin can. Thetwo peaches might have grown on thesame tree, or even the same branch; butthe canned peach grew a season or twoago, the one plucked off the tree did notstop growing more luscious until the

moment it was picked. The plucked peachripened in the sun, the canned peachripened in the shade of a warehouse, orperchance under the action of a chemical.So it is with the music from the phono-graph and the radio. The phonographrecord has been perfected in a studio anddeprived of some of the human element.The radio rendition is the result of growthand it is alive and vibrant.

The artistic phase of radio has alwaysoutrun the technical development. In theearly days when "mechanical performers"were used the technical equipment atboth the transmitting and receiving endswas so poor that nothing but the noveltyof the thing sustained interest in broad-casting.

First -Class Artists NowLater, when mediocre human talent was

employed, the technical equipment im-proved a little but still the reproducedprograms were mediocre.

Now when artists of first magnitudeperform before the microphone, the aver-age reproduction is of first order.

Of course one frequently hears a radioreceiver which gives the illusion of reality,but such receivers are none to plentiful.The defect now lies mainly with the re-ceiving equipment. Soon the listener willnot be satisfied with distorted radio. Thegeneral buyer is learning fast.

Poor reception is not now so much amatter of technical development of re-ceivers as with the exploitation of radio.It is well known how to build receiverscapable of fidelity of reproduction, butthere are many sets built which can not.reproduce any program properly. Andthese sets are in daily use. They servewell to impart news and useful informa-tion to their owners, but they are not ableto create the illusion of reality.

These receivers also serve to keep therhythm of a musical composition and belchforth a great volume of sound. Hencethey serve well those who would fill theroom with noisy cadence. But when itcomes to reproducing classical music asrendered by the great artists or organizedgroups of artists, these sets can do nobetter than create a displeasing caricature.

It is safe to say that more than 80%of the sets in use today fall in this class.


Much Heat Dissipation,New Resistor Demand

By H. E. OsmunCentral Radio Laboratories

The rapid gain in popularity of thenew A -B -C socket power circuits suchas those using the Raytheon 350 milli-ampere or Q. R. S. 400 milliampere tubes,has created a need for resistors of muchgreater current capacity than ally thusfar used in radio receiving circuits. Thishas been brought home forcibly to manyan experimenter who has hooked up theordinary small resistor in the new circuitsonly to see it go up in smoke after afew minutes' service.

These new circuits dissipate much moreenergy in the resistances than has beenthe case in circuits used heretofore. Thisis obvious when we consider that we arenow dealing with a pressure of 300 voltsand a current of :3 to .4 ampere, whilein the past, high voltages have beenused for B battery circuits only, wherethe current seldom exceeds .06 ampere.

To have a sound understanding of thenew resistances needed, it is advisableto refer to some of the fundamental lawsof resistance in electrical circuits. Thefollowing laws are simple and accurate.They should have a prominent place inevery radio experimenter's note book.

The Four Points1The ohm is the unit for measuringelectric resistance. A resistance of

one ohm in a conductor will cause apressure drop of one volt at a currentof one ampere.

2 Ohm's Law is a simple equation todetermine resistance, current, or

voltage drop in an electric circuit. If Iis the current in amperes, E is the voltagedrop through the resistance, and R isthe resistance, the following relations areall expressed by Ohm's law :

I E/RR E/IE=RxI

3 The watt is the unit of electricpower. It represents the energy

expended when one ampere flows througha resistance of one ohm or through adrop of one volt. The amount of energyexpended in any resistance, therefore, isthe current in amperes multiplied by thedrop in volts. It is also determined bymultiplying the square of the current inamperes by the resistance in ohms.

4 Electric energy is dissipated in aresistance as heat, and the amount

of heat is in direct proportion to thewatts of electric energy dissipated, regard-less of the shape or kind of materialused in the resistor. Rheostats or fixedresistors that are to dissipate a largeamount of energy, therefore, must haveample size to radiate the heat generated,and must be manufactured throughoutof material that will withstand high tem-peratures.

Difference in EnergyRule number four has been relatively

unimportant in receiving circuits of thepast, because the amount of energy dis-sipated by any single resistor was small.For example, a filament rheostat, con-trolling two type -01A tubes from a six -volt storage A battery, will dissipate be-tween one and two watts. This energyis so small that most any rheostat, re-gardless of size, will handle it withoutundue heating.

A little later in radio history there camea demand for fewer panel controls andit was partly answered by controllingthe filament of all the tubes in the setwith the same rheostat. For a six -tubeset, using one 1/2 -ampere power tube, thisrequired a possible dissipation of fromfour to seven watts in the rheostat andmany of the small rheostats formerlyused could not carry the current withoutburning out. New and larger rheostatsof low resistance designed for this servicewere frequently called heavy duty. Theserheostats may confuse many purchaserstoday, because while satisfactory for thepurpose for which they were designed, themaximum energy they will dissipate with-out breaking down will not exceed 10watts, and is often less.

The ordinary wire -wound radio rheo-stat does not break down because thewire burns out, for it is normally woundwith the same kind of wire used in elec-tric heaters that operate continuously ata red heat. The wire is wound on andinsulated by fibre, for that material canbe easily wound flat and then bent intothe required shape. Since this fibre iscovered up by the wire, however, it haslittle radiating surface and becomes thehottest part of the rheostat. The limitingfactor, therefore, is the temperature atwhich the fibre breaks down. Fibre dis-integrates slowly at the boiling point ofwater, 212°F, and rapidly at higher tem-peratures.

Many Must Dissipate 18 to 35 WMost resistors needed for the new cir-

cuits must dissipate from 18 to 35 wattsnormally, and should be capable of dis-sipating up to 50 watts for a short periodof time to guard against burning outthrough an accidental short of thethe equipment. While it is possible tomanufacture a conventional radio type ofrheostat to dissipate this amount ofenergy at a temperature within the safelimit of fibre, it is scarcely practical be-cause such a rheostat must be so verylarge in size it is difficult to find spaceenough for it in ordinary radio equipment.The only alternative is to wind the resist-ance on material that will withstand hightemperatures without damage.

The new Centralab power rheostats andpotentiometers are an example of theheat -proof construction necessary forpermanence. The Nichrome resistancewire is wound on a metal strip insulatedby asbestos. This metal strip is thenformed into the rheostat frame. It iswelded to the contact shoe support insuch a way that the entire assembly ispractically heat proof, while the wire isopen to free air circulation on all sides.The finished rheostat is only two inchesin diameter, but will dissipate 50 wattsof electrical energy at a temperature of480°F. Prolonged operation at this tem-perature can cause no possible damage tothe rheostat, because the three materialsused, Nichrome wire, steel and asbestos,are all proof against high temperatures.

While this article has referred particu-larly to wire -wound resistors, the sameratio of temperature to energy dissipatedapplies to the carbon type resistors thatare popular because a high resistance ofcarbon can be manufactured at a lowercost than one of wire. Carbon or graphitevariable resistors are excellent for radio

purposes where the resistance must beof the order of 10,000 ohms or more andwhere only a small amount of energy isto be dissipated. They are at a decideddisadvantage where used to dissipatemore than five watts, however, becausethey must either be extremely large insize so as to operate at a low tempera-ture, or their resistance will fluctuate sobadly as to render them useless as a con-trol. This is due to the high tempera-ture coefficient of carbon.

Wire Versus CarbonMetallic wire has a very low tempera-

ture coefficient as compared to carbon,causing its resistance to remain prac-tically constant over a range of severalhundred degrees. Carbon, on the otherhand, will decrease in resistance rapidlywith a rise in temperature. This changeis so great that the commercial carbonvariable resistance will decrease in re-sistance at least 20% with a rise of 200degrees in temperature.

It is evident that practical resistors forthe new power circuits must be wirewound, have a large area for heat dis,sipation, and be constructed of heat proofmaterial throughout. Faulty resistors arenot only a source of aggravation, but mayactually break down the high priced con-densers or rectifying tube by failing inservice.

The Public DemandThe demand of the radio public is for

convenient and dependable operation ofthe radio set from the light socket with-out sacrifice of radio quality or perform-ance. The listening public is getting moreand more critical of performance andwill not tolerate distortion or hum. Qual-ity not only must be retained but mustbe improved. Furthermore, the publicdoes not want to be limited to loweror so-called dry cell tubes.

So far, economy of operation has notbeen a major factor in radio. The pros-pect has bought the best set he couldafford or, in many cases, the set hisfriends talked about, whether or not hecould afford it, and he has not countedthe costs. This is passing. With moreand more good sets to choose from, econ-my will be the deciding factor in manycases.

It is to the advantage of the customerto purchase standard socket power equip-ment that may be used to operate anygood radio set. He is then free to choosehis set on its merits alone, rather thanto choose some special set because it isdesigned 'for light -socket operation. Heis also free to change to another setif he desires without sacrificing his in-vestment in the power equipment.

Present radio receivers with standardtubes, socket -powered with the presentindirect system of A power and goodrectifier -and -filter B power, set a veryhigh standard of performance, conveni-ence and economy. With this high stand-ard established as a criterion, togetherwith the great commercial advantages, itis not likely that the AC tubes or othernew devices will quickly supplant thepresent tried-and-true system. The ACtube, no matter how good it may be inits ultimate development and application,can only closely approach or, at best,equal present standards of performance.It is not within the bounds of probabilitythat it will attain such perfection withoutgoing through a long period of quantityproduction and application.

ONCE -A -NIGHT IS RULELos Angeles.

No matter how popular a musical selec-tion may be, it is never rendered more thanonce during the course of an evening'sbroadcast at KFI. This is a strict rule,followed in the interest of better and morevaried entertainment.


Get a Tone -Quality Set, Even Old SetsIs Caldwell's Advice CanBelmproved

By Orestes H. CaldwellFederal Radio Commissioner

Our broadcasting stations, especiallythe leading ones, are transmitting musicof irreproachable tonal excellence. Theordinary cheap or old-fashioned radio setdoes not begin to do justice to the musicin the air. When such music is filteredthrough a cheap, poorly designed re-ceiver, its phonograph -like sound offends.Yet, right nearby, a good receiver maybe taking the very same ether impulsesand converting them into gorgeous toneharmonies.

As a matter of fact, the average hometo -night is receiving not the 1927 radiothat is in the air to -night, but rather 1923radio, or 1925 radio-depending on thedate of the set being used. The public

to realize this, and we radio peoplehaven't yet impressed sufficiently uponthem how much they are missing.

Progress SurprisingSurprising progress has been made in

achieving tone quality in receivers duringthe past year or two, and the familywhich can afford to invest several hun-dred dollars in a modern radio receiver,and' has not done so, is simply deprivingitself of values that would cost manytimes more, measured in terms of concerttickets, phonograph records, or any otherform of entertainment.

And after selling a customer a set, theradio industry should see that that cus-tomer is provided with all the accessorieswhich will make radio a convenience andpleasure in the home.

Take the simple idea of letting the fam-ily enjoy radio in every room of thehouse, by operating a number of loudspeakers from the central set.

Jacks Easily InstalledTelephone jacks can be installed in

various rooms throughout the wholehouse for a few dollars, and each mem-ber of the household, including the chil-dren and the maid, can retire at leisureto their own rooms while the programgoes on. A clock switch to turn the pro-gram off (or on) completes the conven-ience. After four years' satisfaction with

such an arrangement, I have often won-dered why more radio listeners lookingfor full radio enjoyment, do not equipthemselves likewise.

Radio is already a great unifying andeducational influence in American life. Ifthe nation is to get the full advantageof radio's benefits, public interest de-mands that there should be a receivingset in practically every American home.

The Trade's TaskElectrical and radio manufacturers, job-

bers and dealers can do much to stimu-late the American public in its naturalinterest in radio, and right now, by well -calculated promotional effort, can tre-mendously accelerate the present annualbuying by the public toward this end ofradio in every home.

The Federal Radio Commission is al-ready well along with its assigned task ofbringing reception to the present 6,000,000radio homes.

But on the radio industry and trade-on manufacturers, jobbers and dealers-rests the responsibility for the three -foldgreater job of the next ten years, the jobof selling radio to 16,000,000 homes yetunequipped-the job of putting radio inevery American home.

Programs From EuropeSent by Copenhagen

An all -European musical concert,a dozen widely separated cities contributed,recently was broadcast by Copenhagen radiostations, according to advices from ViceConsul Ellis A. Johnson, Copenhagen, Den-mark, just made public by the Departmentof Commerce.

The full text of the announcement is asfollows:

"During a period of three hours, bymeans of relaying, the Danish radio publicwas able to hear London, Paris, Toulouse,Berne, Prague, Langenberg, Moscow, Dav-entry, Bruxelles, Oslo, Frankfort andLyons. The concert was satisfactory in allrespects and proved exceedingly popularwith the Danish radio public."

How long will one endure a bad set tosave the price of a new receiver? Oldautomobiles wear out and when they nolonger make the grade the owner buysa new one. But an old radio set does notwear out, but relatively grows a bettercaricaturist as time goes on. The worstpart of it is, to the bystander at least,that the owner of this set has becomeaccustomed to the caricature and doesnot know that the set lacks in fidelity.

The only way to convert this dweller inthe radio stone age is to make him listento an excellent modern receiver. He willsoon give up his old set for a ew oneand recline in solid musical comfort, justas an owner of an old automobile will geta new machine after he has tasted thecomfort of new springs and cushions, andreal power.

Why Hesitate?

Many people realize that their receiversare old and out of date but they hesitategetting new equipment on the ground thatthe advance in radio is so rapid that newsets also will be out of date. That is afoolish reason for sticking to an old set.It is false assumption. Nothing revolu-tionary is in sight. You might as wellnot buy new clothes, when all your ward-robe is past the service state.

But if a set is out of date and needsrefreshing as far as quality is concernedit is not necessary even to get a completelynew outfit. Some of the parts in it areprobably as good as similar parts are now.It will be no improvement in quality tochange them.

Some Suggestions

Perhaps the old set can be renovated bythe simple replacement of audio trans-formers, by the increase in the platevoltage, by the adjustment or introductionof grid bias batteries, by the use of apower tube in the last stage, by the intro-dvction of a suitable volume control, andby the substitution of a better kind ofloudspeaker. There are innumerable littlechanges that can be made at small costin a set whicit will greatly improve thequality. Just what the required changeswill be in any set will depend on theoriginal construction of that set.

Stations Off Waves,Despite Warning

Washington.Since the order of the Federal Radio

Commission requiring stations to keep with-in one-half a kilocycle of their assignedfrequency, reports have been received of anumber of stations failing to live up to therequirement. One station, according to areport, was 28 kilocycles off the channel as-signed it.

In each case the Radio Commission haswarned the offender that a second offensewill result in a cancellation of license.

PUSH-PULL RESISTANCECOUPLED AUDIO

This circuit, developed by J. E. An-derson, was published in the June 11issue. Complete theoretical and practicalinformation on this hookup. The circuitwas operated direct from a DC house linewithout filter of any kind and producedno hum or motorboating. Send 15 centsfor copy. Radio World, 145 W. 45th St.,New York City.

Loop Outside WindowWorks In Steel Building

Is your set well-behaved in some loca-tions and a had actor in others? Twocases of misbehavior may be cited. First,he set may be very noisy and squeally inone place and normal in other locations.Second, the set may be sensitive and se-lective in most locations but be quite in-sensitive in others.

In the first case the noise is probablydue to secondary interference This canbe defined as receiving two stations ofdifferent frequency at the same time.This is an inherent possibility in a Super -Heterodyne. The reason it is seldom no-ticed is that the interfering station maybe so far away that no squeal is heard.The only way to ameliorate this troubleis to tune out the interference in the radiofrequency level.

The second kind of misbehavior is nota fault of the set but is due to the failureof the operator to realize what he is ex-pecting from a set. One of the first

requisites for reception is that there besomething to receive. The most sensitiveset ever constructed will not bring in asignal which never reaches the set. Thereceiver must have something to work on.

One place where not much can be ex-pected is inside a steel railway. coach.The set is completely surrounded by aground electric and magnetic shield, ex-cept for a few tiny aperatures called win-dows. Practically nothing but the strong-est signal gets inside the car. Somethingmight be received if the loop is put outof the window, but not much. An in-sulated wire strung alongside the roofof the car on the outside and connectedwith the set metallically should bring insomething.

In the interior of steel buildings thesituation is just about the same. It iseven worse when this building stands inthe midst of numerous similar buildings,such as big apartment houses.


Music Card -IndexedFor Speed and Safety

"Music on order" is a slogan whichmight easily be adopted by the Musicaland Literary Research Department of theNational Broadcasting Company. Thisdepartment of the concern which ownsand operates WEAF of New York, man-ages WJZ, New York, and WRC, Wash-ington, and furnishes radio programs tothree separate networks of broadcastingstations, has expanded its activities to thepoint where it is prepared to furnish, onextremely short notice, complete orches-trations and vocal arrangements of com-positions suitable for any sort of a broad-cast feature.

This service is only one phase of thedepartment's work, however. Originallyestablished to avoid legal difficulties inconnection with literary and musical ma-terial used in broadcasting, the depart-ment has come to include a very completemusic library, groups of musicians skilledin composition and in vocal and instru-mental arrangements, research workerscontinually in search of new material,copyright experts and clerks, fifteen peo-ple in all. Incidentally, original scriptsfor broadcast programs and original musicto accompany them are now being regu-larly prepared under the supervision ofthe department.

An Accurate Check-upThe question of copyrights in the music

and literary fields is a highly involvedone. Wide distribution of various rightsconnected with musical and literary com-positions and in many cases the overlap-ping of such rights make the whole prob-lem of fees for the use of this materialon the air extremely technical. In manycases, reservations have been made bycomposers, authors and their representa-tives regarding the frequency with whichtheir material may be used in broadcast-ing. Other compositions are limited tothe arrangements which may be madefrom the originals. Sometimes, whileoriginal compositions are not copyright,certain arrangements and translations ofthem may be thus protected. The entirematter is a complicated one.

A very accurate check must be kept bypeople well versed in the intricacies ofcopyrights on all material which is usedin preparing broadcast programs and inaddition complete data on exactly whatworks are used, with dates. This routinerequires the constant attention of a corpsof workers, since the data must be filedand cross-indexed to provide ready ref-erence.

Perhaps a more interesting phase ofthe department's activities concerns itselfwith research work and the manner inwhich the music library is maintained.Skilled music readers are always at workseeking out new and forgotten composi-tions, ranging from grand operas to thesimplest songs. Many different sourcesare used, including indices of all kinds,various reference works, files of old news-papers and magazines and countlessothers.

Versatile ReferenceThe music library itself is cross-indexed

in a number of ways, so that compositionsappropriate to any theme can be locatedwithin a very short time. One index ismaintained by composers, one by titles.one by first lines and several by subjectswith which the music treats. The presentaccurate and helpful condition of theseindices has entailed a great deal of con-tinuous effort, but it has proved its worthmany times.

When a broadcast program is beingprepared dealing with any particular sub-ject, country or period, musical composi-tions which have been written about thattheme are almost instantly available.

Constant work is also necessary to makesure that the proper arrangements are athand. For this reason, the departmentmust forecast the requirements of theprogram department. In most cases, whena selection is added to the music library,both vocal and instrumental arrange-ments suitable for broadcasting are made,so that no time may be lost when a callcomes in for the music.

Constant work is also necessary to makesure that one is correctly keeping track

Mode of Life ChangedBy Stations, Says Gibbs

Radio is giong to change the mind ofman, declares Sir Philip Gibbs, the Britishwriter, who believes that radio is going togive man a mastery over life beyond allprevious dreams.

"Here again the scientists have pre-sented new opportunities to humanitywhich will surely alter their scheme oflife, their habits of mind, their social cus-toms and pleasures, almost as much asthe alteration of material conditionswhich are now awaiting them," he writesin Hearst's International Cosmopolitan.

Threshold of a New Age"Again we stand only on the threshold

of a new age, and yet already we are con-scious of newly revealed wonders whichin the old days would have been thoughtmiraculous and are indeed taking us intoa region beyond mere matter, in thesanctuaries of eternal force."

"Radio has already opened up new vistas

of knowledge, according to Sir Philip, andhas given to people wider sympathies inlife and put them into touch with othercountries and minds.

"Perhaps those are high words to useabout an invention which is called wire-less or radio," he adds, "so common nowafter a few years of use, that most of ushave a wireless aerial over our chimney -pots.

Hopes for Less Vulgarity"One must not underrate the effect even

now on the human mind caused by thisbroadcasting habit which has taken holdof life. One may only hope that it willbe less vulgarized by some of its trans-mitters.

"We are still at the beginning of thisnew knowledge. Marconi's beam systemof wireless telephony is already past itsexperimental stage; it is now possible tofocus the ordinary wireless rays upon aparticular locality with directness.

ROOM FOR A PARROT

(Delano)The cage aerial is coming into its own

in France, and one progressive merchanthas established a shop to furnish suchaerials ready-made, to set up on anyautomobile. On Sunday he sets up a pairof sample antennas on his Ford, connectshis receiving set to them, and gives freeconcerts in the Bois de Boulogne or theGrand Boulevards.

of literary works N\ Inch may form thebasis of broadcast presentations. Thequestion of interlocking rights in the dra-matic field is such that few standard playshave been used in broadcasting. On theother hand, there are few stage playswhich are ideally suited to microphoneproduction. These two conditions haveresulted in original work and the adaptation of standard works as the materialfor most radio dramatic presentations.

Work AccomplishedMost of this work for the National

Broadcasting Company has been done inor under the supervision of the Musicaland Literary Research Department.Standard fairy tales have been adaptedfor radio use, involving the preparationof original scripts and the composition oforiginal music. This series was highlysuccessful.

Other series of broadcasts which havebeen outstanding are two which are nowbeing furnished on regular schedule to theNational Broadcasting Company's Net-work stations, the "Great Moments inHistory" and the Biblical dramas. Muchof the music which has been used to Pro-vide atmosphere for these program fea-tures has been composed especially forthe broadcasts by members of the Musi-cal and Literary Research Department.

Both of these series have attractedwidespread attention, due without doubtto the fact that they have been preparedand broadcast by people thoroughly ex-perienced in the various lines of effortinvolved and well versed in broadcastingasTel

The Musicalusical and Literary Research De-partment is under the management ofNicholas deVore, a musician of wide ex-perience and an expert on the subject ofcopyrights as well. As his assistants, Mr.deVore has a group of men thoroughlyconversant with their particular lines ofwork, who can speak with authority ontheir individual subjects and who arerecognized in their special fields.


A WORD OF CAUTION

(Hayden)

ALWAYS be sure that the rectifier tubeis in the socket of the A or B eliminatorbefore turning on the house line. If theline is turned on before the tube is in-serted, the high voltage in the secondarywindings of the transformer many blowout the condensers shunted across thiscircuit, since the accustomed load-therectifier tube-is missing.

Many Are StimulatedBy Classical Music

Paul Althouse, concert favorite and forten years leading tenor with the Metro-politan Opera Company, broadcast in theAtwater Kent concert recently, over anetwork of twelve stations from WEAF.Afterward he said: "The public likes to be'jazzed' with classical music. People seek anemotional sensation in every kind of musicthey hear, except perhaps the sublimeclassics, which appeal primarily to themind. One finds a distinct reaction tospecific emotional moods of a song. Oneset of individuals will denote by theirmanner a pleasure in words and musicof a tranquil nature. Another set, hav-ing different emotional characteristics,find a keener enjoyment in the swiftlymoving phrases, the more enlivening textof a spirited song.

"This is evident from the light of en-joyment in the eyes, the eager straight-ening of the figure, the clasping or un-clasping of hands, or the relaxing oftensely held bodies. I have come to theconclusion that many people find theirgreatest stimulus in the ,music of the clas-sical composers. The emotional responseto this music is no less pronounced thanthat exerted by a jazzing effect."

Mr. Althouse is a native of Reading,Pa., where he received his academic andearly musical training.

WJZ BROADCASTS BALL SCORESA new service for the baseball fan has

been inaugurated from WJZ. Everyweekday afternoon at 5:30 and 6:50o'clock, the latest baseball scores aregiven, as reported by the AssociatedPress. On Sunday afternoons there isonly one reading of the baseball scores.

HOT STUFFIf at any time you may want some radio

advice,Don't go to any ol' guy who thinks he's

best.For if you do, you're merely gambling, as

with dice.Come to us, we'll fix you as we do the

rest,And rest assured we aim to trim 'em

nice.-Advt. Anon.

Broadcasting Gives WayWhen SOS Is On Air

BY J. T.Unexpecteddrama occasionally flashes

into the lives of radio listeners living nearboth coasts of the United States whensignals of distress from a ship at seacauses suspension of broadcasting.

Picture a listener who has tuned hisreceiver to 492 meters for one of the Na-tional Broadcasting Company's weeklyradio features. The program is progress-ing smoothly when there is a sudden in-terruption. A strange voice remarks,This is station WEAF, New York. Weare signing off because of an SOS." Si-lence follows. The station is standing byto insure that rescue arrangements maybe carried on without interruption frombroadcasting.

A hurried trip down the dials probablydivulges that about half of the local sta-tions signed off at the same time orshortly after WEAF One by one, theremaining broadcasters suspend their pro-grams. Within four or five minutes theair is clear. Pleasure, in the form ofbroadcast entertainment, has given waybefore the pressure of business-and agrim business it is.

Imagination at WorkBroadcast listeners can receive a good

many thrills from following the course ofan SOS signal, even if they are unableto read code. It is simple to picture adisabled steamer wallowing through forty -foot waves while a heroic radio operatorclings to a support in his reeling shackon deck and sends out details of the ship'scondition and position to vessels and landstations which have replied to his signalsof distress

At the station's transmitter, anotherangle of the drama is apparent. Everybroadcasting station situated on or nearthe coast is required by law to maintainwhat is known as a "600 -meter watch."Perhaps the term "600 -meter listen" wouldbe more nearly descriptive, since this"watch" consists of constant listening onthe regular ship communication channelwhile the station is on the air. Keepingthe "watch" is a tiresome job into whichexcitement enters only on those rare oc-casions when signals of distress are heard.

W. MartinHowever, the watch is strictly main-

tained at most of the stations. In thecase of WEAF, WJZ and WRC, stationsmanaged by the National BroadcastingCompany, operators who are assigned thisduty are compelled to keep a log of callsheard, with the times at which the signalsare received.

WEAF's transmitter is at present lo-cated at 463 West Street, New York City.The station's antenna is on the roof ofthis building, and the 600 -meter watch ismaintained in the room which houses thetransmitting apparatus. The watch is be-gun fifteen minutes before the stationgoes on the air, to make sure that theether is clear at that time, and it is keptuntil the transmitter is shut down.

Verifies SignalWhen the "watchman" hears a signal of

distress, he first verifies it by communi-cating by telephone with the DistrictCommunications Superintendent of theNavy Department, located in the White-hall Building. This office is in turn inconstant touch with the Navy Yard inBrooklyn, where the Navy Deparmentradio station for the district, NAH, islocated

On many occasions, before the watch-man at WEAF's transmitter has had timeto verify the call with the District Com-munications office, NAH, the "Watch Dogof the Ether," will have opened up with,"QST DE NAH QRT SOS"-meaning,in dot and dash parlance, "General callfrom NAH, clear the air because of anSOS," an order to all broadcasting stationsin the district to shut down activities.

When this call is heard, or before thattime in the case of an SOS which hasbeen intercepted by the watchman andverified by the District Communicationsoffice, the operator at WEAF's transmit-ter immediately turns a switch whichthrows the station's program off the air.Then, speaking into a microphone infront of him, he announces that the sta-tion is signing off because of an SOS. Thetransmitter is shut down, but the tubesare kept burning, because within a shorttime the air may be clear again.

Not One Station HasExclusive Wavelength

The new frequencies for the broadcast-ing stations have been announced andwere listed in the June 11 issue. No sta-tion has a frequency or wavelength allto itself. Even WJZ and WEAF, whilenot sharing time with any station, findother stations on their very waves forsimultaneous broadcasts.

For instance, WEAF, New York City,610 kilocycles frequency, 491.5 meterswavelength, finds WAPI, Auburn, Ala.,and WSKC, Bay City, Mich., on thesame wave. WJZ, New York City, findsKFRC, San Francisco, on the 660 kc(454.3 m) channel with it.

The power and distance differenceswill make such situations unimportant, butthe mere fact that two of the world's

greatest stations did not get an exclusivechannel shows how scarce the channelsare in respect to the number of stationsthat must be accommodated.

WJZ, which had been authorized underthe Hoover administration of radio, to use50,000 watts, is reduced to 30,000. WBAP,Fort Worth, Tex., formerly 10,000, is now1,500. Other power changes are: WBBM,Chicago, 10,000 to 1,000; WBZ, Spring-field, Mass., 5,000 to 15,000 (increase);WEAF, 20,000 to 5,000; WEBH, 10,000to 2,000; WGN, Chicago, 1,500 to 15,000(increase); WGY, Schenectady, N. Y.,20,000 to 30,000 (increase); WWAE, Chi-cago, 10,000 to 500; KEX, Portland, Ore.,20,000 to 2,500; KOA, Denver, 20,000 to5,000.


Straight Line CapacityFavored for Unit Tuning

By G. T. BurkeEngineering Department, General

Variable air condensers are made withthree general types of plate shapes, al-though there are many modifications ofeach type.

The first rotary variable condenserswere made with "straight line capacity"plates. These plates were semi -circular inshape and are called straight line capacitybecause the curve of capacity plottedagainst dial divisions (angle of rotation)is a straight line.

The relation between capacity, wave-length, and frequency is such that thisplate shape tends to result in crowdingof stations at the lower end of the capac-ity range. That is, there are more trans-mitting channels for each dial divisionat the lower end of the scale than the up-per. This objectionable feature has ledto a widespread use of other plate shapes.

The straight line capacity plates have,however, one distinct advantage whenused in single -control set-ups. Where itis desired to tune several circuits withone control, some form of capacity ad-justment is nearly always necessary tocompensate for different zero capacitancesin the several circuits.

Feature of UnbalanceIf semi -circular (straight line capacity)

units are used, this adjustment can bemade by slightly advancing one or moreof the units. If this be done with con-densers having other plate shapes, thecapacities will become unbalanced as thecontrol dial is advanced. This is due tothe fact that if the plate shape is not"straight line capacity, the capacity vari-ation per dial division increases as thecondenser is turned toward maximumcapacity, and the unit which was advancedgains capacity snore rapidly than theothers.

This feature has caused at least oneimportant manufacturer of uni-controlreceivers to return to the semi -circularplate shape.

Results in Slow MotionIt may be noted that the effect of

"straight line wavelength" and "straightline frequency" condensers is strictly aslow motion action, having a variable re-duction, gradually lessening as the con-denser is advanced. The same result canbe and, in fact, has been accomplishedby a slow motion dial so constructed asto vary automatically its reduction ratioto give the effect of a "straight line fre-quency" plate when used with a "straightline capacity" condenser.

The disadvantage of the semi -circularplate shape was first realized in connec-tion with the construction of wavemeters.This was long before there were enoughbroadcast stations for the problem of sta-tion separation to be serious.

As the relation between capacity andwavelength is not a direct proportion, adial calibrated in wavelengths will nothave equal divisions over its scale if aseani-circular plate shape is used. Thisnot only makes the instrument more diffi-cult to read, particularly as to the esti-mation of readings which fall betweendivisions, but involves difficulty in cali-bration, as the space between two pointsten meters apart for instance, could notbe divided into ten equal one -meter di-visions.

A plate shape which would give equaldivisions for equal wavelengths, i.e.,

Radio Company

Straight Line Capacity

Fig.2

Straight Line Wavelength

Fig.3

Straight Line Frequency

THE SHAPE of the plates determinesthe rate of capacity change. In SLC con-densers the shape is semi -circular. InSLW the plates are trimmed slightly atone side. This retards the higher fre-quency tuning. The SLF condenser ef-fectuates this retardation most emphati-cally.

"straight line wavelengths," was highlydesirable, and a condenser with such aplate shape was first used commerciallyin the General Radio 124 waveaneter, in-troduced in 1916.

When the multiplication of broadcaststations began, the straight line wave-length plate was introduced for condens-ers used in receivers. and became verypopular, due to the better separation ofstations resulting from its use.

Broadcast stations continued to multi-ply, however, until all channels in thewavelength range allotted to broadcast-ing were filled. The transmission chan-nels were assigned on the basis of uni-form frequency rather than uniformwavelength separation, and, as they allbecame occupied, the difficulty of crowd-ing a great many more than half the sta-tions into the lower half of the dialagain rose. The obvious step was, ofcourse, the straight line frequency plateshaped to give equal frequency divisionsover the dial. This plate shape not onlyimproves the distribution of stations overthe dials, but is the only type of con-denser which can be used in a singlecontrol Super -Heterodyne, where thereis a constant difference of frequency be-tween the two circuits being tuned.

Obstacles to Straight FrequencyCertain objections, however, have pre-

vented this type of condenser fromachieving the wide popularity which was

promised for it. In order to obtain astraight line frequency variation an ex-tremely low minimum capacity is re-quired. The stray or zero capacity ofmost receivers is so large as to defeatthis requirement and to prevent the real-ization of a true straight line frequencyvariation.

Another objection was the large phy-sical dimensions of most of the straightline frequency condensers, due to thefact that this plate shape is very ineffi-cient in its use of space. Then, too, thereis the fact that in the conventional typeof condenser, there is a rotation of but180 degrees in which all stations must beincluded. Spreading out stations on thelower portion of the dial necessarily re-sults in crowding them closer together onthe upper.

It so happened that the policy of thegovernment in assigning channels was togive the high-powered stations channelsin the upper portion of the waveband,and the crowding together of these sta-tions, generally having the better pro-grams, proved disadvantageous.

DX by Short WavesNew Lure for Fans

An increasing number of stations is mak-ing use of the short waves in broadcasting.They use the regular broadcast wave forreaching the public in the immediate vicin-ity of the station and the short wave forreachino-6 those located over 1,000 milesaway. Usually the same program is pro-jected on both waves and the two trans-mitters operate at the same time.

The latest to join the short wave broad-casters is WRNY of New York, which hasjust been licensed by the Federal RadioCommission to operate a 500 -watt shortwave transmitter in conjunction with itsregular transmitter.

The steady increase in the number ofshort-wave broadcasters will soon resultin intense popular interest in this form ofcommunication, which may be comparableto the enthusiasm manifested during theearly years of broadcasting. Successfullong distance reception is the lure which willconvert many radio fans to the short waves.

Grid Current ShowsExtent of the Bias

Ordinarily no grid current should flowin an amplifier circuit. Hence if one findsgrid current flowing, indicated by a read-ing on the milliammeter, the bias is toosmall, or there is no bias, or the bias iserroneously positive. Amplifier tubesnever take anything except a negativegrid bias.

On the other hand, in a detector circuit,particularly where the grid return is madeto A plus, grid current will flow. Themethod of detection with grid leak andcondenser actually depends on the flowof grid current. Hence detector tubesmight give a reading, except that thecurrent flow may be so small as to makelittle impression on the grid meter.

WBZ CHIMES INWBZ is telling the radio audience the

correct time daily as measured by the Ham-ilton watch. This service is furnished byTrue Brothers, jewelers. All studio time-pieces are corrected hourly to conform withthe master clock.

WHEN TO TAKE OFF CAPSWhen a trickle charger is used it is not

necessary to remove the vent caps of thestorage battery. But if the charging rateis 2 amperes or more the caps should beremoved during the charging process.

When using the trickle, be sure though,that the small ventilation holes in the ventcaps are always kept clear. This may bedone with a toothpick.


AC Filament Wiring Plane's Aerial

Needs Close Attention Is Small KiteB. F. Miessner, inventor of an AC tube,

described its application to receivers ina lecture before the Radio Club ofAmerica. Mr. Miessner followed his talkwith a demonstration of a commercial re-ceiver made according to his design andit was the concensus that this demonstra-tion was excellent.

The general performance of the re-ceiver demonstrated that there were ad-vantages in the use of this new type oftube. It was brought out in the discus-sion that followed that very little diffi-culty would be experienced in buildingreceivers designed for use with this tubeor in converting existing receivers foruse with it. Mr. Miessner pointed outthat already three independent tube man-ufacturers were in production on thesetubes and he expressed his appreciationfor the wholehearted co-operation whichthese manufacturers have given him inthe tube's development.

In discussing the application of thetube, Ralph A. Clark, Vice -President ofthe Armstrong Company, said that hisorganization had rebuilt at least a halfdozen receivers of standard design, e,rn-ploying various types of circuits, and hadexperienced little difficulty in their work.

Answers Questions

Questions were asked of Mr. Miessnerregarding the characteristics of the audioamplifier circuit used in the receiverwhich he demonstrated. These questionsrelated to the audio frequency range ofthe amplifier with particular reference toamplification at the lower frequencies. Itis possible to eliminate a great deal ofthe hum from an alternating current re-ceiver where the loudspeaker and theaudio frequency amplifier apparatus areof such a nature as to cut off at thelower range.

Eliminating the hum by this process isa poor system, it was pointed out byArthur H. Lynch, recognized as a leaderin the resistance coupled design field.Several receivers applying these tubeshad been used with resistance couplingand that the amount of hum from theloudspeaker was practically nil.

Mr. Miessner said that the filament cir-cuits of the tubes, carrying the heavycurrent they do, would require a certain

amount of precaution in order to preventa direct pickup by induction from thefilament wiring to the windings of theaudio frequency transformers.

Lynch's No -Hum PlanIt was further pointed out by the dis-

tinguished Mr. Lynch that this difficultycould be eliminated by the use of re-sistance coupling, since there was no pos-sibility of a pick-up of this nature, be-cause with resistance coupling no mag-netic apparatus is employed.

A further development regarding humwas brought out in connection with thepower apparatus and a number of thosewho had built these receivers indicatedthat the power equipment could be in-stalled directly in the receiver chassis ifresistance coupling was used.

Announcement was made of the factthat the Mayolian Corporation has readyfor the market a special driver unit whichincludes all the A and B eliminating ap-paratus for the application of these tubesto either new or existing receivers.

Mr. Meissner pointed out that the GarodType E. M. receiver, which was used inhis demonstration, had its filaments wiredin a special manner.

The Filament WiringA pair of heavy leads is run from the

driver unit to terminals inside the re-ceiver and individual pairs of wires runfrom these terminals to the filament ter-minals of each tube socket. This is doneto prevent inductive pick-up as well asto reduce the resistance in the filamentcircuit.

In existing types of receivers, whichmay be remodeled so as to employ thesenew tubes, it was suggested by R. R.Mayo that instead of following the Garodsystem that the heavy wires from thedriver unit be attached to a central por-tion of the filament circuit, so that thefilament current could pass through thefilament circuit in each direction, thuspermitting the use of the ordinary wiringwithout in any way altering the receiver.The resistance drop, when this method isemployed, has been found to be suffi-ciently low to cause no trouble.

Mr. Miessner's talk was accompaniedby a series of technical steriopticon slides.

Washington.Successful experiments with a smaller

and more efficient radio kite than that nowin use have been conducted by the Bureauof Aeronautics of the Department of theNavy, and Navy engineers believe that thiskite, which is used for hoisting radio an-tennas from a plane which has been forceddown, will supplant the present one, the De-partment announced.

The tests have been conducted by SamuelF. Perkins, of Dorchester, Mass., at theNaval Air Station at Anacostia, D. C., inco-operation with naval officers. A new testkite, which measures four feet, is beingconstructed by Mr. Perkins, the statementsaid, and "it is hoped will make trials evenmore successful."

Department's StatementThe full text of the statement follows:"The Bureau of Aeronautics, Navy De-

partment, has been working on the devel-opment of smaller and more efficient radiokites than those now in use. The kite isused for hoisting radio antennas from aplane which leas made an emergency land-ing and the antenna wire takes the placeof the kite string.

"Samuel F. Perkins, of Dorchester,Mass., has successfully concluded radio andsignal kite tests at the Naval Air Station atAnacostia, D. C. Lieut. A. I. Price andEnsign S. V. Edwards, U. S. N., flew thePerkins Man Carrying type of kites withease, showing they could be flown from aplane forced down at sea.

Making a Special One"Mr. Perkins is now constructing a four -

foot special kite of powerful design that itis hoped will make trials even more success-ful, as the five-foot Perkins Radio Kite hadmore than enough lift to carry the 500 feetof aerial wire.

"If the four -foot kite is successful, as allfigures prove that it will be, it will be byfar the smallest kite to be used in any workof this nature. All officers and others wit-nessing the tests on the kites commentedon the fact that the kites flew like birds andseemed determined to get up and stay up,and on the speed with which they could behandled."

The results are also being eagerly watchedby tans who would like to use the kite withtheir portable set.

WRNY Transmits AlsoOn its Tenth Harmonic

WRNY, New York, has been licensedby the Federal Radio Commission tooperate a new 500 -watt short-wave trans-mitter in conjunction with its regularbroadcast transmitter. The short-waveset will operate on 30.91 meters (9,700kilocycles). The new transmitter will beoperated jointly with WRNY's regulartransmitter, which works on 309.1 meters.The short wave set will be on the air atall times when WRNY's regular trans-mitter is broadcasting.

It will be noted that the short wave-length is a harmonic of the higher wave-length, necessary as the two transmittersare housed in the same building. Thelow wavelength was selected by WRNY'sengineers because the station wanted toreach distant points rather than thenearby ones reached perfectly with 309.1meters. It is estimated that an averageradius of between 2,000 and 3,000 miles

will be reached regularly with the newtransmitter, with greater distance occa-sionally.

John L. Reinartz has been retained asconsulting engineer, as he is consideredone of the foremost experts on short-wave work in this country. The trans-mitter itself has been assembled byWRNY's engineers under the supervisionof James V. Maresca, chief engineer ofthe station. The short-wave set will gointo operation during the latter part ofthis month, and listeners -in are asked tosend in reports as to their reception ofWRNY's programs. The call letters ofthe short-wave set are 2XAL. Thesecall letters are used only when the short-wave transmitter is used for code work.With a power of only 50 watts and usingcode, 2XAL, has been frequently in touchwith the West coast, as well as withsteamers 2,000 miles out of New York.

Expert Reports onCondition of Roads

Pittsburgh.The road reports and tourist trips broad-

cast daily from KDKA are prepared anddelivered by a veteran tourist. He is JamesA. Hemstreet, manager of the touring de-partment of the Automobile Club of Pitts-burgh, A, A. A.

Mr. Hemstreet was a highway pioneerin the early days of the automobile. He hascrossed the continent eight times over asmany different routes, and has served asmanager of the Washington and New Yorktouring bureaus of the American Automo-bile Association. He published the Auto-mobile Green Book for many years.

The reports, which are sponsored by theGulf Refining Company, are given at 6:20Eastern Standard Time on Monday,Wednesday, Thursday, Friday and Satur-day, and at 4:50 on Tuesday.

The plan of the reports is : Monday, NewEngland and the east; Tuesday, transcon-tinental routes; Wednesday, Ohio, Michiganand northwest resort country; Thursday,east and south; Friday, Pennsylvania roadconditions and special week -end trips;Saturday, main touring routes.

16 RADIO WOR I, D July 2, 1927

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Freshman LicensedBy Radio Corporation

The Chas. Freshman Company, Inc.,has signed up with the Radio Corporationof America and parent companies for theright to use all the radio patents that theR. C. A. and associates own and controlpertaining to the particular radio circuitsmanufactured by Freshman.

The Freshman organization is said todo the largest yearly radio business ofany of the concerns licensed to use thepatents of the R. C. A. and its associatedcompanies.

"As a result of the completion of thesearrangements," declared Charles Fresh-man, president, "we showed in Chicago anelectric set entirely without batteries,operating directly from the house current."

DISKAY, TENOR, NATURALIZEDLos Angeles.

Joseph Diskay, tenor, who is an exclusiveartist over KNX, recently received his citi-zenship papers and as a result, dropped thetitle of "famous Hungarian tenor," underwhich he went for years.

FOIL FOR CONDENSERSThe tin foil used in the construction of

high-grade paper condensers usually con-sists of 85% pure tin and 15% lead.

Mysterious Sea NoisesMar Radio Navigation

Washington.Mysterious noises of the sea are seriously

interfering with the under water radioacoustic work of the Coast and GeodeticSurvey on the Atlantic Coast, the Chief ofthe Survey's Division of Hydrography andTopography, Commander W. E. Parker,announced. The survey has been develop-ing within the last four years methods ofaccurately locating position of ships whenbeyond the range of visibility of shore ob-jects, and while the work on the Pacific hasprogressed satisfactorily it has been handi-capped on the Atlantic by sounds so farbaffling the Government scientists, Com-mander Parker said.

"We are listening perhaps to the clicks ofthe oyster instead of the sound of the bombsignal in our radio acoustic work," saidCommander Parker. "For the last fouryears we have been developing methods toaccurately locate our ships when beyondthe range of visibility of shore objects.

Where Radio Steps In"In hydrographic surveys, the location of

ships by longitude and latitude by the starsor by the sun observations is not sufficientlyaccurate. Ordinarily a ship is located bymeasuring with a sextant, with two anglesbetween three objects on shore, these objectshaving been accurately determined in theirposition by geodetic surveying. When a shipis beyond the range of visibility of shoreobjects, which is a matter of approximately12 miles or so on the Atlantic Coast, therehas been no means of accurately determin-ing its location until our radio acousticmethod was adopted.

"The radio acoustic method was adoptedby the Coast Geodetic Survey, with the co-operation of the Bureau of Standards andthe Coast Artillery Corps of the Army.

Bomb is Exploded"First we plant hydraphones along the

coast in depths of about eight or ninefathoms or approximately 50 feet. Thesehydraphones are connected with the shorestations by cable. The shore stations haveradio sounding equipment. When the mas-ter of the Coast Survey ship desires to gethis exact position, he explodes a bombunder the water. The bomb contains ap-proximately a pound of TNT. The instantof explosion is recorded automatically onthe Survey ship by means of a hydraphoneinstalled on the ship, which is connectedelectrically with an automatic time record-ing device. The sound travels to the shorehydraphones, which pick it up. It causesa fluctuation in the current that travelsalong the cable. That actuates the radicsounding mechanism, causing a radio sig-nal to be sent out in succession from each

of the stations. The radio signal is pickedup by the ship's receiving equipment andrecorded on the automatic time device.

"From this timing device we can deter-mine within one one -hundredths of a sec-ond the time required for the sound re-corded to reach each one of the recordingstations.

Measures the Distanfe"The intervals, multiplied by the known

velocity of sound in sea -water, gives us thedistance from the ship to each of thesehydraphone stations. It is then a simplematter to strike arcs from each of thesehydraphone stations of radiae equal to thedetermined distance from each. The inter-section of these, of course, is the position ofthe ship.

"On the Pacific Coast, the Coast Surveyhas been using this method successfully forabout two years and we have been able tolocate the position of a Coast Survey shipmore than 20 miles from shore. But on theAtlantic Coast it has not worked so well,because of the noises in the sea which pre-vent the reception of the bomb sound. Whatproduces these is, of course, conjectural.We have been investigating this for thepast six months.

"We had considerable trouble last yearon the Pacific Coast on account of noisessimilar to those now interfering on theAtlantic Coast.

Failed Again"These hydrahones operated on the Pa-

cific Coast were lifted to the surface andexamined several times and found to bein perfect condition. When replaced in thesea, they operated satisfactorily for a shorttime and then they began failing to recordthe bombs because of these noises. Oneof the hydraphones was moved out about1,000 fathoms, where it operated satisfac-torily, but the new position was not a goodone from a surveying point of view. Thecaptain of the Survey ship operating it wasat his wit's end until he heard a fishermanremark that the former position, where thetrouble was encountered,was the best crab-bing ground in that section of the coast.The hydraphone was then hoisted andpainted and we never had any moretrouble.

"The ships that are equipped with theradio acoustic ranging device are thesteamer , Lydonia, now operating off theNorth Carolina coast, south of Cape Look-out, and, on the Pacific Coast, the steamerPioneer, now working south of the Colum-bia River off Tillamook Bay, and thesteamer Guide, which is operating north ofthe Columbia River."

Others will be so equipped.

Radio Effect of AuroraBeing Studied in CanadaThe effect that the aurora borealis has

upon radio communication is being studiedby the National Research Council of Can-ada. As Canada is closer to the northmagnetic pole than any other country andtherefore more favorably situated for thestudy, the International Research Councilmade representations to the Canadianbody as to the advisability of making suchstudy. A committee of physics and engi-neering of the Council met in Ottawaand recommended that the research workhe undertaken. That the aurora has a

remarkable effect on wire communication,is well known. During severe magneticstorms the wire systems of both this coun-try and Canada are often put out oforder, rendering communication impossiblefor hours at a time.

That the aurora has similar effect onradio communication is apparent. A fur-ther object of observing the aurora isthat it furnishes the only means availableof gaining information of the conditionsof the atmosphere at distances 50 to 250'miles up.


Scientific Baron SeeksOnly Exchange of Ideas

By Herman BernardHaving arrived in the United States

from Germany, Manfred, Baron vonArdenne, only twenty years old, but aradio scientist extraordinary, was met ata New York pier by a reporter for anewspaper syndicate. The reporter couldnot believe his eyes. He had been toldthat the Baron would arrive, and hadlooked up a European "Who's Who" todiscover that Baron von Ardenne was aMarshal in the German army during thecampaign of 1870 and 1871. The reporterhad French blood in his veins, and glossedover the identity of the nation againstwhich Baron von Ardenne had done hiscampaigning.

But instead of seeing an old man withgray whiskers the reporter met a veryhandsome youth.

Are you Baron von Ardenne?" askedthe amazed reporter.

"I am," replied the visitor, mostmodestly.

"You're not a marshal, are you?" askedthe reporter.

The inquirer was told that the visitor'sgrandfather had possessed that rank.

A Tube InventorThe young Baron, accompanied by Ed-

ward R. Dietze, of Hamburg, his associatein radio research, went to the HotelCommodore, under the tutelage of EricPalmer. David Loewe, of the Loewe radiofirm of Germany, who was here on a visitmore than a year ago, had cabled Mr.Palmer a request to look after the titledtraveler. The Baron and David Loewe'sbrother, Siegmund, were co -inventors ofthe Loewe tri0ex tube, which contains adetector and two resistance coupled audiostages, all complete and wired right insideone evacuated glass envelope. There isalso a resistance coupled radio frequencyversion of the tube. The Loewe concernmanufactures these valves.

A few days after the Baron and HerrDietze had become reconciled, to theMovietone, the Vitaphone and the Phono-film, which they heard in Broadway the-atres, these two amiable visitors invitedsome radio editors to be their luncheonguests at the Cominodore. At this socialsession the editors did some gasping alongmore pronounced lines than the reporterwho had figured out the Baron to be anonagenarian. For the luncheon discus-sion developed the fact that the Baron'svisit here has no connection whatever withmoney, no business squint of any kind,but is solely scientific and smothered inbrotherly love. He wants to make arrange-ments whereby publication can be ob-tained in the American radio press, in-cluding "Proceedings" of the Institute ofRadio Engineers, of his writings, andperhaps in exchange for which Americanresearch papers may similarly be reprintedin Germany, simply for the mutual ad-vance of the science.

Says R. C. A. Bought PatentThe eleemosynary nature of the mis-

sion virtually took the guests' appetiteaway, and they all had only chicken salad,strawberry shortcake and coffee. M...Palmer signed the check, but not with hisname..

The table talk developed the interestingassertion that the Radio Corporation ofAmerica had purchased the United Statespatent rights to the Loewe three -in'-onetube, but Mr. Dietze explained that therewould be no object in making this tubefor consumption here, as it was too diffi-cult to make, and American tube worksmight not be equal to the task. Besides,

if made abroad, a 40 per cent. importduty would have to be paid here. Headded, however, that the tube is widelyknown and used in every other countryin the world.

David Loewe had come over here prin-cipally to sell the patent to the R. C. A.or one of its allied concerns, but had de-parted without revealing whether his visithad been successful.

The Baron, however, need not concernhimself with business matters here, for hehas 'an income that in Germany ratesquite high, and it all comes from hislaboratory, where he had a staff of en-gineers working under him. The ideassuccessfully applied are converted intopatents and the patents are converted intomoney. As German marks now are worthsomething, he gets along very well.

Some of His WorkPamphlets, documents, photographs and

miscellaneous papers were exhibited byMr. Dietze as showing what the Baronhad done. His forte is audio frequencyamplification, although he has done some-thing along radio frequency lines, also.

He has an Ultradyne, consisting of theusual modulator, the oscillator withoutDC voltage on the plate, a tuned input(filter) into the intermediate channel,three resistance -coupled intermediate fre-quency stages, detector fed by anotherfilter, and three resistance -coupled audiosteps. It is an excellent nine -tube set, theBaron said, and pointed out that the in-termediate channel did not self -oscillate,due principally to the special type of de-tector hookup. This consisted of astatically open grid return, with the lowpotential of the grid coil connected to a.002 mfd. fixed condenser, the other sideof which went to the negative filament.Rectification is obtained by plate overload.

Another work of the Baron, whom Mr.Palmer liked to call the John Hays Ham-mond, Jr. of Germany, is a vacuum, tubemeter, which measures microamperes witha millia.mmeter. Its object is economy,since microammeters are expensive.

Sensitivity Greatly IncreasedThe vacuum tube, used as such a micro -

ammeter, is 10,000 times more sensitivethan the milliammeter alone. The deviceis worked on the basis of plate currentchange under different test conditions.The grid current in microamperes is de-termined by reading the plate milli -ammeter and consulting the characteristiccurve of the tube microammeter. Thesystem is familiar in this country, but theBaron puts a new angle to its utilization.

It was hard to get any English out ofthe Baron, for although he can understandit quite well, he talks it only fairly, where-as Herr Dietze speaks like a lad just outof Harvard. It developed that HerrDietze was born in Scotland, although itmust be added, out of respect to Harvard,he has no trace of Scotch accent. He didthe interpreting. He is only eighteen.

The Baron was somewhat miffed whenhe saw last week's issue of RAnso WORLD,announcing his arrival under the heading"Europe's Science Adonis to 'Rescue'Sopranos."

Not "Praise Indeed"Mr. Palmer had written the article-

but not the headline-and in the text hadreferred to the Baron as one of the hand-somest scientists in Europe. The Baronexplained that in Germany all science istaken very seriously, and while he did notobject to the Adonis appellation per se,he was sure that in Germany such a

GERMANY'S FAVORITES

THIS represents popular equipment inGermany today, according to Baron vonArdenne, on a visit here. The set is adetector and two -stage resistance coupledamplifier, built inside the triplex tube,except for coils, nr hi ch are plugged in. TheB battery (90 vclts) is at left, the A bat-tery at right. A loop may be used insteadof plug-in coils. The speaker is a horn ofthe type popular in the United States two

years ago.

moniker scarcely would be considered ap-probation of Sir Hubert Stanley pro-portions.

The article dealt in part with the re-sistance coupled tube which producedsuch quality that even sopranos soundedlike sopranos when reproduced on theradio.

Discussing reproduction in Germany, headmitted that loudspeakers there werenot of the best quality, and that our trans-mission is slightly better than theirs. Re-mote control work is atrociously doneover there, due to the land wires sup-pressing desirable frequencies and intro-ducing extraneous noises. But Germanyis fast improving in radio, is about totake on high quality speakers, particularlythe cone type, and simultaneously givepopular esteem to tone quality sets. Atpresent distortion in sets is quite con-siderable, he said, hence, as in America,poor speakers work better on bad setsthan good ones, since the finest speakersare faithful reproducers of the distortion,too. He deplored lack of power tubes inGermany and said they would be usedsoon, as well as battery eliminators, in -eluding AC tubes.

An Early StartThe Baron started in radio when he

was fourteen, by sending and receivingcode dealing with school lessons, his fel-low "hams"being classmates. By thetime he was sixteen he had written atextbook on radio that was used in ,theschools. A little later he had ten receiv-ers in his laboratory, and the GermanPost Office Department seized them, forreasons he doesn't quite understand yet,although he doesn't expect his Americanvisit to help clear up this mystery. Sonicmonths later he found one of the set's ex-hibited at a German radio show in Berlin,his home town, as a product of the PoliceDepartment. The police breasts wereseen to swell with vicarious pride, but theBaron was tactfully silent.

The Baron is of a retiring nature-not necessarily that he goes to bed early-is tall and slim, and all wrapped up inhis work, to which he devotes unstintingtime. He is so busy that he has had notime to devote to women, although itwas noted that during leisure momentsaboard the liner on the ten days comingover, he managed to devote nearly 100 percent. of his wakeful hours to the oppositesex.


Radio t niversityWhen writing for information give your Radio

AFREE Question and 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 aty.

University subscription number

The circuitFIG. 546

requested by Harry L. Conder.PLEASE GIVE me the circuit diagram

of a four -tube receiver, employing a re-generative detector, with a three circuittuner, two tuned stages of radio fre-quency amplification, and a stage oftransformer coupled audio frequency am-plification. I have three .0005 mfd. vari-able condensers which are hooked up tofloor or set, a loud ringing sound isall these condensers are common, sim-ilar to the regular gang type. I have an-other separate .0005 mid. variable con-denser. I think it will be necessary touse a trap in the set, since I live aboutfive blocks from a powerful broadcastingstation. Everybody around here has agreat deal of trouble in tuning out thisstation, and only when traps are in-stalled are they successful. Includedwith the above parts are, a ten ohm rheo-stat, a fifteen ohm rheostat, a IA Amper-ite, a .0001 mfd. fixed condenser, a 6megohm grid leak, six binding posts anda single circuit jack. The data on thecoils, and any special wiring hints wouldbe appreciated.-HARRY L. CONDER,Bound Brook, N. J.

The receiver diagrammed in Fig. 546should give vou very good results inyour location. Cl, C2 and C3 are thedrum -controlled condensers. C5 is theindividual .0005 ,mfd. condenser, insertedin the trap circuit. It is shunted acrossa forty-five turn coil L7, which is woundon a three inch diameter tubing, usingNo. 22 double covered wire. In serieswith the antenna at this point, andwound on the same tubing as L7, is theprimary winding L8, which consists often turns. Separate both windings, aboutone -quarter inch. LI, the antenna coil,consists of fifty turns, tapped at thetenth turn from the beginning. It iswound on a three inch diameter tubing.L2 and L4 each consist of ten turns, while1.3 and L5 each consist of forty-fiveturns. 1.2 and L3, and LA and L5 areeach wcund on a three inch diameter tub-ing with No. 22 double cotton coveredwire. Allow one -quarter inch space be-tween the windings. L6, the tickler, con-sists of thirty-five turns of No. 26 singlesilk covered wire, wound on a one andthree-quarters inch diameter tubing.This is placed inside of the tubing car-rying L4 and L5, but near the L5 wind-ing. RI is the fifteen ohm rheostat. R2is the ten ohm rheostat. R3 is the 6megohm grid leak. C4 is the .00025 mfd.fixed condenser. R4 is the IA Amper-ite. AFT1 is a three to one ratio audiofrequency transformer. SCJ is the sin-gle circuit. S is a filament switch, usedto cut off the A supply. B plus 1 equals

Sc04936,94, 8,2

c,

forty-five volts. B plus 2 equals sixty-seven and one-half volts. B plus 3equals ninety volts. Use a four and one-half volt C battery for the audio tube.As to the wiring of LI. which is a bittricky. The beginning of the winding isbrought to the ground post. The tap isbrought to the beginning of the primarywinding L8. The end of Ll is brought tothe G post and to the stationary platepost of Cl. Use -01A tubes through -cut for best results.

* * *

I HAVE a four -tube model Diamondof the Air, which I constructed someenonths ago, using standard parts. I amnot able to get stations which operateabove 400 meters. I also find that thedetector tube does not oscillate very wellI use a standard length antenna. Pleasetell me what to do.-EDWARD MAR-TINS, Pawtucket, R. I.

Add ten turns to the secondaries ofboth the antenna and the three -circuitcoil, to get the higher waves. For moreoscillatory action, add five turns to thetickler coil, winding them over the pres-ent wire, if necessary. Try placing a.00025 mfd. fixed condenser front detectorplate tc A minus.

* * *

RECENTLY I was presented with a1925 model six -tube receiver, consistingof three stages of tuned radio frequencyamplification, a non -regenerative detectorand two stages of transformer coupledaudio frequency amplification. The setworks fine, except that when the panel,which is metal, is accidentally hit, orwhen some heavy object falls upon thefloor or set, a loud ringing sound isheard. This, of course, is very annoy-ing and distorts the signals considerably.Is there anything that could be done toavoid this?-GORDON F. MATHERS,Farmingdale, L. I., N. Y.

Use flexible wire for leads to two RFand detector grids. Try switching theAF and RF tubes around. Then tryswitching the detector tube around witheach one of the AF and RF tubes. Amicrophonic tube in the detector socketusually causes Most of the trouble.

* * *

WOULD I get better results if I tookthe transformer employed in a straightstage of audio freque- amplification,in a three -tube regenerative set and usedit for reflexing? Two tubes would thenbe doing the work of three.-JOHN W.GRATTON, Peekskill, N. Y.

No. But it would be a practical ideafor a portable, for instance.

MANY MONTHS ago there appearedin RADIO WORLD a circuit of a four -tuberegenerative receiver, consisting of astage of tuned radio frequency amplifica:tion, a regenerative detector with vari-able condenser feedback (Hartley), andtwo stages of transformer coupled audiofrequency amplification. I have the cir-cuit and the layout, both of which Icopied out of this issue, which I havemislaid. Now, according to the layout,the coils are mounted horizontally in thesame line, but about sixteen inchesapart, or at the opposite ends of thepanel. Will I get better results if I placeone coil at right angles to the other?

(2)-The transformers are also mount-ed in the same line, and close to eachother. How about mounting them atright angles.

(3)-I wish to use a 171 Dower tube inthe last audio stage. The filaments asthey arc now wired are controlled by a'A ampere ballast resistor. I suppose Iwill have to insert separate ballasts ineach circuit, e. g., .4, in the first and halfin the last. Is this correct?

(4)-Do I have to use a higher C biasthan for the -01A?-MORRIS SHUTZ-ENGER, Boylestown, Ind.

(1)-No. Since they are such a greatdistance away from each other, the fieldbetween them is extremely small.

(2)-Their present mounting is allright. Ground the cores.

(3)-Yes. You can use these separateballasts, or a three-quarter ballast forboth of them.

(4)-Yes.. The 171 requires a muchgreater C voltage than the -01A usedin the preceding stage, e. g., forty andpolnaet-el.lalt, with one hundred -eighty on the

* * *

CAN ANY type radio frequency andthree -circuit tuner coil, with secondariesmatched to variable condensers, be usedin the receiver shown on page 11 of theMarch 19 issue of RADIO WORLD?

(2)-What do the words "optional Bplus" refer to ?-EDGAR WILLIAMS,Emory, Tex.

(1)-Yes. (2)-You can either use a common B

voltage for both the RF and detectoror separate ones for these tubes. Theoptional B plus means that a separateB voltage is being applied to the plateof the RF tube, as well as the detectortube. Of course, the connection betweenthe tickler and the end of the platewinding is broken.

* * *

LAST MONTH a friend presented mewith a one -tube regenerative set. Theset squeals too much. The standardthree -circuit tuner is used. A rheostatis used for filament lighting control ofa -01A tube. I tried reducing the Bvoltage, upon the suggestion of a friendof mine, but this did not help. If I turnthe rheostat down so that it does stopwhistling, the signals disappear. Thelarger tubing of the three -circuit tunermeasures three inches in diameter andfour inches in height. In the smaller

inding there are twelve turns, while inthe larger winding there are forty-seventurns. These are both close to eachother. The smaller tubing, which is in-side of the larger tubing near the largerwinding. is one and one-half inches in di-ameter and one and one-half inches long.On it are wound thirty-nine turns. Thewire on the larger tubing is No. 24double cotton covered, while that on thesmaller tubing is No. 26 single silk cov-ered. What would you suggest doing?-R. THOMAS WYLE, Plainville, N. Y.

Take six turns off the winding on thesmaller tubing. This is what is, of course,known as the tickler winding. Also, sep-arate the smaller and larger windings onthe larger tubing, about one quarterinch.

* * *

I WISH to build the three -tube regen-erative set, shown on page 4 of the Dec.


18 issue of RADIO WORLD, but with somechanges.

(1)-A rheostat is used in the filamentcircuit of the first audio tube and a bal-last in the second audio stage. Coulda single ballast of the one-half amperestyle replace both?

(2)-I am going to place the set inan upright phonograph. This will neces-sitate the use of a small baseboard formounting. Is it all right to place thevariable condensers three inches apart?

(3)-'The coil, sockets, grid leak and.condenser will all be mounted above thesubase. The audio transformer will bemounted underneath, upside down. Isthis 0. K.?-CLARENCE J. HYATT,Los Angeles, Calif.

(1, 2 and 3)-Yes. - Be sure that youkeep the plate and grid wires away Ervinthe panel. Place the sockets with thefilament posts facing the panel, and theG and P posts in the rear.

* *

SIX OR SEVEN months ago, I con-structed a six -tube receiver, consistingof three tuned radio stages, a crystal de-tector, a stage of transformer coupledand two stages of resistance coupledaudio frequency amplification. The re-ceiver works wonderful. I have quite abit of trouble with the crystal, however,which burns out. I have tried manytypes but to no avail. I would, there-fore, like to substitute a tube as a de-tector. The first two stages of RF aretuned by a gang condenser. The nextstage is tuned by a single condenser. Thecrystal circuit is, of course, also tunedby a single condenser. The filaments ofthe first two RF tubes are controlledby a rheostat. The next tube filamentis controlled by a rheostat. Please givea diagram, 'illustrating how to insert thetube as a detector, usiri- a fifteen ohmrheostat to control the filament.-WAR-REN MERCHOF, Acton, Mont.

Fig. 547 shows how to insert the tubeas a detector. The crystal detector is,of course, taken out of the circuit. Thatis, the stationary. plate post connectionfrom the coil in the detector circuit, in-stead of running to the crystal, runsright through until one terminal of the00025 mfd. fixed condenser C and the3 meg,ohm grid leak R is reached. Theother terminal of this combination isbrought to the G post on the new detec-tor tube socket. The rotary plate postof the condenser in this circuit, insteadof being brought to the B post of thetransformer, is brought to the plus Apost on the socket. The resistance wirecontact of the new rheostat is connectedto the minus F post of the socket. Theother terminal or arm is brought to theminus A post. The plate most of the newtube socket is brought to the P post ofthe transformer. The B post of thistransformer is brought to the B plus de-tector post, or forty-five volt post. TheA battery leads may be connected to theA leads in the other portion of the set,instead of making them separate. The Bplus Amp. voltage is the same as appliedto...the plate,s of the other RF tubes. Theheavy dash lines indicate where the newinstallation has been made. The lighterdotted lines show new connections to bemade.

* a *

REGARDING THE three -tube reflex,which appeared in the Radio Universitycolumns of the Jan. 29 issue of RADIOWORLD.

(1)-Could another stage of transfor-mer coupled audio frequency amplifica-tion be added?

(2)-Should I place the RF coils atright angles to each other? About howfar apart?

(3)-Can all ,the parts for this set beplaced in a seven by eighteen inch cab-inet?

(4)-Is it all right to use the baseboardmethod of mounting?

(5)-Would you suggest using regen-

O

O

The circuit

Rr. TUBE

i0

Der

7-, Bpost. op' AFT

84,9111,

Ora

FIG. 547diagram illustrating how to' hook in a tube as a detector, instead of a

crystal, as requested by Warren Mcrchof.

eration in the detector or radio frequencystage?

(6)-Is any special type of antennanecessary?

(7)7 -Would it be 0. K. to use a 112tube in the last stage?-ROY GARD-NER, Valley Junction, H.

(1, 2, 3 and 4)-Yes. Place the coilsabout four inches apart.

(5)-No.(6)-No, the standard 100 foot, invert

ed L can be used.(7)-Yes.

* * *

COULD AN indoor antenna, e. g., sixturns of No. 18 insulated wound around,the moulding ten feet in each direction,be used with much success on a five -tube radio frequency set?-PETER ()S-LOW, Chester, Pa.

Yes. Of course, the signals will not beas loud as with an outdoor antenna, butit will be equal if not louder to that ob-tained with a loop.

* * a

RECENTLY I saw a circuit of a three -tube reflexed regenerative receiver, inwhich the tubes in the first and secondtuned radio frequency stages also actedas AF amplifiers. Do you think that aset of this type would be too difficult fora novice to construct and operate?-WILLIAM OAKS, Phoenicia, N. Y.

Yes. Suggest you build the set as astraight three -tube regenerative set, witha tuned stage of radio frequency ampli-fication, a regenerative detector and astage of transformer coupled audio fre-quency amplification.

* * *

WHAT IS the name of the electrolyteused in Edison element storage batteriesand what is its gravity?

(2)-What substance should be usedto prevent evarffiration?

(3)-How far from the top of the testtube should the solution be?

(4)-Can this type of battery be over-charged or charged in the reverse direc-tion without any harm to the cells?-ISIDOR MANDOWSKY, San Francisco,Calif.

(1)-Potassium hydroxide, known tothe layman as caustic potash. It is usual-ly mixed to a gravity of about 1250.

(2)-Any type of pure mineral oil, suchas Nujol, etc.

(3)-No more than three-quarters ofan inch, or to a greater height than isnecessary to cover the round element.When the solution is above this level, thebattery discharges very quickly. Awhite crystal salt forms aiding evapora-tion. This of course should be wiped off,the top of the cell being kept clean at alltimes.

(4)-Yes.

I AM building a portable, using -99tvoe tubes, and would like to have somedata. Six tubes are used in two un-tuned RF stages, a regenerative detec-tor (three -circuit tuner) and three lowratio transformer audio stages. A rheo-stat is used to control the RF filaments.Ballasts are used in the other circuits.

(1)-Should the tubes be placed verti-cal or horizontal?

(2)-Would I geti just as good resultswith two stages of transformer couplingusing a bit higher ratio AFT?-THOMASA. CHARLES, Nyack, N. Y.

(1)-Always place them vertical, other-wise the elements will sag and hit eachother.

(2)-Yes.

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

This Service for Yearly Subscribers OnlyHave your name entered on our subscription and University lists by special number.Put this number on the outside of the forwarding envelope (not the enclosed returnenvelope) 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 tinder or alongside of each query. Write on one side of sheetonly. Always give your university number.]RADIO WORLD, 145 West 45th Street, New York City.Enclosed Snd $6.00 for RADIO WORLD for 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

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Good Back Numbers of

RADIO WORLDThe following illustrated articles have ap-peared in bath issues of RADIO WORLD!1926-1927

1926

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

Oct. I6-The Bernard, by Herman Bernard. Howto Box an "A" Supply. by Herbert FLHayden.

Oct. 23 --The 5 -tube P. C Samson, by Capt.P. V. O'Rourke. Getting DX on the Ber-nard by Lewitt Wtnner.

Oat. 30-Ths 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 Impedance., by J.E. Anderson

Nov. 13-The 4 -tube ED -Power Set, by HerbertE. Hayden. A Study of Eliminators, by Her-man Bernard.

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

Dec. 4-The regenerative 5 -tube Set, by CanP. V. O'Rourke. The 8 -tube Lincoln Super,by Sidney StarkWItmer'a DC Eliminator, by Lewis Winner.

Dee. 18-Selectivity on One Tuba, by EdgarSpeare. Eliminating Interference, by J. E.Anderson.Dec. 25-A New Coupling Device, by J. E.

Anderson. Function of Eliminators, by Her-man Bernard.

Jan. I, 1927-The 2 Tube DeLuze Receiver, byArthur H. Lynch. The Twin -Choke Ampli-der, by Kenneth Harkness.

Jan. 8-Tuning Out Powerful Locale, by J.Anderson. A Choice Superheterodyne, byBrunaten Brunn. The 2 -Tube De Luxe Re-

ceiver, by Arthur H. Lynch (Part 2).Jan. 15 --The DeLuse Recelver, by Arthur H.

Lynch (Part 3) The Simple Meter TestCircuit by Herbert H. Hayden. The Super-heterodyne Modulator Analyzed. by J. B.Anderson.

Jan. 22 --The Atlantic Radiophone feat. by LewisRand. An Insight Into Redolent, by 2. B.Anderson. A Circuit for Great Power, bySidney Stack.

Jan. 29-The Harkness KR -27 Receiver (Part 1),by Kenneth Harkness. Use of Biasing Re-sistors, by J. E. Anderson.

Feb 5-5 -Tube. 1 Dial Set, by Capt. P. V.O'Rourke. The Harkness KH-27 (Part 2),by Kenneth Harkness. , What Produces Tonequality, by J. E. Anderson.

Feb. 12-Phone Talk Put On Speaker, by Her-bert E. Hayden. All Batteries Eliminated,by Herman Bernard. The Harkness KH-27

Receiver. by Kenneth harknese (Part 3).ConclusionFeb. 19-The 6 -Tube Victoreen, by Harman Ber-

nard (Part 1.) The Big Six Receiver. byWentworth Wood. "B" Eliminator Problem,by Wra. P. Lear. The Phasatrol Circuit, byCopt P. V. O'Rourke. The 9 -Tube Victoreen,

by Herman Bernard (Part 2). ConclusionFeb. 26-The 5 -tube Diamond In a Phonograph,

by Hood Astrakan. How To Read Curves. byJohn F. Rider. Prover Tubes for 5 -ValveReceiver, by J. E. Anderson.

Mar. 5-Introduction of 4 -tube Universal. byHerman Bernard. Discussion on DX, byCapt. P. V. O'Rourke. Sensible VolumeControl. by Chas. Gribben.

Mar. 12-Ten Tell -Tale Points, by J. E. Ander-son. How To Figure Resistors, by FrankLogan. The 4 -tube Universal. by HermanBernard, (Part .1

Mar. 19-Psycho-Analyzing Circuit. by ThomasL. McKay. The Unborn]. by Herman Ber-nard (Part 2). How To Use a Wave Trap,by James H. Carroll.

Mar. 26--1'he Universal, by Harman Bernard,(Part 3). Flow of Current in a VacuumTube, by Radcliffe Parker. Broadcasting Hyp-notism.

April 2-Facts Every Experimenter Should Know,by J. E. Anderson. A Ship Model Speaker,by Herbert E. Hayden. The 3 -tube Com-pact, by Jasper Henry. The Nine -in -LineReceiver, by Lewis Rand (Part 1.)

April 9-A 5 -tube Fielded Set, by Herbert H.Hayden. The Power Compact, by LewisWinner. The Nine -in -Line Receiver, byLewis Rand. (Part S.)

April 16-The Schoolboy's Set, by Wally Frost.The Melo-Heald 11 -tube Set, by Herbert E.Hayden. The Nine -in -Line Circuit (Part5), by Lewis Rand.

April 28-The Melo-Heald Set, by Herbert EHayden (Part 2). The Nine -in -Line. byLewis Rand. (Conclusion). How Frequen-cies Are Cut-off, by J. H. Anderson,April 30-A 1 -tube Portable, by Jasper Jelliooe.

A Ship Model Receiver, by Smedley Farns-worth. A Double Three Foot Cone, by W.H. Sinclair.

May 7-alto Adams -Griffin 6 -tube Set, by DanaAdams -Gratin (Part 1). ' A 2 -tube Portable,by Hood Astrakan. How to Improve Super-heterodyne Seta, by John L. Barrett.

May l4-A 3 -tube Portable, by Herbert E, Hay-den. The Adams -Griffin Receiver, by DanaAdams Griffin. (Conclusion).

May 21-'1'he Victoreen Portable Receiver, byCept. P. V. O'Rourke. A Low -Pass Filler.by J. E. Anderson.

May 25-The Console Cone, by Thorvald Larsen.The 3 -tube Reflex by Edgar B. Francis. TheVictoreen Portable Receiver, by Capt. P. V.O'Rourke. (Part 2).

Any copy, (5e. Any 7 copies, 51.00. Allthese 32 copies for $4.00, or start subscriptionwith any issue. Any 7 of these numbers sent aspremium with NEW yearly subscription. Noother premiums allowed. RADIO WORLD. 145West 45th Street, New York CD),

Stations' Work BrilliantIn "Covering" Lind bergh

By J. T. W. MartinRadio had reported outstanding news

events before, but the receptions to Col.Charles A. Lindbergh presented such amany-sided problem that they could notbe described from any one point. Ac-cordingly, it was decided to pick up de-.scriptions from five widely separated ob-servation posts in Washington and fromseven in New York, so that every phaseof the receptions might be heard by radiolisteners.

The observation sites in Washington

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Ratings of 62 celebrities

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Sent, postpaid, for $1.60THE COLUMBIA PRINT145 West 45th St., New York

and the announcers who manned themwere : the Navy Yard docks-GrahamMcNamee, WEAF; the top of the Wash-ington Monument-Phillips Carlin, man-ager of WEAF; the dome of the Capi-tol-Milton J. Cross, WJZ ; the Ti. S.Treasury Building - John Daniel.WRC; the foot of the WashingtonMonument-Graham McNa,rnee, WEAF.In New York City, the points were: PierA, North River, at the Battery-GrahamMcNamee, WEAF; the offices of MerlinHall Aylesworth, president of the Na-tional Broadcasting Company, at 195Broadway-Phillips Carlin, Manager ofWEAF; the reviewing stand at City Hall-Thomas Cowan, WNYC; the top of theMunicipal Building-Arnold Morgan,WEAF; the Metropolitan Life InsuranceTower at 1 Madison Avenue-RalphWentworth, WEAF; the Welte-Mignonstudios at Fifth Avenue and Fifty-fifthStreet-Graham McNamee, WEAF; theMall in Central Park-Milton J. Cross,WJZ.

The Washington broadcast was heardthrough the largest special chain everlinked together, fifty stations in all, acombination of the Natioinal Broadcast-ing Comnnv's Red Blue and PacificCoast Networks. The greatest radio au&ience ever assembled, estimated at 30,000,-000people, was able to listen to the event,but these facts seem almost insignificantbeside the manner in which the ceremon-ies were reported. Through the mediumof the system utilized, listeners wereable to hear descriptions of all the var-ious functions, the din of whistles, sirens,shouts and applause which greeted theflyer.

Reported from Twelve PointsSitting at ease in their own homes, scat-

tered from Maine to California, they werekept at the main center of interest dur-ing the entire Washington reception.While immense crowds in the capitalwere straining for a glimpse of the hero,radio listeners heard him speak on twodifferent occasions, listening to his replyto President Coolidge after the Chief Ex -

.New and

iviASTERPIEcrAT AUTHORIZED

FRESHMAN DEALERS ONLY

THE NEW AC TUBESEverybody should have on hand for

ready reference full data on the new ACtubes. The filaments of these tubes areheated by alternating current from a step-down transformer and anybody havingAC can put these tubes into a set bymaking some wiring changes. Those whohave AC and who are about to build aset also should possess this full informa-tion. Send 15c for the June 4 issue thatcontains the data on the AC tubes andalso on two new rectifier tubes for Beliminators. Radio World,

WHEN YOU GO AWAY ON YOUR VACATIONTell your newsdealer to save a copy of RADIO WORLD for you eachweek. In this way, you will have a complete file-as sometimes it is diffi-cult to get back numbers.Circulation Manager, RADIO WORLD, 145 West 45th Street, N. Y. City.

July 2, 1927 RADIO W01:1.0ecutive had pinned on his breast the Dis-tinguished Flying Cross and later hear-ing Col. Lindbergh's remarks at the Na-tional Press Club reception.

Portions of descriptions from the fivevantage points in Washington and theseven in New York were combined in amanner which welded the reports intosmoothly running units. Traffic jams andother unforseen events caused the care-fully laid official plans to go astray, butthe radio report never faltered. With anease which has caused thousands' of lis-teners to express amazement, the broad-cast reports shifted constantly as the ac-tual events which were taking placechanged the center of interest. In nocase was the changeover from one pointto another anything but instantaneous,and in no case did the reports clash.

This successful result was obtainedthrough the use of three special circuitsleading from each of the observationposts to a main control board located inthe control room of WRC. An operatorand an announcer were stationed at eachof these points, and by the use of head-phones, all of the announcers were ableto hear the reports irons all other points.Cues to stand by and to take the airwere relayed by the operators from onepost to another and passed on to the'various announcers.

Valuable in News WorkIn working out this system, Capt. H.

W. Angus, vice-president of 'he Nation-al Broadcasting Company, who had consplete charge of the special broadcastsfrom Washington and New York, was as-sisted by Eugene F. Grossman, operatingengineer of the Broadcasting Company,who numbers among his .other technicalachievements the transmission of acts ofgrand opera, as performed by the ChicagoCivic Opera Company, direct from thestage of the Chicago Auditorium througha nation-wide network of stations lastJanuary.

The success with which the "radio re-porting" of the Lindbergh functions wascarded through seems conclusive proofof the real place of broadcasting in thedistribution of news concerning out-standing events. And the manner in whichthe nation-wide transmission was receivedappears positive evidence that radio willnever compete with the established chan-nels of news distribution.

The radio reports of the LindberghWashington and Nesv York receptionswere carried practically instantaneouslyto every radio receiver in use through-out the United States. A many -angled

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sound picture of the ceremonies wasprovided for the listeners at the very in-stant that the events were taking place.Still, it seems positive that this reportstimulated the sale of newspapers whichcarried news reports Of the same func-tions.

Records EstablishedThese two media of spreading information,

the daily newspapers and broadcasting, pos-sess such dierent characteristics that neitherinfringes upon the other. Radio is evan-escent. It is gohe when it is finished. Butnewsprint, presenting a more thorough andmore carefully prepared report, is capableof being preserved for almost. any desiredlength of time.

Broadcast news reports of outstandingevents and newspaper reports of the samehappenings do not clash. But it appearsthat both have their places in a properlybalanced scheme of news dissemination.

A few of the new records established bythe National Broadcasting Company in theNationwide Lindbergh reception follow:

Miles of Wire Line Used -14,000.Number of Engineers Involved -350..Pick-up Points-Washington, 5; New

York, 7.Number of Stations -50.Estimated Audience -30,000,000.Number of "Radio Reporters"-Wash-

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City and State

sories, covered by Neutrodyne patentsheld by the Hazeltine Corporation andIndependent Radio Manufacturers, Inc.,15 Exchange Place, Jersey City, N. J.An accounting of the profits of theGrebe Company, received during the pe-riod of alleged infringement of thepatents, was also ordered.

The defendant contended that in theoriginal patent of Louis A. Hazeltine;filed shortly after he left the employ ofthe United States Navy, where he hadbeen employed as a laboratory engineer,there had been a clause pErmitting thegeneral use of his patent.

New Molded CondensersThe Polymet Manufacturing Corporation

has developed a new line of fixed mica con-densers.

These are attractively molded in genuineBakelite. Each condenser is guaranteed toan accuracy of plus or minus 5%.

Convenient, well -tinned soldering tabs area notable feature of this construction.

B ELIMINATOR BOOKLETThe story of the B eliminator or B power

unit is told in virtually single syllable wordsin the little booklet just issued by .the Ray-theon Mantifacturing Company, KendallSquare Building, Cambridge, Mass. "A FewThings You Will want To Know AboutReliable B Power For Your Radio" is thetitle. A copy is obtainable from the manu-facturer by mentioning Ramo WORLD.

NEW IMPROVEDDIAMOND OF THE AIR $37 50Powertone Wave Trap, List $2.00, Special _51.00Grimes Gradeon, List 517.00 5.95

Send for Free CatalogB. C. L. RADIO SERVICE CO., INC.220 Fulton St. (One flight up) N. Y. C.

World "A" Power Unit --$12.75Automatically provides even. unvarying "A" current fromYour light socket. Absolutely noiseless. Assures fullLora Quality from you set and wider D. X. range. FamousWORLD quality-at less than half of the cost of any simi-lar equipment. Shipped complete. subject to inspection onreceipt of price, or C.O.D. if you wish. 25 amp. unit forsets of 4 tubes or less. $12.75. 60 Amp. unit for sateof 5 tubes or more. $1 5.7 5. 5% discount If cash in fullis sent with order. Send order today. World Battery Co..1 219 So. Wabash Ave., Dept. 52, Chicago. M.

RADIO WORLD'SQUICK -ACTIONCLASSIFIED ADS

10 CENTS A WORD10 WORDS MINIMUM

CASH WITH ORDER

CHOKES -100, so or 30 Henry, 125 MA, $5.75.3011-50H, 85 MA, $2.75. Write for lists. RADIOPARTS SALES CO., Orange, N. J.

NEW DE LUXE BST RECEIVER -5 -Tube Set,resistance coupled audio, built-in C eliminator, gen.uine mahogany cabinet. Price, $60. Five-dayinoneyback guarantee. GUARANTY RADIOGOODS CO., 145 W. 45th St., N. Y. City.

VALET AUTOSTROP RAZOR-The only razorthat sharpens its own blades. Highly polished,nickel -plated, self -stropping Valet AUTOSTROPRazor, with one blade, in velvet lined metal case.Leather strop especially prepared, and completeoutfit in neat, lithographed carton. Mailed post-paid on receipt of 50e. SPECIAL: Send $2 forone-third of a year subscription for Radio World(yearly price $6), mention this particular ad, andcomplete "Pal" set will be sent as a premium.If already a subscriber, your subscription will beextended three months. TILE COLUMBIA PRINT,145 West 45th Street, New York City,

July 2, 1927 RADIO WORLD

When you're dancing to radio music you often wish yourset were just a bit louder. Compliments to partners, shuffleof feet, distance from the speaker all put on the set a demandfor extra volume.

Use a De Luxe Model Bretwood Variable Grid Leak. Turn it toMaximum Resistance and thus increase the volume up to 25 per cent.-the dancing volume you desire.

Also, you thus have a handy combination volume control and sensitivity con -

The De Luxe Model may be mounted on front panel or baseboard.

TO DEALERS: If your wholesaler cannot fill yourorders we will supply you direct.

The De Luxe Model Bret -wood Variable Grid Leakis specified by HermanBernard for Radio World'sfour -tube Universal re-ceiver.

North American Bretwood Co., 145 West 45th St., N. Y. City.

Gentlemen: Enclosed find $1.75. Send me at once oneDe Luxe Model Bretwood Variable Grid Leak on 5 -daymoney -back guarantee. (Or $2.25 for leak with grid con-denser attached.)

STATEInquiries Solicited from the Trade


imaNIMmmt

B.S.T. DE LUXEA NEW AND IMPROVED MODEL

Simply Beautiful-Beautifully Simple

The B. S. T. De Luxe, a 5 -Tube Receiver,with Concentrated, Simplified Tuning, andUsing Resistance Coupled Audio. Price ofset, in genuine walnut cabinet, and includ-ing built-in eliminator of all "C" batteries

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

5 -Tube Set, in genuine walnut cabinet, less accessories, but withfor which kindly ship by express at once one B. S. T. De LuxeGentlemen:-Enclosed pleas, find check (or money order) for $60.00,

built-in eliminator of all -C" batteries, on five-day money -backguarantee.

NAME

STREET ADDRF SS

CITY STATE

$60."The Set That All AdmireThe B. S. T. De Luxe is one of the most beautiful setsmade. Beautiful to eye and ear alike. Thrilling fidelityof tone and fine volume assured. Uses any type tubes.May be used with B eliminators without "motorboating."Awarded Certificate of Special Merit by Radio Worldafter exhaustive tests.A Switch, a Volume Control and a Tuning Unit-These

are the Only Parts on the Bakelite Front Panel.Simplicity and Beauty in the Extreme.

GUARANTY RADIO GOODS CO.145 WEST 45th STREET NEW YORK CITY

i che balanced plan seven - americanradiohistory.com · 2019-07-17 · july 2 /q1,1 peg- u.s. pat....

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