NUMBER! c1E,.s 1? AM 0 WORLD · 2019. 7. 17. · culty might lie exclusively in the failure of C2 to reach sufficiently high capacity for short-wave regeneration. This might be cured

NUMBER! c1E,.s

1? AM 0WORLDVol. 8. No. 7 ILLUSTRATED Every Week

r

RADIO WORLD November /, 19ZS

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A Real Long RangeCrosley ReceivingSet, $9.75 . .

Do not assume from its very interesting price thatthis very unusual Crosley set is a toy. Its impres-sive performance alone entitles it to serious con-sideration.Heretofore, the $10 radio was designed only forlocal reception. Now the Crosley Pup extends theentertainment radius to 1500 miles under ordinaryconditions. Place it beside some costly multiple -tube set and operate the dials. Both tune throughlocal stations sharply. Both get the same programswith equal ease and clarity. Both let you tap theinfinite enjoyment coming through the air. Thereis only one difference-the Pup operates with headphones instead of a loud speaker.The Pup is the newest Crosley set with a pricethat reflects the volume -production economies ofthe world's largest builder of radios. It is substan-tially constructed and permanent in every regard.Its design is an improvement of the famous Cros-ley one tube set with which Leonard Weeks, ofMinot, N. D., heard the MacMillan Polar Expedi-tion while the rest of America listened in vain.Almost overnight the Pup has become the mostpopular Crosley set ever offered. It is being boughtfor youngsters whose curious fingers cannot resistthe lure of dials and switches; for the cook, themaid, the old folks back home, and for shut-ins.Traveling men are selecting it because of its easyportability, and radio enthusiasts to have an inex-pensive check on their larger sets. Hear it once-and you will own one, too!In addition to the Pup, there is a Crosley for everyprice and preference. Operating 1, 2 and 3 tubes,these are encased in handsome Crosley-built cabi-nets and range in price up to the Super-TrirdynSpecial which retails for $60. Each will deliver thesuperlative performance that has made the word"Crosley" a hall mark of radio perfection in mil-lions of homes throughout the world.

THE CROSLEY RADIO CORPORATIONCINCINNATI, OHIO

Owningand operating W L W, first remotecontrol super -power broadcasting station

Crosley 3 Tube52 S. D.

Mahogany daubedcabinet, sloping panel.Holes It batteries.$32.50.

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J theCRO S LEY

Pup -$975

Crosley manufactures receiving sets which are licensed underArmstrong, U. S. patent No. 1,113,149 and priced from $9.75to $60.00 without accessories. None of the prices quoted includebatteries, tubes, headphones, etc. Add 10% to all prices westof the Rocky Mountains.

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A true long range set.easy to tune and hand-some in appearance$23.50.

BETTER' COSTS LESS

November 7, 1925 RADIO WORLD 3

Coast to Coast CO

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For Bretwood VariableGrid Leak

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North American Bretwood Co., 145 W. 45thSt., New York City:-Enclosed find $1.50Send one Bretwood Variable Grid Leak on10 -day money -back guarantee.

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CANADIAN DISTRIBUTOR, RADIO, LTD.PHILLIPS SQUARE, MONTREAL

Vol. Vlll, No. 7, Whole No. IAA anted Nbvember 7 1925, of weekly paper, published every Saturday by Hennessy Radio PublicationsCorporation from the publication office, 145 W_45111 St cetthewNe

Verb. 14.0558,0559.Per copy, 15 cents; $;(i a year. Entered assecondclass matter, March, 1922r, at, postoffice at1'. Telephones, Ile ant

nder the Act of March 3, 1879.

4 RADIO WORLD November 7, 1925

"It Has a Soul for Music"

1HE public demands a set that-(1) has only one tuningcontrol; (2) tunes on straight-line frequency; (3) repro-

duces with superb tone quality; (4) is inexpensivply priced.1 he 5 -tube Bruno Powertone meets every one of these demands.

Build the Powertone and Know What Real Radio Is !Quality-Simplicity-Volume-Distance

Complete boxed kwith drilled, engrave4)9panel and wiring diagramFactory -made set, in cabinet... $39.50

.50 BRUNO RADIO CORPORATION223 FULTON STREET Dept W. NEW YORK CITY

RADIO WORLD[Entered as second-class matter, March, 1922, at the post office at New York, N. Y., under the Act of March 3, 18791

A Weekly Paper Published by Hennessy Radio Publications Corporation from PublicationOffice, 145 West 45th Street, New York, N. Y. Telephones: BRYant 0558, 0559

Vol. VIII, No. 7. Whole No. 188. November 7, 1925 15c per copy, $6.00 a year

A 3 -Tube Dry -Cell Circuit

FIG. 1, the schematic diagram of the wiring. The coil L1L2 is shown horizontally so that the correct polarities are obvious. Aerialgoes to beginning of LI, ground to end, rotors of Cl and CZ to beginning of L2, A+ to 14th turn tap, T1, and end of L2 to grid con-denser and Cl stator. T2 is the short-wave tap, S2 being used to cut out the excess turns on L2 when short-wave reception is

desired.

By Capt. P. V. O'RourkeTHE most economical expenditure on a

speaker set is for one operating ondry -cell tubes, because you thus avoid the

cost of a storage bat-tery and charger, orgetting the batteryrecharged outside. Inthe long run a stor-age battery is cheap-er, even when youhave to buy acharger, but the ex-tra $30 or so may besomething a fanwants to spend at alater date and mean-while he would becontent to replenishdry cells.

The 99 type of tubeaffords best all-around results in the dry -cell class, as it is a good detector anda much better amplifier than the otherdry -cell bulbs.

The volume is almost as good as if the201A type tube were used, these latterrequiring a 6 -volt storage battery foreconomical operation.

Two standard transformer stages as theaudio coupling will do very well, but ifsome volume may be sacrificed qualitymay be increased by using the auto -trans-former method of coupling in one of theaudio stages. This is shown in Fig. 1.The auto -transformer is simply a regula-tion audio -transformer, even a poor oneyou may have rejected for the other coup-ling method. The primary and secondaryare connected so that they are in seriesaiding. This means that the magneticflux is flowing in the same direction. It

CAPT. PETERV. O'ROURKE

is not easy to determine this, only be-cause the experimenter may not have thenecessary apparatus at hand. It is per-haps enough to know that most audio -transformers will be connected in seriesaiding when the P2 and S2 terminals arejoined. These are otherwise identified asB and F or B and A. In any case a sortof roughness in signals heard, and alsootherwise unaccountably low volume, willbe experienced when the coils are con-nected mistakenly in the series -opposingfashion. The wrong method of connec-tion results in low amplification.

The auto -transformer is placed in thefirst audio stage, AF1, and the regulationaudio -transformer hookup couples thefirst AF to the second AF step.

Uses Hartley OscillatorThe tuner is regenerative, as that is nec-

essary in any 1 -tube set if it is to beserviceable. The Hartley oscillatormethod of obtaining regeneration is em-ployed. This develops a very sensitivereceiver and enables you to hear someweak stations that the regulation variabletickler coil type of regenerative receivermay not bring in. In the particular loca-tion where this set was tested WHN andWGBS are hard to get under any circum-stances, but they were brought in by thisreceiver with low speaker. volume andwith fine earphone volume. Other regen-erative circuits failed to bring them inat all.

The set is intended for reception ofbroadcast signals on the regular wave-lengths. but by using an anti -capacityswitch S2 and short-circuiting part of thesecondary one may tune in some short-wave stations. These include WGY andKDKA, operating on their X -call shortwavelengths. The short-wave adaptation

is purely a makeshift, one possible diffi-culty being in obtaining regeneration. Ingeneral the circuit operates on the. prin-ciple of the higher the capacity setting ofC2 the less the regeneration, and the diffi-culty might lie exclusively in the failureof C2 to reach sufficiently high capacityfor short-wave regeneration. This mightbe cured by placing a small fixed con-denser across the CI, one side of the fixedcondenser to the stator plates, the otherto the rotor plates, when short-wave workis contemplated. The value of this fixedcondenser can be best determined onlyby experiment, but .0001 and .00025 aresuggested.

This reversed order of regeneration isdue to the reversely fedback plate currentencountering a high impedance path in theplate part of L2.

The set was hooked up as shown in Fig.1 and the tap T2 located in the middle ofthe secondary. The switch S2 was cut in.The result was that WMCA's second har-monic, 170 meters, came in at a settingof 90 on Cl, hence the highest wave re-ceivable would be about 200 meters, andthe lowest wave would be about 75 meters.However, while regeneration was splendidon WMCA's second harmonic (at 90 onCl), it failed at a setting of about 50 onthe wavelength condenser. Regenerationwas present when C2 was set at 94 and Clat 90 for 171 meters.

The dial settings as given are to beconsidered as applying to straight-linefrenuency condensers.

The short-wave part of the hookup isone which the experimenter will be gladtoincorporate, since it means merely tap-ping the secondary and adding a switchto short-circuit the undesired turns.

The primary LI consists of 12 turnsof No. 24 silk over enftnro NIA.- eft

6 ..1 1 ) I ) \V'0 R. I I) November 7, 1925

Directions for Coil Winding

REAR VIEW. Note where the rheostat is mounted.

BOTTOM VIEW of the receiver. Note the difference between the A batteryswitch, at left, and the anti -capacity short-wave swatch at right. The method ofmounting the coil is shown. The rheostat is mounted on the socket shelf and need

be adjusted only once, then left that way.

outside diameter skeleton form, 4" or 4Yz"high. A space of A" is left, then the sec-ondary is wound, consisting of 67 turnsof the same kind of wire, wound in thesame direction. However, the secondaryis tapped as follows: first at the 14th turn,T1 in Fig. 1, and again at the 37th turn.T2 in Fig. 1. These taps are not identifiedthat way in the picture diagram, but areshown in consecutive position. The wind-ing of the secondary, therefore, insequence, is done by putting on 14 turns,slightly looping the wire and twisting itaround for security, then continuing bywinding 23 turns more, making anotherprovision for a tap, and then putting on afinal 30 turns. This gives the necessarytotal of 67, made up of 14+ 23+ 30.

The insulation is scraped off the wire atthe two tap points so that a piece offlexible wire about 5" long can be solderedto each, making two flexible leads. Thesewill be soldered to their 'proper connec-tions at the open end later, and any ex-cess cut off.

If the fan is keen for short waves itwould be advisable to include an extra tap(not shown in diagrams) at the 7th turnon the secondary, i.e., half way betweenthe beginning and the otherwise first tan,TI, to cut down the impedance and aidshort-wave regeneration.

The form used consisted of quartziterods, supporting two insulated end rim,in which the rods are embedded for secur-ity. If a different form is iced. then usea 3" outside diameter tubing would heeasiest to procure. if it is only card-board, then immerse the cardboard in

molten beeswax and allow to harden be-fore winding the coil. This rids the card-board of its normal vice of susceptibilityto moisture.

If No. 24 silk over cotton wire is nothandy, use No. 22 single cotton and besure to have the tubing W." high.

Two elements of novelty in the hookupmay tend to confuse one in the wiring.These are the Hartley oscillator and the

' auto -transformer. Hence a few wordson these:

Notice that the rotor plates of Cl andC2 go to a common lead, the beginningof the secondary L2. Remember that and,if you prefer, after the panel parts aremounted, join the two rotors with abusbar or bell wire lead, and solder theconnection to the beginning of L2 at

LIST OF PARTSOne fixed antenna coupler, L1L2.Two .00035 mfd. Streamline SLF con-

densers, Cl, C2.One Bretwood Variable Grid Leak, R2.One .00025 mfd. fixed grid condenser, C3.One anti -capacity switch, S2.One A battery switch, Si.One 10 or 15 -ohm rheostat, RI.One .25 mfd. Aerovox fixed condenser,

C4.One .5 Veby meg. grid leak, R3.One socket shelf, 17x2".One pair of brackets.Three 99 sockets.Two Preferred venier dials.One single -circuit jack, J.One 7x18" panel.Two audio -frequency transformers, AF1,

AF2.Accessories: One cabinet, one speaker,

two 45 -volt B batteries; three 44 -volt Cbatteries for use as the A battery; light-ning arrestor; ground clamp; aerial wire;leadin wire; wire for internal set connec-tions, such as busbar or No. 18 bell wire;lugs, screws, hardware.

the nearest point. This will depend onhow you mount the coil, which, in thisset is largely a matter of personal taste.Notice, also, that the stator plates ofthe feedback condenser C2 are joinedto the plate of the detector tube andthat this same lead goes to the jointof the primary and secondary of theaudio -transformer, AF1, normally P andB. The beginning of the secondary 12does NOT go to filament or A battery, butthe grid return is made to A+ at the firsttap, T1 in Fig. 1, i.e., the 14th turn tap.The reason is that the winding betweenthe beginning of 12 and the tap at the14th turn is in the plate circuit.

The end of 12 goes to the grid, and thisis the outside wire terminal of the sec-ondary. Locate this with a certainty.The polarities must not be mixed up,otherwise you may get no regenerationwhatsoever. If you use a commercial coilthat has binding posts on it, see where thewire comes from. You may find that abinding post at one end of the form reallyis used for connecting a wire terminalthat is at the other end of the form, togive the coil greater security.

As for the auto -transformer, AF1, theplate of the detector tube, as explained,goes to the common joint of primary andsecondary. The P post, i.e., the free endof the former primary, goes to one sideof the fixed condenser, C4, which shouldbe .25 mfd. The free end of the erstwhilesecondary, normally G, goes to B+ de-tector voltage. This should be about 45,but do not hesitate to try higher andlower voltages, particularly lower. Thepernicious regenerative "plop" will besmoothed out by reducing the B+ detectorvoltage.

THE PANEL view of the receiver. Although SLF condensers are used, vernierdials are included, too, as they were found advantageous.

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RADIO WORLD November 7, 1925 111

Measuring Inter -FrequencyB)' J. E. Anderson

Consulting Engineer

vXPERIMENTERS and fans who build.12.4 Super -Heterodyne receivers oftenwant to know the frequency of their

intermediate filtercircuit, or of particu-lar coils in that cir-cuit, for the purposeof checking the ad-justment of the vari-ous coils. This maybe done very simplyby the application ofa means always athand. It involves theuse of a formula con-necting the inter-mediate frequency,the frequency of theradio signal received,and the dial settings

of the oscillator condenser in the re-ceiver. The radio -frequency of the signalmust be known and in addition three dif-ferent dial settings must be observed, thetwo settings at which the given .signaltunes in on the oscillator and the settingcorresponding to zero beat between thesignal frequency and the local oscillator.

Capacity Value ImportantThe formula is given by equation No.

1 in Fig. 1. In this f is the intermediatefrequency desired, F is the radio fre-quency of the signal received, C is thetotal capacity in the oscillating circuitwhen this is tuned to zero beat with thesignal, C2 is the total capacity in theoscillating circuit when this tuned toF minus f, and Cl is the total capacity inthe circuit when it is tuned to F plus f.Cl represents the capacity for the lowersetting on the dial at which the signalcomes in and C2 the capacity for thehigher setting on the dial at which thesame signal comes in. In place of thetotal capacity the corresponding dial set-tings may be substituted provided astraight line capacity condenser is usedin the oscillating circuit and provided fur-ther that the zero setting capacity is con-verted into equivalent dial divisions andadded to the reading. If dial settings areused the formula takes the form shown inequation No. 2 in Fig. 1.

Equation No. 1 is an exact formula, andthe accuracy of a determination of theintermediate frequency mainly depends onthe accuracy with which the capacity dif-ference C2 minus Cl can be determined.With a precision condenser like the Gen-eral Radio calibrated laboratory con-denser, which can be read to about .06micromicrofarad, the capacity differencemay be determined very accurately; and.a frequency determination with it may beobtained to an accuracy of better than onepart in a thousand for ordinary intermedi-ate frequencies used in Super -Heterodynesand for signal frequencies ranging from500 to 1000 kc.

Accurate DeterminationWith an ordinary straight-line capacity

condenser used in a receiver the accuracymay be as good as one part in a hundred,or even better. The three capacities en-tering into equation No. 1 are total capaci-ties, that is, they include the zero settingcapacity of the oscillating circuit as wellas the capacities indicated on the dial.The zero capacity is, of course, the samefor all three readings. For precision mea-surements the zero setting capacity shouldbe determined by a separate measure-ment, but for approximate work it maybe obtained by a simpler method whichwill be given below.

As an illustration of how the formula

J. E. ANDERSON

f FC (C,- C, -(I)-9 C, C,f + D.) ()2 )

4(p -f-4)(4+c = c. (3)

_ r(c2-c)c,

f Fig-A) (5)a (0, -t -D002+40.)

K=1-0)2 - - - - (6)V Z2

f = D--0-Y1f - - - (7)

FIG. 1, the table of formulae.may be used for precision determinationof the intermediate frequency, assumethat the G. R. condenser be used and thatthe circuit be tuned to a station operatingon 610 kilocycles. The total number ofdivisions on the dial is 2,500 and the totalcapacity of the condenser is 1,500 mmfd.,so that each division represents .6 mmfd.The signal is found to come in at 777.0and 565.5 and the zero beat position isfound to be at 658.4. These readingsrepresent capacities of 466.2, 339.30, and395.04 mmfd., respectively. A separateexperiment has shown that the zero set-ting capacity is 30 mmfd., so that the totalcapacities are C2=4962, C=425.04, andC1=369.3. Putting these values in formulaNo. 1 together with F=610, gives f=45kilocycles. Dial settings could have beenused directly in the formula provided thezero setting capacity had been convertedinto dial divisions before adding to thereadings. For this condenser 30 mmfd.is equal to 50 divisions.

Approximate ResultsIf only approximate results are required

any ordinary straight line capacity con-denser provided with a dial of equidistantgraduations may be used, and the unit ofcapacity may be taken as a division onthe dial. If the Super -Heterodyne isequipped with such a condenser the prob-lem is very simple. Observe accuratelyand record the two points on the oscilla-tor dial at which a given station comesin, and also the point at which the beatbetween the oscillator and the signal fre-quency is zero. To each of these add thenumber of dial divisions to which thezero setting capacity is equivalent. Insertin formula No. 2 and evaluate to get theintermediate frequency.

The zero setting equivalent reading mayfirst be estimated. It usually lies be-tween 5 and 6 divisions on a 100 -degreescale for a 500 mmfd. condenser. SupposeSix be used first. Determine f for severalstations between about 550 and 950 kc.If six is correct all the calculated valuesfor f will be about the same. If it istoo large the calculated value of f willchange in a regular manner as F is in-creased. If 6 is too small the calculatedf will change in the opposite direction. Itonly requires a few applications with trialvalues of D -O to find the right value. Ina recent test the writer used 6 and foundthis to be too large. Then 5, and thisseemed to be about right, and furthertrials in the neighborhood of 5 showedthat this was the right value to use. Theaverage value of f as obtained from sixdifferent calculations was 40.7 kilocycles,and no value differed from the mean by

more than one half of one per cent. Cal-culations from observations on the lowerend of the dial were unreliable owing tothe difficulty of determining the frequencydifference with any degree of certainty.

The Elusive Zero BeatSometimes it is difficult to determine

the zero. beat position because the squealon either side will not pass through thefilter. If the head set be inserted in serieswith the B battery, however, the beatsmay be heard and the location of zerobeat may be determined. It may also befound by the click method. If the loop orother tuned circuit be accurately tunedto the given station, and then the oscil-lator dial be swung back and forth, therewill be a click at the point desired.

If the zero beat point cannot be foundby either method it may be assumed tobe at the capacity value obtained by takingthe square root of C2 times CI as shownin equation No. 3. This equation meansthat C is only approximately equal tothe square root of the side capacities, butthat the latter is exactly equal to C -m.With this approximation formula No. 1

becomes formula No. 4 and formula No. 2becomes formula No. 5. The latter for-mula is very convenient of application.The intermediate frequency obtained withit is only approximately ' correct. It isslightly too large, and to obtain the rightvalue it must be multiplied by the factorK defined by formula No. 6, as indicatedby equation No. 7. The value of f inthe right hand member of equation No. 7may be one obtained by the use of theapproximate formula No. 5. If f is lessthan one -tenth as great as F, the resultobtained with equation No. 5 differs fromthe true value by less than one percent.;and since this is more accurate than theaccuracy of the capacity difference as ob-tained by reading an ordinary dial, it isusually not necessary to correct for theerror.

A Practical CaseAs an example of the use of formula

No. 5 take the following problem. WEAFoperating on 610 kilocycles was tuned inon a Super -Heterodyne and the twp dialreadings were 892 and 67.9. The zerocapacity equivalent was found to be 5divisions. Hence the total capacitieswere 94.2 and 72.9. The difference is 21.3divisions. The square root of the pro-duct of 94.2 and 72.9 is 82.8. Hence610x21.3/4x82.8=39.2 kilocycles. K as de-fined by equation No. 6 is in this caseequal to .995, so that a closer value is 39.0kilocycles.

If the condenser used in the oscillatorof the Super -Heterodyne is a straight-linewavelength instrument the application offormula No. 1 is not easy. The capacityis no longer proportional to the dial read-ing. Formula No. 2 is no longer applicable.Neither is formula No. 5.

If the condenser in the oscillator is astraight-line frequency, not in name only,but actually and accurately, over themajor portion of the dial, then no formulais needed for the determination of theintermediate frequency. All that is neces-sary is to observe the two positions atwhich a station of known frequency comesin, record the number of divisions betweenthe two points and divide by two. Thenumber thus obtained is the intermediatefrequency in terms of dial divisions, andmust be converted to cycles per second.This is easily done if only two stationsof known frequency can be tuned in. Sup-pose that the dial is divided into one hun-dred divisions and that a 610 kilocyclestation tunes in at 85 and 75 and that a740 kilocycle tunes in at 72 and 62. Thedifference between the frequencies of the

(Continued on page 25)

.\:()% /1i1j,cr 7, 192 5 RADIO WORLD 9

The 5 -Tube Phonograph Set

A CLEAR SIDE VIEW of the set.The pencil points to an Autoformer.

FPUR views of the 5 -tube, 2 -controlL' receiver built to fit in a phonographand to be used with an external speaker,are shown herewith. Note that there aretwo tiers, the one on top supporting thecoils and two sockets, the lower shelfaccommodating the two Autoformers andthe audio -frequency transformer. Thevariable condensers are straight-line fre-quency.

The construction of this receiver wasdescribed by Lewis Winner in the October24 and 31 issues of RADIO WORLD.The set as shown departs slightly fromthe descriptive text in some mechanicalpoints.

THE BACK VIEW of the receiver.

THE PANEL VIEW. HOW the top panel is laid out.


One of the Best Crystal SetsBy Herbert E. Hayden

PROCURE a cardboard, bakelite orhard rubber form, 3%" in diameter

and 4" in height. Now get 1/2 lb. of No.22 double cotton -covered wire. Ifyou have No. 20 or18 around the houseit may be used.

Now exactly in thecenter of the form,2" from the top andthe bottom, andsome place in the cir-cumference make adot. Drill a 3/16"hole there. Take aneedle or some other

HERBERT E. sharp substance,HAYDEN which is 3%" in

length. Put it through the center hole.Make a dot with this needle, where theend of the needle hits. Now place theform in a vise. This can be bought forabout $1. Get a punch, which has a verysharp point. Place it right on the pointwhere the mark was made. Now takeyour hammer and hit the head of thepunch until you have made a small holeon the opposite side. Take the punchout and drill a 3/16" hole. If these holeswere drilled properly, one should bedirectly opposite the other.

At some point near the end of somecircumference, punch two small holes. Dothe same thing at the other end. Nowtake the wires and run the beginning ofthe wire throUgh the hole and out theother. Leave enough wire out for con-necting. Now wind 2 turns and take atap. This means that a loop is made withthe wire. It is not broken or discontinued.This loop is 3" in length. It is madelong enough so that you will have plentyof room for soldering it to the tap. Ifit is not long enough there will be plentyof room for soldering on another pieceof wire. Wind 2 more turns and take an-other tap. Wind 2 more turns and takeanother tap. Wind still 2 more turns, andtake another tap. Wind 2 more turns andtake the last tap. Now continue thewinding over the hole. That is, the endof this winding is passed over the centerhole, and the winding is continued, notbroken and a new winding made. Dothe same with this winding as was donewith the one previous. That is, maketaps, one at each second turn. This meansthat there will be 10 turns made here and10 turns made at the other half, or alltogether 20 turns. The end of the latterwinding is brought through one hole andout the other, in the same manner thatwas done for the beginning winding. Whenthis winding is completed, it means thatyou have made the primary, or the an-tenna coil of the coupler. The secondarywinding shall now be discussed.

Take a form which is 2" in diameter

FIG. 1, showing the electrical diagramof the receiver. ,

and 2" high. Place in the vise. Exactly inthe center drill a hole, which is 3/16" indiameter. Take the needle, run it throughthe hole, and make a mark at a pointopposite the end of the form. Now takethe punch and hammer out the hole. Thehole is not circular enough yet, so takethe drill and make a 3/16" hole. We willnow have two holes one opposite the other,both having the same dimensions. Makea pair of dots at one end of the form, andpunch two holes. Do the same at theother end. Put the beginning of the wirethrough one hole and out the other, leav-ing enough wire out for connecting pur-poses. Now wind 30 turns, very close to-gether. You will probably find that theend of this winding will hit the centerhole. If this is the case (due to someslack in the wire, which will not happenif wound with a machine, etc.) wind thewire over the wire. In other words, get30 turns of wire on one-half of the form,even though you have to resort to a sortof bank winding. Continue the ending ofthis 30 turn coil onto the other half, (halfis indicated by the center hole). Nowwind 30 more turns. Connect the end ofthis winding through one hole and out theother. Leave enough wire for connectingpurposes, and then cut the wire off. Wenow have 60 turns on the secondary and20 turns on the primary.

To fit the rotor into the stator shaft,you will need a piece of stock brass 3/16"in diameter and 5" in length. This ispassed first through the primary on oneside. The rotor is then inserted. Thehole of the rotor will have to come inline with the shaft. Then the shaft willpass through the rotor (both holes). Theshaft is pushed through the center holeof the stator form. This means that thebrass shaft is passed through the centerholes of both these coils. Now in orderto hold the shaft, and also the rotor somesmall mechanical makeshifts will have tobe resorted to. At any end, push thestock brass all the way in, until only aboutTA" remains. Get a lock nut, the samesize as the diameter of the brass, and fitit on. Now get your soldering iron, andsolder the nut on securely. Make it holdtight. Now take the soldering iron, witha large piece of solder, and drop it onthe shaft, just after it entered the stator,..,here the lock nut was soldered on. This

Terrell Buys Pipe for SongIn Paris to Make Wife Happy

WASHINGTONChief Radio Supervisor W. D. Terrell

is a financial wizard as well as a shark onradio matters. Mr. Terrell has just re-turned from Paris where he rep-resented this country at the InternationalRadio Telegraph Conference. While inParis he showed skill at bargaining.

Mr. Terrell wanted a pipe in a Frenchshop window to replace the Missouri meer-chaum which his wife finds so objection-

able. The price of the pipe was 20 francs.The shop keeper could not speak Englishnor could Mr. Terrell parley-voo, butafter wig -wagging for awhile Mr. Ter-rell got the price down to 12 francs. Thenfollowed more violent signaling about thechange for an American dollar.

Figuring up his change after leaving theshop, Mr. Terrell discovered he had paidexactly one franc for the pipe. This heconsidered a good bargain for a foreigner.

solder should be placed near the formproper, taking care that you do not burnthe form. Now place the rotor in thecenter of the shaft, that is, an equalamount of inches from each side of theinner walls of the stator form. Dropsolder on the outside of the rotor form,(before the shaft entered rotor form onthe same side as the lock nut is). Dropsolder on the other outside of the rotorform, or after the shaft leaves the rotor,which is near to the inner wall of thestator, or just opposite to the lock nutoutside wall. This is all the solderingand mechanics that will have to be done.When all of this is concluded, you shouldhave a perfect vario-coupler. The rotorshould turn with ease inside the stator,unless the solder is hitting the walls, whichwill cause the rotor to stick. It will bea good idea if a small spring 54" long,and in diameter, is dropped on theshaft in the place where the solderingwas done, before the shaft was pushedthrough the rotor and the stator. (Dropspring on shaft after it enters the stator,etc.) If this is done, then the spring willhit the side of the walls, which will allowthe rotor to move more smoothly. Nowon the long end of the shaft, place a V,"piece of bushing. This should be slightlylarger in size than the shaft proper, sothat it wil slide on smoothly. At theend of this bushing is a good idea to soldera nut on, so that when it rests up againstthe panel there will be a smooth surfaceas well as large surface to rest up againstit.

How to Drill the PanelThere are four controls on the panel

which is 7x12". The coupling coil dial isplaced at the left and the variable con-denser dial is placed at the right. In thecenter is the potentiometer. Right abovethis is the tap switch arm, Tl. Thecoupling dial is 3%" in diameter. Theshaft of the coupler is placed 134" fromthe left hand edge of the panel. It is also3,/2" from the top and the bottom. Theshaft of the condenser, is placed 134" fromthe right hand edge of the panel. It is3%" from the top and the bottom. Thecoupling shaft and the condenser shaft areon one line. The potentiometer shaft isexactly in the center or 6" from both theright and the left hand edge. It is PA"from the bottom. The tap switch arm isdirectly above the potentiometer, 6" fromeach edge, and 2" from the top. Theonly other large holes that have to bedrilled are for the phone terminals. Thefirst one is %" from the left hand edgeand 1" from the bottom. The other oneis 34" from the one just mentioned. Threeholes for the baseboard will have to bedrilled also. These all should be %" fromthe bottom of the panel. One should beplaced in the center, 6" from the right andthe left hand edge. One other should be3" from the left hand edge, and the lastone 3" from the right hand edge. Theseholes should be 54" in diameter.

Laying the Parts OutAfter you have drilled the panel, you

will naturally mount the parts, wherethose parts for which the holes weredrilled. The coupler you will find will nothold. Therefore you will have to placeangle irons on each end of the circum-ference. These should be 134" long. Theonly parts that will have to be mountedon the panel will be the crystal detector,and the ant., gnd., + and - battery posts.This means that the board can be only4" wide.

Wiring Up the SetThe first portion that will be attended

to. in the wiring un of the set will hethe antenna coil, with all the taps, as this


Wiring the Crystal Receiveris the most difficult. The first portionof the winding (where the beginning ofthe wire was put through the hole is theantenna winding while the portion overthe center hole, or where the end windingwas connected is the ground portion). Thetaps for the ground portion go the switchpoints. The tap arm, Ti goes to the an-tenna binding post. Now as to the groundtaps. This portion is tapped, but they donot have to be used. They should onlybe used when you find the set tunes verybroad. If the latter be the case, then thetaps go to the 5 points and the arm goesto the ground post. If you do not wish touse them, then connect the end of thewinding to the ground post, and forgetthe taps. In order to prevent losses, con-nect the end of the antenna winding to theantenna arm, and the end of the groundwinding to the ground arm. If you aregoing to use the ground switch arm, thenthe antenna switch arm will have to bepushed over. That is instead of the an-tenna arm being 6" from the center, itshould be placed 3" from the left handedge, while the ground arm should beplaced 3" from the right hand edge.

Connecting the CrystalThe beginning of the rotor winding

goes to the stator plates of the variablecondenser, Cl. It also goes to the cat -whisker of the crystal detector. It alsogoes to the resistance wire of the poten-tiometer and to the plus post of the bat-tery. Now to summarize things. Thebeginning of the rotor winding goes to thestator plates of condenser, the catwhiskerof crystal, to resistance wire, and to ±post of battery. The end of this samewinding goes to the rotary plates of thevariable condenser, Cl. It also goes toone terminal of the fixed condenser, C2.Then it goes to the base of the crystaldetector. The next konnection is madeto the phone post. The other phone postgoes to the arm of the potentiometerwhich can easily be identified because itis in the center of the 3 posts. The onlyother post left, and which contains theresistance wire, goes to the - post ofthe battery. That is all there is to thewiring which is very simple.

Making the Set WorkThe batteries should be made up out of

a bank of 6 dry cells, each of which areof the 1% -colt type. This means thatthere will be 9 volts in the bank. The po-tentiometer has a resistance value of 400ohms. The capacity of the fixed con-denser, C2 is .001 mfd. The capacity ofthe variable condenser, Cl is .0005 mfd.The phones should have a resistance of3000 ohms, and no lower. The higher re-sistance phones will give no better results,as far as volume is concerned.

Type of Antenna UsedThe aerial for this set should be con-

siderably long, about 125 feet, excludingthe lead-in. This is just the opposite tothe antenna used with the tube sets. Thisis done because a long antenna meansvolume. There will be broad tuning, butthat is something you will have to put upwith, if you wish to use the crystal set.This set is the most selective of all thecrystal sets, and therefore the broad tun-ing will not be so bad as with some ofthe directly coupled type. The groundshould be made to the water pipe, and nowhere else, even if the lead is 35 feet.Only in certain places, which places arevery extinct, will the steam pipe prove tobe better than the water pipe. Be sure tosolder the wire on the clamp, and ifpossible solder the damn on to the pipeproper. If you cannot do this, put sometin foil underneath the pipe. and makea very tight connection. Keep the an-tenna lead-in wire away from the wall,

FIG. 2, showing the panel view.

and also do not let it run parallel to theground pipe.

When wiring up the set, use only bellwire. Keep the wires well spaced andscrew down tight, or solder all connections. Make sure that they are all solid,by testing them with a battery and phones.

Now as to the tunnig of the set. Setthe antenna switch to point 3. If you areusing the ground points turn it to point 3also. Turn the coupler dial to 60. Turnthe condenser dial to 50. Now turn thepotentiometer arm. You will note thatwhen you come to a certain point, thevolume will be great. There will only beone point that the arm can be brought to,that the set will be at it's loudest. Thecrystal may be of the fixed or of thevariable type. If you are going to usethe variable type, use a piece of Carbor-undum for a crystal and a steel needle fora catwhisker. Just jam the needle in thecrystal, and let it alone.

If the signals are not loud, reverse theleads of the crystal. This set will workright off the bat, if all the connectionsare made properly: When using it in thecity, the signals will be wonderfully loud.The selectivity will not be too geat to raveabout, but as selective as most one and2 -circuit tuners. This receiver will receiveall wavelengths from 200 to 550 meters,without any trouble. The girl on the frontcover is holding the completed set.

LIST OF PARTSOne vario-coupler (L1L2).One variable condenser, .0005 mfd. (C1).One crystal detector, fixed or variable,

(CD).One small fixed condenser .001 mfd. (C2).One potentiometer, 400 ohms (P).One 7x12" panel.Two 3%" dials.Ten switch points.Two switch arms.Six binding posts.Accessories: One pair of phones, an-

tenna, ground and lead-in wire, 6 dry -cellbatteries (11i volts apiece), and groundclamp, etc.

RANGE STUDY COMPLETED BYTHE BUREAU OF STANDARDS

WASHINGTONThe Bureau of Standards has just com-

pleted a two-year study of the distancerange of broadcasting stations. The re-sults of the study will be made publicsoon.

One hundred observers located atvarious distances up to 400 miles fromEast Pittsburgh, Pa., cooperated with theBureau by making observations on thesignals of KDKA. These observers werefurnished with forms which were usedby them to record their observations.These forms were so arranged that thedata which they obtained could be trans-ferred to cards and analyzed by auto-matic machines of the type regularly em-ployed by the Census Bureau. The datawill show the variation of strength ofatmospherics, variation of fading, relativemagnitude of obstacles to reception, vari-ation of interference from receiving sets,relative magnitude of obstacles to recep-tion grouped in bimonthly periods, andmean reliability of reception as a functionof distance.

Cq

Cb

A-.

DIAGRAM of a short-wave receiver, using the Hartley oscillating system in thedetector, with one stage of autoformer audio frequency amplification.

Canada to Be RepresentedAt the National Conference

WASHINGTONThe Canadian Government has ac-

cepted the invitation to the NationalRadio Conference, and Mr. C. P. Ed-wards, director of Radio of the Depart-ment of Marine and Fisheries, has beenappointed its representative, according to

a cable to the Department of Commercefrom the Consulate General at Ottawa.Mr. Edwards will be accompanied by oneof his assistants, probably W. A. Rush,Division Superintendent of the Radiobranch, who is a noted expert in his lineand has had long experience.

12 RADIO WORLD November 7. 1925

Nine Good 1 -Tube Hookups

R R.TOP DIAGRAM shows the 3 -circuittuner, using a rotary tickler coil forregeneration. The grid leak may beconnected as shown if too much oscilla-tion is present, otherwise may be placedin conventional fashion across the gridcondenser CZ. The same fundamentalcircuit is shown in the lower diagram,but regeneration is obtained by incor-porating a fixed coil and tuning it witha variable condenser. If C3 is of thesame capacity as CI in the lower dia-gram, then L3 would have the samenumber of turns as has the secondary,LI. Note that the rheostat in each

instance is in the negative leg.

ANOTHER ingenious method of con-structing a I -tube DX set. The tap (LI)is made at the point where the statorjoins the rotor. The coil, L2, is placed onthe stator coil of LI, either on top, or

where the stator winding ends.

A HOOKUP for short-wave work. L3is an RF choke coil. This hookup maybe used also for general broadcast re-ception, the condenser capacities andthe coil inductances determining thewave range. Data on coil winding forshort waves were published in theOctober 31 issue of RADIO WORLD.

The Bernard 1 -Tube DX Setfor Tuning Ease and Simplicity

+B

+A

THE BERNARD 1 -TUBE SET shown above uses the Hartley system of obtainingregeneration. This is like the set Capt. Peter V. O'Rourke describes in this issue,only the Captain has added two audio stages. The receiver is a sensitive oneindeed. Two of the outstanding features of this set are the simplicity of the coilconstruction and the ease of tuning. The approach to the regenerative state isvery smooth indeed. For reception of local stations it is possible to set CZ forproper feedback for a low -wave station, keep that same setting and turn only Clto tune in stations on the higher waves. The phenomenon of tuning out a stationby tickler variation alone, present in the rotary tickler coil regenerative set, isgenerally absent i nthis hookup. Any oscillatory type of tube may be used toexcellent advantage. The location of the tap T depends to a considerable extent

on the capacity of the feedback condenser, C2.

-B+111111111l11

THE 3 -CIRCUIT TUNER, with anauxiliary fixed condenser, C2, to enablethe use of CI alone in tuning in thelower wave stations with wide separa-tion, by cutting out C2, which is usedonly for the higher waves. C2, whenin the circuit, is in parallel with CI,

hence boosts the wavelength.

C2 IN THE above instance is in serieswith Cl and cuts down the wavelength.Whether to use one system or the otherdepends mostly on the capacity of Cl.For .0001 or .0002.5 for Cl the parallelmethod would be used, C2 being about.00025 mfd. also. If CI is .0005 or .00035,.0005 or .001, then the series methodshould be used, and C2 would be about

.0001 mfd.

BA

A

A-

A UNIQUE method of coupling in aregenerative receiver. A 3 -circuit tuneris used. LILZ are wound on a form 33¢'in diameter. LI contains 10 turns. 1.2contains 45 turns. There are 35 turns on

L3.

AN.

c.

AA

cfla

ANOTHER method of obtaining re-generation, wherein inductive and cap-

acity feedback are both employed.


1926 Diamond and ThordarsonAt I

T

THE 1926 MODEL DIAMOND OF THE AIR, RADIO WORLD'S leading hookup. The radio side is the same as that in the1925 model, but the audio hookup has been improved. There is a slight sacrifice in volume by including the extra resistor, R7,but quality is improved. If the extra volume is preferred. R7 may be omitted, the jack J3 being connected to plate of the lasttube and to B plus No. 2, normally 135 volts. C7 would be put across the speaker connections. Another method would be toconnect an audio choke coil where R7 is shown. This might be an old audio transformer, with 13 anti F pools joined, the P andG posts being connected to plate and B plus respectively. Then C7 would be retained in its position as shown. These minoritems should be the subject of individual experiment, so that the set will be made to suit the builder's preference for volume andquality. The set works well whether hooked up one way or another. Anybody building this set and desiring a free nameplatemay obtain one by addressing Nameplate Editor, RAD1O.WORLD, 145 West 45th Street, New York City. The circuit wasdescribed by Herman Bernard in the September 12, 19 and 26 issues of RADIO WORLD, with trouble -shooting in the October 3

issue.

H.

c, 42,41_0)

C4

THE THORDARSON-WADE SET, which

5

B

C005

uses

C.X2 b '4, .

2 Y.

the Hartley regenerative system and three stages of auto -transformer -coupledaudio.

12

3

a

45

+90 OHO+6

i

0

nk -1111-'-11111----110----1111--C

-

o

THE PRESSLEY SUPER -HETERODYNE. This is one of the best Super -Heterodynes so far developed. The Sangamo Kitwas used in its construction. The mid -tapped grid coil with balancing condenser functioning on the Wheatstone bridge principleeffect neutralization. A tapped loop is used, one setting being for lower waves, the other for higher waves.


Rofpatkin and Inverse Reflexes

00-n.L3

IN THIS CIRCUIT one variometer isused to tune the antenna and the gridof the tube, while the other is used asa tuner of the plate of the tube. Thedifficulty in this set lies in the placingof the variometers. They should beplaced no more than 2%" apart. Notethat the B+ 45 goes to the ground bind-ing post. The complete constructionaldata on this circuit was published in theApril 25 issue of RADIO WORLD, anddescribed by Lewis Winner. Althoughthe value of the grid leak here is 9megohms, a lower value leak may befound to work more satisfactorily. Theresistance of the rheostat is 10 ohms.

when using 6 volts.

C>

a

L, L.

fC> C> C

L2

RI

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'0000

THE SET THAT CAUSED A TUR-MOIL. Feodor Rofpatkin in the Feb-ruary 21 issue of RADIO WORLD de-scribed the construction of the abovecircuit. One fan wrote in that it couldnot possibly work and that it was "a

8 6 cL,Dc, gii_f

II

AFT -2

1/5 1111

4 4A- A 0- B

P

O O

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B\T

AFT -I

THE INVERSE DUPLEX, using two tubes for speaker operation, a crystaldetector being employed. Capt. Peter V. O'Rourke described this set in the

August 8 issue of RADIO WORLD.

f--

-A +A-8

sin and a shame" to publish such hook-ups. Hundreds of others told of theirsplendid success with this circuit. Al-though a reflex it is simple to build andnot troublesome in operation. Thu

UV20IA tube is used here.

CD

TC3+B

Cs

THERE is still some interest in crystalsets and this interest may increase, nowthat stations are usually linked in achain when anything really importantis being broadcast. This set has twotuning condensers and two tap -switches.The capacitative method of couplingis employed. CI and C2 are .0005 mfd.condensers. LI is a 20 -turn coil tap-ped every two turns. L2 is a 60 -turn

coil tapped every 5 turns.

,1G

F.

A-ro A+'-C)

O 8-1-22iO B+900 B+67

THE RX-1, a quality receiver, which M. B. Sleeper developed. J. C .Hightissue of RADIO WORLD.

described the set in the October 17

November 7. 1°25 1:A1)10 \V R I. I) IS

-

Two Popular Audio Circuits

1,

B+Amp.

8+Del.

8-A -

ONE TRANSFORMER stage of audio, followed by two resistance stages. This gives good quality and volume. It is a considerableimprovement over two transformer AF stages. The bypass condensers at input and output may be .001 or .002 mid., but the twoother fixed condensers should be no smaller than .1 mfd., preferably .25 mfd. The rheostat R i 10 or IS ohm. for MIA or equal

tubes. Hi -Mu tubes in sockets 1 and 2 (left to right) are preferable.

G

,C>

P G

c

8+ Amp.

8+ Del .

A+.8 -

THE WAY to obtain the maximum of volume from a 2 -stage amplifier is by usingthe above hookup, wherein two transformers are employed. There are many othermethods of coupling the grid to the plate in an AF amplifier, but this is the bestas far as volume is concerned. All the notes (high, low and middle) are not ampli-

fied equally, however.

C,

ut.

-4

AFT 1

1.00f

MANY desire to have a loop instead ofan antenna, but do not know how todisconnect the aerial and the groundfrom the coil, etc. The above diagramsimplifies matters. The primary and thesecondary of the first radio -frequencytransformer are entirely eliminated. Thevariable condenser which originallyshunted the secondary of this RFTshunts the loop terminals. In otherwords, the RFT i taken out, and wherethe secondary went, the loop is placed.

APT 2

C , D

0 '0 0IC-) r_,

S,

00000 000006- 4-5-V 45 V

G (1) r

651

t.

FIG. 229, showing the 4 -tube Diamond, using the UX tube in the last stage.


A Flexible Short-Wave Set

THE PANEL VIEW of the short-wave receiver.

By Percy WarrenT0 the real devotees of the radio artI there is more to radio enjoyment

than mere broadcasting. To those whseek further thrills inthis king of sports,the short waves pro-vide a field in whichthey can repeat in anew way all of theexperiences and joysthey have had in thebroadcasting range

Ordinary broadcastreceiving instrumentsare not built to tunein on stations thatoperate much below200 meters. Becauseof the need for more

space in the ether it is possible that thefuture broadcast sets will have to have alarger tuning range than at present, andfans may be picking up their entertain-ment on waves in the neighborhood ofbelow 200 meters.

Now is the time to enjoy what the"wild waves" are saying in that regionwhich is a closed book to most of thebroadcast listeners but which is as activewith signals as any other wave band inthe radio realm.

The first step is naturally to obtain areceiving outfit that will enable you totune in the short waves, those below 200meters, and reach to near zero. Yourpresent radio set probably could be con-verted into a short wave receiver, but itis much better and efficient to build aseparate outfit specially for this kind ofwork.

Not only is the construction of such areceiver simple, perhaps simpler even thanthat of a broadcast receiver, but its costis very moderate, and in proportion tothe enjoyment to be derived, very smallindeed.

To build a short-wave receiver like theone which I have been using with greatsuccess at my home, the apparatus cited inthe list of parts is necessary. This listingshows merely what was used in the set,but other parts of equivalent quality, andapproximate size could be used just aswell with equally good results. But besure that the substitute parts that youintroduce in the circuit are good, andfrom reliable manufacturers. In short-wave work, it is essential to use the best,as the greatest possible efficiency is soughtfor the apparatus employed.

The coils may be made by the builderor bought already wound. Lorenz coils, asthese low -loss windings are called, re-quire skill for proper winding for short-waves and the B.C.L. is advised to buythe coils already wound, with the propernumber of turns, and correctly tapped.

A 13 -peg support, on a diameter of 3",will serve as the winding rig for home-made coils. The fixed tickler coil shouldhave at least five or six turns of No. 16DCC wire. Coils are made also for the

PERCY' WARREN

REAR VIEW of the receiver. Note the loosely coupled tickler coil, which isfixed. The mount may be turned about, so that the fixed tickler coil is at left to

shorten the plate lead.

secondary, antenna and grid, circuits, thesebeing one unit. I tie first of the series ofsecondary coils, to tune in from about 10to 30 meters, consists of about nine turns,the taps for the grid and plate coils beingdetermined by experiment. A larger coilfor the next range is wound with 18 turns,and tapped also for the grid and plate cir-cuits. A last coil, with about 36 turnswill afford variety so you can coverpretty well the short-wave band. This

be tapped also.On the low wavelengths tuning is ex-

tremely sharp, and the use of good con-densers in connection with well -designedcoils makes it possible for the 20,000 ama-teurs to operate nightly without notice-able interference to one another.

In the list there are mentioned variablecondensers. These should be of the low -loss type, and if a higher capacity thanthat indicated is used, the tuning will be-come difficult, if not impossible for thenovice.

For the optional radio frequency chokecoil, which is located in the plate circuit,120 turns of wire wound on a form 1" indiameter may be used. No. 30 DCC wireis suggested.

The method of mounting the coils shouldbe of interest. Either a special mount-ing can be devised, using clips to makeconnections as the various size coils arehooked into circuit to cover the variouswave bands, or the simpler plug-in systemmay be adopted. In the latter case, quickchange over from one coil to the othermay be affected, the coils simply beingplaced in a sort of socket -strip whichautomatically connects them in the cir-cuit.

The connecting plugs may be boughtseparately and mounted individually, orsecured with the coils. In either casethey are recommended over the clipmethod. The plug method gives a sureand positive contact and permits of ex-tensive experimentation without -trouble.

When assembling the receiving set, afteryou have obtained all of the parts, be care-ful about. the spacing of the various unitsDo not place anything within 2" of thecoils, and get the best sockets procurable,and if you can't, don't use any socket atall in the detector circuit. This can bedone by removing the base of your tube,and soldering the grid, plate, and filamentleads directly to the leads going to variousparts of the circuit. Mount the tube on

a cushion, and eliminate possible microphonic noises which are very annoying.

Lay out the panel so that a condensewill be located on the right and left-hansides, and the filament rheostat in the conter. Then, on the baseboard, locate thcoil mountings starting at the left, anplace the detector socket, the amplifyintransformer, and the first stage audiofrequency socket in that order. The connetting strip can be screwed down directlin back of this socket, and the choke coiif any is used, is placed in back of thfirst socket.

Use busbar in wiring, making the leadas short as practicable. Every connectiothat is permanent should be solderecHave wires running at right angles whepossible.

When the set has been assembled, teeand check the circuits, and connect to aaerial about 40 feet high, and 40 to 60 feelong. If you prefer, use your regulaaerial.

When the tubes are lit the set wioscillate when the plate condenserturned. While the set is oscillating, turthe tuning condenser until a signalheard. ,Then bring the plate condense

THE FLEXIBLE LEADS are showon the secondary and also on at lee

which tap connection works best


Wonder TubeANT.

®"0

z-TR

-onm00,-t,Pg ES

1

CND. .+A-B0

+45o 0

+90 -A

THE INDUCTIVE FEEDBACK short-wave set, in which plug-in coilsare used for covering the various ranges and for highest efficiency.

LIST OF PARTSOne set of REL low -loss short-wave

coils.One panel, 16"x17"x3/16".One baseboard, 14?4"x9"x12".One radio frequency choke coil (op-

tional).One fixed antenna coupling condenser.Two Wade or Hammerlund .0001 mfd.

variable condensers.Two sockets.One 10 ohm rheostat.One audio -transformer.Two 4' vernier dials.One Dubilier .0005 mfcL grid condenser.One Daven 5 meg. grid leak.One jack.One rear binding post strip (4 posts).One rear binding post strip (2 posts)

complete, with binding posts, lugs, base-board bushings and wood screws.

setting back until just before the circuit"spills _over." Maximum signal strengthwill be obtained.

On the extreme low waves adjustmentsmust be made very, very slowly, otherwisesignals will be passed over. Verniers areuseful in tuning low waves.

There are several broadcasting stationson the low waves now. KDKA, WGY andothers can be heard. Tune them in somenight and notice the difference betweenthe low wave and their regular broadcast.In addition, some foreign stations are nowbroadcasting in the short-wave region.

early in this photograph. There are tapsie of the plug-in fixed tickler coils, but

4 be determined only by experiment.

These may be picked up too with care.For the reception of broadcasting, it isbest to tune the circuit just below thepoint of oscillation. This will obviate adistorted signal.

Key to Numerals1-Auto-transformer-It is advisable to

experiment with the tapped connectionswhen employing the capacity feed -backcircuit. Use the smallest coil for the 20meter band, the next for the 40 and thelargest for the 80. All these particularcoils have taps.

2.-Tickler Coil-The small one to beused for the 20 and 40 meter band and thelarge one for the 80. There are only two.

3.-.0001 mfd. wavelength control vari-able condenser.

4.-.0001 mfd. regeneration control vari-able condenser.

5.-.0005 mfd. fixed grid condenser.6-5 Meg. Grid Leak-It is advisable to

try various sizes. A. defective grid leakwill cause considerable noise.

7.-Radio Frequency Choke-Wind 120turns, No. 30 DCC on 1" diameter tubing.May be omitted.

8.-Hard Detector Tube, preferably201A.

9-Amplifier tube.10.-Audio Frequency Transformer-

High ratio preferred.11.-10 Ohm Rheostat.12.-Single Circuit Filament Control

Jack-Plain single circuit jack may beused instead and connections changed ac-cordingly.

13.-Fixed Antenna Coupling Condenser-Two pieces of brass %x%" spaced,,A" apart.

V. K. ZWORYKIN (above), of theWestinghouse Electric Research Lab-oratories, East Pittsburgh, Pa., withhis thermionic photo -electric tubewhich utilizes the mechanical powerof light. The tube is one of the mostsensitive known to physicists and willsend out electric currents and radioimpulses whenever a ray of light fallsupon it. It is applied for steeringships, controlling railroad trains auto-matically, recording the light fromvariable stars, and may aid transmis-

sion of movin pictures by radio.( \Vide World)

JOIN THE A. B. C.A. B. C stands for American Broadcast

Club, an organization of fans banded to-gether to promote the welfare of radio.There are no dues, no obligations. Ad-dress A. B. C. Editor, RADIO Wcans, 145West 45th St., N. Y. City. The namesand addresses of new members follow:

R. E. Polzin, 24 Freund St., Buffalo, N. Y.Walter L. Suitala, 94 Squachan St., Selfridge

Field, Mt. Clemens, Mich.H. E. Ferree, 2921 Lipscomb St., Ft. Worth, Tex.P. E. Ferree, Burkburnett Bldg., Ft. Worth,

Tex.C. It. Ferree, 1211 Sixth Ave., Ft. Worth, Tex.Lyman E. Rinker, 1245 East Oak St., Portland,

Ore.Arthur Soderstrum, Studio Orpheum Bldg.,

Topeka, Kan.Edward Hassell, 513 Superior St., Grove City,

Pa.Paul J. Belso, 342 Lawrence St., Perth Amboy,

EXPORTS UP $2,951,204The total of foreign sales of American

radio apparatus for eight months of thisyear show an advance of $2,951,204 ofshipments over the corresponding periodof last year. The exports to date amountto $5,556,284. An idea of the increasemay be gained from the fact that inAugust of last year our radio exportswere valued at $641,238, whereas in Augustof this year they amounted to $844,379.

Don't UsePanel Like This forSW

BY PLACING the dials so close together the variable condensers used fortuning a short-wave set would lack the requisite separation.

IRADIO WORLD November 7, 1925

Radio UniversityAQUESTION and Answer Department

conducted by RADIO WORLD forits Readers by its staff of Experts. AddressLetters to The Radio University, RADIOWORLD, 145 West 45th St., New York City.

WILL YOU please give me a diagramof a 5 -tube inductively coupled se_t-T.Hams, Claypool, Okla.

Fig. 226 shows the electrical diagramthat you request. The tubing is 3%" indiameter. Close to the edge wind 16 turns,(L1). Leave out two terminals, (begin-ning and the end of the winding), for con-necting purposes. Leave %" space. Wind45 turns tapped at every fifth turn, (L2).Tap the 45th turn, too, and put on threemore turns, this being a continuation ofthe secondary winding, and anchor thelast turn in the form. Be sure that whenyou wind this secondary there is plentyof wire left, because the secondary wind-ing is continued on the rotor form. Pro-cure the two other 3%" diameter forms.The primary winding (L3) contains 26

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dyne coils differ from a regular 3 -circuittuner? (2) Are the RFT in both thesesets the same? (3) How many turns andwhat size wire should I use to wind on aform 2%" in diameter and the tickler,1%." in diameter for Capt. P. V.O'Rourke's "Most Efficient 4 -Tube, 3 -

Control Set," published in the March 21issue of RADIO WORLD? (4) Are the prim-ary and the secondary of the standardRFT (tuned by a .005 mfd. variable con-denser) good for this set, utilizing thisspecial 3 -circuit tuner?-W. H. Sevita,Mount Vernon, 0.

(1) They are both the same. (2) Yes.(3) There are 10 turns wound for theprimary, and 53 wound for the second-ary. No. 24 silk over cotton or 22 SCwire is used. The tickler contains 36 turns

R4

-Frank Barger, 615 South Edwards Ave.,Eastwood, .N. Y.

Reverse the tickler leads. Take off5 turns from the plate coil. Take out thefixed condenser (if any) which goes fromthe A+ lead to the plate. Reduce theB battery current on the plate of the de-tector tube.

5

I WOULD like to have some informa-tion regarding the DX Set That ThrilledJack, as described by Lewis Winner inthe Oct. 10 issue of RADIO WORLD. (1) Isthis set sensitive, clear and non -distortingon DX stations? (2) What wavelengthswill this set receive? (3) Can the coilsbe wound on a solid bakelite tubing withequal results? (4) If the latter prevails,does the size of the tubing change? (5)How long an antenna should I have to getbest results on the set?-Calvin Martin,518 24th St., Oakland, Cal.

(1) Yes. (2) From 200 to 550 meters.(3) Yes. (4) There is no change in thediameter of the tubing. (5) The antennashould be 100 feet long.

* 5 *

I WOULD like to make some ballooncoils, and therefore would like to havethe follOwing information regarding thesame. (1) How many turns shall I windfor the primary of the coil. (2) How

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FIG. 226, shows the inductive method of tuning in a 5 -tube set.

turns for L3, but 16 for L5. Wind thesecondaries without taps.

Procure forms 254" in diameter. Wind13 turns. Leave about 5" of wire out be-fore beginning to wind the coil. Connectthe long lead from the end of U to thebeginning of this rotary wending. In thesame way the other rotary coils are woundand connected. The condensers Cl, C2and C3 are variable condensers of .0005mfd. C5 is a .001 mfd. fixed condenser. Pis a 400 ohm potentiometer. RI is a 20ohm rheostat. R2 is a 20 ohmrheostat. R3, R5 and R6 are all 10

ohm rheostats. C4 is a .00025 mfd. gridcondenser. R4 is a 2 megohm grid leak.C6 is a .001 mfd. fixed condenser. AFT1and 2 are both of the low ratio type. TheUV201A type tube is used.

* 5 5I HAVE built the Diamond and find

that I cannot cut through local stations.I can cut the local stations out. Couldyou help me?-Chas. F. Bake, 1808 W.Wyandotte, Kansas City, Mo.

Use a fairly long antenna, about 100feet with a water pipe as a ground. Thefact that you get locals proves that theset is functioning. Perhaps you skipover the stations while cruising the air.When tuning in a station, bring the car-rier wave in. Then immediately vary thetickler, so that it will not squeal enoughto annoy your neighbors. Now tune yourcondenser dials in step, slowly. If thestation is there you ought to get it, withcareful tuning.

5 5 *IN A general way how do the Super -

of No. 28 single silk covered wire. (4)Yes. * *

WILL YOU please tell me if dry celltubes will work in the 2 -tube reflex, de-scribed in the Feb. 7 issue of RADIOWORLD by Capt. P. V. O'Rourke? (2) Willa fixed crystal detector work in thisset?-H. M. Horton, 36 Division St.,Providence, R. I.

(1) Yes, but not with much volume. (2)Yes.

* 5 *

PLEASE TELL me the number of turnsto put on a form 254" in diameter of a 3 -circuit tuner. The diameter of the rotoris 1K" in diameter. I wish to use No. 26double silk covered wire. The secondaryis to be tuned by a .0005 mfd. variablecondenser.-A. F. Gilbert, 184 GlebeholmeBoulevard, Toronto, Ont.

There are 10 turns placed on this forthe purpose of making the primary. Thesecondary consists of 52 turns of the samewire wound on the same tubing, with noseparation. The tickler consists of 36turns of wire.

* *

WHERE CAN I get information on theshort wave receivers ?-Emanuel Ugge,care Zeuresch and Co., Pocatky u Jindr,Hradce, Czecho-Slovakia.

See the Oct. 10 and 17 issues of RADIOWORLD, also Mr. Warren's article in thisissue.

* *

I HAVE a 3 -tube regenerative setwhich is very hard to control. It oscil-lates too much. Have you any suggestion?

B4-135B-422

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many for the secondary? (3) What sizewire should I use? (4) What is the dia-meter of the coil? (5) Are the primaryand the secondaries of all the coils alike?(6) Should the winding be in the samedirection? (7) Should there be anyseparation between the windings? Allthese coils are to be tuned by a .0005 mfd.variable condenser.-W. G. Freind, 83Lang St., Newark, N. J.

(1) There are 48 turns wound for theprimary. (2) The secondary consists of195 turns. (3) Use No. 24 double cottoncovered wire. (4) The diameter of thecoil is PA". (5) Yes, all the RFT arewound in the same style. (6) Yes. (7)No.

* *

I AM going to build the 1926 Diamondand would like to know if I could usethe 180e Twin Coupler Co., 3 -circuit tuner,two SLF variable condensers of .00035mfd. capacity. The primary has 12 turnsand the secondary has 43 turns. This iswound on a tubing 3%" in diameter. No.22 silk over cotton covered wire is used.The space between the primary and thesecondary is %". (2) If I use these coilscan I obtain maximum volume and selec-tivity? (3) The tickler is wound on atubing 21%" in diameter and contains 33turns. (4) Is the 1926 Diamond moreselective than the 1925 Diamond?-J. G.Thomas, 5623 Hawthorne Ave., NewOrleans, La.

(1) You will have to increase the wind-ings on the secondary to 63 turns. (2)Yes. (3) Increase the windings to 43 turns.(4) No; both the same.

November 7, 1925 RADIO WORLD

FIG. 227, showing the diagram Mr. Homins required.WILL YOU please give me a diagram of

a 5 -tube loud speaker set.-T. H. Homins,Danville, N. H.

See Fig. 227. The data for winding fol-lows : Using a 4" outside diameter tubing,2" high, wind eight turns of No. 20 DCCfor the primary of the variocoupler, AB,terminate; then leaving the least spacepossible, wind 31 turns of the same kindof wire in the same direction for the sec-ondary, CD, terminate. The tickler EF,should consist of 20 turns of No. 26 SSCon a 3" diameter, 2/t" high. The RFT,GHIJ, consists of the same kind of wind-ing as the primary of the coupler, exceptthat the secondary, IJ, has one turn less,or 30 turns. .C1 is a .0005 mfd. double con-denser. R4, R6, R8 are 1 megohm invalue. R5 is 1 megohm, R7 is IA megohm,R9 is a 3.4 megohm. C4 is a .001 mfd. con-denser. C3 is a .002 mfd. fixed condenser.C2 is, a .001 mfd. fixed condenser. R3 isa 6 -ohm Amperite resistance. R1, R2 are6 -ohm rheostats. Five UV201A tubes areused or a Sodion D21 will serve as a de-tector. Other detectors require a gridleak.

WILL YOU please give me a diagramof a 2 -tube loud speaker reflex, with 1 -control ?-C. Lamons, Colfax, N. M.

Fig. 228, shows the electrical diagramof such a receiver. LI, the primary iswound on a form 3%" in diameter and 4"high. There are 10 turns made. The sec-ondary is wound on the same form andconsists of 45 turns. The primary L3 iswcund on a tubing 3%" in diameter and4" high. There are 10 turns made. Thesecondary is wound on the same tubing.There are 45 turns made. Use No. 22double cotton covered wire for windingthese coils. C2 is a .001 mfd. fixed con-denser. C3 is a .001 mfd. fixed condenser.CD is a crystal detector of either the fixedor variable type. Cl is a double con-denser. Each section has a capacity of.0005 mfd. AFT1 is of the high ratiotype. AFT2 is of the low ratio type.R1 and R2 are both 10 ohm rheo-stats. The UV201A type tubes are used.The ia,lc is of the double circuit type.

I AM contemplating building the 2 -control Diamond of the Air as describedin the May 23 issue of RADIO WORLD. (1)Will the Amsco .0005 mfd. SLF doublecondenser work well in this hook-up?(2) Why are the primary and the sec-ondary of the RFT connected togetherhere and not in the 3 -control Diamond?-Walter A. Sorg, 7 Clay St., Dansville,N. Y.

(1) Yes. (2) This is done so that thevolume of the set might be increased.Local conditions control this point, so trythe hookup both ways.

I BUILT the Diamond and am havingsome difficulty. This lies in the crowdingof the low -wave stations. I am led tounderstand that a SLF condenser willcure this. Is this true? (2) I also have

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FIG. 228, showing the diagram Mr. Lamons requested.some trouble with the high waves. Isthere any way that I can get them easier?-Dr. E. H. Taylor, Pittsfield, Mass.

(1) Yes, or just slip SLF dials on yourpresent condensers. (2) Place a .0005 mfd.fixed or .variable condenser across theantenna and the ground. A small switchmay be placed in series with one of theleads of this condenser. You then will beable to switch in and out without anytrouble. Another way is to lengthen yourantenna.

I HAVE built the Diamond and findthat regeneration is uncontrollable. Howcan I cure this? I cannot rewind thetickler coil as it is too tricky.-E. J.Shockey, 2930 W. 1st, Engine 32. LosAngeles Fire Department, Los Angeles,Cal.

Take off the fixed condenser which goesfrom the plate post of the detector tubeto the A battery. Use a variable grid leak.Use less B voltage. Reverse the second-ary of the 3 -circuit tuner.

WILL YOU kindly let me have the fol-lowing information as regards the Dia-mond and the Powertone: (1) Which oneof the two circuits is the more selective?(2) Which one is the best as to quality

and volume? (3) Are they both loggable?(4) How do they compare with the Neu-trodyne? (5) Would the Powertone as a2 -control have any advantage over thePowertone as a 1 -control? (6) In re-gards to the Percy Warren "Simple 1 -Tube DX Set" described in the May 23issue of RADIO WORLD, I would like toknow if I can use a .00025 mfd. variablecondenser across the grid coil instead ofthe .0005 mfd. variable condenser. If Ican, would you please give me the num-ber of turns.-James Laing, 59 WatchungAve., West Orange, N. J.

(1) Selectivity equal. (2) The Diamondis louder, quality equal. (3) Yes. (4)very favorably. (5) No. (6) You can usethe .00025 mfd. The number of turns onthe coil is increased to 65.

I HAVE built the Diamond and untilrecently have had wonderful results.During the last week or so trouble has de-veloped. The signals are now distorted.I have traced it to the first two tubes.In other words, the trouble does not liein the AF stages. Can you help me?-Frank N. Freuch, 95 South St., Boston,Mass.

The probable trouble lies in either run(Continued on page 28)

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A THOUGHT FOR THE WEEKThe reputed rattle-brained radio in-

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52 sonsecutive tunes 20%20 times oonseeutivell or K 0. W. One reer 11%4 consecutive Imes 10%WEEKLY, dated each Saturday, publiehod Wednesday.

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Entered a. ocoond-clan matter. March 38. 1922, atthe Post Office at New York. N. Y., under the ash ofIllareh 8. 1819.

NOVEMBER 7, 1925

The Weekly Rebus

DE+ ter-

anum W Iii.unevotnummnitunum

WHAT tube function does this represent?

Send your answers to Rebus Editor,RADIO WORLD, 145 West 45th Street,N. Y. City.

RECENT BACK NUMBERS of RADIOWORLD, 15c each. RADIO WORLD, 145 West45th Street, New York City.

Injunction Against SquealersCited As Legally Sound

By Thomas StevensonWASHINGTON

Regenerative receivers or other elec-trical devices which sometimes spoil radioreception in an entire neighborhood maybe banned at some future time by Courtaction.

This is the opinion of legal experts whohave made a thorough study of the sub-ject. Such a case has never been triedin the Courts, but it is believed thereare sufficient precedents in law for aninjunction preventing the operation of a"squealing" set.

Here is how the case appears to a lead-ing legal authority:

"Any disturbance or sound in a re-ceiving set which prevents or impairs thereception of desired matter may comefrom many different sources, be the re-sult of negligence, or be wholly innocent.But whatever the source or the motive,its effects are equally serious.

"The disturbing effects may come fromnon -radio sources, such as X-ray or violetray machines, leaky insulators, elevatorswitches, trolley wheels, contact shoes,poorly bound joints and other sparkingelectrical contacts, high voltage testingapparatus, motor and generator commu-tators and electrical precipitation plants.

Principle Well Founded"It may come from apparatus used

directly for radio communication. Re-ceiving sets of certain types, when un-skillfully used, emit disturbing emana-tions. Harmonics from transmitting sta-tions are of the same class. Instances areknown of disturbances so continuous andfar-reaching as to make reception ab-solutely impossible in entire communitiesduring all of the usual broadcastingperiods.

"The situation is not novel in principle.It has risen before and has given rise tothe maxim --.so use your property as notto injure the rights of another.' The ap-paratus which causes the difficulty is itselflegitimate and ordinarily is useful andnecessary. One who operates a radiotransmitter or receiver, whether for com-mercial purpose or merely for his owninstruction, or amusement, is likewisewithin his absolutely personal rights.

"A radio receiver is merely an artificialaid to hearing. By its use the scope ofaudition is extended far beyond naturalrange, just as the telescope increases thedistance of vision. Man without artificialaid can hear the voice of another onlywithin a few hundred yards. By radio, hehears it a thousand miles or more away,but the principle is the same so far asthe fundamental right is concerned. Areceiving set bears a relation to his earssimilar to that of spectacles to his eyes.

Which Must Yield?"We have then a conflict between users

of radio and of other electrical apparatus,both equally lawful, but one interferingwith and disturbing the other, and thequestion is as to the rights and legal re-lationships between them. If both can-not stand, which must yield?

"Every person shall so use and enjoyhis own property as not to impair theenjoyment of others having an equalright to theirs. It is the first and mostimportant obligation entering into thesocial compact, although it involves re-strictions upon the so-called natural rightsof individuals.

"Perhaps the most general applicationof the maxim has been in the law ofnuisance, one branch of which covers

disturbing noise. Every property owneris entitled to reasonable quiet in the en-joyment of his premises, and a noise mayof itself amount to a nuisance if it isharmful to the health or comfort ofordinary persons.

"Damages cannot be recovered mere-ly for discomfort and inconvenience buta noise nuisance may be enjoined. Noisepreventing comfortable living may be en-joined as a nuisance on the ground of in-adequacy of legal remedy and to preventa multiplicity of suits.

"The doctrine is equally applicable totransmitting apparatus which itself causesundue disturbance to those within hear-ing, certain types of spark for instance,and to the use of a loud speaker for radioreception at improper times and places, tothe discomfort of others, similar to theunreasonable playing of the phonograph.

"But when we come to apply the ruleto interference with radio reception wemust deal with entirely new elements.There is a material dissimilarity betweenordinary noise and vibration cases andthose which arise from radio interference.The usual noise nuisance cannot beavoided by the person disturbed, but in-terference attends the radio listener onlywhen he deliberately puts himself in aposition to receive it. When not operat-ing a receiving set he experiences no an-noyance. Yet he has the legal right tooperate his apparatus to the same extentthat the person creating the disturbancehas to operate the instrumentaliy whichcauses the harm. Both are using electricalcontrivances for proper purposes, one in

business enterprise, the otheras an artificial extension of natural powerto hear.

"The Courts have said that the test isas to whether the noise causes annoy-ance, inconvenience or discomfort. Doesthat necessarily mean that the annoy-ance must come to him in one conditionrather than another? The courts maywell say that the rule stands as a protec-tion whenever he is in the lawful enjoy-ment of his property, whether by naturalor artificial means.

Neutralization Hinted"Consistent with the rule that a per-

son may make a reasonable use of hisown property, without subjecting him-self to damages for injuring the prop-erty of others, the courts scrutinize thecircumstances under which the adverseparties are operating and endeavor to docomplete equity between them. Thuswhere the interference can be obviated bycomparatively inexpensive devices thecourts seem to impose their installation.The courts require cooperation betweenthe two adverse parties in order to elim-inate injury, on the theory that one mustmitigate his damage if he can.

"Certainly, the fair inference is that ifthe injury can be lessened or preventedby practicable devices, the party creatingthe disturbance must adopt them, par-ticularly when the injured party cannotprevent or lessen it. The Court will notdictate how the interference shall be pre-vented or lessened, but will restrain theinjurious operation, leaving it to the re-sponsible party to apply such means asit elects to accomplish the required re-sult.

"Radio disturbance is actually an an-noyance-a discomfort to persons of aver-age habits and tastes, making an ordin-ary use of property. That it is new isof no importance. Time and advancementof the social state demand and createprogress."(Copyright, 1925, by Stevenson Radio Syndicate)


The 4 -Tube Roberts Receiver

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CIRCUIT DIAGRAM OF THE ROBERTS SET, un-reflexed and using two audio transformers. Regenera-tion is controlled by a variable resistor connected across

the fixed tickler. (Fig. 1).

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By Neal FitzalanONE stage of tuned RF, followed by a

regenerative detector, the RF tubebeing neutralized, is shown above, thisbeing known as the Roberts set. In thepresent instance four tubes are used, asthe audio circuit consists of two trans-former stages. A fixed tickler is usedin the detector plate circuit, the regenera-tion being regulated by a variable resistor.This is one of the forms of obtaining re-generation with fine ease of control. Theactual operation of the variable resistoris as shown in the diagram, although thephysical connections to the instrumentwould lead one to believe that' the resistorwas always across the coil. This is nottrue, of course, because it is possible toturn the knob until there is zero resist-ance, hence no connection between thetickler and P of AFT1.

Eliminating a ControlThe circuit as shown uses the antenna

coupling and interstage inductances of theAmerican Mechanical Laboratories. Thecondensers that match these coils are .0005mfd. each, shown as Cl and C2. Normallythe set would have three controls-onefor tuning the RF stage, one for tuningthe detector input, and one for regenera-tion control. These may be reduced totwo either by using a double condenser,two sections of .0005 mfd. each, such asBruno No. 21, National DX or GeneralRadio, or by employing a mechanicalmethod, whereby one knob turns a gearthat moves the rotors of the two con-densers. This is known as an S -C unit.

Numerals ExplainedThe numerals on the coils are the same

as those that appear on the commercialproduct. The variable resistor, made bythe same firm, is known as the Clarostatand is incorporated in the coil unit.

The odd RF plate coil connection simplyrepresents the usual primary, followed byanextra few turns wound in the oppositedirection. The point at which the re-versal of winding takes place is connectedto B plus 67% volts, while the other endof the reversed winding goes to the statorplates of the neutralizing condenser, C3.

C5 is .001 mfd. The rheostat valuesdepend on the type of tubes used. Theother constants are standard.

WLS TO BE AT CRETEWASHINGTON

WLS, Chicago, will increase its powerto 5,000 watts within the next few weeks,according to reports. The new 5,000 wattstation will be located at Crete, Ill., withland wires connecting it to the Chicagostudio.

0 B+ 611

0B+222

0 A

REAR VIEW of the set. Ordinarily there would be three controls-the two tuningcondensers and the variable resistor-but these may be reduced to two by usingthe Hanscom S -C unit, as did the constructor of the above set, Charles Golenpaul.

(Kadel & Herbert.)

GroundClamp k -h

HOW to connect a loop jack. The insertion of the plug opens the circuit con-nected to Lo (secondary), leaving only the loop tuned by Cl.

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22 R .1 1) I 0 W () R I. D November 7, 1925

THE RADIO TRADECRESCENT LAVITES POPULARMorton W. Stearns, C. E. of Crescent

Radio Supply Co., who for twenty yearshas been active in Radio Research ismeeting with great favor with theirCrescent Lavite Resistances among setbuilders and manufacturers, and many ofthe large broadcasting stations as nospecial mountings are necessary and verylittle space is required. These amplifierscan be easily added to any set after thedetector.

DIOPARTS

CONDENSERSVERNIERSRHEOSTATS

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Cresson, Radio Supply Cs, 9 Liberty St.. larnalea. N. T.

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In Greenwich Street. New York CityDistributors, Jobbers. Dealers, writs tor

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SUPERTRON IN NEW HOMEThe Supertron Mfg. Co., manufacturers

of the guaranteed Supertron tube, arenow established in their new factory at228 Washington Street, Hoboken, N. J.,and are running under full production.Henry Bobker, sales manager, predictsone of the greatest radio seasons in his-tory, judging by the demand for Super-tron tubes. They are now running thefactory night and day. Another extensionof factory space, with additional ma-chinery, is being planned to take care ofthe expansion. Supertron tubes can behad in all types, 1% volt, 3 volt with smallbase, 3 volt with large base to fit standardsockets, and the regulation 6 volt %-amp.tube.

(Tested and Approved b7 RADIO WORLDLaboratories.)

New CorporationsDavid Grimes, Wilmington, Del., wire-

less sets, $10,000. (Corp. Trust Co. ofAmerica, Del.).

Mort -Smith Corp., Paterson, N. J., radiosupplies, $100,000; Mortimer 0. Smith,Hawthorne; George A. Jacob, Paterson;Louis J. Wassel, Brooklyn. (Atty., Wil-liam F. Delaney, Newark, N. J.).

H. & D. Radio Co., Jersey City, N. J.,$50,000: Richard Harris, Louis Demeter,Mary Demeter, Jersey City. (Atty., Ern-est B. Biro, Newark, N. j).

Literature WantedTHE names of readers of RADIO WORLD

who desire literature from radio job -tiers and dealers are published in RADIOWORLD on request of the reader. Theblank below may be used, or a poet cardor letter will do instead.Trade Service Editor,RADIO WORLD,145 West 45th St., N. Y. City.

I desire to receive radio literature.Name

City or Town

State

Are you a dealer?

If not who is your dealer?

His Name

His Address

Martin T. Clayton, 180 E. Dwight St., Holyoke,Mass.

E. Cecil Tabor, R.F.D. No. 5, Winchester, Ky.J. F. Shaughnussy, 30734 Bissel Ave., Oil City,

Pa.Forest Neighbors, Sedalia, Mo.Walter Moore, 3 Dove Court, Roxbury, Mass.R. D. Briggs, St. Louis. Mo.G. T. Finch, 110 Dorchester St., South Boston,

Mass.James Michael, Box 107, Canonsburg, Pa.J. D. Nichols, 24 Anable St., L. I. City, N. Y.E. C. Slicer, 5637 S. Loomis St., Chicago, Ill.

(Dealer.)R. J. Brooks, Cadiz, 0. (Dealer.)Peter J. Pierce, Box 521, Hartford, Wis.M. W. 'Purcell, 2325 Ingersoll St., Des Moines,

Ia. (Dealer.)F. W. Durn, Holland, Mich. (Dealer.)A. Herbert, 5434 Richmond St., Newark, N. J.J. N. Fennelly, 35 N. Burnett St., East Orange,

N. J.L A. Patrick, Box 153, Torrance, Pa.Lawrence Lamb, Mount Vernon, Liverpool., Eng-

land. (Importer.)Robert Steidley, Lewistown, Pa. Agent.)Wallace E. Rushing, Millhaven, Ga. (Dealer.)R. T. Bragg, 2120 Emmet St., Omaha, Neb.

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November 7. 1025 \ I .) I \ V I I 23

Two of the best sets yet designed!Herman Bernard's

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LIST OF PARTSe Bruno No. SS R.F. Transformer, LOLL.

Cr.e Bruno No. 99 3 -circuit tuner, L2L3L4.Two Bruno 20 -ohm rheostats, RI. RZ.Two General Instrument low loos pyrex con-

densers, CI, C3.One Bretwoed variable grid leak, RO.Two double -circuit tacks. ..II, J.1.One single -circuit jack. .13.One Federal No. 65 AFT.One ,a -ampere ballast resistor. RI.Fired condensers: One .00025 mid. grid con-

denser, without clips, C2: one .001 add- C4;three 0.25 mfd.. CS, C6. C7.

One double -throw, double -pole switch. SI.One A battery switch, SZ.Two Veby leaks, 1.0 meg.; R6. 0.5 meg.Three 0.1 meg. Veby resistors, R3. RS, R7.One Bruno S -gang

socket shelf.Five sockets.One pair of Bruno $37.50

brackets.Three vernier dials.One 7" x 24" drilled

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posts.

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Capt. Peter V. O'Rourke'sDry Cell Set

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LIST OF PARTS01110 6104 antenna coupler. L112.Two .00035 mid. Streamline SLF conderwers,

CI, C2.One Brtwood verlable grid teak. R2.One .110026 mid. fixed grid corulenum, C3One antluspacity .witch. SLOne A battery switch. SI.One 10 or IS -ohm rheostat. RI.One .2S mid. Aroy, a band cone/enc.,. CLOne .5 meg. Veby grid teak, R3.Op* socket hell, 17 x r.One pair of bracket..Three 09 sockets.Two Preferred vernier dials.One single - chcent

lack. J.One 7" II" panel $ 50Two audio -I requenc

tranformers, AF1.AFL

One battery cable.

"Bruno 99" 3 -circuit tunerwound on quartzite glass endanecifind in the Diamond of theAir MSC

"Bruno SS" matched Radio fre-quency call for 99 and used inthe Diamond Si the Air 53.00

"Bruno rr tuner woundon quartzite gins. with specialtickler bar smooth regenerationcontrol 15.50

"Bruno"' short a coil. Tunicsfrom II -Ill meters with .1101125 con.denser. Wound with flat ribbonwire

Bruno 3 Section Condenser for Sidney E. Finkelstein's 3 in 1 receiver -$6.95

Complete Kits for Hookups Shown in this IssueBernard's 1 -Tube DX Set, Using 75SLF Condensers, Complete Kit 41Winner's 1 -Tube Variometer Set, e7 7=Complete Kit tio

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Standards Bureau AdvisesWays to Cut "Human Static"

WASHINGTON.Cooperative effort on the part of radio

fans and the owners of electrical sourcesof disturbance is the most effective remedyfor man-made interference, according tothe Radio Laboratory of the U. S. Bureauof Standards.

"Much of the work in mitigation ofelectrical interference results in an im-provement in the operation of the electricaldevices or supply lines and is thus adouble gain," the Standards Radio Labor-atory asserts. "There are, however, someelectrical devices which, even when inperfect working order cause disturbanceswhich result in interference with radioreception. In many cases it is possible toprovide filters, shields, chokes, etc., eitherat the source of disturbance or at thereceiving set, which do much to relievethe difficulties.

Some of it Inevitable"Part of the disturbance from electrical

devices is practically inevitable and mustbe regarded, like atmospheric disturbances,as part of the inherent limitation of radioreception. In other words, the limitationof radio reception is not only the distanceand the power of the transmitting stationsand the sensitiveness of the receiving set,but also the omnipresent background ofslight electrical disturbances which drownout signals below a certain intensity. Thisbackground of electrical disturbances isthe underlying reason why reception fromlocal stations is inherently superior to re-ception from distant stations."

Here are a few suggestions offered bythe Bureau of Standards Radio Labor-atory towards decreasing interference:

"The first thing to do in tracing thesource of trouble, is to make sure that itis not in the receiving set itself. Thenext thing is to open the electrical switchat the house meter; if the interferingnoise is still heard, the source is thenknown to be outside the house. It is thendesirable to report the situation to theelectrical power company. Many of thecompanies have apparatus for the purposeof following up complaints of this kind.

RESTER Radio SOLDERtRositt.Coral

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tector plate voltage bad. Tested and approved byleading autherltlea such as Popular Radio labor -/aerie.. Over 3 years cold on a non -red tape, 80 -daytrial offer with complete refund if not thoroughlysathdled. Further guaranteed 2 years. Knock -downalto at great savings. Complete -Howler "B" bat-tery charger, $2.75. Sample cell. 35e. Order direct-send no money--eimPlY pay the expressman coaton delivery. Or write for my free literature, teat -motels and guarantee. Same day shipments. B.Hawley Smith, 218 Washington Ave.. Danbury. Conn.

Usually a sensitive receiving set with acoil antenna is used to determine thedirection from which the interfering noisecomes, and this outfit is taken from placeto place until the source is found.

Hard to Locate"The location of such sources is often

a very difficult and baffling undertaking.The trouble sometimes comes from aspark discharge over an insulator to

(Continued on page 27)

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HOOK -UPS! --A lot of them, some of whichare sure to suit your purpose, appeared inRADIO WORLD dated August 15. lk a copy,or start your subscription with that number.RADIO WORLD. 145 West 45th St., N. Y. City.

COMPLETE LIST OF BROADCASTING STA-TIONS appeared in RADIO WORLD dated Oct.3, 1925. 15c per copy, or start your subscriptionwith that number. RADIO WORLD, 145 W. 45thSt., N. Y. C.

cLA

Ask about Oh.Clarostat, heart ofthe Clarotuner.

If your dealer cannotsupply you, write toAmerAmerican MechanicalLabs., 285-7 N. SixthSt., Brooklyn, N. Y.

HERBERNARD of Radio World specifies Clarotuner.

So does Hayden and a host of other experts. Theyall recommend Clarotuner because no other tuner

nas such perfect control over regeneration, such freedomfrom interference. Model 2RK (two units) consists of atuner and a coupler that mounts with one hole andeliminates separate switches $7.50

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The 4 -Tube Erla PathfinderAfter you have completed the wiring of

this set the most important event takesplace and that is the testing of the set.After tinkering around with the tools youwill certainly want to know how the setreally works, and will want to make itwork as well as the laboratory would.

Before connecting up any batteries, an-tenna, ground or phones, it is a good policyto test all the parts individually for ccn-plete circuits, even though you should havedone this before you started to build theset. During the wiring you might haveaccidentally shorted an instrument or madean open circuit on one of the instruments.The testing is done with a small dry celland a pair of phones. After you havetested all the parts and found them to bein perfect shape, attach the A battery. Pullthe switch out. If the tubes light, attachthe B battery, at the same time turningoff the A battery switch. If possible, putin a paralyzed tube which still has a goodfilament. If the tube does not blow out,when placed in the various sockets, thenit is safe to put the good tubes in. Thi

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"THE LOW LOSS COIL PIONEERS"

is one place where a poor tube plays animportant part. Finding the A and B bat-tery circuts O.K., attach the antenna andthe ground to their respective posts. Nowplug in the phones, not the loud speaker.If you hear a distinct click, which is accom-panied by some rushing noise, then you maybe certain that you will bear music, andyou can prepare to call in your friends tolisten to the set. Tune both the variablecondensers in step.

FrequencyCakulation(Concluded from page 8.)

two stations is 130 kilocycles and the dif-ference between the corersponding read-ings is 13 divisions. Hence each divisionon the dial represents 10 kilocycles. Thedifference between the two readings forthe 610 kilocycle station is 10 divisions,and this represents a frequency differenceof 100 kilocycles. But this is twice thevalue of the intermediate frequency,which is, therefore, equal to 50 kilocycles.The same result is obtained from the tworeadings for the 740 kilocycle station.

This method of determining the inter-mediate frequency may be used for thepurpose of matching the transformers inthe intermediate frequency filter. It ispossible to measure the natural frequencyof each coil separately by means of thismethod. Thus out of a large numberavailable those coils which have verynearly the same frequency can be selectedfor a super -heterodyne kit. Or if thetransformers are made at home, themethod may be used for adjusting all tomatch some coil used for a standard, saythe first one made. The adjusting mayeither be made by varying the numberof turns or by varying the capacity acrossthe secondary winding.

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WGY Tests Transmission onHorizontal and Vertical Waves

Tests to establish the value of horizontalradiation on broadcast wavelengths weremade from the radio developmental labor-atory of the General Electric Company,near Schenectady, on two succeedingnights recently. C. J. Young, of the radioengineering department, was in charge.

Both tests were conducted on super-power, 50 kilowatts, through WGY, usingthe normal wavelength, 379.5 meters. The

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listener had an opportunity to comparereception on both horizontal and verticalradiation on each night. The scheduleprovided for a half hour period of broad-cast entertainment on the horizontal an-tenna and from 12:45 to 1:15 on the verti-cal antenna, regularly used for super-power transmission. A period of fifteenminutes was required to change connec-tions from one antenna system to theother.

Nearly All SW WorkThere has been considerable specula-

tion as to the advantages of horizontaltransmission. Practically all experimentalwork with horizontal waves has been car-ried on with the very high frequenciesand much valuable data have been col-lected. Reports on short wavelengthdemonstrations were necessarily few be-cause of the comparatively small numberof short-wave sets in use. It is alsopointed out that results on higher wave-lengths may be directly opposed to theobservations made on wavelengths from50 to 150 meters.

Instituting these tests, Mr. Young re-quested that all radio listeners report onthe quality, volume, comparative signalstrength and the fading characteristics ofboth forms of transmission. Work intransmission development necessarily de-pends upon the co-operation of all thosewho are interested in improved broadcasttransmission. Receiver development canbe carried on in the laboratory but trans-mitter work makes the entire country alaboratory and every listener an experi-menter. The reports received will bedigested and expertly analyzed and it ishoped by this procedure to collect a vastfund of information which must ultimatelyadvance the art of broadcasting.

A New DevelopmentSending out radio power which vibrates

parallel to the earth's surface is a com-paratively new development. In earlierdays it was assumed that an antennawhich lay parallel to the earth's surfacewould neither transmit nor receive sig-nals, and that is largely true of the longwavelengths which were used beforebroadcasting.

However recent experiments made byE. F. W. Alexanderson, consulting en-gineer of the General Electric Company,and by others, have shown that shortwaves horizontal radiation may be more

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effective than the vertical radiation ob-tained from the usual upright type ofantenna.

Alexanderson's TheoryMr. Alexanderson's work showed that

the short, horizontally polarized waves donot follow the surface of the earth likethe low waves but are launched into spaceas though fired by a high angle gun andthat they travel in a curved trajectorythrough the upper atmosphere. It is Mr.Alexanderson's theory that the wave onreturning to earth is vertically polarized.

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GET A NICE RADIO TABLE for Xmas for$6.00. From this advertisement, or send stampfor circular. Purcell Radio Dept., 2325 Ingersoll,Des Moines, Iowa.

PULLMAN CONDUCTORS, PORTERS. Menwishing such positions can easily qualify, informa-tion free. Supt. 123C, Railway Exchange, KansasCity.

LISTEN IN every Friday at 7 P. M. and hearHerman Bernard, managing editor of RADIOWORLD, discuss "Your Radio Phiblern," fromWGBS, Gimbel Bros., New York City, 315.6meters.

RECENT BACK NUMBERS of RADIOWORLD, 15c each. RADIO WORLD, 145 West45th Street, New York City.

HOOK-UPS !--A lot of them, some of which aresure to suit your purpose, appeared in RADIOWORLD dated Aug. 15. 15c a copy, or startyour subscription with that number. RADIOWORLD, 145 West 45th St., N. Y. C.

HOW TO BECOME AN AMATEUR OPER-ATOR-A comprehensive, illustrated article ap-peared in issue of June 27, 1925. 15c per copy, orstart your subscription with this number.RADIO WORLD, 145 West 45th St., N. Y. C.

HAVE YOU ANYTHING TO SELL OR EX-CHANGE? Use RADIO WORLD'S ClassifiedDepartment and get great results. 10c a word.RADIO WORLD, 14S West 45th St., N. Y.

HOW TO BUILD The POWERTONE, 1 dial,5 tubes, described in RADIO WORLD, issues ofAug. 29 and Sept. 5. Powertone Trouble -shooting,Sept. 12. Send 45c for all three. Special diagramsand "blueprint in black" included among the manyillustrations. RADIO WORLD, 145 West 45th St.,N. Y. C.

"LIBERTY AFLAME" and other patrioticverses. By Roland Burke Hennessy. In 'loth,$1.00. Columbia Print, 145 West 45th St., N.. Y. C.

November 7, 1925 RADIO \V 0 R I., 1) 27

onlinmed frOol lase 24)ground, or between a pair of wires, or itmay be that the wire is touching sonicobject such as a tree, pole, guy wire, etc.Such a spark discharge is a loss ofpower to the operating company and apotential source of serious trouble and forthese reasons the company is probablymore interested in finding and eliminatingthis type of trouble than the radio listener.Large leaks and sparks may often beobserved at night, especially in hot

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Freshman Eliminators-D.C., $17.50Freshman Eliminators-A.C., 20.00

Clarostat 1.70Freshman Kit, Regular $17.50 8.95Complete Bremer Tully Kit, including

Drilled and Engraved Bakelite Panel 39.50Amperites .79Erla Balloon Coils, set of three 8.95Eels Kits, complete coils and con-

densers 16.5fAmsco Cond., sty. line Ire., .0005 3.95Morrison Units adj 3.25Sterling double reading meter, 0-0

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weather. Ilowever, sparks which are toosmall to be readily noticed, may causeserious interference to radio reception.

"A frequent cause of interference ispower line inducted which is due to thepresence of power wires near the antennaor receiving set. A humming sound inthe telephone receivers will usuallyidentify this source of interference. Amethod of eliminating, or at least reducingthe magnitude of this interference, is toplace the antenna as far as possible fromthe wire lines and at right angles to them.

"Sparks are produced in the normaloperation of many types electrical appar-atus (such as motors, doorbells, buzzers,gasoline engines, X-ray apparatus, violet -ray machines, some forms of batterychargers, rural telephone ringers, heatingpad thermostats). Sparks are also some-times produced at defective insulators,transformers, etc., of electric wire lines.Sparks usually give rise to electric waveswhich travel along the electric powerwires and by them are radiated out and.are then picked up by radio receivingsets. The noise thus produced in a radioset may come from a disturbance whichhas traveled several miles along the elec-tric power wires.

"One remedy for such types of inter-ference is to eliminate the spark. Thisis possible if the spark is an electricalleak and not necessary to the operationof the machine in which it occurs. Manyvery useful electrical machines, however.require, for their operation, the makingand breaking of electrical circuits whilethey are carrying current and wheneverthis happens a spark is produced. It isimpossible to eliminate these machines sothat it is necessary to make the spark ofsuch nature or so arrange the circuits thatthe radio -frequency current is reduced orprevented from radiating.

"To prevent the radio -frequency cur-rent produced by a spark from getting onto the lines connecting the sparking appar-atus, some form of filter circuit is nec-essary. A condenser (1 microfarad, moreor less) connected across the sparkingpoints will short circuit a considerableamount of the radio -frequency current,or. a condenser connected from each sideof the line to ground will serve the samepurpose. A choke coil in each side of theline in addition to the condensers con-nected to ground forms a simple filterr,r,liit which chould prevent frequencies

in the broadcast range front getting 1.11 theline. A high inductance (choke cell) orhigh resistance connected in each sideof the line changes the characteristics ofthe circuit so as to reduce the amount ofpower radiated."

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Sangamo Condensersfor accuracy that endures.Heat proof, moistureproof, fume proof.

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Doubletoroid Coilsfor efficiency in radio fre-quency construction. Noexternal magnetic field.

LABORATORYTESTED

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Lid splined both ends to prevent warping.Nickeled piano hinge.Nickeled lid support of artistic design.Anti -vibration cushion feet (not visible in cut).Edges of lid moulded to match bottom.Shipped securely packed in strong carton.Prompt shipment.

7 x 18 x 71/2 or 10 in. deep7 x 24 x 7,/2 or 10 in. deep7 x 26 x 7V, or 10 in. deep7 x 28 x 7% or 10 in. deep7 x 30 x 7% or 10 in. deep7 x 21 x 10 in. deep

Hardwood, SolidRubbed Black

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CASH WITH ORDER or C. 0. D. if % of price issent with order.Prices F. 0. B. Hickory, N. C.Order express shipment, often cheaper than mail andmuch safer from damage.FREE WITH EACH CABINET a glued -up stocknon -warping %-inch BASEBOARD.

THE SOUTHERN TOY COMPANY, INC.Dept. R.W. HICKORY, NORTH CAROLINA

28 RADIO WORLD November 7, 1925(Continued from page 19)

down A or B battery. If you are using abatch of batteries, there might be a run-down battery among them. There mightalso be a broken cell in one of the B bat-teries. *

I HAVE a Neutrodyne set and wouldlike to find out the number of turns to

FOR "FANS" FOR "HAMS"III1 new 64 -page Radio NTRW 82 -page booklet ofO Catalog Including all 1st army and navy transthe bed and latest Kits, milting apparatus and mi.-

Parts and Acceseorim for cellaneous special. f o rbroadcast receiving nets. -harms such as W. /1Lowest prices In the coun- Choke Coils. Generators.ter. Resistance Dotes. eta

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BECAUSE this method of amplifi-cation is the only way to procure

quality of tone without the slightestdistortion. The Daven Super -Ampli-fier can be conveniently put into anyexisting set. Use it also in the newset you are going to build.To increase volume 50% and have nodistortion use Daven High Mu Tubesin Resistance Coupled Amplifiers.Prices-High Mu -20, $4.00. Mu -6 (forlast or output stage), $5.00.

Mail the coupon for complete information.

'M Ate grA6,-11.

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Newark nee. U.S.Pat. Dir. New Jersey

Get the ilundbooUna,kof Resistanceled Amplification. At111:it Ag ° 200. Or

Der. Ramo Conronerme1:44Sumen it Street, Newark.Meese send tee the following:....Rettletor Manuel. 30e is enclosed.....Complete Catalogue ((reel.

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WORLD Battery owners "tell theirfriends... Th 'Vs our beet proof of per-form... Send your order in lodes.

Solid Rubber Ca. Radio Dane..6 -volt. 100 Amorres . . . $11250 -volt. 120 Amperes . . . 13.256-voll, 100 Amperes . 14.00

Solid Rubber Cannata Sannle6 -volt, . . . . 511 250 -volt, 13.Plate . . . 13 25

place on a form 23 e" in diameter, usingNo. 24 double cotton covered wire. Thesecondaries will be shunted by .000375mfd. variable condensers.-George D.Sullivan, 803 West 180th St., N. Y. City.

The primaries contain 15 turns. Thesecondaries contain 60 turns. The tap onthe first and the second secondary of theRFT is brought from the 15th turn fromthe beginning of the coil. In other words,the tap number of turns is equal to theprimary number of turns. The primariesare the same on all three coils.

IN LOOKING over the RX1 radio re-ceiver, described in the Oct. 17 issue ofRADIO WORLD I find all the parts tobuild this set, but am in doubt about thecondensers. (1) Can any type be utilized?I ask this because I have a pair. (2)What is the capacity? (3) What type oftubes should be used in the variousstages?

(1) Yes, any type. (2) The capacity ofthese condensers are .0005 mfd. (3) 201Athroughout are efficient. Magnavox for\F and detector were used by the author.

*

WOULD LIKE to ask a few questionsregarding the Thordarson-Wade Set asdescribed by Herman Bernard, in the Oct.3 issue of RADIO WORLD. (1) Would a coiland variable condenser inserted in theplate circuit of the detector tube be anyadvantage? (2) Would tapped primary ofthe first coil improve the reception ofhigher wavelength stations, thereby rais-ing the normal aerial wavelength? (3)Mr. Bernard suggested improvement byusing Hi -Mu tubes in the 1st and 2ndaudio stages; is the Hi -Mu 20 correct?(4) Is there any change of wiring or partsto be made?-L. D. Phillips, 323 NorthState Street, Dover, Delaware.

(1) No. (2) Not enough to warrant in-clusion. The set regenerates even beyond600 meters. (3) Yes. (4) No.

* * *

I AM contemplating building the 4 -tubeDX receiver which appeared in the Octo-ber issue of "Radio Review," the one re-published from the Aug. 1, issue of RADIOWORLD. I would appreciate it very much:f you would tell me if I could use the 199

World RadioBttrie rfamou for

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ansee.fol manufacture and thouaanda of satisfied nen..Elsompad with Solid Rubber Cox. en Insurance againstacid and ...ago. You ene per.eent.

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SEND NO MONEYrelate bat., wanted and we will hip dy order

le received, by Er re C. 0 D.. cabled to yourexamination on nrival. Cana Offers 5 per cent dia.count terbit full WORLD BATTERY COMPANYwith order. Papa. 17Buyeewand 1219 So. Wabash Av... Chicago. Ill.get e guaranteed bat-tery at 60per cent so -stag talon.

tube instead of the 201A type such asused by Herbert E. Hayden. (2) Will thevolume of the set depreciate very much?-Harry G. Sashks, 4712 Behrwald Ave.,Cleveland, 0.

You could use these tubes successfully.The volume may be a little less, but only

NO BACKLASH

ir The Best Dialfor the

Finest TuningEquip your set with Fynur

Vernier Controls.They operate by traction

(no gears) so there isn't theslightest backlash or lost mo-tion. It's a new dial-beauti-fully and perfectly made, andso simple in construction thata child can take it apart andreassemble it. The dual con-trol, moreover, permits of aquick, general setting as wellas the infinitely fine vernieradjustment.

The Fynur is a quality dialfor those who want the verybest. Ask to see on; at yourSealer's, or write to us.

Price $3.50

August Goertz & Co., Inc.270-256 Morrie Ave., Newark, N. 3.

FYNITRVERNIER

November 7, 192.5R A 1) 1 (*) , ORf.0 29

a little. You will have to change the ir-sistance of the rheostats to suit the tubes.

I HAVE wired up the Roberts circuit.but am having some trouble with it. (I)The trouble does not lie in the detectorand RF stage, but in the AF stage. WhenI plug in on the last two tubes I get ahigh-pitched whistle in the speaker --Russell Julien, Arcanum. 0.

Put a .002 mfd. fixed condenser acrossthe output (speaker tips). Test ourstopping condensers for a short, also theresistors. Run-down A or B batterieswill cause such a whistle.

AS TO the RXI receiver, pubished inthe Oct. 17 issue of RADIO WORLD. (l)Could I use the Amsco or Streamlinestraight-line frequency condenser withbasket weave coils? (2) Could I use a199 tube with an Amperite to control thefilament of the tube, using a et -volt storagebattery. (3) Is it necessary to use a Hi -Mu tube for the resistance coupler? (4)If this is the case will a Daven do? (5)Could I use a 201A tube for a detector,and a 301A for the last stage of audio?-A. W. Green, N. Y. City.

(I) Yes. (2) Yes, the 6\199 type. (3)No, but volume is increased. (4) TheDaven is a good one indeed. (5) Yes.

I AM building the 1926 Diamond fromthe parts supplied by the B -C -L RadioService Co. As I ant situated severalhundred miles front the nearest broadcast-ing station, it is therefore necessary thatthe set give me good DX. (1) I wouldlike to know if I can use the UX tube inthe Last stage of AF. (2) Would it bebetter to use Hi -Mu tubes?-Oscar Bast.Wenatchee. Wash.

(1) The UX tube will not be of muchadvantage in the last stage, due to the

ARE YOU THE MANto be Yen In year Sono . ss ' sad demonlents PO,v1-110L.e. the , et as I tab.. rebattery enable eat nate reiesherI ISA 1.0 attaitsretal fee D C C. (144-113 4/.44 ry-to ses!and denoratretiett by the See Tat WiserCa.. poblie

stseonpaalse the/ retts

ant! ani elea!ers enerebera tY''<--.,.. feD7 nay -snood. then -

an you Is. te tabs Inn OteerteelneaAare Is 14100 Olsen Malt.

Write for We...nor, rpm, std ,,..,i

POWEROLA RADIO CORP.445 BROADWAY NEW YORK CITY

HOW TO BUILD THE POWERTONE, I dial,S tubes, deecribed to RADIO WORLD. tissue. ..a4

Aog. Zi and Sept. S. PE...try:roe Troublealmoting,Sept. 12. Send 4k for all three. Sthmal diagrrostad -blueprint in black" included among the en.,

alostrattoo. RADIO WORLD. la! West

r wit or, which would require too highIt voltage. 2) The tube, may beused in the Al: stages.

I WOULD like to know if a stage ofamplificatioti can be added to a crystal

detector. (2) If it can, will you pleasetell me how? ---W Moore, 2150 7th Ave,N. V. City.

(1) l'es. (2) Connect one of the t,Mats which went to the phones toP post of the AFT. Connect the othr:phone post to the B post of the APTApply no B battery to the ft terminal

.° pg

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Constant vigilanceis the price of kxxxxxxxuniformitivm.v.m,v,and constant vigil-ance is maintainedover Magnatrons.That is why Magna-trons are uniformandunicormly good.\\'0,

IR E xth. naA

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I he I' poet usually goes to the base.while the B pest goes In the return of thesecondary, which conies hem the cat-win.ker of the crystal. The 0 of APTgees to ti of the socket, the p to A minus.

Long Ditaiier Radio$2.95

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Radio Laboratories. 254 SootsLas *

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hi AG MATRON SRADIO 2 -For -Price -of -1 Subscription Offer

For NEW RADIO WORLD Subscribers Ordering NOWRadio World has made arrangements

-To offer a year' subscription FREE forany one of the following publications

with me year's subscription for RADIO WORLD-RADIO NEWS or -RADIO DEALER or-POPULAR RADIO or -RADIO JOURNAL or-RADIO BROADCAST or -RADIO (San Frnciscoi ce

-THE EXPERIMENTER or-SCIENCE AND INVENTION or -RADIO AGE

this is the wety to gat two pol.lictiona-for the prici of mot --Add II 40 year entre bee- Send $.111/ today for RADIO WORLD --Canadian or Foreign Poottaa..-for ono year (rrulnr price - Present RADIO WORLD toilsneettrer.-for S2 numbers.; -cam Inks advantage of tide near by- and select Kay tam of the other entansdng subscriptionr eon von,-nine publications for treeiv toontka. -If they .and rmgre, al NOW.

RADIO WORLD'S SPECIAL TWO -FOR -PRICE -OF -ONE SUBSCRIPTION BLANKRADIO WORLD, 145 Wat 45th Street, New York City.Enclosed find 56.00 for which send me RADIO WORLD for twelve months (52 numbers), beginning..and also without additional roc, Radio News or Popular Radio, or Radio Broadcast. or Science and Invcon,ri. Ore..rri orFrancisco), or The Experimenter, or Radio Journal, or Radio Age (or VOA) for two yearly sobseriptionin.

Indicate if renewal.Offer Good Until Street Address..

November 20, 1925. City and State..

30 RADIO \\ ORLD November 7. 1925RESL Lis LDITOIt :

1 have built The Midget 3 -Tube setdescribed by Herbert E. Hayden in theAugust 6 issue of RADIO WORLD, andit certainly works great. I don't thinkany more could be expected from threetubes. The first night that I completedthe set the following stations were re-ceived by me, all on the loud speaker:WSB, WCCO, WOK, \VBBM, WIBO,WAFD, WFAM. WTAM, WENR,WCEE, WCBM, KDKA, WBZ, WBAP.WEAR, WEBH, WGN and WGY. Ifthis is not considered a good record Iwould like to know what is. Anybodywishing r., build a good set, take my ad -

A Satisfied Radio DealerThe Scat at

Satulection

ablosoents. guar..teed Larsolucts reliable r,Pair* licnions1 Muumuuitled teal SERVICE A.Iof thew thing. are ret,resented by "THE PEALO F SATISFACTION "Lout fur 10! It appears

.11 radio soonties boldbd wt. It 111 your guar-antee Of eatisisettuIt rite us card 1.101.Just say I am Duet -coedM The Seal of &Mal.-

od three toy-s, CAM, fur ow nest

is! Leaf Cotalos

THE BOWER RADIO SHOPREADING. MICHIGAN

EVERY SET BUILDERNEEDS MgrTHIS

"Morsing Bus -Bar linion"Makes for gulch ssembling. Repaint

can be made by ruing Mussing Bus -BarUnion without takma .1 apart.

Auemble round or square Bus -Bar andsold., tkoee eti, es et time. Order No

for No. No. 2 Ice 12 wire. SendLS cents for enough for budding ma set.or ten dose. for II 011.

Newark Watch Casa Material Co.is Ward Street Newark, N. J

1" 1,,,HUTORS WA.% TEL)

EASTERNPICKLE COILSBOTTLEid

BLelotitely Welt.* NYkiimiye for lie see.

wirlatlea wo -elite tau -Aube RX.1 crrutswaulbed l Roils World Per sot $6.00

Eastern Pickle Bottle Coilsare Wu. lest.** Ira Porter, PorlwwwIre1.140161 Weird.:S UPERDYNE (511.150 per asi1. BROWNING.DRAKE 114 00 sr tot). ROBERTS t5411 50 Pr,sell. TUNED R. F CIRCUITS 152.0 ON 5510

Certlged by Norman Sweat.AI your testers or direct. p.atoald

EASTERN COIL CORPORATION22 WARREN t.1 NE* Oils

RESULTSReaders report on their ex-

periences with sets built fronthookups published in RADiu

Address Results Editor,RADIO VLSICID, 145 west 45thStreet, New York City, and sendphotographs of sets, if possible.

vice and build this one. They will neverbe sorry, once they get it working right.

Thanks to Herbert E. Hayden andRADIO WORLD for this circuit.

LAZARUS HARRIS,258 East Market St., Wilkesbarre, Pa.

IRESULTS EDITOR:

I have tried five hook-ups from RADIOWORLD and they all worked fine. 1now hale the Transcontinental Reflex,published in the January 10 issue ofRADIO WORLD, and it is great. It tunesvery sharply.

JAMES \V. FARR,c/o H. T. Shannon,

Cary Station, Ill.* *

RESULTS EDITOR:I have just built The Diamond as a

portable, using the 199 tubes. The setwas built on a 7x18" panel. The set waswired with bell wire. At first the resultswere poor, due to the uncontrollable os-cillations. 1 then reversed the ticklerconnections and the following stationscame rolling in with speaker volume:WMAK, WBBM, WOK, WSAI, WMBF,WEBH, KY\V, WLW, WHT, WCBD,WTAS, WCAU, WJJD, WGBU, WCEE,WHO, KDKA, WBZ and WKAQ. It isreally a DX hound, and if handled prop-erly, will bring in the stations withoutany whistling.

Any set published in RADIO WORLDwill work if properly wired. I say thisfrom experience, as I have wired severalsets which were built from RADIOVVORLD's diagrams and they all workedafter the diagrams were followed.

THOMAS D. SUTTON.1450 Chapel St., Norfolk, \V. Va.

yowsmuurrrlpum

THE STAND \144.4°V)NNECTOEL

HOWARD B. JONESau S. CANAL STREET CHICAGO

LISTEN IN ever) Friday al 7 P. M and hcarfit line. Bernard, managing editor of RADIOWORLD. shun. "low Radio Problem," fromNUBS. Gimbel Ken York City, 210,6meters.

FILL OUT AND MAIL NOWSUBSCRIPTION BLANK

RADIO WORLDRADIO t4'URLD

Please send me RADIO WORLD tor..

please Pied enclosed I

S1'IISCR1 rill" KATES.Smile CalPF $ .LS'Mee Mantas 1.76

.SLR Mouth* LitOS Year, Si Imes. 5.LC

Add SIAM Year tor rennetFleSaillo: iar Caaadraa Peetas. -

14:. 11 sri Nets- York City

............. ler wewk

kcstkrs kauTus:I base built three of the sets "A Baby

Can Build- as described in the August 29issue or RADIO WORLD by HerbertHayden and they are all 0. K 1 canbring in DX right through thePittsburgh. Chicago. New York and At-lantic it) are among the carcs that arereceived

1 hale also built the --Tube SpeakerReflex. described by Brewster Lee its theAugust 15 IS51.1C. It sure IS a wonder fortwo tubes. I can hear it all on er thehouse.

ROBERT K FM Y.85 Magnolia St., Dorchester 25. Mass.

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Ow buns, wiruittlon With ouud uosIsie Aerial Tut*distance seta. ineludios Ulm at it. we It. lug 1.twildsAloha Eagle Hullo Town are handaoweWe ship on a to way-baol poaretitee Ad toeor write w for IlleratoreJ. B. Berreil Cl.. 714 N. Gambill.* Aso SIIIaukes. WI.

Dept. 15

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NAMEPLATESFOR

RADIO WORLD'S 1926

Diamond of the AirNOW READY FOR DELIVERY

Those who have already orderedthese nameplates will receive themin the course of a few days.

If you are building the Diamondof the Air, and have not alreadyrequested a nameplate, semi us yourname and address and we will sendyou one

RADIO WORLD145 W. 4Sth St. New York City

November 7, 1925 RADIO \V 0 R 1. D

Hammond's 8 -on -1 InventionRejected for Broadcasting

WASHINGTONApplication of the new invention of

John Hays Hammond, Jr., by which itis possible to transmit eight separate radiosignals simultaneously on one wavelength,is not considered by experts of the NavyDepartment as of practical application tobroadcasting.

The invention was examined by theNavy experts. An official report is be-ing prepared which soon will be for-warded to Mr. Hammond. Although itis considered impractical for broadcast-ing purposes, Mr. Hammond's inventionis regarded as having enormous commer-cial possibilities.

Operation of the Hammond device onwavelengths between 200 and 600 meterswould complicate rather than solve thepresent congestion, the experts say. Thefirst objection is that none of the 5,-000,000 receivers now in operation would

$4.75POLLO

A loud speakerof surprising musi-cal quality a n dvolume. In theclass with high-priced speakers.Artistically d e -signed. Swan neck

type. Adjustable unitwhere volume and toneare at all times underperfect controL Sendno money. Just pay thepostman.

RIX RADIOSUPPLY HOUSE, INC.

!".1115 4th Ave. Dept. 43 Brooklyn. N. Y.

EvEREADyRadio Batteries

-they last longer

Get Your CoilConnections Right

When You Build

The

Powertone

LE

L1

Construction of this 1 -dial, 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. Trouble -shoot-ing in this set, Sept. 12 issue. Send 45c.Get all three.

be capable of receiving the multiple sig-nals. The only thing they could getwould be a heterodyne squeal. A secondobjection is the creation of a greaternumber of harmonics by the device. Ifeight signals are being transmitted on a500 meter wavelength, eight harmonics arecreated at 250 meters, causing just eighttimes the present interference.

The' Hammond machine makes pos-

sible the transmission of eight signalssimultaneously through the use of a dis-tinct net of "sub -frequencies." The deviceoperates with a single carrier wave, butwith eight sub -frequencies superimposedon the original wave.

NEW STATION FOR BALTIMOREWASHINGTON

A new class B station will take the airin Baltimore within a week or two. Thestation, which is just being completed bythe Gas and Electric Company, will havea call of WBAL and, it is understood,will operate on 256 meters with 1,500watts power.

TROUBLEPROOFOnce a variable condenser is in

a set, if anything goes wrongwith the condenser, you have torip the set apart just to enableyou to hunt for the trouble.

erefore, use a coed thatis not as fragile as peanut -brittle,but as sturdy as an oak-one thatgives the best possible service,and gives it unfailingly!

"Built to Last a Lifetime"The Streamline Straight -Line Frequency Condenser assures you of the greatest

possible tuning ease, with wide separation between stations otherwise crowded togetheron the dial. The rotor plates turn gently and are safeguarded against touching thestator plates. Rigid mechanically, low -loss electrically, the Streamline is also a thingof beauty and a joy forever!

.0005(23 plates)

$2.50.00035

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Enclosed find for which send me by return mallcondensers, capacity

Streamline SLF

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

NAME CITY

ADDRESS STATE

RADIO WORLD November 7, 1925

?fie ,New WAVE MASTER- a Radio SetWorthy to Bear the KELLOGG Name

The Wave MasterConsole Model

A handsome genuine maho-gany. design with battery compartmentsand inbuilt horn. Price, $275.00

Wit ehout bacettery $225.00tablAlso made in the beautiful Con.aolette model, genuine maho-

gany, price,$235.00

A Year Ahead! The WAVE MASTER, 5.Tube Standard ModelCabinet of solid, Genuine Mahogany, beautifully finished,28 inches long, n inches high. Price,

$125.00

A Separate Circuit for Each40 Meter Wavelength BandOne -Dial Control, Yet Greater Selectivity.

KelloggSymphony

Reproducer$25.00

fe, .'""--

c.:4.04

s.

"I never dreamed it was such funk"I used to be content to enjoy radio merely es a listener.never realizing how much greater pleasure I was mis-sing. I had no idea of the fascinations of radio tuning-the fun of going after any station and getting it."WHEN you make a telephone call, the operator con-nects you first with the "exchange" and then withthe desired number of that group or division.

To "connect" the WAVE MASTER instantly with any de-sired broadcasting station, you first set the pointer for the"Exchange" or wave zone group to which the station belongs and then merely turn the Station Selector dial. "Ex-pert" tuning becomes child's play. To separate stations veryclose together in their wavelengths, is astonishingly easy.When buying any radio set, protect yourself by learningsomething about the firm that produced it - their reliabilityand experience. For 28 years Kellogg has produced thefinest of telephone apparatus. Since radio begin Kellogghas built the highest quality parts.If you do not know where you can see, try and hear the WAVEMASTER in your neighborhood, write us. We'll give you the nameof your nearest dealer. and, if you wish it. a full technical explanatiotof the Wave Master Circuit. Ask for Folder No. Z.K.

Radio Dealers and JobbersThe WAVE MASTER franchise backed by Kellogg resourcesand our powerful advertising campaign, is most valuable.Open territories are being rapidly taken up. If interested,wire or call on us promptly for our money -making proposition.

Kellogg Switchboard & Supply Company1066 West Adams Street, Chicago,

Documents

NUMBER! c1E,.s 1? AM 0 WORLD · 2019. 7. 17. · culty might lie exclusively in the failure of C2 to reach sufficiently high capacity for short-wave regeneration. This might be cured