the 4 -tube dx symphony radio a study of pilot lights for ...€¦ · radiothe 4 -tube dx symphony...

THE 4 -TUBE DX SYMPHONY 15 Cents 1

RADIOWORLDvol. 8. No. 16 ILLUSTRATED Every Week

A Study of Pilot Lightsfor A Battery Switches

A Single -Control 5 -TubeResistance -Coupled Set

RADIO WORLD January 9, 1926

More Popular than Ever Before-The 1926 Boxed and Sealed

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$29.50 CABINETFREE!

One antenna coupler, LOL I(Bruno 99 RF ).

One 3.eircult interetage coupler.L2L3L4 (Bruno 99).

Twe .0005 mid. SLF condensers,CI. C3 (Streamline).

Two '/a -amp. ballast., 112, R7(Amperites. b(pe I -A).

One 3VatoI AF transformer,AFT (Thorardeen).

One Ye -amp. ballast. RI (Veby).Two 0.1 men. resistors R3. R5

(Veby).One 1.0 meg. leak. R4 (Veby).One 0.5 meg. leak, R6 (Veby).One variable grid leak. 80 (Bret -

wood ).Three 4" moulded Bakelite dials

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Two double-eircult lacks, 11, 12(Preferred).

One single -circuit leek, .13 (Pre-ferred).

One 7:24" drilled and engravedpanel.

Five standard sockets (Ne-old).One socket shelf and brackets

(Bruno). (Cortland).Two 0.25 mad. fixed condensers.

C4. C5 (Aerovox).One 5 -strand multi -colored battery

table (De Luxe).Two battery switehee. SI , 52.One .00025 mid. fixed grid con-

denser. C2.Four binding posts. W, X. Y. Z.Fire battery cable markers.Ton lengths of busker (Cornish).Two flexible leads for C battery.Screws, nuts. spaghetti.

No Kit Is Genuine Without the Seal and Signature of Herman BernardBRUNO BRACKETS

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RADIO WORLD[Entered as second-class matter, March, 1922, at the post office at New York, N. Y., under the Act of March 3, 1879]

A Weekly Paper Published by Hennessy Radio Publications Corporation from PublicationOffice, 145 West 45th St., New York, N. Y. of

Just Eastway Phones: BRYant 0558 and 0559.Broad

Vol. VIII. No. 16. Whole No. 198. January 9, 1926 15c per copy, $6.00 a year

The 4 -Tube DX Symphony Set

77-

9

CA

045FIG. I shows the circuit diagram of the 4 -tube DX Symphony. This set uses one stage of tuned radio -frequency amplification,a detector regenerated by the Hartley system, and two stages of audio -frequency amplification, employing transformers. As for

the switching plan consult text.

Excellent Distance Recep-tion Obtainable on 4-Tube Set Which Pre-serves the Tonal Qualityby Using High -GradeAudio Transformers-Two Simple Coils theOnly Tuned Inductances-Capacity Feedback bythe Harlety OscillatorSystem is Employed-Regeneration Control isSmooth

By A. Irving WitzARECEIVER that has given a great

deal of pleasure, and which I amsure will delight all fans who constructit properly, is shown in Fig. 1, as to itselectrical diagram, and in the accompany-ing cuts of photographs that I took.Throughout the recent cold spell-per-haps because conditions made the recep-

FIG. 2, the rearview of the set.Straight-line fre-quency tuningcondensers a r eused, and as thefeedback is con-denser . control-led, regenerationadjustment issmooth and easy.Note how the bat-tery cable is intro-duced. The methodof mounting thecoils at an ex-treme di stancefrom each otherprevents inductive

feedback.

tion of distant stations easier than ordin-arily-I have been able to bring in stationsthat I never heard before at my particu-lar location in Philadelphia. These in-clude KOA, Denver; CNRF, Canada;KSD, St. Louis, and WOC, Davenport, Ia.It must be understood that I am not lo-cated very fortunately from a radio view-point, due to local shielding by structures,and due also to electrical interference thatis purely local. Chicago stations come inregularly on this set and I can dependrather faithfully on the other distant sta-tions I have enumerated. Others, morepropitiously located, no doubt will be ableto do a great deal more in the way ofreceiving DX than I have accomplishedon this set, and I am looking forward toreports from constructors that they builtthe receiver and heard the British broad-casting in the International Week tests(January 24)

Fine Tone TooThis faculty of bringing in distance I

mention merely because it is romantic tobe able to turn the dials to bring in thebig catch of "stationary" fish, yet fullyon a par with this proclivity of the re-ceiver is the fine tonal quality of the sig-nals heard. This of course is appreciatedon local stations, too, but many musthave noticed the huskiness that attendsthe vocal renditions, either spoken orsung, from distant stations, which (often

due to the audio -amplifier) makes listen-ing to this sort of reception hardly bear-able. To bring the quality of the audio -amplification up to a very high point, yetconsistent with the maintenance of fullvolume, I used two Modern Symphonytransformers, not without a friendly ges-ture towards the manufacturer, to be sure,yet with the knowledge that the partsafforded me, and would afford others,complete satisfaction.

Not ExpensiveThe set is a very fine one, and yet it

is not expensive. It affords a degree ofradio amplification that is high enough toenable the reception of distant stations,'it is of course selective, otherwise dis-tance would not be brought in so con-sistently, and it represents as high de-gree of radio circuit as one could expectfrom two RF tubes (including detector asRF). Nothing exceeds a stage of tunedRF and a regenerative detector for radioamplification efficiency on two tubes. Yousimply can not obtain more. It would befolly to regenerate the RF stage, in addi-tion, because then the set would becomea very tricky tuner and would be so criti-cal that it would occasion more backachesin trying to tune in a station than it wouldenjoy from actual success in getting sig-nals, near or far.

Most Volume on Two TubesThen, as for the audio side, you can not

4 RADIO WORLD January 9, 1926

Panel and Top View of the Set

FIG. 3, the panel view. Three vernier dials are used. The two rheostats show upplainly. The jack and switching arangement may be selected to suit the con-

structor's taste. See text.

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100 200 500 WOO 2000 4000 5000

TIT

THE CURVE of the transformers, voltage amplification plottedagainst frequency.

Careful Arrangements ofParts Guarantees Re-sults of Surpassing Merit-Locals Often May beTuned in by TurningOnly Two of the ThreeDials

under any other circumstances get asmuch volume from two tubes as you canby using audio transformers. The objec-tions against audio transformers havebeen lodged mainly on the score of thesteepness of the curve of amplification

FIG. 4, the topview of the re-ceiver. The firstaudio transformeris near center.Just to the rightof this a toggleswitch may beplaced on thesocket shelf, ifone incorporatesa detector jack.The arrangementof the parts on theplan here showngreatly simplifiesthe wiring and in-sures best results.The panel is 7x21'and the socketshell of 23ix20".

plotted against frequency, but you cansee from the characteristic curve pub-lished herewith that the curve is flat in-deed between 200 and 4,000 cycles, whichcovers the effective range of speech andmusic, and that above 4,000 cycles theslight upturn is hardly worthy of notice.As for the curve from 100 to 200 cycles,next to nothing is sung, played or spokenin this region, so we have an overall ef-ficiency that is compelling. The trans-formers are in the quality class, beingwound with 'all -sufficient inductance, par-ticularly on the primary, which necessi-tates them being of the size they are. Itis generally true of transformers that theirefficiency is not so much if their size islittle, and the great improvement madein transformer design within the last sixmonths or so has been in the direction ofphysical development for electrical gain.

Option of Detector JackI do not know whether most persons

want to listen to locals, using earphones,nevertheless Fig. 1 shows a detector jack,the double -circuit one, for those whohave such preference. I myself do notcare for a detector jack and do not useearphones except occasionally to listen tosome far -distant stations on the final audiooutput. I got a peep out of KFI, LosAngeles, on this set, using earphones atthe final tube output, but the distant re-ception I mentioned previously was onthe speaker, and I do not count a stationas "in" unless it conies in on the speaker-not even if I "crossed the continent."

If you omit the double circuit jack inFig. 1, then the rest of the wiring shouldbe followed just as shown. The switch Swould turn off the set or turn it on andthere would be no other switch necessary.But if you include the detector listeningpost, then an extra A battery switch isneeded. This is not shown in Fig. 1.You will notice the boxed zigzag figurein the wiring diagram, in the negativefilament legs of the audio tubes. This isa No. 112 Amperite. Between the baseof this Amperite and the horizontal minusA lead insert the extra switch, which maybe located on the socket shelf, to the rightof the first audio transformer, when thepanel is facing you. As you will not usethis switch often (to turn off the audiotubes) it is just as well to put it on thesocket shelf, for then to manipulate theswitch all you need do is to lift the panellid. It is a good plan to have this switchof the toggle type, with left and rightmotion, rather than of the push-pull type,which might be all right for the panelmounted switch.

coils L1L2 and L3L4 are woundalike, excepting that L4 has a tap. Thecoils used were Bruno No. 55, having a3/2" diameter, the wire being No. 24 silkover cotton. These are wound on quart-zite forms about 3%" high. Ll has 8turns, Vs" space being left, then the sec-ondary, L2, is wound, with 50 turns. Thisis more than is usually needed with .0005mfd. tuning condensers, but as SLF con-densers have a very low minimum capac-ity, as a rule, and always represent a veryslow capacity change at the higher fre-quencies (lower wavelengths), it is wellto provide ample inductance and thusgain full benefit from SLF tuning, indeed,actually use the most spread -out portionof the dial for tuning purposes, otherwisenot accomplished.

Locating the TapAs for the tap, this is taken six turns

from the filament end of L2. Granting the

January 9, 1926 RADIO WORLD 5

SymphonyVery Easy

To TuneWiring Is Simple and Even

a Novice May ConstructThe Receiver and ObtainFine Results - CoilsShould be of the TypeSuitable for Tuning WithStraight-line FrequencyCondensers

primary, L3, which has 8 turns, too, isalready put on, 2/4" 'space is left and thesecondary winding is begun. As the coilsare to be connected with low potentialsadjoining, thus making B plus and A plusconnected to adjoining leads of L3 andIA, the secondary IA is wound for 42turns, the wire is looped, and the eight re-maining turns are put on (50 in all). Afterthe coil is wound the insulation on thewire at the loop point is scraped off forconnecting purposes.

The condenser connections are madewith stator plates of the .0005 mfd.to grid. Note that A plus is connectedto the tap on IA, while that terminal ofL4 that in conventional hookups goes toA plus, instead goes to rotary plates ofthe .00025 mfd. feedback condenser, whosestator goes to plate.

The grid leak may be variable, andsomewhat better results are obtainable,but in the construction of the receivershown in the photographs I used a fixedleak. No doubt a variable one would en-able me to get stations I have not heardup to this writing, and when I get timeI'll try that stunt with a Bretwood.

LIST OF PARTSTwo RF transformers, LIL2 and L31.4

(the latter tapped once.) (Bruno SS).One pair of Bruno brackets.Two .0005 mfd. Streamline SLF con-

densers.One .00025 Streamline SLF condenser.Two Modern Symphony audio -trans-

formers.Two 20 -ohm rheostats.One double circuit jack.One single circuit jack.One .00025 mfd, grid condenser.One fixed grid leak, 2 meg.One No. 112 Amperite.One 7x21" panel.One 2x20" socket shelf.Four sockets.Three 4" vernier dials.Two A battery switches, S and another

(a toggle switch) not shown in Fig. 1.See text for choice.

McClelland New ManagerOf WEAF Broadcasting

J. A. Holman, formerly manager ofbroadcasting for WEAF, has gone on thestaff of the Commercial Engineer of theAmerican Telephone and Telegraph Com-pany. G. F. McClelland, formerly man-ager of Programs, becomes manager ofbroadcasting, and F. S. Spring, formerlyin charge of office management at WEAF,becomes assistant manager of broadcast-ing.

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THE circuit d agram (Fig. 1) of the 1 -dial receiver, with a separate B -plus lead for the RF amplifier tube, as this voltagemust be just right. The primary is adjustable, as distinguished from a variable primary. A pilot lamp is used (lower right).

By Herman BernardAssociate, Institute of Radio Engineers

WIAT need there is for compensa-tion when a multiple tuning conden-

ser is used for gaining single -control is asubject of debate among radio engineers.Probably the truth is that there is nospecial need for compensation if thetuned circuits are so established that theydo not have to tune finely. If each oftwo or more stages must be tuned veryselectively, then of course compensationis absolutely necessary.

Compensation may be defined here asminor adjustment for establishing reson-ance in the tuned circuits. In Fig. 1 isshown a circuit diagram where no com-pensating device is needed. The adjust-able primary is not to be rated as a com-pensating device, since once the best com-promise of adjustment is made, no furthervariation is made, and there is no panelcontrol for it.

Definition of Variable PrimaryA variable primary is one that may be

moved by a control, usually a knob onthe panel, and this is indeed a compen-sator of a very pronounced order. So isa small variable condenser connected inparallel with a section of the tuning con-denser. Sometimes, instead of a smallcondenser of this kind being used, a mov-able stator plate is controlled from thepanel to alter slightly the capacity of asection of the multiple tuning condenser.

This is the same electrical effect, estab-lished by slightly different mechanicalmeans.

Its use (for another purpose) has longbeen jeered under the battle cry of "extraend plate."

A third way of achieving compensationis by winding the secondary in two parts,nietallicly conected. Most of the sec-ondary turns are wound on the statorform, and a few turns, say six or eight,are placed on a rotary coil. When thesewindings are conductively coupled, thefree terminals joined to a section of themultiple tuning condenser, the inductanceof the secondary is varied by rotating themovable coil inside the stator coil.

Three Ways of CompensatingTherefore compensation may be made

in the following principal ways :(1) By having a variable primary in in-

ductive relationship to the tuned sec-ondary.

(2) By using a small variable capacityin parallel with a section of the tuningcondenser.

(3) By using a small variable coil, con-ductively coupled to the major part of thesecondary winding, in variometer fashion.

All three of these methods, no doubt,are based upon the mechanical difficultyof making multiple tuning condensers thathave exactly the same capacity value ineach section for any given dial setting.The achievement of this end dependsmuch on how you define "exactly." Avariation of .00006 mfd., found present in

Three Ways of EffectuatingSynchronized Unit Tuning

A2

A-

C

FIG. 2-A variable primary may be used as a balancer (Fig. 1) or small extracondensers may be used ("A"), or inductive variation in a conductively coupledsecondary may be employed ("B") or the inductance of a rheostat may be utilized

(a bad method).

one particular make of condenser, wassatisfactory indeed, since neither tunedcircuit in Fig. 1 had to be so selectiveas to make a .00006 mfd. variation of anyimportance.

Broad Alone, Fine TogetherTherefore we will call the tuning accom-

plished by a 2 -section condenser of thiskind exact resonance for the tuning pur-poses to which each section is put. Re-member that the input to the radio -frequency tube represents approximatelythe tuning accomplished in a simple crys-tal set, and one must know that .00006mfd. would not make any difference in thetuning that could be expressed in termsof visibility on the dial, even in the lowerwavelengths.

The selectivity of the receiver (Fig. 1)is due to the filtering effect when thecircuits are tuned to the same wavelength,rather than to any virtue of selectivitythat exists in either circuit as a unt, foreach separately tunes broadly, while asunits in the chain they are an effectivedam against the undesired radio stream.This is the principle applicable to all tunedradio -frequency receivers, even if thereare two stages of R.F.

For instance, KDKA is tuned in regu-larly while WGBS is on the air, with onlytwo miles from the point of reception.WGBS is the Gimbel Bros. station in NewYork City, operating on 315.6 meters (950kilocycles), while KDKA, East Pittsburgh,uses a wave of 309.1 meters (970 kilo-cycles). The channel of separation be-tween stations, as apportioned by the De-partment of Commerce, is 10,000 cycles (10kcy.), hence there are only two channels(20 key.) between WGBS and KDKA.Any set that is as effective as that undersuch conditions is selective.

Two Ways of Doing Same ThingThis tuning was accomplished with an

adjustable primary, fixed for best cou-pling at 299.8 meters ,1,000 key.). An ad-justable primary is much like the conven-tional fixed type, since the factor of ad-justment means relative physical angle ofthe primary in respect to the secondary,while the same effect is gained by wind-ing a fixed primary and using greater orfewer number of turns or increasing ordecreasing the space between primary andsecondary.

For instance, maximum amplificationand most favorable coupling at 1,000 key.may result from winding a radio -frequen-cy transformer on a 3,4" diameter, usingNo. 24 silk covered wire, with a 10 -turnprimary 5/4" space, and a 45 -turn second-

January 9, 1926 RADIO kVORLD 7

Efficiency Data on 1 -Dial Setary, to be tuned by a .0005 mfd. variablecondenser. The 1,000 kcy. determinationwas made on the basis of the geometricmean, since the broadcast band is from1,500 to 500 kcy., the 1,000 kcy. repre-senting the difference between maximumand minimum frequency (lowest andhighest broadcast wavelengths).

Adjustment for MatchingBut the adjustable primary serves a

special purpose. If secondaries L2 andL4 are nearly alike, they may be broughtto the same reactive value by readjustingthe primary Ll. The closer the coupling,the greater the reactance of the second-ary, because the aerial -ground system isthus made to contribute more generouslyof its inherent capacity. With loosecoupling the secondary functions almostas if it were isolated from the circuit, thatis, the tuning is based almost solely onthe condenser - secondary combination.Many experimenters probably havenoticed that a condenser hooked up to agiven coil will show a calibration scaleunder ICW tests, as with buzzer used tocalibrate a wavetrap circuit, but when thissame coil -condenser unit is hooked up in abroadcast receiver, with an untuned pri-mary coupled to it rather closely, thereadings will be lower for any given wave-length. This is because the inductanceof the untuned primary, as well as itscapacity and, most importantly, thecapacity of the pickup system, have addedthat much reactance. The effect is equiv-alent to that of placing a small fixed con-denser in parallel with the tuning con-denser, for that too would make the dialreadings lower. It is assumed that 0 onthe dial represents the minimum capacityand 100 the maximum capacity of thetuning condenser.

Objections to Both MethodsHence, by utilizing this effect of added

reactance we spare ourselves the necessityof adding more turns to the secondaryL2 to equalize its reactance with that ofL4. The two theoretical objections to thissystem are:

(1) If an adjustable primary is usedto facilitate matching, then the degree ofcoupling is arbitrarily established on thebasis of obtaining synchrony, not maxi-mum eficiency at any predeterminedwavelength.

(2) If the adustable primary is in theaerial circuit, the method works only ifthe CIL4 combination gives lower read-ings (has more inductive reactance) than

THE REAR VIEW (Fig. 4) shows the coils mounted at an angle of about 57degrees, simply as an extra safeguard against stray coupling. The aerial andground posts are at right. The two cup -like objects a few inches to the left ofthese posts are the phone tip jacks. The speaker cord tips are inserted here. Thesockets are, left to right: first AF, detector, second AF, third AF and RF, i.e., as

designated in Fig. 1, they are 3, 2, 4, 5 and 1.

THE TOP VIEW (Fig. 5). The coil LI L2 is at left, while L3 L4 is at right. TheRF socket is at left, the detector socket between condenser Cl and coil L3 L4(foreground). The audio runs in the opposite direction-first AF at right rear, thensecond and third AF in the same row. The phone tip jacks are to the left of the

third AF tube.

the C1L2 combination, or only when L4is established as having more inductancethan L2.

Meeting the IssueThe objection relative to the degree of

coupling is not so serious as one mightimagine, for the selection of 1,000 kcy. isa matter of personal taste, and is itselfopen to attack, since some may hold thatit would be better to have the most ef-ficient degree of coupling at some point

Pilot Light Shows RedOn Panel When Set Is On

THE PANEL view of the 5 -tube receiver diagrammed on the opposite page. Theknob at left is the RF rheostat, RI in Fig. 1. The switch at right lights or unlightsall five tubes. The aperture above it is an opaque maroon window, illuminatedby a pilot light when the set is "on." In center is the single tuning control, a dialthat makes any condenser that is not straight-line frequency tune just as if the

condenser were such. (Fig. 3.)

representing a higher wavelength, be-cause on this part of curve of wavelengthplotted against amplification, the inevit-able amplification drop takes place.

The obection to the other objection-that the remedy applies only when L2has too few turns-may be found in thesuggestion that the adjustable primarymay be L3 instead of Ll.

The Oscillation ProblemAll of these considerations are inde-

pendent of the effect upon rampant oscil-lations. The rheostat RI is included inthe circuit as a stabilizer of. truant oscil-tions, and its functioning as such isvery effective, but it is possible to makethe coupling so loose between LI andL2 that it will be hard indeed to stopthe oscillation nuisance. The looser thecoupling the greater this tendency to over -oscillation, because the resistance of thetuned secondary L2 is reduced the far-ther Ll is moved away from L2. Resist-ance, therefore, is not a vice per se, buta certain amount of it is an important,valuable factor in a radio receiver, con-tributing a wholesome stability, one ofthe chief necessities in any set. In thecircuit (Fig. 1) it is perhaps going a bitwide of general experience to expect riot-ous oscillation beyond control by RI ifone takes for granted that the B batteryvoltage on the plate of the RF tube willnot be made purposely excessive or in-ferior. In this set 45 volts of B batteryat this point may not be sufficient tomaintain desired volume, hence somevoltage between 67% and 90 normallywill be used.

The RF B battery voltage, in this re-


A Skillfully -Made 1 -Dial Set

THE BOTTOM VIEW. Note how the arrangement of parts simplifies the wiring.The 50,000 -ohm resistor (grid circuit of tube No. 5) is the one at right, directly

above the central bypass condenser. (Fig. 6.)

spect, is critical, for if it is too low or toohigh over -oscillation may result, while,of course, it is easy enough to get it justright.

How Grid Bias WorksA table has been prepared with a

20 -ohm rheostat as Si, the tube beingone requiring normally 5 volts at the fila-ment, the supply source being a 6 -voltstorage battery. The B voltage used ex-perimentally was 97 at all times. Thefilament terminal voltage was varied in%-volt steps from 5 to 2%, giving six in-dividual readings. The tube used is ratedat .25 ampere filament consumption. At5 filament terminal volts this consump-tion actually was .26 ampere, while at

volts it was .18 ampere, or about 25per cent. less than at twice the filamentvoltage. Notice, too, that the plate cur-rent drain dropped as the filament tem-perature was lowered. This was due tothe bias, whereas the A battery drain wasnot due to this. Naturally, when the low-er filament voltage were recorded theelectronic emission from the filament wasso small that the reduction of plate cur-rent drain was slight at those points. At5 volts on the filament plate current drainwas 6.78 milliamperes. At 1.3 volts auto-matic negative bias, while at 2% volts onthe filament terminals the plate currentdrain was .5 milliamperes, at 3.8 auto-matic bias.

These laboratory determinations weremade with the rheostat R1 operating inthe circuit to cut down the voltage at thefilament terminals and also to bias thegrid. The bias range is shown in thetable, starting with 1.3 volts negative biasat 5 volts at the filament terminals, andending in the test with 3.8 volts negativebias when there were 21/2 volts at the fila-ment terminals. Hence the bias encom-passes 2.5 volts, the same range as be-tween maximum and minimum filamentterminal voltage, only, of course, the biasis inversely proportional to the filamentheating. The discussion of the bias ques-tion, published in last week's issue ofRADIO WORLD (January 2), should beconsulted by any one interested in thissubject.

The Laboratory TabulationFollowing is the table of grid bias

variation with the six diferent filamentterminal voltages, the plate current col-umn showing the plate drain on the Bbattery at zero grid bias (left-hand) andat the resultant bias (right). The biasfigures are at extreme left. Note theeconomy of B battery drain, determinedby subtracting the figure in the right-hand plate current column from the left-hand plate-curent column.

Effectiveness ProvedTherefore the effectiveness of the rheo-

stat to vary the grid bias, and at the sametime reduce filament and plate current

Analytical Table of Grid Bias EffectsThrough Rheostat, in Respect to SixDifferent Filament Terminal Voltages, at

a Plate Voltage of 97.

Tr2Vj

1724E2

1.3 51.73 4.52.36 42.8 3.53.3 33.8 2.5

iiL.26.24.233.217.2.18

dYY

Go7.87.446.64.421.8.55

3='611

;13

:21

6.765.924.83.521.7.5

drain, was confirmed experimentally. Theeffectiveness of the rheostat as a checkupon oscillations was proven in the opera-tion of sixteen different receivers con-structed for the sole object of furnishingexperimental background for this articleand the one published last week.

Constructional DataAs for the construction of the single -

control receiver designed on the basis ofexperiments covering several weeks, thediagram is shown in Fig. 1 and the photo-graphs give valuable assistance. It willbe noticed that commercially -made coilswere used. These were Bremer -Tully.The tuning condenser Cl was a Bruno.This is slightly in excess of its ratedcapacity per section of .00025 mfd., hencea few turns had to be removed from thesecondary of each coil to cover the wave-length band. How many should be takenoff had better be determined by experi-ment, along the lines previously discussed,although in this particular instance sixturns were removed.

Crescent Lavite AudioAn important part of the circuit is the

audio hookup. This consists of threestages of resistance coupling, and thevalues of the resistors, as shown in Fig.1, are those recommended by the manu-facturers of these parts, which are Cres-cent Lavites, famed for their noiselessoperation. There is some difference ofopinion among experts as to the degree ofresistance to be used, but it can be saidin favor of the constants as given in thediagram that the result was superb.

The location of the parts is given in thecaptions under the pertinent photographs.A neat wiring job results if busbar is used,Fig. 6 showing valuable hints in this direc-tion.

Coil WindingThe coils, if made by the constructor,

may consist of 12 turns of No. 24 doublecotton covered wire, on a 21/2" diameter

FIG. 7, the adjustable primary. Thisdiffers from a variable primary in thatthe adjustment, once made, is left

that way.

tubing, 2" high, for LI, while the second-ary 1.2 has 60 turns of the same kind ofwire. The tubing for this stator form is3%" diameter and 4" high. Of course thesmaller winding is placed inside the statorform in such manner as to enable somerotation and is adjusted for that degree ofcoupling that affords most satisfactory all-around results, and left that way. Theother coil, L3L4, consists of 10 turns forthe primary and 60 for the secondary, theform being 3%" diameter and 4,A" high,the separation between primary and sec-ondary being %". The primary LI shouldbe at the low potential end of the second-ary, as shown in Fig. 1, while the primaryL3 should likewise be so connected so thatthe B plus and A minus leads adjoin. Forthis method of wiring it will be necessaryto ignore markings on some commercialRF transformers.

LIST OF PARTSTwo radio -frequency transformers, LI

La L3L4.One 2 -section multiple tuning condenser,

Cl.One 20 -ohm rheostat, RI.One %-ampere ballast, R2.One No. IA Amperite, R3 (for -0IA

tube).Five sockets.One 73E21" panel.One 61/2x20" subpanel (hard rubber).One 4" straight-line frequency dial.Six Crescent Lavite resistors: R5, R6,

R7, R8, and R9, each 0.1 meg.; RIO, lastaudio grid leak, 0.05 meg.

Three 0.25 mfd. fixed condensers, C3, C4and C5.

One fixed grid leak, R4, about 2 meg.,and one fixed grid condenser, C2, .00025mfd.

One pair of phone tip jacks, PTJ.One Yaxley filament switch with pilot

light.


Tuned Aerial Used to Aid DXTwo Interesting 1 -Tube

Receivers-One ReachesHigher Efficiency Thanthe Usual Run Becauseof Variable Condenserin the Antenna Circuit-The Other Is Experi-mental, Because SameTube Is Used for RF,Detector and AF.

By Lewis WinnerAssociate, Institute of Radio Engineers

HLt"T1-tu?e ceI ve rsand

two sets represented, that in Fig. 1 is thebetter. That is, it is the easier to constructand get working right. The one shownin Fig. 2 is tricky and requires some skillto get it operating successfully. This isdue to the attempt to get the same tubeto function as an RF amplifier, detectorand audio amplifier.

Fig. 1 is a 3 -circuit regenerator, withtuned aerial for greater DX. Instead ofthe plate being tuned by the tickler, as isdone in Fig. 2, a condenser, which shuntsan inductance, tunes the plate. This methodwas found to be very practical and effi-cient. The regeneration is sometimes moreeasily controlled in this manner, althoughwith the tickler more feedack is com-monly obtained.

LI, the primary of the tuning coil, L1L2,is wound on a tubing 3%." in diameterand 4" high. This tubing may be hardrubber or bakelite. A skeleton form maybe used with success. There are 10 turnsplaced on this form, which constitute theprimary. Leave %." and put 45 turns onthe form. L3, the plate coil, is wound ona separate form 31/4" in diameter and 2%"high. Here 35 turns are put on. Whenwinding these coils use No. 22 double cot-ton covered wire.

A very important thing as to the suc-cessful operation of this receiver is theplacing of the parts. There is no base-board necessary. The only pieces of ap-paratus that require a basemounting arethe bending posts and the socket. Thesemay be placed on a special socket shelf173" long and 21/2" wide. The cabinetinto which these parts are to be placedis 7x18". The large size of this cabinetis due to the three variable condensers

employed as tuning elements.Nine inches from the right and the left

and 31/2" from the top and the bottom, drilla hole which is large enough to fit the shaftof the variable condenser, C2. Now, 4%"from the left hand side and 3%" from thetop and the bottom, drill a hole largeenough to fit the shaft of the variablecondenser Cl. Four and one-half inchesfrom the right hand side and 3%" fromthe top and the bottom of the panel, drilla hole for the shaft of the last variablecondenser, C3. Now the only other hole

. beside the small holding holes for thevariable condenser and the bracket, thatare to be drilled, is that for the shaft ofthe rheostat, which is directly in the cen-ter or 9" from each and 2%" from thebottom.

On the end plate of the variable con-denser, C2, mount the antenna coil L1L2,so that the windings run parallel to theplates of the variable condenser. On theend plate of the variable condenser, C3,

FIG. L showing set No. Imount the plate coil. This coil should haveits windings at right angles to those of theplates. This means that it will also be atright angles to the antenna coil. Themounting can be made with the aid ofangle irons. On the socket shelf, you willhave to mount the socket, terminal bind-ing posts and phone tips.

Bring the rotary plates of the variablecondenser Cl, to the antenna binding post.Bring the stationary plates to the begin-ning of the primary winding, Ll. Bringthe end of this winding to the groundbinding post. Bring the beginning of thesecondary winding 1.2, to the F+ poston the socket. It also goes to the rotaryplates of the variable condenser C2. TheF+ post goes to the A -I -B- post. Bringthe end of the secondary winding L2, to thestationary plates of the variable condenserC2. It also goes to one terminal of thegrid leak and the condenser. The otherterminals of the condenser and the leakgo to the grid post on the socket.

The beginning of the plate coil L3, goesto the plate post on the socket and to thestationary plates of the variable condenserC3. The rotary plates of this condensergoes to one terminal of the small fixedcondenser C4 and to one of the phoneterminal tips. The other phone terminaltip goes to the B+ binding post. Theresistance wire of the rheostat goes tothe F- post on the socket. The arm ofthis rheostat goes to the A- post on theterminal strip.

The receiver shown electrically in Fig.2 will now be described. Here we have aregular 3 -circuit receiver, except that it isreflexed. There are only two controls.

Those who are experimentally inclinedmay try out this receiver. The same coilLI L2 may be employed as in Fig 1. L3,

LIST OF PARTSFor Set No. I

One antenna coupler L1L2. Three .0005mfd. variable condensers, C1C2C3. Oneplate coil, L3. One 6 ohm rheostat. One2 megohm grid leak. One .00025 mfd. fixedgrid condenser. One .001 mfd. fixed con-denser, C4. One 7x18" cabinet and panel.Three 31/2" dials. One pair of brackets.One socket strip. One socket. Five bind-ing posts. Two phone tips. Accessories :Phones, batteries, 201A tube, connectingwire. etc.

FIG 2, showing set No. 2

B-A -

which in tile oilier set was stationary, isvariable here. Therefore, place 35 turnsof No. 24 double cotton covered wire on afrom 21/4" in diameter for L3. Put this in-side the stator, with rotor shaft protrud-ing through the panel.

Bring the beginning of the primarywinding, LI, to the antenna binding post.The end of this winding goes to theground binding post. The end of the sec-ondary winding. L2, goes to the station-ary plates of the variable condenser Cl.It also goes to one terminal of the gridcondenser and the leak. The other term-inals of the leak and condenser goes tothe grid post on the socket. The be-ginning of this winding goes to the rotaryplates of the variable condenser Cl. Italso goes to the G post on the audio -fre-quency transformer and to one terminalof the fixed condenser C3. The otherterminal of the fixed condenser goes tothe F- post on the audio -frequency trans-former, to the arm of the rheostat, to theA- binding post and to one terminal ofthe fixed condenser C4. The resistancewire of the rheostat goes to the F- poston the socket. The F+ post on the socketgoes to the A+ binding post. The otherterminal of C4 goes to the plate post onthe socket, to the beginning of the ticklerwinding and to the top terminal of thesingle circuit jack. The end of this ticklerwinding goes to the plate post on theaudio -frequency transformer. The B+post on this AFT goes to the 8+ 67% volttap on the B batteries and to the bottomterminal of the jack.

Trouble ShootingTrouble shooting on the first set de-

scribed : (1) If the set doesn't oscillateenough, add more turns to the plate coilL3. About 5 turns at a time will be 0. K.Increase the plate voltage. Take the fixedcondenser C4 out of the circuit. (2) Ifthe set oscillates too much, take off 3turns at a time until the squealing is con-trollable. Decrease the plate voltage. Increase the amount of resistance in the gridleak. (3) If the signals are not loud, re-verse the A Battery leads. Reverse thephone tips. Place another tube in thesocket. Make the grid return negative in-stead of positive. (4) If the tuning isbroad, see that all the soldered connec-tions are solid. See that the antenna isnot too long. About 100 feet in lengthis 0. K. Make sure that the ground ismade to the water pipe. The lead shouldpreferably be soldered.

Trouble shooting on the second set de-scribed: (1) Items 3 and 4 of the othertrouble shooting paragraph apply to thisreceiver also. (2) If the set oscillatestoo much, reverse the tickler leads. De-crease the number of turns on the ticklercoil. Take the condenser, C4, out. De-crease the amount of voltage on the plate.(3) If the set doesn't oscillate enough, add 5turns to the tickler coil, reverse the A bat-tery, or decrease the amount of resistancein the grid leak. (4) If the set howls, re-verse the secondary leads of the AFT,place a .001 mfd. across the secondary ofthe AFT, or see that the fixed condenseracross the primary is not shorted.

LIST OF PARTSFor Set No. 2

One 3 -circuit tuner, L1L2L3. One .0005mfd. variable condenser, Cl. One low -ratio AFT. Two .001 mfd. fixed condens-ers, C3 C4. One of 6 ohm rheostat. One.00025 mfd. fixed grid condenser. One 2megohm grid leak. One single circuit jack(optional). Remaining articles are thesame as for Set No. 1.

10 RADIO WORLD January 9, 1926'

How to Take Care of BatteriesThe Radio

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By Capt. P. V. O'RourkeAGREAT many persons now have a

radio receiving set in their homesfor the first time, as a consequence ofthe spirit of holiday giving. Maybe theset was a self -gift. Even so, the rulesof the game are the same!

Most sets these days have tubes thatare lighted from a supply source knownas a storage battery. Practically, themain point of difference between a storagebattery and a dry -cell battery is that astorage battery may be recharged, where-as a dry -cell battery can not be. Themost common storage battery is of thistype, i. e., to light the tubes, and is knownas the storage A battery. The only otherkind of storage battery used in radio isthe storage B battery. While an A bat-tery is connected to the filament, i.e.,lights the tubes, the B battery serves anentirely different purpose, and whether itis connected or disconnected can not bedetermined by any visual test of the tubealone. If disconnected, of course the in-evitable result is that the set will notwork. All radio receivers require both Aand B batteries, because tubes requirethem.

How Batteries Are RatedNow, if You have a storage A battery,

say of the 6 -volt kind, it will have a cer-tain maximum rating, exoressed in termsof ampere hours. This means that at adrain of one ampere the battery, if fullycharged, will be in a totally exhaustedstate after the specified number of hours.If the battery is of the 80 -ampere type,then the number of hours is 80. Mostbatteries are rated at 80, 100, 110 or 120ampere hours. If the drain is 1A amperethe battery may be used twice as longbefore becoming exhausted.

How to determine the condition of thestorage A battery, thus to know whenit needs recharging, is the problem. Theinstrument used for this purpose is thehydrometer. This is a syringe whichsucks up electrolyte from a cell of thebattery. You will notice on a 6 -volt stor-age battery there that there are threecaps. When you unscrew each you findthat a fluid that looks like water is pres-ent. This is the electrolyte. It is addand should be treated with respect. Donot drop any on the carpet or elsewhere,for it will eat a hole in textile of any kind,unless ammonia is applied quickly, forammonia is the best household antidotein this emergency.

Where Variation ExistsYou should know what the maximum

rating of the battery is. This usually ismarked on the battery itself. Also youshould know what reading of the hydro-meter indicates a fully charged condition.

This figure is not the same for all makesof batteries. It is often 1.250 or 1.300.This is actually the specific gravity of theelectrolyte. The figures are spoken ofpopularly as 1,250 and 1,300, although sci-entifically they are simply the unit fol-lowed by the decimal.

If you do not know the specific gravityrating, write to the manufacturer for thisinformation.

At any rate you may act upon the safesupposition that 1.250 is the maximum, be-cause then you will not run into the dil-emma of charging a battery for fifteen ortwenty hours, only to find the reading is1.250 and never gets higher, which thehydrometer, at one side of its scale, pro-claims as a condition near "half charge."In fact the battery probably is fullycharged, because hydrometers are madeless on a standard basis, while batteriesare not.

Do Not Work at Zero1t is a mistake to assume that the bat-

tery may be operated to the zero point,a state of complete discharge. The betterpractice is not to let the battery go lowerthan a condition of half charge, so you al-ways operate it in on the upper half. Inmost cases if the battery is rechargedevery two weeks this end will be fulfilled.

The hydrometer, therefore, is an essen-tial if you have a storage A battery. Donot use a voltmeter. The voltage of thestorage A battery does not vary so much,as when the battery is fully charged thevoltage may be 6.4, while at discharge thevoltage may be 5.6, but the amperagemay vary from nearly zero to the maxi-mum amperage rating of the battery.Hence, as a general rule, one may bearin mind that with the storage A batterythe amperage is the important thing towatch.

A Point That Deceives ManyDo not be misled as to the condition

of the storage battery by the fact thatit will light the tubes. Even in a stateof discharge it will do this, i.e., even whenthe hydrometer gives a reading of "dead."It is risky to allow a storage battery todrop that low, for one effect is that it hasa great tendency to resist a recharge andindeed the plates of the battery may beinjured.

With a storage battery it is just as im-portant to see that there is enough elec-trolyte as it is to watch for the conditionof the battery content itself. The platesshould be covered with electrolyte at alltimes. When you remove one of the threecaps you should not be able to see theplates, unless because of conditions ofexcellent light your eye can penetrate thecovering of electrolyte. Remember, too,that each cap represents one of three cells,and that the electrolyte in all three cellsshould be tested with the hydrometer, oneat a time.

The Use of a ChargerIf you have a storage battery and have

electricity in the house you may want tohave a charger. This may be either ofthe vibrating or of the chemical type, ifyour current is alternating. If you havedirect current there is only one type ofcharger generally made, although severalmanufacturers make this type. The DCchargers are constructed on the basis ofcutting down the main supply by intro-ducing resistances. If this were not donethe voltage would be too high-or, rather,the product of the voltage and the amper-age, which is known as the wattage-and the battery would be ruined.

Assuming you have AC, your choicewould then depend largely on whether youprefer a silent charger. The chemical typeis silent. It uses the electrolyte principle.

The vibrating type makes a hummingsound that is penetrating.

The Charger RatingThe charger has a rating, too, and you

should know what it is. The rating usu-ally is plainly marked on the charger. Itwill be rated at 2%, 3i or 5 amperes,probably, which means that it passes thatmany amperes an hour. If you have a100 -ampere battery, assumptively in a deadcondition, theoretically it would take 20hours to charge it fully, if the charger isof the 5 -ampere type. Actually it wouldtake longer than that, because after acertain point of battery charge is reachedit is harder for the charger to push thecharge into the battery.

When charging a battery, leave the capsoff the top of the cells, thus exposing theelectrolyte to the air of the room. Someslight fumes that develop during thecharging process thus are dissipated inthe air, otherwise they' might accumulateand be rather intensive. Under some con-ditions, if allowed to become intensive,they might be inflammable, hence danger-ous if a lighted match is placed near itunder such circumstances.

As for economical considerations, it isjust as expensive to charge your ownbattery from DC, if you charge only onebattery at a time, as it is to have it re-charged outside.

More ConvenientAssuming that the cost of outside re-

charging is 75 cents, the difference will beonly a very few cents in favor of charg-ing the battery yourself. This ignores theinitial cost of the charger.

However, convenience is served by hav-ing your own charger, and also economyif you have to pay the battery man forthe privilege of using one of his batterieswhile yours is being electrically restored.If, beside having to pay a battery use fee,you feel you should give a quarter as a'tip to the man who does the batterytoting, you can see that financial reasonswould impel you to install a charger.

As for the AC chargers, they are botheconomical and convenient.

Use of a VoltmeterSo far we have discussed the hydro-

meter and the charger. Now for the volt-meter. This is necessary to gauge thecondition of the B batteries. Most per-sons use dry -cell batteries, the red ob-longs, and when these batteries becomeexhausted they are discarded. But theylast a long time. Three months is thegenerally accepted average life, althoughof course special conditions will enlargeor restrict this useful period of life.

With B batteries the amperage is im-portant, of course, but an ammeter neednot be used, because it is safe to assumethat the amperage will be sufficient, but'that the voltage bears watching. Thus acondition exists which is opposite to thatpresent in judging the storage battery.With the dry -cell B battery the voltageis the more important, because it is themore likely to give out, while with thestorage A battery the amperage is themore important.

Adding the VoltagesB batteries are made in 22% -volt and

45 -volt sizes. To add up the voltages ofa block, connect them in series, that is,plus of one battery to minus of another,etc. Then there will be two posts, theminus of the first battery and the plusof the last, and there will be no otherminus post, not even the minus post ofthe second battery, which is markedminus, for that has been converted toplus. It is a positive voltage exactly equalto the positive voltage of the previous Bplus tap to which it is connected. Also


"PRIDE COMETH-" By Dan Napoli"3-- ONE HUNDRED FEET OF AERIAL

VI RE - SIXTY FEET OF NO la WO,SOME SCREWS- NAILS -TAPE. ETC

Two COOT

POLES " It PEELAW RIGHTS

ESOT- OH BOY!WHEN I GET

THIS AERIAL UPIT'LL BE THEotoT IN TOwN

Day NexPo,.:-.

the actual voltages are not the voltagesthat are marked on the batteries, exceptin the case of the first battery. Let ustake a concrete example. Suppose youhave a 22% -volt B battery. That hasposts marked thus: one is minus, marked"-" the others are marked plus ("+")16%,, 18, 19%, 21 and 22%. Now, if youconnect to the 22% post the minus postof a 45 -volt battery, the first battery postreadings still are correct (0, 16%, 18, 19%,21 and 22%), but the second battery postsrepresent the reading marked thereon,plus 22% volts, that is, the voltage of thepreceding battery is added thereto.

Now, you measure the voltage by con-necting the voltmeter with its positive sideto the positive side of the battery or partof the battery to be tested, and the nega-tive side of the meter to the negativeside of the battery. Remember that in-termediate cells or batteries in the samebattery may be tested, too, but keep inmind that if the test is being made be-tween 16% and 22% volts that 161/ isnot that at all, for the moment, but issimply the minus post, and 22% is really+6. The voltmeter will not register ifwrongly connected, so simply reverse con-nections to get a reading.

Good Service on Lower VoltageA B battery does not have to maintain

its rated voltage at the given posts torender efficient service. Sometimes a bat-tery will not work so well as it shouldwhen the voltage reading for a 22% rat-ing is 17 or when a voltage reading for45 volts post is 37, but this is by no meanscontrolling and many B batteries willrender excellent service although theactual voltage is considerably less thanthe figures previously cited as evidenceof voltage drop due to use.

When the B battery voltage drops re-ception results may not be so good aspreviously, due to the total voltage beingless than that required for efficient service.So, if 135 volts are good for a resistance -coupled audio amplifier, 101 would pro-duce a noticeable drop in volume, in whichcase a fresh 22% -volt B battery may beadded to the chain for a good compromisevoltage of 123%. While this tends tobring down the level of the new battery,net economy may result, due to the con-tinued usefulness of the three 45 -volt bat-teries used to constitute the original 135.

The Storage B BatteryOf course storage B batteries are serv-

iceable, and these may be recharged.They are exceedingly more expensive inoriginal outlay and require the purchaseof a charger or an adapter for use inconjunction with the charger otherwiseemployed on the A battery. Also theyrequire attention. Some persons greatlyprefer them and there is a market forsuch devices, but many more dry -cell Bbatteries are used than storage B bat-teries.

The EliminatorThis season in particular there has been

great interest in B battery eliminators.These operate from the lighting main,

hence can be used only in places thathave electricity installed. The purposethat they serve is largely one of con-venience, since they do not require re-plenishment by any charging process norreplacement. The chief difficulty attend-ing these devices is that a hum may bepresent, the notorious 60 -cycle note,caused by the motor generator in theplant that supplies the electricity. Theseat of the trouble, of course, is in theplant, not in the eliminator, but if the humis there, the causes for its presence aresecondary, their elimination primary. Itcan not be expected that the power com-pany will use some other economical formof supplying current, because the methodwould have to be invented, and the com-panies are certainly entitled to stick towhat they've got. Hence the total elim-ination of the hum will be a problem forradio engineers to tackle for some time tocome.

Line FluctuationsAnother important item in connection

with B battery eliminators is fluctuationin the line, due to voltage surges. Oftenyou have seen the electric lights growsuddenly bright for a second, or growdimmer, then quickly return to normal.This is due to the change in voltage onthe line. Hence a B battery eliminatormight be of such construction as to com-pensate for this. But such a device islikely to be expensive, since it shouldbe capable of dropping about 30 volts,

with a comparatively large amperagestrength. At 1 ampere this device shouldbe able to handle 30 watts, and a ballastresistor of this type would cost littleless than $10.

The Faint HumAs for the hum, some persons do not ob-

ject to it, because there are eliminatorsthat product a hum not great enough tobe heard at the same time that a programis being received. But when the carrierwave alone is on, the announcer pausingfor a moment, or there is a lapse betweena program feature and an announcement,one usually can discern the hum. There-fore, when one refers to a humless Beliminator one will mean a device thatdoes not produce an audible hum whilethe program is on, but which relies onthe drowning effect of the voice or musicto prevent audibility of the hum. Per-sons who object to hearing the hum dur-ing the otherwise silent interval will notbe keen for a B battery eliminator.

An A battery eliminator presents evena stiffer hum problem, since the hum ismore readily modulated on the detectortube.

Dry Cell A BatteriesAs for dry cells used as A. batteries, the

1% -volt type preferably should be meas-ured with an ammeter, the maximum be-ing 35 amps. for the No. 6 dry cell. The4% -volt dry battery (otherwise called aC battery) may be tested with a volt-meter.

How to Connect InsulatorsFor Best Results From AerialBy C. H. Campbell

Associate, Institute of Radio Engineers

A glance at the antennas in the averagecommunity shows that few persons knowhow to insulate an antenna properly. Itis a common occurrence to see a multi -wire antenna with the insulators arrangedas in Fig. 1. The antenna works, nodoubt, but much insulation is wasted andconsequently the efficiency is lowered.

Every insulator acts as a very highresistance between the antenna andground and when resistances are con-nected in parallel, the total resistance isfound by dividing the value of one resist-ance by the number of resistances inparallel. Suppose each insulator had aresistance of 40 ohms. This small numberis used for convenience as a resistance ofthat value would be far from an insulator.In Fig. 1 we would have 40 (the valueof one insulator) divided by 4 (the num-ber of insulators in parallel) which gives atotal resistance of only 10 ohms. It wouldbe far better to use only one insulator

INSULATORS"\d lor.saLP

Vial

Fig.2

INSULATOR

sBa

INSULATORS

placed at the extreme end of the antenna,as in Fig. 2, for then the total resistancewould be 40 ohms. If the four insulatorswere connected in tandem as in Fig. 3,the total resistance would be 160 ohmsor sixteen times as much insulation aswith the arrangement in Fig. I.


A Study of Pilot Light DrainRADIO WORLD'S

LaboratoryReports for the Guidance of Its Readers

Address problems to Laboratory Director, RADIO WORLD, 145 West 45th Street,New York City.

0-

eri es_

rZe 313 tante.

+ iJi -

laop

Rheostat

Switch.

HE incorporation of a pilot light forI the purpose of illuminating the tuning

dial, or as an indication when the tubesof the set are "on," is an innovation ac-quiring increased popularity each day,among both constructively inclined radiofans and radio receiver manufacturers.But even such a simple item has its com-plication. This is the selection of thelamp with respect to the filament voltageand current constants.

A person selecting a lamp of this typeto be used as a pilot light usually neglectsto consider the current drain imposedupon the storage battery by the insertionof this lamp in the circuit, and conse-quently when making the purchase hefollows the path of least resistance, byrequesting simply a 6 -volt lamp. This issatisfactory in one respect since the useof a 6 -volt lamp means the simplest wiringand the elimination of the resistances re-quired if a lower voltage lamp were used.But the question arises if the simplestchoice is the best, the most economicalchoice. Unfortunately, it is not, and thedifference from an economical standpointis sufficiently great to warrant giving thesubject consideration.

Use in a SetAssume a 5 -tube tuned radio -frequency

set, although the type is immaterial, whichutilizes five standard tubes, each tubeconsuming 25 ampere at 5 volts at thefilament terminals. The tubes being con-nected in the conventional manner, inparallel, the total current drain is 1.25.amperes. Under normal conditions whenan 80 -ampere -hour storage battery is usedat the filament voltage source, approxi-mately 50 to 55 hours of service life will beobtainable before recharging is necessary.Now, if we add to this load another drain,that of the pilot light, say .5 to 2 amperes,it is very obvious that the battery servicelife per charge will be materially reduced.And if the utility of the item causingthis heavy additional current grain islimited, as in the case of the pilot light,the importance of the current consumed isobvious. Were this additional currentdrain available to increase the sensitivityor output of the receiver, the matter wouldassume ari entirely different aspect.

Now, if we add to this 5 tube receivera pilot light arrangement, it is essential

that the current drain be as little aspossible. But-and it is unfortunate thatthere must be a "but"-the use governsthe brilliancy and the brilliancy is de-pendent upon the candle power, whichvalue in turn, with tungsten filamentlamps, governs the filament current char-acteristics, or the value of the current con-sumed to light the lamp to the desiredbrilliancy. So we see that if the lampis to illuminate a dial or parchment, theprime requisite is the brilliancy, and thecurrent drain becomes of secondary im-portance. But if the lamp is only an in-dicating device in the filament battery cir-cuit, the paramount item is the currentconsumption.

Rating Is ConfusingWith respect to the current consumption

values of various 6 -volt lamps, it is indeedunfortunate that the manufacturers' ratethe lamps in filament volts and candle-power, and make no mention of the cur-rent consumed. For the convenience ofthose fans who possess a 0-10 voltmeterand an 0 to 2.5 ammeter, a measuring cir-cuit is suggested whereby the filamentcurrent drain at various voltages may bedetermined. The wiring arrangement isshown in Fig. 1. The polarity signs in-dicate the porality connections of the am-meter and voltmeter. The rheostat is in-serted to obtain various voltage valuesacross the lamp filament terminals.

Two methods are available for effectingthis minimization of current of consump-tion. Let us first consider the 6 volt tubeto be used for dial or indicator illumin-ation. A certain filament brilliancy is re-quired for proper illumination. With theinstruments the exact current drain can beascertained. Without the instruments itwill be necessary to follow the rule thatthe lower the candle power for a certaintype of lamp, and the filament voltageconstant at the same value, the lower thecurrent consumption. In other words a6 candle power 6 -volt bulb will consumeless current than a 12 -candle power bulb,and a 3 candle power bulb with the samefilament voltage rating will consume lesscurrent than the 6 candle power bulb.

Use As An IndicatorBut if the lamp is used as an indicator

in the filament circuit, to show the posi-tion of the A battery switch, whether it is"on" or "off," full brilliancy is immaterial,and the lamp need just glow sufficiently toshow that current is flowing, thus in-dicating that the filament circuit is closed.Therefore the lowest candle powered 6 -volt bulb operated in conjunction with aseries resistance is the logical method. Inthis way the voltage applied to the lampfilament is reduced and the current con-sumption mmimized. A 30 -ohm rheostatstat or fixed resistance is suggested.

As an alternative to the above arrange-ment, a 2 or 2,4 volt flashlight bulb oper-ated with a fixed series resistance can beused with a 6 -volt source. In fact thismethod may be preferable when the fanhas no means of dtermining . the currentdrain of the 6 -volt lamp. In practically

FIG. 5, a pilot light in use in a setThe top instrument is a voltmetermeasuring the radio tube filament

voltage.

all cases the current drain of the 2% -volt lamp is less than that of the smallercandle powered 6 -volt lamps, and whenoperated with the series resistance thedrain is still further reduced, and a savingin current effected. As to the actual gain,it depends on the type of lamp. Themethod of installing a pilot lamp andseries resistance arrangement is shownin Fig. 2.

Tapping Made Easy

INSTEAD of using a small tap, shownat right, to make holes that takescrews, you can take the small drilland install it into the brace of thelarger hand drill. This will simplify

the tapping.

Wonderful SetI have just completed the 1926 Model

Diamond of the Air. I am having greatresults, not possible here with any otherset. I have received WFAA, WSB,WJAX, WMBD, WJBJ, WJJD, WSBC,WREO, KGO, WGN, CNRO, CKCK,WLW. I am now convinced that theDiamond of the Air is the best set as toclearness, volume and DX.

JOSEPH A. CORCORAN,3610 Whitney St., Oakland Sta..

Pittsburgh, Pa.

A SPECIAL 4 -TUBE DX SET appeared ivRADIO WORLD dated Nov. 14. 15c per copy, orRADIO WORLD, 145 W. 45th St., New York Qty.


,c)OiC>

A 4 -Tube Toroid ReceiverTHE wiring diagram (Fig. 1) of the 4 -

tube toroid set.CO A r

c).

0 0O

(1)

By Chester CharltonARECEIVER

from which signals ofwonderful quality can be obtained

is shown in ig. 1. The coils employed areof the Toroid type. It seems that thesetype of coils work very well with a crystalas a detector. The condensers are allganged on one ratchet, thereby making itpossible to have only one control. Eachindividual condenser may be so adjustedso tha tthey tune in step, if it is foundthat the coils do not match. This makeseach condenser individual of the rest ofthe circuit, which is not true of the realgang condensers, where the rotary platesare all ganged together, while the statorplates are individual. In other words withthe common gang condenser, the rotary iscommon and the stators are individual,while with this condenser both the rotaryplates and the stator plates are individualof each other although tuned at one time.There are only two rheostats used, oneto control the filaments of the radio -frequency tubes and one to control thefilaments of the audio -frequency ampli-fiers. The crystal detector employed isof the fixed variety. Those which arevariable may be employed. They werefound to be, not as efficient as the fixedtype. This was due to the fact that theycould not stand up under a load. Theaudio -frequency transformers used wereboth of the low ratio type. Do not use ahigh ratio AFT in the first stage and alow ratio AFT in the last stage.

There is no direct method of regenera-(Concluded on page 25)

0

0 A-0 B -

1O At

THE PANEL VIEW showing the tuning dial in the center, with the compensatingknobs at right and left thereof. The RF rheostat is at left, the AF rheostat atright, these bearing arrows. The 1 -control dial arrangement is the Kurz -Kash.

REAR VIEW showing the manner of mounting the Radio Foundation toroids, theCarborundum fixed crystal detector, the sockets, AF transformers and other parts.

TOP VIEW. The tuning dial is vernier, while the compensating knobs adjust the first RF and detector input condensers forsynchronized tuning. The toroids are mounted on the socket shelf behind the U. S. L. condensers.


Disappoints Millions

CHARLES HACKETT, tenor, didn'tsing from WEAF, as scheduled.

Always Add the Acid

IN making a storage battery solutionalways add the acid (sulphuric,H2SO4), slowly to the water, and notthe water to the acid. If the oppositemethod is employed, a boiling andsputtering of the solution will takeplace. After each few drops of theacid are added in the correct fashion,

stir carefully.

SOME of the appurtenances of medi-cine and dentistry serve useful radiopurposes. Here we see a dental mir-ror used for getting an accurate viewof an otherwise obscure point in a

coil.

White Bill in Committee;Provisions Given in Detail

WASHINGTON.THE White radio bill, which was re-

ferred to the House MerchantMarine and Fisheries Committee after in-troduction, contains the following import-ant features

The ether is the property of the peopleand it is the duty of Congress to regulateits use.

Apparatus for the transmission of radioenergy or radio communications shall notbe operated without a license from theSecretary of Commerce, except in the caseof certain government stations.

The Secretary of Commerce shall clas-sify licensed stations, prescribe the natureof service to be rendered by each stationand class ; assign wave lengths ; determinepower; determine location; determine thekind of apparatus to be used; regulate theemissions from stations; establish areasor zones to be served by any station; andto make such regulations as are not in-consistent with the law to prevent inter-ference between stations.

Call Letter RestrictionThe Secretary may not change the call

letters, wavelengths, authorized power ortime of operation of any station withoutthe consent of the station licensee unlessin the judgment of the Secretary suchchange is required by public necessity orby public interest.

The Secretary will have the authorityto exclude from regulations any radio sta-tion upon railroad trains and operators

required therein provided such stationsare not used for sending communicationsfor hire.

In time of war or national emergencythe President may close or seize any sta-tion, upon just compensation to the own-ers thereof.

Station licenses shall not be grantedto aliens or alien companies.

Limitation on TransfersStation licenses shall not be granted

without the consent of the Secretary ofCommerce in writing.

No station license shall be for a longerterm than five years ; and any licensegranted may be revoked or renewed bythe Secretary.

The Secretary is directed to refusea station license to any firm found guiltyby any Federal court of monopoly throughthe sale of radio apparatus or through ex-clusive traffic agreements or other means.

Written application, prescribing citizen-ship, character, financial and other techni-cal ability of the applicant to operate astation, signed by the applicant underoath, will be necessary before, the sec-retary may grant a station license.

The license shall state that there shallbe no vested property right in the licenseissued or for the wave lengths authorizedto be used therein.

Revocation ClauseThe Secretary may revoke any station

license for failure to operate as set forth

Drill Use Simplified

With the above chart, which is calleda drill and Wire Gauge Chart forMachine Screw Taps, you can learnthe standard number and size in deci-mals of an inch, of all types of ma-chine screws. This enables you toknow what size hole to drill in thepanel. Besides finding out the sizeof screws, the diameters of shafts,of condensers, couplers, etc., may alsobe ascertained by inserting the shaft

into the holes.

in the license or for violation of regula-tions, or when the Interstate CommerceCommission or any other Federal bodyshall find and certify to the Secretary thatthe station has failed to provide reasonablefacilities for the transmission of radiocommunications. Provided, that such orderof revocation shall not take effect untilthirty days' notice stating the cause hasbeen given. The station may make writ-ten application for a hearing and upon thefiling of the application for a hearing theorder of revocation shall stand suspendeduntil the hearings are concluded.

All laws of the United States relating tounlawful restraint or monopolies, combin-ations, etc., are declared to apply to themanufacture and sale of radio apparatus.Upon conviction of violation of any ofthese laws, the Secretary shall revoke thestation license of such violator.

Further RestrictionsAny applicant for a license whose ap-

plication has been rejected may appealto the Court of Appeals; and any holderof a license which has been revoked bythe Secretary may appeal to the Court ofAppeals.

All matters broadcast by any radiostation for hire shall be announced asadvertising except when the advertisingconsists solely of the announcement ofthe person or company paying for thefeature. In such latter cases it shall besufficient to announce that such featureis "paid for or furnished" by, etc.

No person shall operate a station with-out an operator's license.

No license shall be issued for the oper-ation of any station "the construction ofwhich is begun or is continued" after theact takes effect unless a permit for itsconstruction shall be granted by the Sec-retary of Commerce.

January 9, 1926 RADIO WORLD l7

Prevents Slipping

PHOTOGRAPH shows how tohole in a panel, without having

11 slip oll over the panel, thereby ling it and delaying the work.

i piece of wood snug up againstace where the hole is to be

Tighten down with a vice.you can drill the hole without-ar of the drill slipping, as itrest up against the board.

;usbar Prong Lifter

4 r TIMES the terminals of the.thet lo not touch the prongs of the3ckt We, therefore, have to pushse rings up. However, the prongs,ue awkward position, are oftenery lifficult to get at. Thereforeihe piece of bus bar and make aHall ,op. Run the loop underneathie p ngs and pull upward. See thate h, bar is composed of hard copper.

-0-Prlor Utilitarianism

N1/EL short wave coil may be',Lind on a glass ash tray.

Russians Rally at Station Opening

A VIEW outside the main building of the General Electric Trust's newest powerand radio station which was opened in the presence of Leon Trotsky, Russianleader, who is president of the electric company. The station is in Shaturka.

(International News.)

The Difference in Clicks New British Station

WHEN you test a coil for a completecircuit, with a 112 -volt cell or a 412 -volt C battery in series with a pairof phones, you will hear a loud click,

if there is no short.

WHEN you test a variable condenserfor a complete circuit a faint clickmay be heard, due to the charge anddischarge of the condenser. Shouldyou hear a loud click there is a shortcircuit in the condenser, that is, plates

are touching each other.- -Comb Guides Winding

THE windings on short-wave coilsmay be spaced as above.

A BIRDSEYE VIEW up one of the820 -foot steel masts of the new radiostation at Hillmorton, near Rugby,England. This is the first step of animperial chain of radio transmittingstations, which will send commercialradio messages around the world.The complete station covers an areaof over 900 acres. The power outputof the station is 100 kilowatts. Thesignals are transmitted on a wave-

length of 6,000 meters. (Acme.)

-0-Radio Commission Established

A national radio commission is estab-lished consisting of nine members whoshall be appointed by the President. TheSecretary of Commerce may refer to theCommission for its decision in any mat-ter authorized or any applications forlicenses or for the use of wavelengths orfor power in connection therewith.


Radio UniversityWILL YOU please give me a diagram

of a 5 -tube receiver, employing two stagesof tuned radio -frequency amplification

.(non -regenerative), a non -regenerativedetector, with two stages of transformercoupled audio -frequency amplification.The filaments of the first two RF tubesshould be controlled by one rheostat. Thefilaments of the detector and the audio -frequency amplifier tubes should be con-trolled by one rheostat.-T. Robins, ThreeRivers, N. M.

Fig. 250, shows the electrical diagramof such a receiver. Ll, L3 and L5, theprimaries consist of 10 turns wound ona tubing 31/4" in diameter, with No. 22double cotton covered wire. 12, IA andL6, the secondaries consist of 45 turnsand are wound on the same tubing thateach primary was wound on. The wireused is No. 22 double cotton covered. Cl,C2 and C3 are .0005 mfd. variable con-densers. R1 is a 10 ohm rheostat, with acarrying capacity of at least 1A ampere.R2 is a 15 ohm rheostat, with a carryingcapacity of 44 ampere. R3 is a2 megohm grid leak. C4 is a .00025mfd. fixed condenser. AFT1 and

39pb

10 L4 Cz

A Question and AnswerDepartment conducted byRADIO WORLD for itsReaders by ita staff of Ex-perts. Address Radio Uni-versity, RADIO WORLD,las West oth St., N. Y. C.

coils are not placed properly. Where can1 obtain a layout scheme of the placementof the coils?-D. C. Wiser, P. 0. 197,Harmony, Pa.

(1) Use straight-line frequency dials.(2) By placing the parts as per diagram,published in the Dec. 5 issue of RADIOWORLD, you will remedy this effect. Ablueprint of the layout is obtainable. Saeadvertising columns. Following this plan,you probably would not hear KDKA withthe RF tube out of the circuit.

* * *

I BUILT a 3 -Tube 3 -Circuit receiverand wound my own coils. Now I havenoted a peculiar action of the tickler coil.When the winding of the tickler is in thesame direction as that of the primary andthe secondary I seem to get poor results.As soon as I reverse the windings of thetickler coil I get fine results. (2) Inmaking a 3 -circuit tuner how many turnswill be necessary on a form 31/4" in diam-eter (for tickler winding), so that I maycover the entire broadcast band, from205 to 550 meters? I wish to use No. 22double cotton covered wire.-George B.Smith, Box 45, Rose Creek, Minn.

regenerative receiver, where can thepower tube be used? (3) Can a 1 -tubeloop set be made that will give speakerresults on local stations using a WDIIor WD12 tube?-Joseph P. Lewis, 3826Dennison Place, N. W., Washington, D. C.

(1) Use it in the last stage of amplifica-tion, without rheostat, and incorporate aC battery there. If you are using 135volts on the plate of the tube, use a 9 -volt C battery grid bias on this tube. (2)Same answer. (3) No.

* * *

I WOULD like to know if the Dynergy5 -Tube receiver, which requires no bat-teries, is selective ?-John Murray, 40Evergreen St., Providence, R.1.

(1) This set is selective. A hum maybe expected during the operation of thereceiver.

* * *

I WOULD like to have the followingqueries answered: (1) What is the ratioof the transformer with the P, B, G and Fterminals used in the set which was dia-gramed in Fig. 182 in the Aug. 22 issue ofRADIO WORLD? (2) Is it an audio -fre-quency transformer? (3) What are theratios of the two transformers used in the2 -Tube reflex, Fig. 192, in the same issue?-Edward DeBold, 4156 Brandon Ave.,Woodhaven, L I.

(1) The ratio of the transformer is 3 to

`Mt'

FIG. 250 shows the diagram Mr. Robins requested.AFT2 are both low ratio audio -frequencytransformers. J1 is a double circuit jack.J2 is a single circuit jack. The -01A typeof tube should be used. S is a filamentswitch.

* *

I HAVE built the Diamond of the Airand find that it does everything that wasand is claimed for it. However, I amhaving a little trouble. The set squealsa great deal. In fact, sometimes I cannotcontrol this action. When I try totune in the stations with a great deal ofvolume, a large noise is built up. Thisnoise drowns the music out.-Ovid Delage,11 Wardell Court, Southbridge, Mass.

Take five turns off the tickler coil. Re-duce the detector plate voltage. Reversethe tickler leads. Change the tubesaround. Decrease the resistance of thegrid lead. Test your A and B batteries.

* * *

WOULD IT be possible to use theAmsco Siamese Allocating condenser inthe Pathfinder, described by Sydney E.Finkelstein, in the Oct. 31 issue of RADIOWORLD, so as to have a single control re-ceiver?-F. Arthur White, 55 BulkleyAve., Mansfield, 0.

No, not in this type of receiver as it istoo difficult to match toroid coils. Therotors on a double condenser are alwayscommon. Therefore the grid returns wouldhave to be common, i.e., negative.

* * *I HAVE built the Diamond of the Air

and have trouble controlling the oscilla-tions on the low waves, due to the crowd-ing of the stations. (2) When the radio -frequency tube is out of the Circuit I canhear KDKA, which is on an air distanceof 30 miles, fairly well. I think that my

(1) If you will reverse the leads of thetickler winding, the same results as thoseof a complete reversed winding will beobtained. (2) The primary consists of 10turns. The secondary consists of 45 turns.The tickler consists of 35 turns. The sec-ondary should be shunted by a condenserhaving a maximum capacity of .0005 mfd.and a minimum of .0001 mfd.

* * *

I HAVE the 1925 Diamond of the Air,and get wonderful results. However, Iget a continuous whistle. Is there any-thing that could be done to get rid of thisinterfering noise ?-George L. Seibert,2964 Cooper Ave., Glendale, L. I., N. Y.

Place a .001 mfd. fixed condenser acrossthe plate and the grid terminals of thelast AFT. Test your A and B batteries.Change tubes around.

* * *

WHICH OF the following two sets isthe better, the Thordarson-Wade, whichwas published in the Oct. 3, 10 and 24issues of RADIO WORLD, or the Diamondof the Air (1926 Model) described in theSept. 12, 19 and 26; Nov. 21, 28 and Dec.5 issues of RADIO WORLD ? -A. W. Lamb,Box 554, Hopedale, Mass.

They are on par. The choice rests withthe builder-whether he prefers threeauto -transformer audio stages or onetransformer and two resistance stages.The Diamond costs less to build.

* * *

I AM building a 3 -tube reflex set suchas the Freedom, which appeared in theJuly 4 issue of RADIO WORLD. I would liketo know if I can use a Daven power tube.If it can be used, where should it beplaced? (2) If two stages of audio -fre-quency amplification are employed in a

0B+90013+45

a-1OA

1. (2) Yes. (3) The first AFT is of thehigh ratio type. The second AFT is ofthe low ratio type.

* *

I HAVE constructed the 1926 Diamondof the Air, and am having trouble withthe amplifier stages, that is the signalsare very much distorted. I think that Iam not using the correct resistances forthe AF stages. I asked for two .1megohm resistors but was given two 1megohm resistors. Now would this causethe signals to be distorted?-ArthurCowley, 1421 Addle St., Alhambra, Cal.

Yes, a .1 megohm resistor is one thathas a resistance of 100,000 ohms. A 1megohm resistor has a resistance of 1,000,-000 ohms. Be careful also to get thecorrect bias on the last audio tube.

* * *

I HAVE everything necessary to con-struct the 1926 Diamond of the Air, ex-cept the 3 -circuit tuner. Now I haveseveral vario-coupler forms 4" in diameter,while the rotors have a diameter of 3'A".How many turns are necessary to placeon the stationary form, for the primaryand the secondary, and also for the tickler.Also please state the kind of wire to use.(2) What is the difference between silkand cotton covered wire? (3) I am goingto use the UV199 tubes. Could I use 201Atubes in the two stages of transformercoupled AF amplification, or do I haveto use the 199 throughout?-P. M. For-tuey. 1930 North 4th St., Harrisburg, Pa.

(1) The primary of the 3 -circuit tunerconsists of 10 turns. The secondary con-sists of 40 turns. There is a 1/4" separationbetween the windings. The tickler consistsof 30 turns. Use No. 24 silk over cottonor 22 DCC throughout. (2) Mainly the


resultant spacing. (3) The 201A wouldbe better. If you are going to use thesmaller tube in the detector and RF stage,and the larger tube in the AF stages,either a different set of batteries will berequired, or a larger battery with a largerheostat to cut down the voltage.

* * *

ABOUT A year ago I built an Ultra -dyne as designed by R. E. Lacault. How-ever I wish to make some changes andtherefore would like to have these queriesanswered. The primary, L3, consists of 8turns wound on a tubing 3" in diameterwith No. 20 double cotton covered wireas the conductor. The secondary, L4, iswound on the same tubing, 4" separationbeing left, and consisting of 72 turns. Theoscillator coil is wound on the same sizedtubing, with the same sized wire. Theprimary or the plate coil, L6, consists of24 turns, while the secondary or the gridcoil, L5, consists of 32 turns. The prim-ary for the inter -frequency RFT consistsof 300 turns of No. 28 double silk coveredwire wound on a tubing 3" in diameter.The secondary consists of 1,100 turnswound on the same tubing, with the sametype of wire. For the other three theprimaries consist of 500 turns, while thesecondaries consist of 1,100 turns. Theyare all wound on tubing 3" in diameter.No. 30 double silk covered wire is used.The primaries and the secondaries arewound on one tubing. (1) Which is thebetter type of coil to use in this receiver,the diamond or the basketweave? (2)For the type recommended, please givethe number of turns, size of tubing, etc.(3) Are the number of turns on the RFT0. K.? (4) Are the turns on the tuner,L3L4, 0. K.? (5) When our local stationsare on the air, I can tune them in on twoor three places on the dials. Is there anymethod that could be employed so thatthis could be prevented? (6) I intend touse an antenna. What provisions willhave to be made for the same? (7) Is itpossible to use a tickler coil on the an-tenna coupler, so that I can have a sortof 3 -circuit tuner effect? (8) Is there anyadvantage in a 20 or 30 strand aerial wireover a solid or 8 strand wire type?-F. E. Whipple, LL.D., 311 Majestic Build-ing, Detroit, Mich.

(1) The solenoid type. (2) See Ans. to1. (3) Yes. (4) No. You have the wind-ings confused, e.g., the loop supposedlybeing used, the grid coil (primary, L3), ofthe tuner consists of 20 turns wound ona tubing 2%" in diameter, the plate coil(secondary L4), wound on another tubing2" in diameter, and consisting of 20 turnsalso. The coupling between these twoshould be very close, when set at maxi-mum. L4, of course, is variable. (5) No.This is a peculiar characteristic of thisreceiver, and only with careful tuning canthis be avoided. (6) When using the an-tenna, a loop jack and antenna coil willhave to be put into use. The primary, LI,will consist of 10 turns wound on a tubing31/4" in diameter, while the secondary willconsist of 47 turns wound on the sametubing. The secondary is to be shuntedby a .0005 mfd. variable condenser. No.22 double cotton covered wire is to beused. The top terminal of the double cir-cuit loop jack goes to the stator plates ofthe condenser, which also goes to the Gpost on the modulator tube socket. Thetop inner terminal goes to the end of thesecondary winding. The beginning of thesecondary winding goes to the 3rd innerterminal from the top. The bottom term-inal of this jack goes to the rotary platesof the condenser. When the plug fromthe loop is inserted, the secondary and in-cidentally, the primary winding is cut outof the circuit. (7) That is a very goodsuggestion, only applicable if you intendto use the antenna and the ground only.That is, the plate coil, IA, may be put ininductive relation to the grid coil, L3, orsecondary winding, L2. In this case thecoil, should be wound on the same tubing,and consist of the same number of turns.

The grid coil, L3, becomes obsolete, asthere is no *further use of the same, sinceit only acted as an inductive relation coil,when the loop was used. That is, theplate and the grid were magneticallycoupled through this coil. An ordinary3 -circuit tuner may be put here and con-nected in standard fashion. (8) The 20or 30 strand wire has a greater surfaceand therefore is a better conductor of theelectromagnetic energy which was at-tracted, since radio -frequency currentsflow on the surface. When using thistype of antenna, be sure that you have asmall antenna coupler, with a small vari-able condenser shunted across the second-ary winding. This type of antenna isusually bulky and heavy, but if both canbe accommodated, is a very wonderfulantenna to use.

* * *

I HAVE a set that does not tune inany stations above 370 meters. I havetried a fixed condenser in the groundlead, but it made little if any change.Would cutting down the capacity of thebook type condenser by cutting off someof the foil help?-Clarence E. Brewer, 20Summit Ave., Warsaw, N. Y.

Either increase the length of the anten-na or put a .001 mfd. fixed condenseracross the antenna and ground. Do nottouch the condenser or any of the internalwiring of the receiver.

* * *

I HAVE an XJ Crosley receiver. Ienjoy listening to amateur stations. Isthere any method that I can employwhereby stations from 80 to 200 meterscould be heard on this particular receiver?-Francis Martin, Deal, N. J.

There is nothing that could be doneother than to rewire the receiver, wherespecial plug-in coils would have to be used.However, it is not advisable to do this.A simple 2 -tube regenerative receiver,such as was described in the Nov. 28 issuemay be built and used for the short wavepurpose.

* * *

I WOULD appreciate it very much, ifthe following queries were answered: (1)Would the Diamond of the Air circuitbe suitable to make up as an all -waveset? I would like to employ the oldhoneycomb idea, with the three honey-comb coils on the front of the panel, etc.(2) Will this set work satisfactorily withone 6 -ohm rheostat controlling all thetubes? (3) Would it be advisable to tunethe primary of the antenna coupler ?-H.Decker Lee, 73 Tremont St., Boston, Mass.

(1) Yes. The primary and the second-ary of both the RFT and the detector unitas well as the tickler unit, will have tohave its plug-in fixtures in a position so'that for all the wavelengths, the chang-ing can be accomplished Without anytrouble. Do not forget, that every timeyou change the secondary coil of thedetector unit, you have to change the sec-ondary unit of the RFT. Would adviseyou to see the Dec. 5 issue of RADIO WORLD

where the 70 to 1208 receiver was de-scribed. (2) Yes, provided it has a carry-ing capacity of 2 amperes, if the 201A typetubes are to be employed. (3) No.

* * *

I HAVE built the receiver outlined inFig. 182, page 12 in the Aug. 22 issue ofRADIO WORLD. Volume is low-John A.Silah, 2016 West Columbia Ave., Phila-delphia, Pa.

Take out the fixed condenser, C2. Takeout the fixed condenser C3. Test theaudio -frequency transformer for a shortor an open circuit. Reverse the A batteryleads. Reverse the leads of the phones orloud speaker unit.

* *

CAN I add two stages of audio -fre-quency amplification of the transformercoupled type to the Bernard 1 -Tube re-ceiver described in the Oct. 24 and 31issues of RADIO WORLD?-J. B. Hunton,1914 2nd St., North Bergen, N. J.

Yes. Connect the plate post of the firstAFT to the P post of the detector tube.Connect the B+ post of this same AFTto the B+ 22% -volt post.

* *

I HAVE a 4 -Tube Diamond of the Air,which I wish to check up upon. Whenusing the detector tube alone on localstations, the volume is good. When Iturn on the RF tube the volume is re-duced. What can be the trouble? I usestandard parts throughout.-Arthur B.Smith, P. 0. Drawer C., Houston, Tex.

See that the grid return of the RF tubeis negative. Test the tube. Push theprongs of the socket up, so that theymake good contact with the terminal ofthe tube. Change the tubes around. Re-duce or increase RF plate voltage. Seethat the variable condenser makes a per-fect electrical contact with the beginningand the end of the secondary winding.See that the variable condenser is notinternally shorted. Disconnect the leadsof the condenser and test with a pair ofphones and a small 15/2 -volt battery. Ifyou hear a decisive click when the platesare turned around after the tips of thephones have been put on the leads, thereis a short. You may hear a slight clickwhen you first put the tips to the leads.due to the charge and the discharge ofthe condenser. This does not indicate ashort.

*

WHICH RECEIVER is the better tobuild, the 1926 or the 1925 Diamond of theAir?-A. G. Allen, 151 Brighton Ave.,San Francisco, Cal.

They have the same RF circuit. The1925 model has two transformer AFstages, the 1926 model has one transformerand two resistance AF stages. The 1926model usually will give better signal qual-ity.

* * *

I HAVE built the receiver described byCapt. Peter V. O'Rourke in the March 21issue of RADIO WORLD. I have trouble in

(Continued on page 26)

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Have 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 it in your queries and the questions will be answered the samday as received. If already a subscriber, send 56 for renewal from close of presentsubscription and your name will be entered in the Radio University.

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Name

Street

City and State


Disappoints Millions

CHARLES HACKETT, tenor, didn'tsing from WEAF, as scheduled.

Always Add the Acid

IN making a storage battery solutionalways add the acid (sulphuric,H2504), slowly to the water, and notthe water to the acid. If the oppositemethod is employed, a boiling andsputtering of the solution will takeplace. After each few drops of theacid are added in the correct fashion,

stir carefully.

SOME of the appurtenances of medi-cine and dentistry serve useful radiopurposes. Here we see a dental mir-ror used for getting an accurate viewof an otherwise obscure point in a

coil.

White Bill in Committee;Provisions Given in Detail

WASHINGTON.THE White radio bill, which was re-

ferred to the House MerchantMarine and Fisheries Committee after in-troduction, contains the following import-ant features:

The ether is the property of the peopleand it is the duty of Congress to regulateits use.

Apparatus for the transmission of radioenergy or radio communications shall notbe operated without a license from theSecretary of Commerce, except in the caseof certain government stations.

The Secretary of Commerce shall clas-sify licensed stations, prescribe the natureof service to be rendered by each stationand class ; assign wave lengths ; determinepower; determine location; determine thekind of apparatus to be used; regulate theemissions from stations; establish areasor zones to be served by any station; andto make such regulations as are not in-consistent with the law to prevent inter-ference between stations.

Call Letter RestrictionThe Secretary may not change the call

letters, wavelengths, authorized power ortime of operation of any station withoutthe consent of the station licensee unlessin the judgment of the Secretary suchchange is required by public necessity orby public interest.

The Secretary will have the authorityto exclude from regulations any radio sta-tion upon railroad trains and operators

required therein provided such stationsare not used for sending communicationsfor hire.

In time of war or national emergencythe President may close or seize any sta-tion, upon just compensation to the own-ers thereof.

Station licenses shall not be grantedto aliens or alien companies.

Limitation on TransfersStation licenses shall not be granted

without the consent of the Secretary ofCommerce in writing.

No station license shall be for a longerterm than five years; and any. licensegranted may be revoked or renewed bythe Secretary.

The Secretary is directed to refusea station license to any firm found guiltyby any Federal court of monopoly throughthe sale of radio apparatus or through ex-clusive traffic agreements or other means.

Written application, prescribing citizen-ship. character, financial and other techni-cal ability of the applicant to operate astation, signed by the applicant underoath, will be necessary before, the sec-retary may grant a station license.

The license shall state that there shallbe no vested property right in the licenseissued or for the wave lengths authorizedto be used therein.

Revocation ClauseThe Secretary may revoke any station

license for failure to operate as set forth

Drill Use Simplified

6 ; *

.

to

With the above chart, which is calleda drill and Wire Gauge Chart forMachine Screw Taps, you can learnthe standard number and size in deci-mals of an inch, of all types of ma-chine screws. This enables you toknow what size hole to drill in thepanel. Besides finding out the sizeof screws, the diameters of shafts,of condensers, couplers, etc., may alsobe ascertained by inserting the shaft

into the holes.

in the license or for violation of regula-tions, or when the Interstate CommerceCommission or any other Federal bodyshall find and certify to the Secretary thatthe station has failed to provide reasonablefacilities for the transmission of radiocommunications. Provided, that such orderof revocation shall not take effect untilthirty days' notice stating the cause hasbeen given. The station may make writ-ten application for a hearing and upon thefiling of the application for a hearing theorder of revocation shall stand suspendeduntil the hearings are concluded.

All laws of the United States relating tounlawful restraint or monopolies, combin-ations, etc., are declared to apply to themanufacture and sale of radio apparatus.Upon conviction of violation of any ofthese laws, the Secretary shall revoke thestation license of such violator.

Further RestrictionsAny applicant for a license whose ap-

plication has been rejected may appealto the Court of Appeals ; and any holderof a license which has been revoked bythe Secretary may appeal to the Court ofAppeals.

All matters broadcast by any radiostation for hire shall be announced asadvertising except when the advertisingconsists solely of the announcement ofthe person or company paying for thefeature. In such latter cases it shall besufficient to announce that such featureis "paid for or furnished" by, etc.

No person shall operate a station with-out an operator's license.

No license shall be issued for the oper-ation of any station "the construction ofwhich is begun or is continued" after theact takes effect unless a permit for itsconstruction shall be granted by the Sec-retary of Commerce.


Prevents Slipping

iE PHOTOGRAPH shows how to11 a hole in a panel, without havingdrill slip oll over the panel, thereby

hatching it and delaying the work.'ace a piece of wood snug up against

to. place where the hole is to bedied. Tighten down with a vice.:en you can drill the hole withouty fear of the drill slipping, as itwill rest up against the board.

Busbar Prong Lifter

-ANY TIMES the terminals of theues do not touch the prongs of theiket. We, therefore, have to pushI. prongs up. However, the prongs,s to awkward position, are oftenry difficult to get at. Thereforeie a piece of bus bar and make arill loop. Run the loop underneath

prongs and pull upward. See thati bus bar is composed of hard copper.

-0-3arlor Utilitarianism

NOVEL short wave coil may bewound on a glass ash tray.

Russians Rally at Station Opening

A VIEW outside the main building of the General Electric Trust's newest powerand radio station which was opened in, the presence of Leon Trotsky, Russianleader, who is president of the electric company. The station is in Shaturka.

(International News.)

The Difference in Clicks New British Station

WHEN you test a coil for a completecircuit, with a 112 -volt cell or a 412 -volt C battery in series with a pairof phones, you will hear a loud click,

if there is no short.

WHEN you test a variable condenserfor a complete circuit a faint clickmay be heard, due to the charge anddischarge of the condenser. Shouldyou hear a loud click there is a shortcircuit in the condenser, that is, plates

are touching each other.- -Comb Guides Winding

THE windings on short-wave coilsmay be spaced as above.

A BIRDSEYE VIEW up one of the820 -foot steel masts of the new radiostation at Hillmorton, near Rugby,England. This is the first step of animperial chain of radio transmittingstations, which will send commercialradio messages around the world.The complete station covers an areaof over 900 acres. The power outputof the station is 100 kilowatts. Thesignals are transmitted on a wave-

length of 6,000 meters. (Acme.)

--0-Radio Commission Established

A national radio commission is estab-lished consisting of nine members whoshall be appointed by the President. TheSecretary of Commerce may refer to theCommission for its decision in any mat-ter authorized or any applications forlicenses or for the use of wavelengths orfor power in connection therewith.

is RADIO WORLD January 9, 1926

Dah Dit-DahZAPJ

Dit-Dah !By Philip Irving Wolfe

The Sixth Annual Radio Show and Con-vention of the Executive Radio Council,2nd District, will take place March 8 to13 inclusive in the Hotel Pennsylvania,New York City.

* * *

The Manhattan (N. Y. C.) City Managerof the A.R.R.L. Harold Sachs (2CHK)won a 250 -watt tube at the CanadianA. R. R. L. Convention held in Montreal.That means that another station will beQRMing the signals on 40 meters.

With 2BBX and 2CTQ working all these"sixes" it seams that the second districtis out for the Jewell Co. low power prizes.

* * *

The well-known ham 2AM J is slowlyrecuperating from a serious accident hehad some time ago. Now his favoritetricks are working Brazilian stations andlistening to the South Africans.

* * *

9GH is stepping out with his pure DCnote. At 12 midnight E. S. T., you canalways hear it just at the top of the 40 -meter band.

* * *

RAA8 is consistently being worked byU. S. and other hams. Another stationthat breaks up the works around 35 metersis Panama Canal 99X.

* * *

Many BCLs in the country are makinglow wave tuners and learning the code.This means that next year there will bean increase in the number of amateurs inthe country.

* * *

Here is the standard Schnell tuner thatmany amateurs believe is the best of allthe low -wave circuits:

ANT.

GNP. -1-A-13

The constants of this circuit follow, withthe apparatus used at 2APJ cited:

(1)-Secondary coil, 9 turns wound ona 3%2" quartzite form. A tap is taken3 turns from the grid side of the coil.The condenser (3) is placed across theremaining 6 turns.

(2)-Tickler coil, 5 turns wound on thesame form and spaced %" away.'

(3) and (4)-.00025 mfd. tuning and re-generation condensers. Amsco SLF areused at my station.

(5)-Grid condensers, .00025 mfd.(6)-Grid leak, Amsco Grid Gate (if

201A tube is used, 3 megohms is aboutright).

(7)-Radio Frequency Choke Coil, 100turns of No. 30 wire on a 1" diameterform about 5" long.

(8) (9)-Vacuum tubes, 201A.(10)-Audio Freuency Transformer,

high ratio (Western Electric 201G typeused, 29 -to -1 ratio).

(I1)-Rheostats, 20 ohms, used to con-trol both tubes. May be dispensed withwhen Arnperites are used.

(12)-Single circuit filament controljack. An ordinary single circuit jack andseparate filament switch may be used.

(13)-Antenna condenser, may be threeplate with the plates all the way out, ortwo wires wound around each other 3 or4 times.

The set operates best when just at thepoint of oscillation. When tuning in turnthe dial very slowly for it is only thenthat DX will be received.

*

AMATEUR EDITOR:

I am a Russian radio amateur, whowants to be put in touch with the U. S.radio amateurs. I would like to exchangeideas regarding the subject. I am verymuch interested in the technical side ofradio.-P. N. Kostyleff, 5A BulvarnajaSt. Tomsk, Siberia, Russia.

* * *

Don't forget, fellows, that the new bandwe have just been allotted for phone workis from 83 to 85 meters. Many stationsare already down there and they say itsfb.

* * *

[Address all amateur news and queries toAmateur Editor, RADIO WORLD, 145 West45th Street, New York City, or call 2 APJon the air (40 or 150 meters).]

+45a90 -A

Patents Nelwy Granted1,563,709-Electrostatic Condenser. Peter G. Jac-

obson, Chicago, Ill. Filed Jan. 19, 1925.1,563,958-Radio Receiving System. John B.

Brady, Somerset, Md., assignor to Morkrum Co.,Chicago, Ill. Filed Aug. 11 1923.

I,564,303-System for Location of Source of WaveEnergy. Pater Irving Wold, Schenectady, N. Y.,assignor to Western Electric Co. Filed April 18,1921.

1,564,476-High Frequency Alternator. C. S.Franklin, London, England, assignor to RadioCorp. of America. Filed June 21, 1921.1,564,555-Variable Electrical Controlling Element.

A. N. Goldsmith, New York, assignor to RadioCorp. of America. Filed July 31, 1919.

1,564,627-Wireless Telegraph and TelephoneTransmission. Henry Joseph Round, assignor toRadio Corp. of America. Filed March 31, 1920.

1,564,641-Detector for Wireless Systems. RobertT. St. James, Chicago, Ill., assignor to ChicagoMiniature Lamp Works, Chicago. Filed April 10,1922.

RESULTSReaders report on their e.8-

periences with sets built fromhookups published in RADIOWORLD. Address Results Editor,RADIO WORLD, 145 West 45thStreet, New York City, and sendphotographs of sets, if possible.

Builds 1 -Tube Set;Hears 115 Stations

RESULTS EDITOR:I made "The Set A Baby Can Build,"

described by Herbert E. Hayden in theAugust 29 issue of RADIO WORLD. Sincebuilding this set I have received 115 sta-tions. Some of the most distant stationsare: KFI, Los Angeles; KOA, Denver,Col.; PWX, Havana, Cuba; WOAI, SanAntonio, Texas; CFCF Montreal, Canada.I get our local stations on the loudspeaker on this 1 -tube set.

I am using a single wire aerial whichis 100 feet long, including the lead-in.I am using a WD12 tube with 45 volts onthe plate. I am using a S.L.F. condenserwhich has 17 plates.

My biggest DX thrill came about threeweeks ago. The announcer said: "Thisis radio station KFI, Earl C. Anthony, Inc.,located at Los Angeles, California."About a week later I got Havana, Cuba.

In closing I will say this set tunes verysharp and gives very much volume. This1 -tube set is hard to beat for DX orvolume.

WILLIAM L. MARTIN.734 Clay Avenue,Norfolk, Virginia.

*

RESULTS EDITOR:I have just built the 4 -tube, 3 -control

set described by Capt. P. V. O'Rourke inthe March 21 issue of RADIO WORLD: Itis the best set I have had. The volumeand quality are excellent. By followinginstructions and the schematic drawing,one cannot fail.

I am not very far from WEEI andWNAC, but can tune through both ofthem and pick up outside stations.

ROBERT C. HEYDER.Rosendale, Mass.

* * *

RESULTS EDITOR:I have constructed many hook-ups pub-

lished in RADIO WORLD and have foundthey all work great, the Diamond of theAir being the best.

CLYDE HAWLEY.3012 Madeline St.,Oakland, Cal.

*

DIAMOND EDITOR:I desire to let you know of the excep-

tional results we are having with ourDiamond of the Air, that I constructedmyself, following plans and description inthe Sept. 12, 19, 26, Nov. 21, 28 and Dec.5 issues of RADIO WORLD. I might sayright here, that I formerly bought nearlyall of the Radio magazines each month. Ihave now dropped them all in favor ofRADIO WORLD. I am convinced that I ammissing something very important if I donot get RADIO WORLD every week. It isthe best, most readable and understand-able magazine I ever saw.

I have built nearly all of the circuitsdescribed by the various magazines andfind that the Diamond is the best of themall.

510 Ridge Road,Rochester, N. Y.

JOHN METCALF.

January 1020 RA1)10 WORI, 1) I')

Inductance Tuning Is Loud

C

Cib

13.135

%A-

THE electrical diagram of a quality 4 -tube receiver. LI is a variometer. L2L3 is a radio -frequency transformer, 10 turns forLI and 45 for L2 on 3'2" diameter. L4 is a variometer. Three a utoformers are employed. R2, R and R4 are all 500,000 ohmresistors. Cl, C2 and C3 are 1 mfd. fixed condensers. RI is a 1 ampere resistor. All the tubes are of the 201A type. Thefirst C battery in the RF stage has a voltage of 4%. The second C battery, in the audio circuit, has voltage of 6.

A.

0

0

Uct,

8 Amp

.8

A

A DIAGRAM of a set similar to that above, except that a tube is used as detector, instead of a crystal. L1L2 and L3L4 areall standard radio -frequency transformers.

A 3 -TUBE regenerative receiver with a variable condenser, C2, having a capacityof .0005 mfd. tuning the plate. RI is a 10 -ohm rheostat, while R2 is a 6 -ohm rheostat

HOW an AC transformer with an out-put of 340 volts is wound is shownabove. No. 22 SCE wire is used towind the primary and No. 30 SCE is

used to wind the secondary.

20 RADIO WORLD January 9, 1926A THOUGHT FOR THE WEEK

Those few broadcasting stations thatare not too particular about the qualityof their programs are here reminded ofwhat Lincoln said about not "fooling allof the people all of the time." In thesedays, when there is such a great numberof programs for selection, you can't foolpeople more than once.

5.0. Fu,Dulvo.J.17_IIDurtrabutor and blanufattunr

---11,1-170KWWWEM-a4Mir

Radio World's Slogan: "A radio set for every home."

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Entered as second-class matter, March 29, 1922, atthe Post Office at New York, N. Y.. under the act ofMarch 3, 1879.

JANUARY 9, 1926

How to Safeguard Tubes

WHEN you are testing out a new set,and you do not know if the filamentand the plate circuits are connected upcorrectly, the above scheme will bevery handy. Take a 40 -watt lamp andinsert it between the B+ and the A-leads of the set. This will preventburnout of the radio tubes, as the 40 -watt lamp will light up, thus taking

up the load.

Dellinger and Craven ReviewAchievements of the Past YearBy Dr. J. H. Dellinger

Chief of Radio Laboratory, Bureau ofStandards

THE year 1925 was the one in whichradio became grown-up. The whole

atmosphere of wonder and mystery wasreplaced during the year by definite en-gineering evaluation of radio's possibili-ties and achievements.

The outstanding progress was on twomain lines ; the evolution of broadcastingand the advances in the understanding ofwave propagation. Under the first head,this year definitely marks the time whenbroadcasting became established as a defi-nite service instead of as a novelty. Be-sides the evolution of programs of an ex-ceptionally high standard, this progresswas marked by an introduction of highpower broadcasting and interconnectionof stations as a routine everyday proced-ure.

Receivers ImprovedThe principle of limitation of the num-

ber of stations adopted at the FourthNational Radio Conference definitelyclinched the position of broadcasting as aservice in which the public interest isparamount. The utilization of the wholebroadcast system has been markedlyadvanced this year by the improvement ofreceiving sets, particularly in respect toquality and also as to selectivity and theintroduction of uni-control and alternat-ing -current power supply.

Wave PropagationThe other great development, increased

knowledge of wave propagation, has comeabout through a number of outstandingcontributions to the theory of the subjectand extensive experimental work, includ-ing transmission experiments and pro-grams of measurement. While heretoforethe whole progress of the radio wavesbetween transmitter and receiver was un-known, there is now the beginning of def-inite knowledge of the vagaries of thewaves and how they are produced. Thisadvance in knowledge has been accom-panied by the utilization of a much widerpart of the spectrum of radio frequencies,particularly the high frequencies or shortwaves which are now employed on a regu-lar engineering basis.

By Lieut. CommanderT. A. M. Craven

Radio Division, Bureau of Engineering,U. S. Navy

THREE features stand out promin-ently1 as the most important de-

velopments in radio during the year 1925.The first is the Fourth National RadioConference, the second is shortwave com-munication, and the third is a new theoryon wave propagation.

All of these developments are out-growths from previous years, but in 1925they became of such importance as towarrant consideration from us all. Theireffect on the radio industry, and perhapson the whole economic structure of thecountry, cannot be estimated, but onemight safely venture a prediction that thiseffect surely will be felt my many. Orperhaps the exact opposite effect will benoticed by the man on the street, becausein some respects one might interpret thesedevelopments as stabilizers rather thanradical progressive advances.

The Stabilizing TrendTake, for example, the allocation of

wavelengths or frequencies adopted by

the Fourth National Radio Conference.There were but minor changes made inthe 1924 recommendations. This is surelya symptom that the radio industry is atlast taking fast strides toward stabilizationand standardization.

Persons who have been in the radio en-gineering profession for many years havenoted that this is the first time that radicalchanges in ideas of radio have not occur-red from one year to the next.

In radio broadcasting, a field familiarto everyone, this stabilization in wave-length allocation means that receivers canbe more easily standardized. Already wehave seen evidences of this in coils, con-densers, dials, tubes, etc. Manufacturers,instilled with a feeling of confidence inthe continued stability of wave band al-location are forming associations with theview of determining steps toward furtherstandardization of radio apparatus.

That this will mean cheaper receiversno one can deny. It is also a sure indica-tion that the radio industry has come tostay, with continued employmesit andprosperity for thousands.

Value of High -FrequenciesEconomy is again indicated in the de-

velopments made in shortwave radio com-munication during 1925. This is not a newdiscovery by any means; the amateurshave been experimenting with thesewaves for years. Short waves were usedby military and naval forces in the WorldWar. The development of vacuum tubesgreatly assisted progress in this form ofcommunication; but it has not been untilthe past year that full knowledge has per-meated the world in general and theUnited States in particular that there arewonderful commercial possibilities in shortwaves or high radio -frequencies.

During 1925 it has been demonstratedthat low power short wave radio stationscan communicate at distances not evenreached by high power long wave stations.It has also been shown that for certainperiods of the day it is possible for a one -kilowatt short-wave station to handle traf-fic that has heretofore required the serv-ices of a 100 -kilowatt station, a saving ofnearly one hundred per cent.

No one can doubt that short waves mustbe used for trans -oceanic radio communi-cations-at least as adjuncts to the presenthigh power system. In spite of the fact,however, that all indications point to theearly development of short wave appar-atus capable of maintaining reliable radiocommunications at long distances for atleast twenty hours out of each day, noone can safely predict that high powerlong wave stations will be discarded.

Limitation Due to PoliticsMuch of the success in super -distance

short-wave communication will dependupon both national and international co-operation in avoiding interference. Thosewho are familiar with the broadcastingstuation of today will realize the difficul-ties ahead of us in this respect, and this,coupled with the long practiced customof the United States in avoiding interna-tional associations, does not paint a rosypicture for the continued success of short-wave stations for trans -oceanic communi-cations.

However, there are other commercialuses for these short waves here in theUnited States. The cost of short-waveradio apparatus is small enough to warrantthe use of such a radio system by manywho have heretofore avoided the employ-ment of radio because telegraph and tele-phone service was cheaper. Today onehears of electric power service corpora-

January 9, 1926 RAD ll) ()P I I) 21

tions, railroads, factories and large retailmail order stores entering the radio fieldby means of short-wave stations.

A Utilitarian PurposeIt seems that short waves have made

radio a practical utility to the businessman. Their Ise by electric power corn-panies alone will save the public millionsof dollars which are now lost every timea storm raises havoc with the high tensionlines in isolated stretches of the country.Radio communication to these isolatedspots will enable greater rapidity in ef-fecting repairs and hence shorter shut-downs of power supply to factories. Thusradio is again an important economic fac-tor in the life of the country.

The third outstanding development for1925 is more of a scientific contributionthan a concrete invention or design ofapparatus. This contribution to the realmsof science is made by Commander A. HoytTaylor, U. S. Naval Reserve Force, andDr. E. 0. Hulbert, Physicist, of the U. S.Naval Research Laboratory.

These gentlemen, in their studies of theappNcation of short waves for naval use,noted certain phenomena. From this theydevolved a theory as to why short wavesshould carry so far with such small power.In their experiments, in cooperation withthe National Research Council, theymeasured the height of the so-calledHeaviside layer about the earth's surfaceand found it to be over one hundred andfifty miles high. This confirmed theirbelief that waves are refracted from thislayer and that the "sky component" of awave, instead of being lost in space, camedown to earth and performed useful serv-ice.

This new theory will mean much toscientists the world over. It should alsobury the hope of radio communicationwith Mars.

There have been other radio develop-

WJZ's Super -Power Requires Huge Equipment

ONE of the motor -operated oil switches of WJZ's super -power station is at left.Although in a separate building, this, like all other switches, is operated from the

control board in the operator's room. Note the huge condensers at right.(Kadel & Herbert.)

ments in 1925, the use of quartz crystalsin radio sets being somewhat prominent.These all tend toward improving the qual-ity of voice transmission, which meansbetter radio concerts.(Copyright 1925 by Stevenson Radio Syndicate)

Sales Surface Hardly Scratched;Prospects Fine, Says Gem sback

.11 the r,J est of RANO NA, ORLD, HugoGernsback answered the question of whatradio holds forth for America in 1926 asfollows:

EDITOR, RADIO WORLD :According to the Department of Com-

merce there are at the present time.4,250,-000 radio sets in this country. There arealso about 25,000,000 families in the UnitedStates. There are in use at the presenttime over 14,000,000 phonographs. No onewill contradict the statement that wher-ever there is a phonograph there should,or could, be a radio set. Not only that,but there should be more radio sets thanphonographs for reasons too well knownto state here. Furthermore, only 8Y210of our farms have radio sets today, while91%% of our farms have none. Thisshows us that the surface has not as yetbeen scratched and that such a thing asa saturation point for radio sets is not insight for many, many years to come.

Couple with this the fact that the lifeof the average radio set is about twoyears and that people who have boughtsets two years ago are buying new onesnow, and it can readily be seen that radiomust be good for years to come-alwaysproviding there are not too many radioset manufacturers in the field. Otherwise,the business spread over the year, dividedinto so many parts, will result in no onemanufacturer making a profit.

From the broadcast listener's standpoint,1926 should be auspicious for the reasonthat the Department of Commerce haseractically decided not to allow furtherstations to go on the air. Rather, thetrend is downward. The Department is

anxious to do away with all interferencebetween the too -numerous stations in usetoday, and by the end of 1926 such a thingas a heterodyne whistle between two sta-tions will probably be a thing of thepast. There will be fewer stations, butthose that remain will put out better andbetter programs.

Countersinking Simplified

INSTEAD of taking the drill out ofthe bit to insert a countersink youmay use a combination drill andcountersink. After the drill haspierced the panel the countersink

functions.

Big Tubes at WJZ

WJZ's new super -power station atBound Brook, N. J., uses 50 KW.,which is 100 times the power of theaverage broadcasting station. Recep-tion is possible over far greater dis-tances, even in the daylight hours.The experimental work with the newstation has shown that it does not in-terfere with other stations and im-proves receiving quality. The stationis owned and operated by the RadioCorporation of America. Above wesee a few of the 64 ten -kilowatt tubes,which are all water-cooled. Note howthe coiled waterpipe enters the tube

jacket. (Kadel & Herbert.)

NIGHTLY CALLS BY NAVYWASHINGTON.

To insure an increase in the efficiencyof aircraft communications, orders havebeen issued by the Navy Department toall radio equipped aircraft that they mustattempt communication with ships, shoreor other aircraft at least once during eachflight.

) ) RADIO WORLD January 9, 1926

THE RADIO TRADEProsperous Outlook for Radio Industry;

Broadcast Stations to HelpIf industrial history repeats itself, and

the records prove that it generally does,then the radio industry as represented bythose manutacturers who have been andare contributing to the development ofthe art and who are helping to raisebroadcasting to higher levels, either bythe better operation of broadcasting sta-tions or the contribution of broadcastingprograms, and who are pursuing soundfinancial atal sales policies, is enteringupon an even more prosperous era thanhas passed.

It would have been easy indeed duringthe period of liquidation for the leadingmanufacturers in the industry to followthe sales tide, if they were indifferent tothe further loss and disorganization whichwould have resulted.

It would have been easy to join the

chorus of "stabilization," when the radioart to the contrary called for further ex-perimental development.

It would have been easy to concentrateupon production regardless of the inade-quacy of the apparatus.

It would have been easy to pile on im-mediate profits, regardless of future loss,by producing and selling radio apparatusupon an experimental rather than a serv-ice basis.

The marked improvement in broadcast-ing, both front the standpoint of tech-nique and of programs, will soon be dem-onstrated on a wide scale by high powerbroadcasting. The selective processeswhich have been going on in the upbuild-ing of distribution systems will be markedby stronger and better equipped retailsales channels, by servicing arrangementsand by modern time payment plans.

Radiall Markets Dial;"Tune -rite" Is SLF

THE Tune -rite dial which, when usedon a SLC condenser makes it tune on

the SLF basis.

Because of the tuning difficulty oc-casioned by the use of straight-line capac-ity condensers (those having semi -circularplates), the Radiall Co., manufacturers ofAmperites, has put on the market theTune -rite dial, which makes that type ofcondenser tune on the straight-line fre-

quency basis. Thus stations are evenlyseparated, instead of the low -wavelengthones being crowded together and those onthe higher waves kept too far apart.

The purpose is accomplished br meansof an ingenious arrangement of two geartrains within the front plate of the dial.The two gear trains move independentlyin such a way that, while one moves apointer at a regular rate over the gradu-ated scale of the dial, the other train ro-tates the condenser. This latter gear traincomprises gears, which work insuch a way that at the lower readings ofthe pointer the condenser moves fasterthan the pointer. This, as can be readilyseen, causes the stations at low wave-lengths to be separated on the scale andto bring stations of higher wavelengthscloser together. It is in this way thatstraight-line frequency characteristicshave been obtained.

The Tune -rite dial is constructed as avernier dial as a matter of course, and dueto its properties the vernier action withregard to the actual condenser settingchanges gradually from a ratio of 24 to 1at low wavelengths to 2-2/3 to 1 at highwavelengths. Of course the pointer movesuniformly. The importance of this gradualdecrease in vernier action will be readilyappreciated by any one who has everhandled a high reduction vernier at thehigher wavelengths, where such vernieraction appears to be worse than useless.

New Export RecordWASHINGTON.

American exports of radio apparatusduring October reached the new highrecord of $1,317,846, compared 'to $769,249for the same month last year. The prin-cipal purchasers of American equipmentduring the month were: Canada, $808,943;apan, $151,247; United Kingdom, $71,577;Australia, 'q7,849; Mexico, $66,118, andArgentina, $22,247.

RECENT BACK NUMBERS of Radio World15c each. RADIO WORLD, 145 West 45th St.,New York City.

Coming Events

JAN. 24 to 35 --International Radio Week.Trans -Atlantic tests.

New CorporationsMarshall Radio Corp., New York City, 200 com

mon, no par; W. A. Sands, J. Newton, S. Schub.(Attys., Rabenold & Scribner, 61 Broadway, NewYork City.)

Kelso Radio, Trenton, N. J., $50,000 preferredand 1,000 shares, no par; J. Russell Kelso, J.Russell Kelso, Jr., Herbert B. Frost, Trenton.(Atty., Herbert W. Backes, Trenton, N. ,J.)

Everready Radio Corp., New York City, 100common, no par; M. Neustadt, I. L. Rollins.(Atty., 11. N. Selvage, 51 Chambers St., New YorkCity.)

Wireless Ignition Manufacturing Corp., Wilming-ton, Del.. $500,000. (Delaware Registration TrustCo., Del.)

Kayl's 34th Street Store, Brooklyn, N. Y.. radios,$20,000; L. Harris, J. L. Edinson, B. Levenson.(Atty., M. L. Kane, 50 Court St., Brooklyn, N. Y.)W. P. F. Radiophone Corp., New York City,make telephone instruments, $25,000; B. Kelly, P.and H. Gallen. (Atty., J. S. Twaddell, 150 NassauSt.. New York City.

R. B. Radio Co. New York City, $75,000: H.Seiden, A. Rebay, 'L. Ross. (Atty.. J. E. Ankus,35 West Seventy-second St., New York City.)

Portmorris Electric & Radio Qbrp., Bx., N. Y.City, $81,000; C. and L. Mogul, G. Burstein.(Atty., A. S. Karasick, 110 West 40th St., N. Y.City).

Stanley Radio Co., N. Y. City, 200 common,no par; E. Husschman, G. W. Joel. L. V. Reilly.(Attys, Finkelstein & Wellig, 36 West 44th St.,N. Y. City).

Literature WantedTHE names of readers of RADIO WORLD

who desire literature from radio Job-bers and dealers are published in RADIOWORLD on request of the reader. Theblank below may be used, or a post cardor letter will do instead.

Trade Service Editor,RADIO WORLD.145 West 45th St., N. Y. City.

I desire to receive radio literature.Name

(Sty or townState

Are you a dealer?If not who is your dealer?

His NameHis Address

J. W. Truesdell, 140 Academy St., Trenton, N. J.R. A. Robinson, Columbus, Ga. (Dealer.)Leslie A. Kumpula, 411 Penn Ave.. North,Minneapolis. Minn.G. A. May & Co., Box 122. Three Rivers. Tex.Harold Weatherall, 136 Florence St., Ottawa,

Ontario, Canada.James B. Brown, Jr., McKee City, N. J.William Thomas. 1443 South 49th Ave., Cicero.

Ill.Dan Pizzira, 1163 Grant St., Indiana, Pa.William C. Hobbs, 2436 South 6th St., Ironton, 0.Carleton Kinch, 28 North St., Waltors, N. Y.H. Lindquist, 4111 -41st Ave., South, Minneapolis,

Minn.B. L. Wright, Madison Heights, Va.Chas. H. Clark, Box 50, Mt. Ephraim, N. J.David White. 514 W. 177th St., N. Y. C.Louis A. Bremser 18 Pearsall St., JamaicaJunction. L. I.. N. Y.Margaret J. Wilson, 34 Fenn St.. Pittsfield,

Mass.W. Paradzinski, 1236 Mautini Court, Chicago,

Ill.H. A. Westermeyer, Cleveland, Wis.Wm. Lubs, 90 Jackson Ave., N. Tonawanda,N. Y.Ed. Sampson, Consoe, Ia.P. R. Grotheirn, 523 South High St., Belleville,Ill.J. A. Peterson, Box 460, Sauk Center, Minn.Ted. Phillips, 390 Jamieson Ave., Winnipeg,

Manitoba, Canada.J. W. Bannister, care Standard Handkerchief

Co., Hobberlin Bldg., 366 Adelaide St., WestToronto 2 Ontario, Canada.

L. G. Clement, R. D. No. 2, Spencer, 0.A. Joe Rutz, 523 Liberty St., Allentown, Pa.Walter 0. Clark, 1518 Pauline Ave., Rockford,

E. Howarth, 18 Brittania Ave., Hamilton. On-tario. Canada.

Business OpportunitiesRadio and Electrical

Rates: 10c per word; Minimum, MOO; Cashwith order.

LARGE WELL-KNOWN radio set manufacturerwants national sales organization able to sell en-tire production. Wonderful opportunity for highcalibre organization. Box X, RADIO WORLD.

STORAGE BATTERY manufacturer wantsactive or silentp artner with capital; more busi-ness than present finances permits, state amountavailable. Box XX, RADIO WORLD.

A RADIO MANUFACTURER who is shortlygoing to sever his connection with his presentcompany, is desirous of obtaining an investor withbetween $15,000 and $25,000, who is willing to in-vest mainly in the ability and knowledge of theadvertisers; the advertiser isrepared to makean investment, but comparatively small and nominal to capital actually needed; unquestionablebank, business, family and character referencescan be furnished. Box 96, Doremus & Co., 44Broad St., New York.

$100 WEEKLY UP. We want experienced radiomen to operate branch assembly plants. Partor whole time. Barfield Radio Co., 13 Tillary St..Dept. \V. R., Brooklyn, N. Y.

PERFECT MUSIC from radio is possible withnew loud speaker; utilizes principle of acousticshitherto neglected; cost of manufacture extremelylow; capital required for expansion; will bearthorough investigation. Box 3, RADIO WORLD.

REPUTABLE RADIO ENGINEER, 15 year,'experience, wishes to make new connection withpart ownership of business and reasonable aseur-ance annual income not less than twenty thou.sand. Box 4, RADIO WORLD.

atmary 9, 1926 RADIO WORLD 2.1

Short -Wave RevolutionPredicted by Saltzman

WASHINGTON.The year 1926 will see many improve-

ments and novelties in broadcasting activ-ities, according to General C. McK. Saltz-man, Chief Signal Officer of the Army.

"While the technical advance in radiobroadcasting apparatus for transmissionand reception during the year 1925 hasbeen confined largely to improvement inprograms and wider dissemination of thoseprograms as a result of the use of greaterpower and linked -up stations," said Gen-eral Saltzman, ''there has been much de-velopment in other fields of the art, prin-cipally long distance telegraphic communi-cation.

"The outstanding advance of the yearin telegraphic communication has been onthe short wave bands where it has beendemonstrated that on certain frequencies,with an insignificant amount of power andat small cost, communication has been con-ducted over distances that had hithertobeen considered only possible of accom-plishment with the extremely high powerlong wave stations.

"I predict that in 1926 we shall see manyimprovements and novelties in the broad-casting activities. In the commercial fieldand as a result of the short-wave develop-ments we may look for some revolution-ary advances in radio communication andcorrespondingly increased use of radio forinternational correspondence.

Radio Vision This Year,Says Jenkins, Inventor

WASHINGTON.C. Francis Jenkins, inventor, believes

that experiments in radio vision during1926 will progress to such an extent as topermit actual service before another twelvemonths has passed.

"As to the outlook," says Mr. Jenkins,"I can only say that the groping progresswhich always attends revolutionary re-search has so far advanced as to lead usto expect that radio vision will be putinto useful service before another twelvemonths has passed."

Date Set for Hearingson White Radio Bill

WASHINGTON.January 18 has been set tentatively by

the House Merchant Marine and Fisher-ies Committee as the date for hearings onthe White Radio bill. Extensive hearingsare planned and all those interested willbe given an opportunity to express theirviews.

It has not yet been decided whether Sec-retary Hoover 'will appear before thecommittee to testify in regard to the radiobill. The Secretary has been asked by theCommittee for his views but it is notknown whether he will appear personallyor whether he will forward a ritten state-ment.

Spool Backlash Avoided

\\:1414'snYOU may unwind wire from a spoolwithout having the wire bulge on thespool by using a small ratchet screw-driver. The ratchet screwdriver can

turn only in one direction.

Power Losses Measured by Standards Bureau

BETTER results from your radio receiver will result Iron experiments now beingcarried on by the U. S. Bureau of Standards in determining power losses in

electrical insulating materials at radio frequencies. M. S. Struck of the radiolaboratory, is shown engaged in making some of the tests.

(Underwood & Underwood.)

Basket -Weave and Single LayerCoils Officially Approved;

24 DCC Wire SuitableWASHINGTON.

The Bureau of Standards has just com-pleted an investigation on radio -frequencyresistance and inductance of certain low -loss coils within the range of broadcastfrequencies. A published paper contain-ing the data will soon be available at theGovernment Printing Office, Washington,D. C.

"The coils were of different shapes andwound with different kinds of wire," thepaper will state. "Of the coils measured,

Radio Fog SignalsMade More Efficient

WASHINGTON.Considerable progress has been made

during the past year in increasing theefficiency of radio fog signals by syn-chronizing the signals emitted by adjacentstations by the use of special controlclocks so as to avoid overlapping neigh-boring stations, according to the annualreport of the Lighthouse Service to Con-gress. Since October, 1924, the radio fogsignal on Nantucket Lightship has beenoperated for 15 minutes out of everyhour day and night, regardless of wea-ther, thus providing a signal for long-distance bearings in approaching theAmerican coast and also facilitating thetesting of apparatus.

The report also states that the numberof ships equipped with radio directionfinders has materially increased and favor-able reports have been received of thevalue of this system in safeguarding andfacilitating navigation.

RADIO GIFTS NUMBER OF RADIO WORLDdated Dec. 12.

I5c per copy. or start subscription with thatnumber. RADIO WORLD, 145 W. 45th St.. N. Y.

the loose basket weave coil and the single -layer coil have the lowest radio frequencyresistance. No. 24 A. W. G. D. C. C. wireis a suitable size of conductor, though No.32-38 Litz has somewhat smaller resis-tance. This holds for the entire broad-cast ranke of frequencies and for all theshapes of coils measured. Collodion wasfound to be a suitable binder for holdingthe turns of certain shaues of coils to-gether. There was little reduction of re-sistance by spacing the turns of an ordi-nary single -layer coil."

A New One to Her

Daughter-This card says "R.S.V.P."I wonder what the wavelength is?


Higher Power for Small StationsRefused as Interference Source

WASHINGTON.The need for legislation giving the

Secretary of Commerce authority to reg-

7OR CLEAR, QUIET "B" POWER

INIro ik1F7*Rti

"Nt

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RADIOStorage "B" Battery

11,;:g: Lasts Indefinitely-Pays for ItselfE, -annoy and performance unheard of before. Recharged at a neglb

lig;o'vedanielliFerra?.":1:22arrs;m3,,a,l'it =road =A:4, shored...0er. Yon. Sul. Inat. Standards, Radio NeapSal;W.TIL.TAiZal,=,1".'r,'"12",".441°.'d Tipped w.th

Lenny "Ia.. Pug. Heavy rugged plates. 'Order soureitodZr a."SEND NO MONEY .Z.,;"::;1r ,,,,":"Itbi," I(I. received. Extra offer: 4 batteries inand.. (96 voltai5. $10.;0°P;

eZoTcrat:',nbettrri". 5tWORLD BATTERY COMPAIIY

1219 So. yobWash Ave.. Dept. 82 Chicago,ID`Atakora Pomona. World Rocha'. Storage HaltomPrkea: ZOO Ap. III,: tro Am.112.16; I40Anty.t14.00.

Ail .v..00ed Iola. Solid ilysbefr Cam.

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WorldSTORAGE BATTERIESklaSikLBTAF,W6f4,WJS s KtiLiNatITJ771, r019

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r tir

le.tx.n..11:d LI 31 a Is at

h'

2,1.3

or eV TIltr'"'..Watcoe announcement..

ulate radio has been emphasized bydevelopments since the Fourth NationalRadio Conference which decreed a limita-tion of stations.

Announcement was made by SecretaryHoover following the conference that noaditional stations would be licensed ex-cept in unusual conditions. Several dis-appointed applicants therefore undertookthe purchase of small stations of 10 and50 watts in their locality with the inten-tion of remodeling them and increasing

LOUD SPEAKER RECEPTIONfrom either coast on three tubes

Blueprint and instructions $1.00Necessary low loss coil $2.50Beautiful finished instrument $35.00

S. A. TWITCHELL CO.1930 Western Avenue Minneapolis, Minn.

SHORE F.'CHOKE COILS

and TRANSFORMERSPRICES ON REQUEST

SHORE ELECTRIC CO., Inc.64 University Place N. Y. City

(71 PReaOnTHE TUBE WITH A SENSIBLE GUARANTEE stAAEurrini,r-'7,

Qu ail tyPerformance

1 1Depo itt a,niiitye'/

are the factors which made Supertron theforemost Independent Tube in America! I

The Public buy and enjoy Bunertrona because they are assured of satisfaction by a serial numberedAmirante. on each tube for their protection --at their own price; the public demand price-two dollars.The best dealers sell Supertrons because they give the most satisfaction: the best profit and apermanent good will. Backed by a rigid policy: aubstential organisation and clean merchandlahig.

ALL TYPES $2.00 EACH (Canada, $2.75)

SUPERTRON MFG. CO., Inc., Hoboken, New JerseyExtort Department, 220 Broadway, New York

SUPERT RONA SERIAL NUMBER GUARANTEE 4:

FILL OUT AND MAIL NOWSUBSCRIPTION BLANK

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

(Just East of Broadway)Please send me RADIO WORLD for months, for which

please fad enclosed $SUBSCRIPTION RATESSingle Copy $ .15Three Months LSOSix Months 3.00One Year, 52 Issues 6.00Add $1.00 a Year for ForeignPostage; 50e for Canadian Post-age.

their power. Several other small stationsalso have applied for permission to in-crease their power with the intent, insome cases, of selling the higher -powerstation.

As a 10 or 50 -watt station has not avery large radius it does not cause muchinterference. If the power of that sta-tion is increased, however, it creates asmuch interference as a new station, andthe effect is the same as the licensingof a new station.

Officials of the Department of Com-merce have announced they will not per-mit small power stations to increase theirpower except in localities 'not alreadyserved by the high -power stations.

Army Signal Corpsin Need of Operators

In spite of the thousands of amateursthroughout the country and the generalinterest in radio, the United States Sig-nal Corps is badly in need of radio oper-ators. This is pointed out in the annualreport of the War Department to Con-gress.

"A critical situation exists," says thereport, "in the proper functioning of theSignal Corps due to the lack of trainedenlisted men in sufficient numbers to op-erate and maintain the Government radioand telephone systems, and for operatingother Signal Corps activities for thearmy."

Victoria Police to UseRadio for Their Work

WASHINGTON.According to a report to the Depart-

ment of Commerce, the police of Victoria,British Columbia, plan to erect a wirelesstransmitting station as police headquar-ters and to equip two new patrol carswith transmitting apparatus.

ARE YOU THE MANto be first in your two to sell and demon-iacal@ POWXROLA. the faramm 1 -tabs. PO -battery Ei.seratc LIGHT MOCKS?RADIO BACIIIIVNEt (not an attachment).universal for D.C. of A.C. (106-115 v.40-60 cycle). now sold and demonstrated bythe New York Edison Co.. public utilityCOMPalthin and radio, electric and mustsdealers everywhere. Absolutely dependable,fully guaranteed, powerful, prattles', perfectin performance,

Are You the Mars Who Sees Oppor-tunities Ahead for Real Money linking

You, too, can make PowerolaSend $1.00 for wiring diagrams showing partsused and how to make any set or circuit(1 to 8 tubes) operate satisfactorily without

B or C batteries, from A. C. or D. C.

Writs for literature, term, and priers at once.

POWEROLA RADIO CORP.1841 BROADWAY NEW YORK CITY

The

PowertoneConstruction of this 1 -dal, 5 -tube qualityreceiver fully described and illustrated, with"blue print in black" included, in Aug. 29and Sept. 5 issues. Special discussion of howto connect the coil terminals. Troubleshcoting in this set, Sept. 12 issue. Send 45c.Get all three.

RADIO WORLD145 West 4Sth St-, N. Y. City

DID YOU GET RADIO GIFTS NUMBER OFRADIO WORLD DATED DEC. 117 15c copy, orstart subscription with that number. RADIOWORLD, 145 W. 45th St., N. Y.


(Concluded from page 13). tion employed here. If you find that re-genreation is present it is due either tothe internal characteristic action of thetube or the placing of the parts not ac-cording to photos.

How to Wire the SetThe antenna terminal of the primary

winding, Ll, goes to the antenna bindingpost. The ground terminal of this samewinding goes to the ground binding post.The filament terminal of the secondarywinding, 12, which adjoins the groundterminal, goes to the arm of the rheostatRI. This in turn goes to the A- bindingpost. The only remaining terminal, whichis the grid terminal, goes to the grid poston the socket 1. It also goes to the statorplates of the variable condenser Cl. Therotary plates of this condenser goes to thearm of the rheostat Rl. The resistanceof the rheostat RI goes to the F- poston socket 1. The plate terminal of theprimary winding L3, goes to the plate postof the socket 1. The B+ terminal on thisRFT goes to the B+ binding post. Theterminal which adjoins that of the B+terminal goes to the F+ post on socket2 and to the rotary plates of the con-denser C2. The stator plates of this con-denser goes to the grid terminal of thesecondary winding L4. The F- post onthis socket goes to the resistance wire ofrheostat RI. The F+ posts on both thesesockets connect together. The plate term-inal on the primary winding L5, goes tothe plate post on socket 2. The B+terminal of this same winding goes to theW -j- post. The terminal on the secondarywinding 1.6 adjoining the B+ terminalgoes to the B+ terminal of ATF1. Theother terminal goes to the low potentialterminal of the crystal detector. Thehigh potential side of the crystal detectorgoes to the plate post on AFT1. Thegrid post on AFT1 goes to the grid poston socket. The F- post on theAFT1 goes to the arm of rheostat R2.Connect the plate post of AFT2 to theplate post on socket 3. Connect the B -4 -

DXQualityVolumeSelectivity

MI that you desire-more than you ex-pect-are at your command If you build

RADIO WORLD'S1926 Model

DIAMONDOF THE

AIR5 -tube set for home construction that

work splendidly on either loop or outdoor

Read Herman Bernard's full exposition ofhow to build the set that le sweeping thecountry.

Constructional data. In text and diagrams,

aIn the Sept. 12, 10 d 25 issues;v=21 anlaboratory data In the Nov. 21,

25 and Dec. 5 Issues. Any of these issues,15c a copy.

Send 75c and get all six!Full-sized blueprint of the wiring, 50c

extra.Send $11 now fora year's subscription and

get these six copies, the blueprint andnameplate FREE!

RADIO WORLD145 West 45th Street New York City

Send for a free name plate

LIST OF PARTSThree toroid coils, LIL2, L3L4, L5L6

(Radio Foundation, Inc.).Three .0005 mfd. variable condensers,

CIC2C3 (U. S. L. with the Kurz-Kaschpinion and rack scheme. Dials includedalso).

One 7x21" panel.One fixed crystal detector, CD (Car-

borundum Company).Two low -ratio audio -frequency trans-

formers, AFT1, AFT2.Two 10 -ohm rheostats, RI R2.One filament switch, S.Five binding posts.Two phone tips.Four sockets.Accessories: Connecting wire, batteries,

loud speaker, etc.

post of AFT2 to the B+ post. The gridpost of AFT2 goes to the grid post on

socket 4. The F- post goes to the F-post on socket 4. This in turn goes tothe resistance wire of the rheostat R2,Connect the F+ posts together. Theplate post of the last socket goes to onephone tip. The other phone tip goes tothe B+ post. One terminal of theswitch S, goes to the arms of both rheo-stats, Rl and 2. The other terminal ofthis switch goes to the A -I -B- post.When following the diagram, reverse theA battery leads.

RADIO DEALERS-GET THAT NEW CATALOGUEFROM VAN-ASHEINew circulte--new parts-new sets. AUthe hard -to -get item, - and extraseeddiscounts!

VAN-ASHE RADIO CO.204 N. 10th Street St. Loeb', Me.

List Price

$6.00

You Never Heard Music Like ThisNew SYMPHONY Transformer Produces

When there's music on the air are you justgetting or really appreciating it?The new SYMPHONY Transformer willbring out the real art in the classicalmusical programs being broadcast. Itfaithfully reproduces every note on thescale from High C to the lowest note inthe basso's throat.Take out your old antiquated transformersand replace them with the SYMPHONY.Its softness and fullness of mellow tonewill give you a greater appreciation formusic, the universal art.

If your dealer can't supply you, writedirect to us sending $6.00 and his name.

MODERN ELECTRIC MFG. CO., Toledo, OhioRepresented by

GRAY SALES COMPANY611 Widener Bldg., Philadelphia, Pa.

MODERN

TRANSFORMERS


UNIVERSITY(Concluded from page 15)

controlling the oscillatory action of thefirst tube. When the tickler is turned

-LINK YOUR SUPER-to an OUTDOOR AERIAL!

DOUBLE YOUR CHANCESto hear the

OVERSEA STATIONS!The new SUPERADIO Type G AntennaCoupler provides an EFFICIENT LINKbetween outdoor or indoor antenna andSUPERHETERODYNES or other loop re-ceivers.

The heart of the SUPERADIO Type G AntennaCoupler showing the special coil and strident

S. L W. Condenser.For increased RANGE and VOLUME, forimproved SELECTIVITY and CLARITY,remove the great handicap under which allloop receivers operate. Order your Su-peradlo Type G Antenna Coupler TODAY!

Necessary Coll with blueprint and $6.00Nil instructionsCoil and Condenser Unit as shown above withblueprint, Instructions and calibre-$10.00tIonComplete factorybuilt Type G Coupler. mountedIn handsome Mahogany Cabinet. 7"013"01".Polished or Grained Bakelite Panel, 4 Inch Bake-

lite Dial. Tested end Calibrated.

$19e5019.50ready for use. Blueprint and TullInstructions

POSTAGE EXTRANor, ready for immediate delivery

The Superadio Co. 136 LIBERTY ST.NEW YORK CITY

THE SUPERADIO CO.,136 Liberty St., New York City.

Enclosed find $ for Which send me

NAME9DDRESSCITY STATE

so as to get the station in a bit louder, aclick is obtained and the station is lost.Reducing the tickler does help much. Thatis, when I reduced the tickler windings,the signals became much weaker.-Q. M.Standley, 1610 Kenlin St., Willstern, Mo.

Ground the A- lead. Take the fixedcondenser, C4, which goes from the platepost of the detector tube to the A- post,out. Increase the resistance in the gridleak. Reduce the plate voltage on the RF

CILLUSTRATED RADIO CATALOG FREEI

Describes folly the complete Crosier line of radiofreuueney sets. regenerative sets (licensed underArmstrong V. B. Patent No. 1,113,149) and Pens.

THE CROSLEY RADIO CORPORATIONCincinnati. Ohio

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Especially madef o r ResistanceCoupled Ampli-fiers to give morevolume of greaterclarity with less"B" Battery volt-age.

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At Good Radio Stores

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5Tube Radio Seto 2951

oDYNOLAThe Biggest 5 Tube Valueon the Market ly the bond's greatest 5 TUBE SET575.00 value, fully built and wIretItiunbUniubluatga4gcatet of latest design, slopingBakelite panel, Satin finish. handsomely etched and engraved. Constructed of theBakelite

condensers, coils and sockets. Bakelite baseboard panel and dials. $29.10 for setonly. Transportation charges extra, shipping weight 25 lbs.

This set with 011 accessories. including the famous American Bell loud sp eeeee withadjustable unit, 2-45 volt "B" batteries, one guaranteed Ampere Hour. storage "Abattery. cable for battery connection, 5-201A tubes, aerliTI andground equipment. and everything complete ready to set upand operate. Nothing else to buy. Pelee 659.75. Trans-portation charges extra. Shipping weight 100 lbs.

Send For ThisRadio Book FREE

Contains thousands of bargroos radill

Oill:4Te.iTg"r vat 74'Fia'01.eonsole models with loud speaker. bujit

.bineto °,."`.`4`;'Z Co""1.:011fr;tnticrange. Also contains everything In note eun-olies, Including batter's., chargers. loud sneakers. tranrformere. condensers, rheostats and

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for Improving your net1%1T. Agent'o'licyl2lovroradio mall order house.

RANDOLPH RADIO CORPORATION159 North Union Ave.. Dept, 232. CHICAGO

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1926Catalog

Containing64

Illustratedpages

of RadioBargains

Writefor ItToday

DO YOU WANT TO BUILD ONE OF THEBEST CRYSTAL SETS? See Herbert E. Hay -den's article, "One of the Best Crystal Sets,"lhat appeared in our Hookup Number, datedNov. 7. RADIO WORLD, 145 W. 45th St., NewYork City.

HAVE YOU ALREADY CONSTRUCTED Capt.P. V. O'Rourke's 3 -Tube Dry -Cell Circuit thatappeared in RADIO WORLD'S HOOKUP NUMBER, dated Nov. 7? If not, send 15c for a copy,or start your subscription with that number.RADIO WORLD, 145 W. 45th St., N. Y. C. .

tube. This should be done by making thislead individual of the AF amplifier lead.This will then give you three B+ leads.

* * *

I HAVE built the Browning -Drakereceiver, which appeared in the Nov. 7issue of RADIO WORLD, described by NealFitzalan. However, I am having quitesome trouble with it. The signals arereceived very well, but on the low wavesthe stations are very much crowded to-gether. Would SLF variable condenserssolve the problem of separating the sta-tions on the low waves ?-L. E. White, 355West Onondague St., Syracuse, N. Y.

Yes.* * *

I WOULD be very glad to have the fol-lowing queries answered regarding theRX1 set as described in the Oct. 17 issueof RADIO WORLD. (1) Would a set of thisdescription be capable of receiving thesame distance with the same volume, as a5 -tube tuned radio -frequency set? (2)Could I use the UX199 tubes throughoutand a UX120 power tube in the last stageand get good results? (3) If the abovecould be used, what changes should bemade in the filament wiring, so that Imay use a 6 -volt battery on the same?(4) Would the new Signal variable con-densers of the 360° type work satisfac-torily on this set? (5) I understand that135 volts B battery is necessary to oper-ate a UX120 power tube satisfactorily.Would the 135 be connected directto the phone jack? (6) Would a neu-tralizing condenser be necessary on theradio -frequency tube, if the above tubeswere used?-P. Hutton, 415 Kingswood,oad, East Toronto, Ontario, Canada.

(1) The same distance, if not more thana 5 -tube TRFT receiver, will be obtained.The volume will not be as great as thatdelivered by the 5 -tube set provided thatset uses transformer coupled AF. If youuse two stages of transformer coupled AF,the volume will be equalled. This dependsupon the quality of the apparatus placedinto the set, location of the set, the man-ner in which the set is wired up, etc. (2)Yes. (3) To use a 6 -volt A battery, RL

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NAME

I ADDRESS

CITY

January 9, 1926 RADIO WORLD pshould be a 50 -ohm rheostat, R2 shouldalso be a 50 -ohm rheostat, R3 should be a25 -ohm rheostat. However another rheo-stat should be placed in the last tube. Thismeans that there will be a rheostat foreach tube, each of which will have a re-sistance of 50 ohms. A separate C batterywill have to be used also. This C batteryshould have nothing to do with the Cbattery used in the resistance coupledamplification portion. This C batteryshould have a voltage of 22.5. (4) Yes.(5) Yes, it will be 0. K. to use 135 voltsfor both AF tubes as will be the case,when you connect the 135 volt tap to thebase of the jack. (6) No.

* * *

I HAVE built H. E. Wright's 3 -TubeReflex receiver, that was described in theMay 23 issue of RADIO WORIA3 and am hav-ing some trouble in making it work suc-cessfully. When I put my hand within6" of the grid leak, I get a loud howl.This is also obtained when the plug isput into the jack of the last stage. Thepotentiometer has no effect whatsoever.-F. R. Mulney, 1411 2nd Ave., South,Minneapolis, Minn.

Reverse the crystal detector leads. Re-verse the A battery leads. Increase theB battery voltage. Place a .001 mfd. fixedcondenser across the plate and the gridposts of the last audio -frequency trans-former. See if the fixed condensers,which are shunted across the primary andthe secondary of the first audio -frequencytransformer are not shorted. Try placingthe terminal of C4, which now goes tothe arm of RI (A-) to the A+ lead. Re -

V -201 A. 5 Volt*at filament.V199. 3i/a Saltsat filament.Fully Guaranteed.

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BLUE PRINTFOR 1926

Diamond of the AirA blue print for wiring the circuit thathas swept the country may be obtained bysending 50c in stamps, money order, cashor check. This blue print is full size andIs personally certified by Herman Bernard.

RADIO DIVISIONTHE COLUMBIA PRINT

145 West 45th Street New York City

verse the secondary terminals of the thirdradio -frequency transformer, L6.

* * *

IS THERE any advantage gained byconstructing an underground antenna?(2) Will electric light wires carrying 2300volts, which are within 50 feet of parallel

Dealers!Write for our Prises on Standard Podia Parts and

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RADIO WORLDAS A HOLIDAY OR BIRTHDAY GIFT

FOR HIMNo doubt there is someone you know towhom a subscription for RADIO WORLDwould he a welcome Holiday gift. Sendus $6.00 for RADIO WORLD with nameand address of your friend, and we willsend him RADIO WORLD for fifty-twoweeks, and also a card indicating that youare the &nor. This gift will mean thathe will think of you fifty-two times a year,and bear your thoughtfulness in mind.In sending subscription order, specify thatIt is a gift, so we will be sure to send thecard.

RADIO WORLD145 West 45th Street New York City

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NAME

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28 RADIO WORLD January 9, 1926direction to my receiver have any effectupon the same? (3) Do telegraph andtelephone lines which run parallel to theantenna have any effect upon the re-ceiver?-Clyde Barton, Odessa, Tex.

(1) At the present moment, this type ofantenna is not as yet developed to suchan extent that it is advisable to use it for

. broadcast receivers. (2) There will no

$1.50 for Your Old Radio Tubesregardless of make or condition, toward pur-chase of each new standard $2.50 tube. Posi-tively guaranteed. We do not sell rebuilt orbootleg tubes. Agents wanted.

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45 volts. $5.25; 90 volts, 210.00; 112% volts,312.50; 195 mite, ;14.75; 157% volts. 018.80.Trois% the higgeet buy today. Easily charged on anycurrent, including 32 -volt systems. Any special de-tector plate voltage had. Tested and approved 14leading authorities such as Popular Radio Labor-starles Over 3 years sold on a non -red tape. 90 -daytile' offer with complete refund if not thorough'?satisfied. Further guaranteed 2 years. knock -downkits at great savings. Complete "Bewley" "B" bat-tery charger, 22.75. ample cell, 35e. Order direct-eend no money --simply Day the erprensman coston delivery. Or write for my free literature, tart-moniale and guarantee. Same day shipments. B.Hawley Smith. 318 Washington Ave., Danbury, Cone.

noise heard in the receiver, provided thatthe generator delivering this voltage hasno commutator (D.C.), or slip ring(A.C.) faults, which cause sparking. Anattempt should be made to run the an-tenna at least 10 feet above the paralleldirection of the lines. Run the lead-in atright angles to the line, placing a coppershield around the whole length of thelead-in. Ground this copper shield. (3)Telegraph and telephone lines will inter-fere with the radio reception if the an-tenna or lead-in- wires are parrallel with-in a range of 20 feet.

* * *

CAN I use No. 34 enameled wire forthe two secondardy windings on the A.C.stepup transformer employed in the BBattery eliminator described by LewisWinner in the December 12, 19 and 26issues of RADIO WORLD? (2) Can I useNo. 34 enameled wire to wind the chokes?-H. A. Archer, 4055 Ellis Ave., Chicago,Ill.

(1 and 2), No. Use the wire specifiedonly.

* * *

I AM using an 8 -tube Ultradine. Theplates of the modulator and the radio -frequency tubes receive a voltage of 45.The voltage on the plate of the oscillatortube is 22. The voltage on the audio -frequency amplifier plates is from 90 to

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1925 BACK NUMBERS OF RADIO WORLD WANTEDMall Its copies of any of the following 1915 issues of RADIO WORLD, and we will *end youcopy of a current issue for every copy sent us: January 10, March 28, April 4, 11, 18, 25; May2, 9, 16, 73. 30; June 6, 13, 20; July 4, 11, 18, 25; Aug -at 1, 8, 15, 29; September 5.

TWO -FOR -ONE SUBSCRIPTION OFFERRadio World has made arrangements-To offer year's subscription FREE for any one of the followingyear's subscription for RADIO WORLD:-RADIO NEWS or-POPULAR RADIO or-RADIO BROADCAST or-SCIENCE AND INVENTION or

publications with one

-RADIO DEALER or-RADIO JOURNAL or-RADIO (San Francisco) or-THE EXPERIMENTER or-RADIO AGE

This is the way to get two publications-for the price of one:-Send $6.00 today for RADIO WORLD-for one year (regular price-for 52 numbers)-and select any one of the other-nine publications for twelve months.

-Add 51.011 a year extra for-Canadian or Foreign Postage.-Present RADIO WORLD subscribers-can take advantage of this offer by-extending subscription. one year-if they send renewals NOW.

RADIO WORLD'S Special Two -For -Price -of -One SUBSCRIPTION BLANKRADIO WORLD. 145 West 45th St.. N. Y. City:Enclosed find $6.00, for which send me RADIO WORLD for twelve months (52 number.), begin-ning and also, without additional cost, RadioNews, or Popular Radio, or Radio Broadcast, or Science and Invention, or Radio Dealer, or Radio(San Francisco), or The Experimenter, or Radio Journal, or Radio Age (or $10.00 for two yearlysubscriptions).

Indicate if renewal.Offer Good UntilJan. 31, 1926.

Name

Street Address

City and State

135. Would it be possible to tap off an-other B+ lead, in the B battery eliminatordescribed by Lewis Winner in the Dec. 12,19 and 26 issues of RADIO WORLD, wherebythe above voltages could be obtained?-C. E. Cronin, 103 W. Price St., Linden,N. J.

Yes, this can be done very easily. Ob-tain another Clarostat. Connect one ter-minal of the Clarostat to one terminal ofthe amplifier terminal before the resistanceis connected in the circuit. Connect thearm to the post. In other words, connectthis in the same manner in which therheostat for the detector is connected. Ifyou do not wish to use a variable resist-ance place a 100,000 ohm resistance in se-ries with the amplifier output, connectingthe end of this resistance terminal to abinding post.

* * *

I HAVE just completed the article byHerman Bernard in the Nov. 21 issue ofRADIO WORLD, regarding the Diamond,and am very interested in the same. NowI have a 3 -Tube set using a Bremer -Tullyold style tuner. Could this tuner be usedin the Diamond? (2) Could I use a Bre-mer -Tully air core transformer, whichtunes with a .00025 mfd. variable con-denser shunted across the secondary? (3)

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Should the condenser be of the SLFtype?-E. Willhausen, 4058a CastlemanAve., St. Louis, Mo.

(1) Yes. (2) Yes. (3) Not necessarily,although it will help the tuning in of thestations on the low waves.

* * *I HAVE purchased an Uncle Sam 3 -

circuit tuner. I would like to know if Icould use this coil successfully in the 1926

Diamond of the Air? I intend using anUncle Sam antenna coil to match thistuner. (2) Could I use the 201A type oftube ?-Frank Schrenk, 192 Keystone St.,Buffalo, N. Y.

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

I BUILT the Phonograph set, as de-scribed by Lewis Winner in the Oct. 24,

31 and Nov. 7 issues of RADIO WORLD.Until recently the set worked great, butrecently the volume decreased so that Icould hardly hear it. My A battery ischarged full. I put new B batteries in.That pepped up the set a bit, but still thevolume is not good. How can I remedythe trouble?-Y. Corol, Omaha, Neb.

Change your tubes around. Put a newdetector and radio -frequency ampli.tube in place of the old tubes.

* * *

IS IT possible to obtain good results(loud speaker) from the radio -frequencyamplifier and the detector tubes in theDiamond of the Air? Many fans havetried this around here, but with not anytype of real success.-Ernest J. Whistle,East Greenwich, R. I.

The results obtainable on these twotubes will be equal in volume to that ofthe 1 -tube regenerative set. That is, thesignals will not be loud enough to operatea loud speaker, but just comfortable

enough to hear on the phones.* * *

I HAVE built the 1926 Diamond of theAir, and have had great results. As amatter of fact the first night that it wastried out, I received 35 station, whichincludes KFI, Los Angeles, Cal. This isabout 2600 miless from here. However, Ihave trouble with broad tuning. Is itpossible to remedy this without sacrificingany volume?-F. S. Gregory, Bloom-ville, N. Y.

Reverse the secondary of the radio-requency transformer and the 3 -circuit

FREEOur Latest 100 PageRADIO CATALOGBSPORE)

you build be sure to consult ourlatest 100 -page radio catalog. A de-pendeble guide for eel -builders. Knock-

down Bets end kite for all the hunt cIrculteNo liner or more complete assortment to befound anywhere. Latest designed parte-Acme, All-American. Bremer -Tully, Carter,Freshman, Prost, General Instrument, Wel-bort, etc. And the prices-every one tootedmeans a big laving for you!

Write for your FREE copy todaytCHICAGO 509 So.SALVAGE State St.STOCK Chicago, U.S.A.STORE Dept. R.W.

tuner. See that all the connections aresoldered solidly, with no excess of fluxon the joints. Ground the A-. See thatthe ground connection and also the an-tenna connections are solid.

* * *

I WOULD like to know if the 1 -TubeReflex described by Franz Von Steifel inthe Oct. 10 issue of Radio World willoperate efficiently on 22% volts?-H. J.Offner, 904 Monroe Boulevard, SouthHavin, Mich.

No, at least 67'% volts must be used.

DIAMOND EDITOR:

Until last night I was the biggestRoberts Circuit booster you ever saw, butmy experience surely converted me to theDiamond of the Air for life. I built thetwo -tube radio part out of a set of SicklesDiamond Weave coils for the Roberts Cir-cuit, a pair of old low loss SLC con-densers and wired it with No. 18 annunci-ator wire, the sorriest looking job I ever

DI()PARTS CONDENSERS

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did and, without any audio -amplifier ofany kind, the thing ran a loud -speaker onWLW, WLS, KYW, WSB and the stationat Fulford, Fla., and a great many otherstations came in on the phones. I amstarting tonight to build the thing in per-manent form placing it in a cabinet whichit deserves. Kindly send a nameplate. Iam going to build an AF amplifier soon.

COURTENAY BATEMAN,Care Palmetto Ice Co., Columbia, S.C.

go -day -inevery

good set

Less wiring-Fewer losses

Full, clear. Nth tone depends on morethan on justgood apparatus. It depends,first ofall, upon careful, compact wiring.AMPER1TE eliminates complicated wir-ing, avoiding leaks and losses. Requiresno attention. Controls the filament per-fectly, bringing the utmost out of eachindividual tube. Permits use of any tubesor combination of tubes. Used in all Pop-ular construction sets. Price, $1.10.There is an AMPERITE &revery tube

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MAGNATRONS in your set will give sweetpurity of tone-clear and complete renditionof all the wealth of overtones. Music and

speech come from the loudspeaker of the Magna-tron equipped set with rich fidelity and generousvolume, recreating in your home the actual per-formance itself, whether it be ten or a thousandmiles away.Magnetrons are the product of the oldest exclusive makers ofvacuum tubes. That, in a large measure, explains their ex-cellence. There's a Magnetron for every purpose. TheDC -201A, the DC -199 [large or small base], the DC -120

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CONNEWEY ELECTRIC LABS.Magnetron Building

Hoboken, N. J.

Complete factory stock for Pacific Coast carried at PacificRadio Labs., 256 So. Los Angeles St., Los Angeles, Cal.

CHANGES OF ADDRESSshould be sent to Subscription Department at least two weeks in advanceof publication in order to insure early and proper attention. RADIOWORLD'S subscription list is so large that it is necessary that changes besent in as requested. Address, Subscription Department, RADIO WORLD.145 W. 45th St., New York.


NAMEPLATESFollowing is a new list of names and

addresses of persons who requested and

Ita 17:16MFirMIBIME.1470:t8 Wf

IIF YOUR INVENTION Is new and useful It ispatentable. Send me your sketch.

Z. H. POLACH EK. 70 Wall St.. New YorkAllES.1.1111 Reg. Patent AtterneyEng I neer 1111.11111111.11.

G -K BINDING POSTSengraved or plam. For en-graved ones, specify fromfollowing: Ant., Goad., A-, 171,Cft+, B-, Br Det., BI- Amp. EACH

Binding Post strip complete by mall 91.25Ganio-Kramer Company, Inc.

238-R West 53d Street New York, N. Y.

GEM TUBEA Guaranteed Radio Tube

Within Reach of AllEvery tube guaranteed. A tubefor a dollar of 92 value. Atrial order will convince you asIt has thousands of others.Send your oniers at once.Orders sent C.O.D. parcel poet.Type..Type . 199 $ 00Tyne ..200Tyne ..201A(with standard hue) EACHDealers. Write for Diseounts.

GEM TUBE CO.Dept. W., 200 trim., N. Y. C.220 So. State St. Chicago. III.Lafayette Bldg.. Detroit, Mich.

Makes condensers that IMO netstralght.11ne frequency Mee as Ifthey were. Moulded Bakelite. No $2.50gears, no link lashBruno" Sit -Motion Vernier Dial $2.00POWERTONE ELECTRIC CO.

Subsidiary of Bruno Radio Corp.223 FULTON ST., NEW YORK CITY

received free nameplates for the 1926model Diamond of the Air:G. F. Smith, Fort Plain, N. Y.J. M. Smith, Box 507, Riverhead, L. I. N. Y.S. E. Reid, 3518 San Francisco Ave., Chicago,

Joseph Santon, 130 Chestnut St., Oakland, Cal.Stanley Wallace, Newport High School, N. Y.G. D. Worsivick, 517 Cherry Ave., San Jose, Cal.Jay W. Spaulding. City Hall, Ithaca, N. Y.M. Carter. 166 N Kitchner, Detroit, Mich.J. R. Fletcher, 1222 Lamar St., San Antonio, Tex.G. Schaefer, 65 Benninger St., Buffalo, N. Y.I. B. Fisher, P. 0. Box 165, Beebe, Ark.13. W. Baker, Langley, Ky.C. Brown, 1550 South Lambert St., Philadelphia,

Pa.Frank Smetak, 505 E. 73rd St., N. Y. City.H. L. Christman, 521 Chew St., Allentown, Pa.George Hayek, Junmerman, Minn.Leonard F. Jones, R. 3, Guthrie, Okla.Dr. E. Taylor, care Agricultural Bank Annex,

Pittsfield, Mass.C. La Dan, Santa Rosa Theatre, Santa Rosa,

W. M.John T. True, P. 0. Box 303, Frankfort, Ky.C A. Smith, Box 421, A. R. T. 3, Meldrum Sta

lion, Milwaukee, Ore.F. L. Witt, Box 785, Goose Creek, Texas.I. A. Archer, 4055 Ellis Ave., Chicago, Ill.William Blair, 1335 North Howard St., Phila,

Pa.Harry G. Jones, 28 W. Bowers St., Lowell,

Mass.M. F. Brookshier, Hamburg, Iowa.Edward G. Straub, 49 Watkins Ave., Woodbury,

N. J.F. Carr, 3434 No. 21st St., Philadelphia, Pa .

F. A. Eisenhart, 524 Howard Ave., New Haven,Conn.

F. C. Orr, R. F. D. 2, Box 30, Mellette, S. Dak.J. R. isher, 100 Springville Ave., Station "H",

Buffalo, N. Y.F. N. DeLye, 3189 Maplewood Ave., Toledo,

Ohio.Dr. R. A. Mason, 473 -35th St., Milwaukee, Wisc.Everett Hackett, St. Joseph, Ill.John Block, 340 E. 55th St., New York City.F. L. Winters, 2533 -8th Ave., W. Seattle, Wash.W. E. Alexander, Houston, Texas.Clarence J. Noel, 59 Hamoden St., Indian

Orchard, Mass.H. J. Pollard, 649 West 5th St., Wahoo, Neb.Paul Sievert, 10 Wellington St., North East, Pa.R. A. Sheperd, The Pur Oil Ca, Mexia, Texas.James W. Premim Wynnewood, Oklahoma.Cook Bros., Bersey Sask, Canada.Austin Sturnick, Alexandria, Minn.Edwin reit, Alexandria, Minn.Arthur Jesson, Alexandria, Minn.William Westman, Alexandria, Minn.Kenneth Foslein, 216 Lincoln Ave., Alexandria,

Minn.C. A. Dean, 2610 Washington Ave., Ogden. Utah.Carl Santon, 1500 Oakdale Ave., Phila, Pa.George Hagstrom, 166 Conover St., Brooklyn,

N. Y.

RADIO CATALOGalso LOG

SA VE on all the lateststandard radiomerchandise I No

exception. Our 1926 Beautifullyiustrated CatalogJUST OFF THE PRESS!Everything new in Radio ATSLASHED PRICES. Write for Ittoday. before you buy anything. Delaymeans losing exceptional chance toParticipate In this great BARGAINSALE. Rush your name and addressat once and get also

LOG BOOK FREE!ECONOMY RADIO SALES COMPANY

28$ 6TH AVE. Dept. E. NEW YORKDeal Direct and Save Real Money

(No Dealers)

BEAUTY -QUALITY -LOW PRICETYPE 5085 -Tube Toned Radio Frequency.

$45TYPE 6RR8 -Tube Resistance Coupled Audio Tuned $50Radio Frequency

If your aealer cannot make immediatedelivery we will ship direct from factory

American Interstate Radio Service183 Greenwich Street, New York City

Distributors. Jobbers. Dealers, write for special trade term.

TOROID COILSMeasure only 3%a Inches in diameter. Both primary

and secondary windings are complete torsida.

List price per set $6.00for set of three cells.

NOLTE MANUFACTURING COMPANY193 Plainfield Avenue Jersey City, N. J.

The Daven Super -Amplifierfor volume and tone quality

STAGES RESISTANCE COUPLEDECONOMICAL DISTORTIONLESS

Easily added to any set.Saves Several Hours' AssemblyFor Sale by All Good Dealers

Vacuum TubesRebuilt

$1.00 eachPOSITIVELY GUARAN-

TEED equal to new tubes inevery respect. Money will berefunded if lobes prove un-satisfactory for any reasonother than burn -outs.

Send us your broken andb. irned out tubes by parcelPosi. (Not necessary to Insure or guard against breakage,. We make return Oil,meats by parcel post C. O. Eawl try to maintain 24 -boarservice.

HARVARD RADIOLABORATORIES

200 Old Colony AvenueSouth Boston, Mass.

Mailing ListsWill help you increase CalaSZV,Irgen.P&TatniVoyfwaivla.11..11:1=1::-dr= gala:

Professions. Busess Concerns..n Guaranteed Ci0 b refund of J each

RADIO WORLD'S QUICK -A CTION CLASSIFIED ADS.10 Cents a Word. 10 Words Minimum. Cash With Order.

SALESMEN!MAKE $100 WEEKLY IN SPARE TIME. Sell

what the public wants-long-distance radio receiving sets. Two sales weekly pay $100 profit.No big investment, no canvassing. Sharpe ofColorado made $965 in one month. Representativeswanted at once. This plan is sweeping the country-write today before your county is gone.Orarka, Inc., 126.J, Austin Ave., Chicago, III.

SPECIAL-$3.00 delivered. 500 Watermarked BondLetter Heads, 8Ysx11, and 250 Envelopes. Moneywith order. Commercial Printing Specialty.National Printing Company, Dept. W, Goshen, Indiana.

SILVER -GILT! THE NEW BUS -WIRE. Silverplate on copper with a light cover plate of gold toprevent tarnish. Low loss, high conductivity,handsome appearance. Price 4c per foot, cash ormoney order. 10 feet C. 0. D., 55c. J. A. ARM-STRONG, 124 Pleasant St., Attleboro, Mass.

20% DISCOUNT. Standard Radio Apparatus.Catalog 5c. GOODRAD RADIO SHOP, Shelby,Mich.

BULLDOGSBEAUTIFUL REGISTERED BULL PUPS, $15.

Bulldogs, 501 Rockwood, Dallas, Texas.

5 -TUBE RADIO SETS. Regular price, 98.00complete. Our price, $49.50. Heath's variable con-densers with vernier, price each, $1.25. FixedCondensers, .001, .002 ,.0001, .00025 mfd., Dubilierand Splitdorf type, price each, 15c. Spider webcoils, 2 for 25c. No order smaller than $1.00 ac-cepted. Write for price list. Money orders only.HEYER RADIO SUPPLY CO., 654 BloomfieldAve., Bloomfield, N. J. (Phone: Bloomfield 2722).

HELP WANTED MALEEARN $110 to $250 monthly, expenses paid as

Railway Traffic Inspector. We secure positionfor you after completion of 3 months' home studycourse or money refunded. Excellent opportunities. Write for Free Booklet. G.161 Stand. Buainess Training Inst., Buffalo, N. Y.

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8 Weeks' Trial Subscription, $1.00KEEP ABREAST OF THE LATEST

RADIO DEVELOPMENTSRADIO WORLD

145 WEST 45th ST. NEW YORK CITY

January 9, 1926 R A 1) 1 0 W 0 R 1.1)

Innocent "Hands Up!"Brings Police to House

PORTLAND."Hands up, one, two--"A housewife heard these words in her

home at 7:15 a. m. and called from an up-stairs extension of the telephone for policeto rout the robber.

When the police arrived, however, theylearned it was the radio, accidentally lefton all night, reproducing the setting -up

,ses broadcast by the Y M. C. A.

"How to Make-"The following Illustrated constructional

articles appeared in 1925 Issues c RADIOWORLD,

1 -TUBE SETSA $25 DX Wonder. Jan. 17.An $18 DX Set for Novices, Jan. 34.A 1 -Tube Reflex for the Novice. Feb. 31.A Set a Baby Can Build, Aug. 29.A Powerful 1 -Tube Set, Aug. 29.The Thoroughbred, Oct. 17, 24 and Nov. 7.The Bernard DX Set. Oct. 24.

2 -TUBE SETSThe Transcontinental. Jan. 31.Speaker Reflex, Aug. 15.

3 -TUBE SETSPortable. Jan. 3.The Freedom Reflex, July 4.The Marconi, July 18.The Metropolitan, Aug. 1.The Midget, Aug 8.The 3 -Tube 3 -Circuit Tuner, Oct.The Dry Cell Set, Nov. 7.

CRYSTAL SETSA Selective $15 Set, ;an. 24.Honeycomb receiver. Feb. 21.Sets You Can Log, Aug. 22.One of Best Crystal Sets, Nov. 7.

4 -TUBE SETSSet for Professional Folk, Feb. 21.Utmost DX, March 21.The Twinplex, May 2.The Divided Circuit, Aug. 1.The RX-I, Oct. 17 and 24.The Roberts. Nov. 7.The A -A Receiver, Nov. 14 and 21.

5 -TUBE SETSRADIO WORLD's 1926 Diamond, Sept. 13,

19 and 26; Nov. 21, 28, and Dec. 5.The Regenerative Neutrodyne, Jan. 31.The 1.Dial Powertone, Aug. 29, Sept. 5,

Dec. 12.The Thordarson-Wade, Oct. 3. 10 and 17.The Pathfinder, Oct. 31, Nov. 7.Browning -Drake, Sept. 26.The Phonograph Set, Oct, 24, 31 and

Nov. 7.

SUPER -HETERODYNES8 -Tube Set, by A. J. Gelula, July 4.Anderson's 6 -Tube, July 18.Welty 8 -Tube, Sept. 26.8 -Tube DX, by J. E. Anderson, Nov. 21.

SHORT WAVESSimple Circuits, June 13.25 -to -110 -Meter Set, Sept. 12.Hookups for Short Waves, Oct. 10.O'Rourke's Favorite, Oct. 17.A Flexible Set, Nov. 7.Coil Data, Oct. 31.Reinert., Nov. 28.

PRACTICAL GUIDESA Valuable Leak, March 21.Battery Eliminators, June 6. 13 and 20;

Sept. 19 and 26; Dee. 5, 12 and 19.How to Use Fixed Condensers, Oct. 24.Audio Circuits Compared, Oct. 3 and 10.Ohm's Law, Rheostats and Juice Econ-

omy, Dec. 5.A Home -Made Toroid, Aug. 22.

LOOPSHow to Make a Simple Loop, Nov. 7.Zero Potential Loops, Nov. 28.Any copy, 15c; any 7 copies, $1.00, or

start our subscription with any issueRADIO WORLD. 145 W. 45th St., N. Y. C.

S. HAMMER RADIO CO.303 Atkins Avenue, Brooklyn,N. Y.

Please send me FREE, Your NWRADIO CATALOG

NameAddressCity

"A Variable Grid LeakNecessary in Every Set"

"EXTENSIVE TESTS have proved that a variable grid leak is necessary in every setthat uses a tube as detector," says John F. Rider, noted radio engineer, shown above,testing the Bretwood Variable Grid Leak in the 1926 Model Diamond of the Air. "Theoutput voltage." he adds, "may be increased as much as 25 per cent. by correct leak

setting." (Foto Topics)

More Volume -More DX -Sweeter Tone -When You Use

The Bretwood Variable Grid Leak PsT.c5E0Each Leak Thrice Tested Before Shipment

GUARANTEED PRECISION

The Bretwood may be installed inany set in five minutes. Single hole

panel mount.

The North AmericanBretwood Co.

145 West 45th Street, N. Y. City

Canadian Representative, Radio, Ltd.,Phillips Square, Montreal

RANGE, to 10 MegohmsTHE NORTH AMERICAN BRETWOOD CO..145 West 45th Street, New York City

Gentlemen: Enclosed find 31.50 for which youwill please send me one Bretwood Variable GridLeak prepaid. Satisfaction guaranteed or mymoney back after trial within ten days ofreceipt by me.

NAME

STREET

CITY

STATEState

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TheseEvereadyBatteries are the correctsize for yourset.With average use they will last

you a year or longer"

"You have been one of themany who use 'B' batteriesthat are too small in capacityfor their receivers. That isnot economical. It makesyou buy 'B' batteries twiceas often as necessary. Fitthe right size Eveready's toyour set and add a 'C' bat-tery,* if you haven't one, andyou'll get the maximum ofservice at the minimum ofcost."

The life of your Eveready"B" Battery depends on itscapacity in relation to yourset and how much you listenin. We know, through acareful investigation, thatthe average year-round useof a set is two hours a day.Taking that average we have

'NOTE: In addition to the increased lifewhich an Eveready "C" Battery gives to your"B" batteries, it will add a quality of receptionunobtainable without it.

proved over and over that onsets of one to three tubes theNo. 772 Eveready "B" Bat-tery used with a "C" batterywill last a year or longer. Onsets of four and five tubes,the larger heavy duty Ever-eady batteries used with a"C" battery will last eightmonths or more.

The secret of "B" batterysatisfaction and economy is:

FT-ErcreadvLayerbilrit"Bat-term No. 486. 45rolta.forniastonuoneconomy an four,fire or more tuba.

0 Il T-ErernIdYDryeellItadio"A"Bo tt,Ty. 1 by volts.The battery builteayerially for dry

cell tubes.

Radio Batteries-they last longer

With sets of from 1 to 3 tubes, useEveready No. 772.With sets of 4 or more tubes, useeither of the Heavy Duty Batteries,No. 770, or the even longer -livedEveready Layerbilt No. 486.

We have prepared for yourindividual use a new booklet,"Choosing and Using the RightRadio Batteries," which we willbe glad to send you upon request.This booklet also tells about theproper battery equipment for usewith the new power tubes.

Manufactured and guaranteed by

NATIONAL CARBON CO., INc.New York San Francisco

Canadian Notional Carbon Co., LimitedToronto, Ontario

EVEREADY HOUREVERY TUESDAY AT 9 P. M.

Eastern Standard TimeFor real radio enjoyment tune in the "Eveready

Group." Broadcast through stations--WEAY-NeW York wet -Philadelphia wsns-Cirscinnatiwpm -Providence woo -Buffalo ww,t-Detroit

werm-Pittsburgnwest -Boston

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woe -DavenportKso-t. Louis

warm-Cleveland WGN-Chicago

the 4 -tube dx symphony radio a study of pilot lights for ...€¦ · radiothe 4 -tube dx symphony...

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