Vol.IV, No.6 June 1975 Monthly except during July and August Price ' $4.50 yearly Single Issue 750

Second-class postage paid at Dallas, Texas Office Address: 9820 Silver Meadow

THE NEWSPAPER FORTHE HOBBYIST OF VINTAGEELECTRONICS AND SOUND

HE HORN SPNEW TELEPHONE TRANSMITTER.

We give an engraving of a new transmitting telephone,patented by Mr. E. Berliner, of Boston, Mass., and owned andmade by the American Bell Telephone Company, of thatcity. Fig. 1 is a front view and Fig. 2 a perspective viewshowing internal parts.

The instrument is very simple and compact, and has theall important advantage of not being liable to disarrangement.

The principal feature of the invention is the dispositionof the carbon con-tact surfaces, onebeing attached tothe diaphragm, theother being sup-ported by a metalsocket attached toa hinged plate se-cured to an armthat projects fromthe back of themouthpiece down-ward over the dia-phragm. This armserves the doublepurpose of support-ing the free carbonelectrode and clam p-i ng the diaphragmin its place againstthe back of the ironmouthpiece. Thediaphragm is boundaround the edgeswith soft rubber,and is separatedfrom the mouth-piece by a ring ofpasteboard. T h eiron mouthpiece ishinged to a castingfastened to the cir-cular box which contains the induction coil and supportsthe binding screws for the battery, line, and ground wires.To the front of the induction coil is attached a plate con-nected with the battery wire, and carrying a spring havingin its free end a screw which bears against a spring connectedwith the center of the diaphragm and acts as a dampener aswell as a conductor, through which the current passes to thecarbon electrode at the center of the diaphragm. The bat-tery current enters at one of the binding screws, passesthrough the primary wire of the induction coil, through the

&yl

TR F TUNED RADIO FREQUENCY

NEUTRODYNE, A GOOD WAY

Considerable interest has beenexpressed about tuned radio frequencyradio, especially the neutrodyne whichstabilizes the circuits and at thesame time utilizing all of the av-ailable electrical gain.

Since a triode detector gives aresponse porportional to the squareof the voltage applied to its grid,a twofold gain in voltage across

spring and carbon electrode at the center of the diaphragm,through the hinged electrode, metallic mouthpiece and itshinge, and back through a binding screw to the battery.

The variation of the current in the primary circuit occursat the contact of the two carbon electrodes, the contactbeing varied by the vibration of the electrode attached to the

)ill)

IIIIIIIIIBERLINER'S TRANSMITTING TELEPHONE.

diaphragm.When the transmitter is used for long distance telephony,

the pendent carbon electrode is made heavier, to reduceresistance in the local current and to amplify the electricalundulations.

The terminals of the secondary wire of the induction coilare connected with the two remaining binding screws, whichare connected, one with the ground and the other with theline, in the usual way.

The accessory devices connected with this transmitter may

coil E by tuning it will result ina fourfold increase in signal. Moregain may be secured by placing avariable condenser (capacitor) acrossthe secondary of the R.F. transformerE. This makes it possible to tunethe circuit E C to the frequency ofthe impulses in coil D and much highervoltages are induced.

Before manufacturers ganged allthe variable condensers together, pro-vided all the circuits had the sameelectrical characteristics, two stageradio amplifiers had three controls,which is familiar to the old batteryset collector. However, the straight

Publisher, Jim Cranshaw

214-286-1673

MORE P.: GES

EVERY QUIRTER

To give more need-ed space in The HornSpeaker, especiallyafter going to thesmaller format, theMarch, June, Sep-tember and Decembereditions will beplanned for 12 pages.During the period ofa year the newspaperwill have more space.

be of the usual character. It will operate well with any ofthe well known forms of receiver, and is easily managedand thoroughly efficient. This transmitter has been wellintroduced, and large numbers of them are being used inEurope. They have been adopted on several of the leadingGerman railways, and are extensively used in the Germanpostal service.

SCIENTIFIC AMERICAN, May 21, 1881

tuned radio frequency stage would tendto oscillate.

Some of the methods wasted energyin order to prevent oscillation.Since a vacuum -tube oscillates be-cause electrical impluses are exchang-ed or thrown back and forth betweenthe grid and plate circuits which re-quires some sort of coupling whichmay be magnetic or between a platecoil and a grid coil or electrostatic,as in a condenser. The grid andplate of a triode form a tiny conden-ser (interelectrode caaacitance)which

acts as a coupler between the twoparts of the system. This coupl-

2 The HORN SPEAKER 9820 Silver Meadow Drive, Dallas, Texas 75217

ing is so small that it is not ef-fective until the parts are tunedwhen very little coupling is need-ed to cause oscillations.

That explains why small neutra-lizing condensers are placed be-tween the grids of the R.F. stages(C!, C5) in the diagram (Schematic).You will see in the diagram thatthe plate coil D is not tuned di-rectly, but the magnetic reactionof current in E upon D gives thesame effect as placing the variablecondenser across D.

When a small condenser of pro-per capacity is connected betweenE and G an electrical impulse isimpressed upon the grid (G) equalin amount and opposite in sign tothe impulse given to it by the con-denser G -P. This action destroysthe coupling and makes the circuitvery stable.

Shielding of various parts ofthe old sets helped the neutraliz-ing condensers to make oscillationimpossible by preventing magneticand electrostatic coupling betweenthe parts.

Later, we will see how screentubes took over the job of neutra-

lizing

RF.

8E

Fig.17

Det. AF A.F

TWO -STAGE TUNED RADIO -FREQUENCY AMPLIFIER (NEUTRODYNE), AND TWO -STAGE AUDIO -FRE-QUENCY AMPLIFIER (TRANSFORMER -COUPLED)

CI C2, Cs, tuning condensers; C4, Cs, neutralizing condensers; Ce, grid condenser and grid leak; R.F., radio -frequency tubes; Det., detector; A.F., audio -frequency tubes; D -E, DI-EI, tuned transformers; F -H, Fr -HI,

audio transformers; R, rheostat; C7, by-pass condenser; V.P., volume -control potentiometer.

The neutrodyne circuit was developed by Professor L. A.Hazeltine.

ALIGNING TRFs

Put a signal generator on the an-tenna and an output meter on thespeaker. Start in the middle of thedial and adjust the first stage formaximum gain, then the second stage,etc. Then repeat the adjustments,if needed, on the lower and highersides of the dial, making the bestof all locations.

If the receiver is of later con-struction and is provided with bothtrimmer condensers and slotted endplates for alignment, read the pro-cedure in the September '75 issue ofThe Horn Speaker or read page 691 ofGherardi's Modern Radio Servicing,1935.

LETTERSEDITOR'S MAILBAG

Dear Jim:I have enjoyed reading The Horn

Speaker and look forward to receivingeach copy as the articles are par-ticularly interesting.My collection of tubes and lamps

has been growing slowly and I haveadded a 1881 Edison lamp to the col-lection recently. It cost me C80.but was well worth it. Other recentlamp acquisitions include some 1000watt 1920 vintage bulbs and colouredglass bulbs I have waited 15 yearsfor. The only valves of interesthave been some British and Europeanones of the mid '20s.

Sincerely,Fin StewartFerrowatt Electrical Museum673 Great Western Highway,Faulconbridge, N.S.W. 2776Australia

To the Editor:I own several Scott receivers and

have an antenna problem. Because oflimited space, I have erected a "L"antenna on my house. The problem a-rises as to lead-in, and input im-pedance of Scott receivers. I am

trying to feed my early Philharmonicwith 75.k. coax with the hot wire tothe antenna and shield free. At thereceiver, one ant. post is connectedto gnd. and coax shield; the hotwire goes to the other ant. terminal.This results in low noise, as fromTV, but poor signal transfer. I have

tried 30Qit TV twin lead, but whilesignal improves, noise goes up dras-ticly. This happens no matter whatcombination of antenna connections Ihave tried at the receiver end.

I experimented with a twisted

pair of wires recently. I used

only a 50 foot section of twist-ed telephone cable and no antenna.The results were as hoped for; no

signal. It is apparent that thismight make a good lead in. Un-

fortunately, this cable doesn'tlook as if it is suitable; If oneconsiders outdoor conditions. I

am considering, therefore, twisting

some good quality wire and making

my own 1935 vintage lead-in wire.

Can anyone confirm the usefulnessof this type of lead-in?

Also, my research indicates thatthe old RCA double -doublet, withmatching tkansformers was quite a

good antenna. It seems to have beencopied by everyone in those days.Does anyone know if it is available

in any form and where?I hope someone can suggest a less

lossy, yet well shielded lead-inthan coax. Any takers?

Mike StosichLiJJ.& Assembly Dr.

Bolingbrook, Ill. 60439

Dear Sir:The data you published on the in-

put characteristics of old tubes hasbeen most helpful to me. I also

find the output characteristics tobe helpful, especially in designingpower supplies (battery eliminators)

for old sets. I recently found the

enclosed output characteristics inProceedings of the Institute ofRadio L`ñgineers vol. 14, 15/6. Youmay be interested in publishing themalso.

Sincerely,Jack R. Smith

Dear Jim:I am enclosing a copy of a brochure

that I found in an old radio I re-cently acquired. It came out a little"light struck," as the original wassort of an orange color & would notreproduce very well. But the old ra-dio I: have is just exactly like thepicture & is in real good condition.The front panel with its sterlingsilver plated escutcheons & hard-ware really cleaned up nicely andtook on a high polish. It is one ofthe most beautiful old battery setsI have ever seen. But, other thanthis brochure, I can not find anyreference to such a radio or the com-pany that made it. Perhaps, if youfind this of sufficient interest tomention it sometime in your publicat-ion, someone may know something aboutthe set or the manufactor.

I have a feeling that it may havebeen assembled by the Allied peoplefrom parts furnished by "Erla" asthat name (ERLA) is stamped in theback of all three variable conden-sers, on the grid leak & on 3 or 4bypass condensers so it certainlylooks as if there may be a connect-ion.

Lionel Haid26 Circle DriveRichmond Ind. 47374

The HORN SPEAKER...., 9820 Silver Meadow Drive, Dallas, Texas 75217

EDITOR: The brochure Mr. Haid in-cluded with the letter would notreproduce but it naned Ramway,"The Most Sensational Value in theWorld."

Club NewsKEN LONGENECKER, SECRETARY

OHIO CLUBFrom Soundings, the official pub-

lication of The Buckeye Antique Radioand Phonograph Collector's Club,there is news that Ken Longenecker,1937 Stoney Hill Drive, Hudson, Ohio44236 has accepted the job of clubsecretary for 1975.

ANTIQUE WIRELESS MUSEUM,NEW YORK

The Antique Wireless Associationhas opened a museum free of chargeto the public from May through Oct-ober on Sundays from 2 to 5 p.m. andWednesdays from 7 to 9 p.m. It will

be opened to radio clubs, schoolsand engineering groups at other timesby advanced appointment.

"The exhibits will try to tell thestory of electrical communicationstarting with Samuel F.B. Morse's1840 telegraph to present day tele-vision and solid-state circuitry,"noted Bruce Kelley, association sec-retary. "In addition to communicat-ion items, there will be a largeelectrical display - early electricmotors, light bulbs, measuring in-struments and phonographs."

The museum in East Bloomfield,New York is located on South Avenue(off Routes 5 and 20) and acrossfrom Elton Park, the village green.

Information and quotes are fromDaily Messenger, Canandaiqua, NewYork, May 2, 1975, contributed byErnest E. Mintel

SOUTHWEST VINTAGE RADIO ANDPHONOGRAPH SOCIETY

The Society had fun and success atthe 011a Podrida exhibit in Dallas.they enjoyed seeing their radios ex-hibited and were pleased to learn a-bout other collectors unknown to theSociety previously.

The Society will be regional andit would like to hear from otherswho would like to join. Those whowould like to join write to thenewly -elected secretary, Walt JacksonSouthwest Vintage Radio and Phono-graph Society, P.O. Box 19406, DallasTexas 75219. Phone 214 262-7855.

A monthly newsletter is mailed tothe members which is edited by BobSullivan. It is reported that thenewsletter will be designed to in-terest members who can't attend anyof the meetings as well as the oneswho go to all the meetings.

John Alford is head of a committeeto work out the details of dues,membership forms, etc. By the way,Jim Cranshaw was elected Chairman andMel Zemek is the Vice -Chairman.

The next meeting has been set tobe at the home of Bob Sullivan, 513Hanover, Irving, Texas at 7 p.m. onJune 21, 1975.

Plans are being made to have anexhibit at the Chapman AutomobileMuseum in Grand Prairie Texas. Forinformation call Jim, 2i6-1673.

BIG SWAP MEET MID -AMERICA

"The Mid -America Antique RadíoClub is going full gun. In only

6 months we now have around 50 paidmembers. Last week we had a dis-play at the Electronics World show,then had a table with displays atIndian Springs shopping center for4 days & then on Sunday a display etPHd Ham fest. About 12 members par-

ticipated. We're having our bigswap -meet July 13 at Loose Park, con-

test & picnic. Hope to have FredStein, Jr. (son of the Steinite man-facturer) there.

Picked up nice Radiola VII, Gen-eral Radio GR-3, Tresco 3 tube re -

gen., Steinite, Crystal, Grebe CR 8& 9, National HRO lately," wrote Bob

TII1: nl'II'IT 1'll \II \I'tF.111-11.'V 111' .\\1I'1.11-Ih:II Tl'IIF:

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Lane on May 6, 1975. His professionaladdress is 2301 Independence Ave.,Kansas City MO 64124, phone (816)241-6796.

AIERANDERSON, RADIO PIONEER DIESFamous not only for the high fre-

quency alternator which produced acontinuous wave transmission for suc-cessful broadcasts with 2 kilowattsand 1.00,000 cycles in 1909, an im-provement of Fessenden's alternator,Ernst Frederick Werner Alexandersondied May 14, 1975 being hailed byGeneral Electric as their most pro-lific inventor. His many inventionsmentioned frequently in the old radiobooks and magazines are familiar toradio collectors and historians.

In addition to the admirationfrom other radio engineers he wasgiven the honors first of the goldmedal of the Institute of Radio En-gineers, and then of the presidencyof that organization in 1921.

At the May meeting of the South-west Vintage Radio and PhonographSociety, Earl McDonald, a radio en-gineer showed some slides of the

Alexanderson Alternator atHaiku, Hawaii Naval Station,in commemoration of Dr.

Alexanderson.

FIND OF

THE MONTHDuring the last month no

collectors have reported un-earthing anything rare underunusual circumstances at"steal" prices. Since THS

skips two months during thesummer, there should be a lotof "finds" in the Septemberissue.

BACK ISSUESORDER NOW!

The Horn Speaker

All 20 back issues for 1973and 1974 `10.00

All 10 back issues for 19731.00

Any issue from January 1973to now 50¢ea.

Later, we should have completevolumes for 1972.

The Horn SpeakerBox 12 Kleberg, Texas I

75145

4 The HORN SPEAKER 9820 Silver Meadow Drive, Dallas, Texas 75217

ta?CLatPJ'LC

9adie"CUSTOM BUILT FOR E.H. SCOTT"

By J.W.F. Puett

Receiving a number of requests

for a "professional type communicat-tions receiver," E. H. Scott, whobuilt radios during the old days thatconnote the ultimate in electronicachievements and cabinet styles, soonfound himself at the proverbial draw-ing board. This would be one of the

last and greatest of his ingeniousdesigns -- perhaps the most elaboratecommunications receiver the worldhad ever seen. The circuitry of hisScott Philharmonic radio would bethe basis for his design.

In 1941, the Scott Special High -Fidelity Communications receiver wasannounced in the Scott Newa. Sellingprice? -- 1,650.00 F.O.B. Chicago.

Two tuner circuits were incor-porated on the sane chassis, one forthe seven short wave bands (1.7 to64 MHz) and the other for the twolower ranges (1710 to 520 KHz and395 to 140 KHz). Each tuner utiliz-ed two rf amplifier stages with aseparate mixer and local oscillator.The alignment procedure requires 94different adjustments. There were

three I.F. amplifier stages. In ad-

dition to a diode type noise limiter,a Scott scratch suppressor circuitwas provided to improve the signal-to-noise ratio on weak signals with re-spect to high frequency hiss andstatic.

E. H. Scott spent many happy hourswith his own Special. He maintaineda listening station in his upstairsden. His antenna system consistedof two Scott super double doublettAntennas, one being positioned fromNorth to South and the other from Eastto West. Switching was provided toselect the desired antenna; however,"about 90% of the time the antennafacing North and South gave the bestsignal."

With separate tuners for standardbroadcast and short wave, Mr. Scottreported in a 1941 issue of the

you'll have funwith this....

OLD TIME

Transistorizedonly 3%21 high!

TL?A SISTOL FAIDIC 9 i 90Postpaid

Remember the good old days ... when every-one sat around the parlor listening to theradio? This is a miniature copy of that famouscathedral -style old-time radio and measures31/2 x 11/2". Our model has five transistors andtwo diodes and comes in handsome wood-grain plastic case. A wonderful piece of nos-talgia. Uses one 9 -Volt battery which is in-cluded. Each comes gift -boxed.

ALTS BMPOflIUMP 0 BOX 19406 DALLAS TEXAS 75219

EVENINGS 214.262.7855

Scott News, "I can have two stationstuned in on the Special at the sametime, one on the short waves, anotheron the broadcast band, and by a flickof the switch marked "Wavechange" andwithout touching any other control, Ican bring in either station instantly.""It is extremely interesting, whenone of the local stations is rebroad-casting war news from Europe, toswitch over and receive the same pro-gram from the European station, thenby throwing the control switch, makean instant comparison between recep-direct from Europe and the same pro-gram being rebroadcast from the localstation.

No one seems to know how many ScottSpecials were built. The general con-sensus of opinion is that they werenever manufactured in the same waythat Scott home -entertainment setswere. Some broadcast stations usedthis set to monitor foreign news-casts during World War II. It isquite possible that a few Specialsare still floating around in thearchives of "obsolete" equipment atsome of the older broadcast stations.

This receiver consists of a largeblack crackle -finish metal cabinetwhich houses the chrome -plated tuner

The Microphone-Radio's Electric EarContinued from last month.

The condenser microphone, althoughof ancestry quite as ancient as the loose -contact one, owes its present developmentchiefly to an engineer of the telephoneindustry of today. Dr. E. C. Wente ofthe Bell Telephone Laboratories. Likethe carbon microphone, its principle issimple. The thin metal diaphragm merelyserves as one plate of an electric con-denser. If this plate moves back andforth with reference to the other plate,all other conditions remaining the same,the electric capacity of the condenserchanges in accordance with the familiarformula in which the distance betweenthe two plates of the condenser is oneitem of the equation. Rhythmic altera-tions of the condenser capacity thus arecreated by sound, are picked up electric-ally, amplified and constitute the outputof the microphone.

This condenser microphone has been atruly invaluable device, not only in broad-casting and sound recording during thepast few years, but in the developmentof the art of acoustic measurement. Un-til very recent months microphones ofthis type have been the only ones con-stant enough in efficiency and other char-acteristics to be used at all for precisemeasurements. With nothing better thancarbon microphones, no modern noisemeter could have been developed.

By possible, although difficult, precau-tions concerning mechanical dimensionsand the like, condenser microphones maybe made to respond to sounds as high inpitch as 10,000 cycles and to have vir-tually the same response ratio betweensound energy and electric energy over theentire frequency range between 40 cyclesand 10,000 cycles. This is what is meantby a microphone the response character-istic of which is flat.

Not every condenser microphone, evenof responsible manufacturers. has thismuch -desired flat characteristic, but thebest types can be made to have it by per-fect design and adjustment, avoiding thepeaks or hollows of response at specificfrequencies due to mechanical resonancesin metal parts or in inclosed air spaces.What is even more important practically.the response characteristic of a condenser

microphone, whether flat or not. com-monly remains the same over long periodsunless the instrument is actually takenapart or damaged.

All condenser microphones suffer, how-ever, from a serious defect which appar-ently is incurable and which seems tome sufficient to destroy any chance ofthis type of instrument becoming the per-fect microphone of the future. This de-fect is the necessity of placing the actualmicrophone diaphragm, the so-called but-ton, within a few inches of the firstvacuum tube of the amplification system.Usually this first tube is placed in the casecontaining the microphone, which makesthat case bulkier than is desirable andalso requires the supply to it of batteryor other voltages for the tube.

This necessity, any radio engineer willperceive immediately, springs from thefact that the thing which this microphonereally detects is a minute change of elec-tric capacity. The capacity of the wiresleading from the two condenser plates inthe microphone to the terminals of thefirst amplifier tube naturally becomes apart of the total capacity which is beingvaried by the sound. If these leads aremore than a few inches long their inva-riable capacity . becomes too large a partof the whole capacity which operates theinstrument and the microphone will notperform satisfactorily. It is hard to seehow this limitation of condenser micro-phones can be escaped any more thancarbon microphones can escape the han-dicap of variation in the behavior of itsloose contacts.

These serious defects of both othertypes provided the opportunity of the new-est microphone to be perfected, the so-called dynamic or electrodynamic type.Again the principle is old and familiar; itis merely the interaction between an elec-tric current and a magnetic field, respon-sible for the electric motor, the telegraph,the galvanometer, the modern dynamicloudspeaker and literally hundreds ofother devices. In the kind of dynamicmicrophone which seems to me the mostpromising a small coil is attached to adiaphragm which is vibrated by thesound waves so that the coil vibrates ina fixed magnetic field. This is the reverseof a dynamic loudspeaker, the micro-

The HORN SPEAKER 9820 Silver Meadow Drive, Dallas, Texas 75217

chassis. The chrome -plated amplifierchassis and the wide -range 12 -inchspeaker are housed in separate blackcrackle -finish metal cabinets. A

nameplate in the center of the tunerfront panel of each Scott Specialwas inscribed - "CUSTOM BUILT FOR

" with the name of the customer.MY-four Scott Specials are knownto exist in collections in the United

phone coil corresponding to the voice coil.Vibration of the diaphragm causes smallcorresponding currents in this coil.

A reversed variant of this sometimes iscalled the magnetic microphone. In thistype a small magnet or bit of iron is at-tached to the diaphragm and vibrates inthe neighborhood of a coil of wire, thusgenerating corresponding currents in thecoil. This is the reverse of the magneticloudspeaker. Both types are closely re-lated. it is obvious, to corresponding typesof phonograph pick-up.

The great practical advantage of thesemicrophones is that the electric impulsedelivered is a small current rather than aminute change of capacity. No battery isrequired. The leads from the microphoneto the amplifier may be of any reasonablelength; probably up to several hundredfeet. Tests that have been made on mod-ern forms of this dynamic instrument in-dicate that its constancy and its freedomfrom disturbance are as great as those ofthe condenser microphone, if not greater.The only difficulties now left to confrontthe dynamic microphone seem to be me-chanical ones inherent in the diaphragmand its accessories, not electric ones. Theenergy output, while less than that of thecarbon microphone, may be made equalor superior to that of the condenser de-vice.

It is not difficult to write the specifica-tions of an ideal microphone. The troubleis to meet them, for several involve phys-ical impossibilities. One requirement, forexample, is that the mechanical partswhich vibrate in response to the soundwaves should have no inertia. If theyhave, the response to high frequencies islessened, since the vibrating mass doesnot have time to start before the soundwave reverses in direction and the vibra-tion is ready to start back. This meansa diaphragm with no mass at all, whichprobably is impossible.

Only two vibrating units now knownto science are virtually massless: a streamof electrons like those in a cathode-raytube and a beam of light. Both havebeen tried for microphones and perhapsone or both can be perfected, but nothingreally successful has been accomplishedas yet. Even the dynamic microphone,therefore, seems destined to be handi-capped for a few years at least by a dia-phragm which has mass. This means thatthere will continue to be an upper limit offrequency beyond which the microphonewill not respond, although this limit cer-tainly is above 10,000 cycles per secondand probably can be made higher.

Another characteristic of an ideal mi-crophone would be that neither the me-chanical parts of the device such as thediaphragm nor the attached electric cir-cuit have any resonance of its own, tobuild up the signal at some special fre-quency or frequency range and produce apeak of response not present in the origi-nal sound. This is a present-day fault ofalmost every type of condenser or dy-namic microphone, especially of the cheapones for which there is so great demand.The remedy is careful design of the purelymechanical features, for it is chiefly themechanical resonances that are trouble-some rather than electric ones.

A third requirement of the ideal micro-phone is that it should not itself inter-fere with, or limit, the electric circuits towhich it is attached, as present condensermicrophones do by requiring short leadsto the first tube of the amplifier. Thisrequirement the new dynamic micro-phones promise to meet satisfactorily.

Finally, the ideal microphone shouldnot itself interfere with the sound wavewhich it is detecting; another virtual im-possibility, since this would necessitate,

States. The nameplate on one ofthese is inscribed "CUSTOM BUILT FORE. H. SCOTT." This set may very wellhave belonged to Mr. Scott himself,and it is probably the same one shownin the Scott News and Scott salesbrochures of that period.

While most communications re-ceivers are "notoriously deficientin tonal quality, the Scott Special

circuitry included a 25watt R.M.S.high-fidelity audio amplifier. Anoptional 40 -watt amplifier was ava-ilable. Separate bass and treblecontrols allowed the operator tovary the tonal response from high-fidelity performance to levels moredesirable for communications recep-tion.

The Dual Tuning Chassis of the Special High Fidelity Communications Receiver

The Scott CommunicationDURING the past twelve months we have

received many requests for a professionaltype Communications receiver, and the

Scott Special has been designed to meet thesedemands. It is a 26 tube receiver incorporating22 separate controls, and while a genuine Scottin every respect it is not recommended for theaverage listener as it has been designed prin-cipally for the use of the professional radioengineer.

Two Tuners in One ChassisThe Scott Special is not an ordinary Com-

munications receiver. Actually, it is two re-ceivers in one, for there are two tuners in theone chassis. One tuner is for the reception ofshortwave stations from 60 to 1,500 Kc., whilethe other tuner covers the broadcast band andlongwave frequencies from 1,600 to 140 Kc. Inthis way, it has been possible to combine onone chassis an extremely efficient high frequencyreceiver with one that efficiently covers thebroadcast band and long waves.

This extended tuning range is covered withnine wave bands, seven for the ultra high and

Top view of chassis

in physical theory, either that the micro-phone should occupy no space or shouldallow the sound waves to pass through itexactly as they would do through emptyair. The closest practical possibility isto make the microphone as small as pos-sible, another item in favor of the dy-namic type of instrument, since theseprobably can be made much smaller thannow, although probably not so small as a

shortwave frequencies, and two bands for thelong wave and broadcast frequencies.CALIBRATION-Precisely calibrated on allwave bands with a micrometer scale abovemain dial so that each band may be set atexactly the same point. This feature also en-ables the operator to accurately log the maindial.BAND SPREAD-Both mechanical and elec-trical band spread are used.I. F. SELECTIVITY-Variable, providingvarying degrees of Selectivity from 3 Kc. to16 Kc. for 6 db attenuation.CRYSTAL SELECTIVITY-Variable, highgrade plug-in crystal unit, providing 6 degreesof extremely sharp Selectivity.BEAT FREQUENCY OSCILLATOR - Withvariable pitch control for the reception of CWsignals.AUTOMATIC VOLUME CONTROL - WithOn and Off switch to cut out Automatic VolumeControl when required for the reception ofcode signals.ANTENNA COMPENSATOR-Providesmaximum signal strength on ultra high andshortwave stations.SENSITIVITY CONTROL - Variable, allowsSensitivity to be adjusted for maximum signalto noise ratio on all bands.NOISE SILENCER-Dickert System.STATIC SUPPRESSOR-Special circuit to re-duce or eliminate certain types of high fre-quency static and noise.SIGNAL STRENGTH INDICATOR - Metercalibrated both in db's and r's. The indicatorpointer may be set on each wave band tocancel out noise, giving accurate indication ofsignal strength on any station received.SEND-RECEIVE-Switch is provided con -

carbon microphone. The Bell TelephoneLaboratories recently have developed,however, an exceptionally small condensermicrophone, the so-called "fountain penmicrophone," which is said to be smallenough to make its physical interferencewith the sound wave almost negligible.

Many other types of microphone areconceivable; some, perhaps, based onprinciples not hitherto tried, others as

Receivernected to relay so that receiver may be in-stantly switched with push button control onreceiver panel from receiving to sending posi-tion. If transmitter is used in connection withthe receiver, relay can be wired to transmitterOff and On switch.DIAL MECHANISM-Special Dial Mechanismwith fly wheel spinner providing fast tuningspeed with beautifully smooth tuning control.Back lash completely eliminated.BASS AND TREBLE CONTROLS-Continu-ously variable to provide finest possible toneon all signals or programs received.HEADPHONE JACK-Yes.POWER OUTPUT -25 to 40 watts.SPEAKER-Special 12" High Fidelity.PRICE-$650.00 FOB Chicago.DELIVERY-Four to six weeks after receiptof order.TECHNICAL DESCRIPTION-Manual withcircuit diagram, complete set of curves, andengineering specifications available for 50c.

Underneath view of chassis

revivals and improvements of principlesonce tested. and discarded. One of thelatter is the hot-wire microphone, re-sponding to the changes of air tempera-ture created by the passing sound waves.Another is the liquid resistance micro-phone like one of the first successful onesof Alexander Graham Bell. The effect ofsound waves on a high -voltage, glow -dis-charge maintained between two metal

6 The HORN SPEAKER,.,., 9820 Silver Meadow Drive, Dallas. Texas 75217

points in air, was used a few years agofor microphone purposes by Dr. PhilipsThomas of the Westinghouse Electric andManufacturing Company and proved tobe the only microphone, which I know of,capable of responding to sounds wellabove 10,000 cycles per second in fre-quency. The device proved to be toounstable for the majority of practicaluses, but it embodied a near approach tothe idea of a vibrating unit, like a streamof electrons, which would have no inertia.

But even if nothing better appears thanthe present and promised forms of dy-namic microphones there is every assur-ance that radio's electric ear will keeppace with the rest'of the radio engineer'sequipment, to say nothing of the direc-tional characteristics of the new reflectorand ribbon instruments.RADIO NEWS FOB JANUARY, 1932

SPEARING WATCHES.To get up anything new in the way of watches

seems difficult. The precision of the present con-struction leaves little margin to progress, and theindications that it has been possible to give thesesmall instruments are so numerous and interfere solittle with the perfect running of them that we mightconsider perfection as having been nearly reached inwatchmaking.

Mr. Sivan, a French watchmaker, established atGeneva, has, nevertheless, succeeded in steppingoutside of the beaten track in devising a chronome-ter that speaks the hours, instead of striking them,through an ingenious application of the phonograph.

The ordinary repeating watch carries a detentthrough which it is possible to free a small movementthat actuates little hammers which strike spring bells.It is thus possible to strike the hours, quarters andeven the minutes at will. This bell device, which is

essentially monotonous, requires, moreover,close attention on the part of the ownerof the watch, who is obliged to count the

Pig. 1.-SPEARING WATCH, WITH ITS PHONOGRAPHIC DISK.

Questions and AnswersJ. B. A., Courtland, Kansan. -1. Is Cal Stewart the

same person as Andrew Keefe? ,2. Who sings in theEdison Mixed Quartette?

[1. Cal Stewart and Andrew Keefe are two indi-viduals. 2. Because of more or less frequent changesin the personnel of the Edison Mixed Quartette, wedo not publish the names.]

J. S. R., Ellenburg, Wash. -1. Some one informedme that Ada Jones is dead. Is she? 2. Do GoldMoulded Records harden with age? 3. How longshould a copper diaphragm last? 4. Does furniturein the room have any effect on Record making?

[1. Miss Jones is still living. 2. We do not thinkso. 3. We cannot say how long a copper diaphragmshould last. With proper care we do not see why itslife should not be several years. 4. The rooms inwhich we make Records are almost entirely devoidof furniture. For making vocal or solo Records,however, where the speaker or singer talks right in-to the horn, the furniture in the room does not affectthe Record.]

Mrs. D. C. M., Everett, Mass. -1. How should about250 Records be packed to go on a journey of 6,000miles ? 2. Are there any cases made for that pur-pose ? 3. There are five changes to be made on thetrip, so would it be safe to express them ? 4. Do youhave felt cases made to sell for the large horns ?

[1. If we were shipping them we would first putthem in paste -board packing, similar in constructionto the brown board used for packing eggs, and thenwe would put them in a strongly built wood case.2. We could furnish the foregoing but it would costmore to get it than it is worth. Try packing themin a good sized box, protecting the Record boxes withan ample supply of excelsior. 3. Yes, if properlypacked. 4. No, but perhaps your local Dealer canget one for you.]

H. I. S., Grand Ledge, Mich.-What is the materialused in the recorder weight that holds the diaphragmin its place ? Is it paraffine wax ?

[It is a special composition called stratena,]

N. L T., Seattle, Wash. -1. Are "Cyrus Pippins"and Byron G. Harlan identical ? 2. Is Record No.9779 made with the assistance of Byron G. Harlan ?

[1. Yes. 2. Yes.]

THE NEW PHONOGRAM, May 1909

strokes and to distinguish the intervals be-tween the hours, quarters and minutes.There are no such inconveniences in theSivan watch. The spring bells are replacedby a vulcanized rubber disk provided withgrooves upon which the hammers bear,through a point. The accompanying fig-ures will permit of the operation being un-derstood.

Fig. 1 represents the watch open, with itsphonographic disk, which is provided with48 grooves that correspond to the 12 hoursand to the 36 quarters traversed by the handin making one revolution of the dial. Fig. 2shows the same watch, from which the diskhas been removed in order to allow themechanism to be seen. This disk is seenon the side opposite that carrying thegrooves.

When the detent is pressed, the rubberdisk begins to revolve, the point that fol-lows its sinuosities vibrates, and the vibra-tions are manifested by such expressions as

" It is eight o'clock," "It is half -past twelve," etc.The grooves, in fact, are the exact reproduction, upona plane, of the helicoidal groove produced by a humanvoice upon a phonograph cylinder.

Naturally, watches are not the sole pieces of wheel -work to which this ingenious system is applicable. All clocks may be provided with it, and, for the moment,Mr. Sivan is already constructing alarm clocks which,instead of the strident and ear -piercing bell that everyone is acquainted with, have speaking disks. Onecan thus have himself awakened by the crowing of thecock, or by the vigorous accents of a well knownvoice. The inventor is constructing some alarmswhich, with a disk of 6 or 7 centimeters, cryout to you from one room to another,through closed doors, such phrases as "Getup 1" " Come, wake up 1" loudly enough andlong enough to snatch you from the armsof Morpheus.

In addition to the difficulty resulting fromthe disproportion between the smallness ofthe grooves and the force that is necessaryto give the sound, Mr. Sivan has had sev-eral others to surmount. It was necessary,in the first place, to introduce the systeminto a watch case without exaggeratingthe latter's dimensions, and afterward tofind a plastic, although resistant, materialfor the disks. These obstacles have beenhappily surmounted. Mr. Sivan's watchesresemble the ordinary repeaters ; and theirdisks, despite the pressure of the point, arecapable of speaking several thousand timeswithout showing any appreciable wear.

Further, by retouching the phonographicgrooves, suppressing some of them, andexaggerating others, the inventor has suc-ceeded in giving the words pronouncedthe peculiar accent characteristic of suchor such a locality. Amateurs who may not be con-tent with ordinary disks will thus be able to orderothers that. will be true family souvenirs. There isno limit to the variety of the combinations of whichthe realization becomes possible with this system.

There is one thing, however, that it will be neces-sary to see to, and that is, that in houses that possessseveral speaking watches or clocks, the latter shall runin perfect unison. Otherwise their disputes, sourcesof pernicious examples, might chance to disturb thetranquillity of serious households and cause steadypeople to lose their reckoning. But the precision ofthe apparatus easily permits of avoiding such an incon-venience.-La Nature.

SCIENTIFIC AMERICAN, Sept, 29, 1894

THE NEW PHONOGRAM

FOR MAY, 1909

MISS MABEL McKINLEYSoprano

122 Golden Rod Mabel McKinleyMiss McKinley is one of the most notable additionsever made to the staff of Edison artists. She is aniece of the late President McKinley, a composer ofgreat merit, the possessor of a delightfully sweet so-prano voice, a woman of charming personality and auniversal favorite on the stage. "Golden Rod" is oneof her own compositions. It is dedicated to Vice -President Fairbanks. Miss McKinley also wrote"Anona" and other musical successes. "Golden Rod"is a song of the national flower. Its words arepatriotic, its musical setting is perfect and MissMcKinley's singing of it is artistic in every sense ofthe word. Orchestra accompaniment.

10134 Shine On, Harvest MoonAda Jones & Billy Murray

Scarcely less popular than Miss

491

Jones' solo Records are those madewith the assistance of Mr. Murray,himself one of the best of the Edi-son artists. The duet Records by

e. Miss Jones and Mr. Murray areeagerly sought for in each month's

list. This selection is a serio -comic song, featuredin "The Follies of 1908." The dialogue between thechorus is alone worth the cost of the Record. Or-chestra accompaniment. Music, Nora Bayes-Nor-worth; words, Jack Norworth.

Fig. 2.-SPEARING WATCH, WITH THE DISK REMOVED, INORDER TO SHOW THE INTERNAL MECHANISM.

The HORN SPEAKER 9820 Silver Meadow Drive, Dallas, Texas 75217COLLECTIBI,FS

Radio News for June, 1925

MEET RADIO ROSE. Miss LouiseHenry, an inventor of New York, de-signed Radio Rose. The doll bu acomplete three tube receiver built in itand there is a loud speaker cleverlyconcealed in the chest Radio Rosewill receive music from any stationwithin a liberal radius and sings or lectures while she is taken for a walk

of) Underwood & Underwood

RADIO CLOCK THAT CALLS YOUAT ANY TIME. Instead of the old-time alarm clock, the sleepy radio fanMay be awakened at a certain time bythis new cenbinatíon of clock and radioreceiver. photo courtesy Plato Speak -

leg Clock Co., Inc.

1925 ad

The "LINCOLN'Enclosed Fined

Adjustable DetectorKills your Reties

TYoub lesNew ListPrlce !1.5O

Manufactured brLINCOLN MFG. CO.

Dept. E. I

Los Angeles, Cal.

PERFECT REPRODUCERTone loud and pleasing. Handsome material and design.

Black-$22.50 Shell-$25.00AMERICAN ELECTRIC CO.Stat,- and 64th Sts. Chicago

1925 ad

RADIO CANDYBORES. Below:These two candyboxes especially ap-peal to the youngradio fans, mainly be-cause these sets look"just like Father's"

1h111á110i0Latest Addition to Our Series

LMorgan E. McMahon's

A FLICK OF THE SWITCHyour new 1930.1950 adventure.

Your TicketFrom Static to Snow

A FLICK OF THE SWITCH is com-ing! Customer friends have been askingfor an enjoyable and authoritative bookon radio of the 1930's and 1940's. Thisbook will be great reading, and its 1,000-plus pictures will make it the 1930-1950standard reference for collectors and his-torians. It is well worth your time andmoney if you're interested in any ofthese:

Re -living the 30's and 40's.Collecting radio -TV artifacts.Broadcast history.Early radio -TV programs.

Ham radio.Shipboard radio.World War II electronics.Browsing.Circuitry.

This First Edition will be a real col-lector's item some day. It is already val-uable as the 1930-1950 pictorial refer-ence. An ideal companion to the otherbooks in our series. Available in hard-cover for your library shelf and hand-book for handy reference wherever yougo.

SEND TODAY toTEN-DAY

ENJOY OLD RADIO -TVRe -live those early days in

A FLICK OFTHE SWITCH

-our new 1930-1950 bookHere's your time trip to the great days of

radio broadcasting and the dawn of television.Revisit the Lone Ranger Atwater -Kent radios,Will Rogers, Scott All daysand many more.

You'll read about the people and programsthat swept us into a new era. You'll get a chuckle out of old-time radio ads. See over 1 000sets that will become collector's items, and dis-cover the rewards of collecting as a hobby.

You'll have a great time reading and re -read-ing this book. When you're through, put it onyour shelf as the new standard collector's refer-ence on 1930-1950 radio and television. Highquality, 260 pages, $9.95 deluxe hard -cover or$6.95 handbook.

Meet the rest of our family-VINTAGE RADIO is the fascinating 1887-1929story and collector's photo reference. Over 1,000photos. 263 pages, $7.95 deluxe hard -cover.$5.95 handbook.RADIO COLLECTOR'S GUIDE is the collect-or's data book, with 50.000 facts, 1921-1932,264 pages, $4.95 handbook.1927 RADIO ENCYCLOPEDIA is your tech-nical book on wireless and early radio. Highquality reproduction of the original. 175 pages.$12.95 deluxe hard -cover. $9.95 handbook.

MOST -OFTEN -NEEDED 1926 - 1938 RADIODIAGRAMS covers 600 popular early radiomodels. 240 pages, $7.00. ALSO: circuit dia-gram for any pre -1951 radio $3.50.

VINTAGE RADIO SERIES

Other Offersfrom Vintage RadioWe're proud of our growing series of

books for collectors, historians and nos-talgia hounds. In addition to the bookslisted in the middle column of this re-lease we have these offers:

FREE AGE GUIDE with each order.This is a handy wallet -sized card withhints on how to tell the true age of aradio from patent numbers, tube types,style, etc. Keeps you from being skinnedby sharpies.

RADIO DIAGRAMS SERVICE pro-vides the circuit diagram and any otherinformation we can find on pre -1951radio sets. Just send us the model num-ber and $3.50. Your money back if wedraw a blank.

MOST - OFTEN - NEEDED RADIODIAGRAMS books from our previousoffer are running low. We've reprintedthe 1926-1938 volume, so there are plen-ty available at $7.00. 1941, 42, 46, 48and 50 are still available at $4.00 each.all six volumes $25.50.

Vintage Radio, Dep't M, Box 2045, Palos VerdesGUARANTEE. WE PAY POSTAGE. Californians add 6%

Pnsla., CA, 90274Sales Tax.

$ Name

S Street$ City$ State Zip

Total $

FREE! Radio Age Guide with Each Order. FREE!

8 The HORN SPEAKER

Radio Service Apparatus

9820 Silver Meadow Drive, Dallas, Texas 75217 TROUBLE -SHOOTING CHART

A real efficient inductance, woundon a slotted Formica form, 41/2"diameter of 31 turns of Number rohard drawn copper wire. Suppliedwith 3 special clips making adjust-ments variable to any fraction of aturn. Suitable for panel or benchmountings. Materials and work-manship the finest obtainable.Type 550 Inductance, price $8.50

Part of 1921 ad

Alfred Graham & Co.,London, Er. gland,

Patentees

AMPUOISiíNaze do `d Standard

Loud SpeakerLEADS IN SALES THE WORLD OVER. HEAR IT !

THIRTY years have perfectedand made The Amplion the

finest loud speaker. This is to urgeyou to hear it-in comparison.Not only is The Amplion the mostsensitive of loud speakers. In its

reproduction ofspeech as well asvocal and instru-mental music,it isalso unrivaled forclarityand naturaltone. Literatureand dealer's nameon request.Phonograph Units

in two sizes

THE AMPLION CORPORATIONOF AMERICA

Executive Oces: Suite W280 Madison Avenue, New York. `

1925 ad

POSSIBLESOURCE OPTROUBLE

SYMPTOMS OF TROUBLENO RECEPTION VOLUME WEAK

IRREGULARRECEPTION DISTORTION NOISY RECEPTION HUMS AND WHISTLES

BATTERY

Battery exhausted,No water in storagebattery.Battery terminalscorroded.

Battery exhausted.Poor connection at cor-roded terminals.Charger not equal todemand on batteryTrickle charger notfunctioning.

Loose connec-tion.

Battery exhausted. Battery sulphated.Connected charger op-erating.

Hum from charger operat-ing.Whistles from depleted bat-tery.

"B"BATTERY

Battery exhausted.Battery not proper-ly connected.

Batteryexhausted. Vol-ume starts off well butquickly diminishes whileset is played.

Defective cell. Battery exhausted.Loose connec-tion.

Erratic noises -- bat-tery exhausted.Fluttering, motorboat-ing - high resistanceof run-down battery.

Whistles from run-downbattery.

POWERPACK

Not connected topower socket.Rectifier tube notoperating.Filter coils burnedout. Resistor burnedout.Fuses in power sup-ply burned out.Plate of rectifiertube red hot-con-denser broken downor short circuit infilter.Electric light linepower off --or fuseblown.

Eliminator overloaded.Rectifier tube worn out.Transformer short cir-cuited.Buffer condensers punc-tured.Filter condensers punc-tured.Improper resistor valuesin voltage divider.Electric light line volt-age too low.

Interruptedcurrent supplyfrom powerlines.Poor voltageregulation ofpower line.

Plate voltage toolow.C bias resistors notproperly adjusted.Too high resistancein choke coils.Insufficient capacityof filter condensers.

Defective resistor involtage divider.Sparking-over punc-tured condenser.Motorboating-inauffi-cient capacity of lastfilter condenser.Improper value of re-sistors in voltage di-vider.Rectifier tube wearingout.

Transformer not balancedon center tap return.Eliminator overloaded.Insufficient inductance inchokes : cores too small ;ohmic resistance too high.Insufficient capacity in con-denser bank.Choke coil short circuited,or not functioning.No grounded shield betweenprimary and secondary ofpower transformer.Eliminator not adequatelyshielded.Coupling between A.F. am-plifier stages and elimina-tor, placed too close to set.

ANTENNAAND

GROUND

Antenna grounded.Antenna discon-nected.Ground connectionopen.Defective lightningarrestor.

Antenna disconnected.Antenna poorly insula-ted, grounded or wirecorroded.Antenna too short.Antenna too long: in-sert midget condenser.Coupling between an-tenna coil and secon-dary too loose.Loose or corrodedground connection.

Swinging an-tenna becom-ing groundedat times,Loose or cor-roded groundconnection.

Parallels, or too closeto antenna of near-by oscillating re-ceiver.

Antenna too close, orparallel, to powerlines.Antenna too long-picks up too muchstray noise.Loose or corrodedground connection.Antenna runs too nearinterfering electricaldevices.

A.C. hum or commuta-tor ripple picked up fromnearby power lines.Negative side of filter cir-cuit not grounded. IB--).

TUBESTube burned out.Tube paralyzed.Tube prongs notmaking contact.

Tubes exhausted,Wrong type of tubeused.

Power detector notwarmed up.Too. much grid bias,Corroded tube contacts.

Imperfectprong contacts.Detector tubeparalyzed.Improper val-ue of grid leak.

Tubes worn out.Tubes getting in-sufficient current.Improper "C" biason grids.Detector tube over-loaded.Wrong type of tubein last stage.

Microphonic tubes:require cushionedsockets.Gaseous rectifier tubeaging.Hissing, due to powerdetector tube start-ing characteristic, orworn-out tube.

Tube deteriorating.Too high voltage on detec-tor tube.

Wrong type of A.C. tubein detector stage.No center tap in detectortube's filament circuit.

CIRCUITSwitch open.Open circuit in set.Burned - out A.F.transformer wind-ing.

Insufficient regeneration1S. W. set).Antenna too long (S.W. set).Grid leak improper value.Imperfect contacts.Defective piece of ap-paratus.Neutralization systemout of adjustment.Insufficient plate volt-age.Burnt out A.F. trans-former winding.

Loose connec-tion some-where in set,eliminator,power supplyor speaker con-necticsn.Sharply mov-ing wires or setwhile in oper-ation will ac-centuate trou-ble.

Over -regeneration.Nearby oscillator.Poorly designedtransformers.Coupling condens-ers too small,Circuit too sharplytuned.Last stage inade-quate.No biasing on tubes.

Squeals, bloops -- setnot neutralized.Neutralizing condens-ers not properly ad-justed.Defective grid leak.Motorboating- lowerthe value of resistorsin resistance coupledamplifiers.Broken wire or im-perfect contacts.Burnt out audio trans-former.

Oscillation f -r ow' over -regeneration,Set not properly neutral-ized.Magnetic feed back be-tween stages.Open grid circuit.Center tap of transformernot balanced.Grid return to center pointof potentiometer acrossA.C. tubes not properly ad-justed.

SPEAKERSpeaker discon-nected.Open circuit inspeaker unit, jack,plug or cord.Speaker short cir-cuited.Coil in speaker unitburned out.

Speaker out of adjust-ment.Loose contact.Leak across speakercord,Choke coil in outputcircuit has too high re-sistance or insufficientimpedance.

Defective cord,jack or plug.

Speaker overloadedeliminate directcoupling by usingoutput transformeror choke condensercoupling.Not matched to tubein last stage.Poorly designedspeaker.

Sound vibrations com-municated from speak-er to tubes in set.Electrical feed backfrom speaker cord toamplifying circuits.

Buzz or rattle in dynamicspeaker due to moving coilrubbing a g a.i n s t polepieces.Hum due to worn-out rec-tifier.Feedback from speaker cir-cuit to amplifying stagesdue to sound vibrationscommunicated from speakerto tubes in set.

GENERALIncorrectly wired setShielded location or.dead spot."SOS" on air.Set not turned on.Breakdown at broad-casting station-tryanother station.

Set inadequate.Spot poor for recep-tion.Fading.

Breakdown inbroadcasting --t r y anotherstation.

Improper tuning.Fading.Weather condition.Unsatisfac torytransmission fromstation --try anotherstation.

Static : try disconnect-ing aerial and ground.Eliminator too closeto set.Near -by regenerativeset.

Sparking electri-cal machinery.

Two stations on nearlysame wavelength cause het-erodyne whistle.Interference from near -byoscillator.Near -by regenerative or os-cillating receiver.

Information from page 291 ofS. Gernsback's RADIO ENCYCLO-PEDIA, second edition 1931.

1921 ad1975a

Arnold Navy Model Loose Coupler Back toPre -War Price, $15.00

The moat consistent piece of Radio Ap-paratus to bear the Wireless 'telephoneun without distortion.

Range from 200 to 3000 Meters.AMATEURS, COMMERCIAL AND

ARLINGTONuse this Loose Coupler and the ArnoldAudlon Detector which sells complete withBatteries and Bulbs for $20 if you wantresults Dut you must buy from themanufacturers to get these prices.

t -rder todry. Prompt shipment prom-ised or fiend 3c stamp for Catalogue.

J. F. ARNOLD, 2082 Lexington Ave., NEW YORKESTABLISHED 1E10

SILVER GHOSTSBY JWF PUETT

PHOTOGRAPHS - SCHEMATIC DIAGRAMS -STORIESOF EVERY KNOWN RECEIVER MANUFACTURED BY

THE EH SCOTT RADIO LABORATORIES

70 PAGES IBM PHOTOCOPY 10.00 POST PD.

PUETT ELECTRONICS!3008 ABSTON DR. MESQUITE, TEXAS 75149

The HORN SPEAKER..... 9820 Sil\er Meadow Drive, Dallas, Texas 75217

Cl atf'ttr c C

"DOUBLE -SUPERHET."By heterodyning the signal first to I ,600 kc.,

and then to 125 kc.,

1934

All -Wave Receiver

`Ilse MATTHEWS' /

Challenger.Bottom v',ew of receiver chassis.

See next page fortext and schematic.

9

Quality paper capacitors for replacements in AC radiosand B -eliminators. Cheaper than new Mylars; even cheaper

than electrolytic&

3 mfd, rated 250 voltsbut will stand more (I'vetested some at 750 v for 8hours with no failures, andone at 1500v). Will replaceany capacitor up to 4 mfdin early AC power packs orB -eliminators. Oil -filled.

4 sections, each 3 mfd600 volts. One of these willtake care of an entire powerpack. Boxed w/mtg brackets.

75¢ 10/$6.50 50/$25 $3. each 2 lbs.

Add postage: 4#/10, 20#/50Mark this ad -- it won't be repeated for at least 6 months.New boxed tubes: 2A7 & 71A $3. Used old-style; 81 4, 74 $2Lacquer-Stiks $1. Alan Douglas, Box 225, Pocasset MA 02559.

VICTOR VICTOREdison PhonographPrice $60.00 Catalogue No. A 3090 Code Word Victor

Size I Height,,[iv, in(IrcBass, s',3 by IONet Wt. 481bs. Gross' too

Is equipped with electric motor (wound for battery)and governor: fitted with instantaneous speaker clamps

for instant Interchange o? speakers. It sets in an oak

body box and is finished in black and gilt enamel.The mandrel is nickel plated and polished.

A battery is not a part of the Phonograph, but Is anindependent apparatus. Storage or primary (chemical)

battery maybe used, see pages 32 and 33. The motor

requires a steady curren'. of 2yí volts and 2 amperes.

Its uniform action and continuous power supply recom-mend the Victor Phonograph for all occasions where

these requisites are desi-ed.so

From Edison cata

ARKAYLoud Speaker

Radio News for January, 1922

Edison Phonograph(CONCLUDED;

Every Victor Phonograph includes, free of charge,

an Edison Automatic Reproducer, an Edison Recorder,

a sapphire shaving knife, a 14 -inch polished brass horn,

a two-way hearing tube, an oil can and camel's hair

chip brush. The only change we make in the above

equipment is to substitute a speaking tube for the 14 -

inch polished brass horn, if so desired.

CONQUEROREdison PhonographPrice $73.00 Catalogue No. A 3001

Code Word Conqueror

/Pig's!,ight, ii% inchesBase, .,o% by so in.

Net weight, 48 lbs.Grose weight, too lbe.

In general appearance and equipment this Phono-graph is exactly the same as the Victor described on

page 20. (wi'Moul Storage Batteries). Is furnished

with an electric motor wound to run on the 114120

volt direct current.

The most convenient style of Phonograph made.

The power is both continuous and handy, as con-necting wires need only be attached to the nearest

electrio light connection. Equipped with resistance

block fitted with lamps and cord, attaching plug of any

make required, to (It customer's lamp socket.at

logue for 1901.

Sold for $5.00

Sound AmplifierIn an endeavor to produce a low priced

loud talker, a manufacturer of radio appa-ratus has designed the sound amplifiershown in the photograph. The advantageof this type of sound amplifier is that anymake of telephone receiver may be used inconnection with it. The telephone receiveris merely mounted in the base with a screwapplying it against a rubber ring, prevent-ing any loss of sound. The screws are fur-nished with this instrument so that flat re-ceivers may be used as well as amplifyingtypes, which, of course, give best results.A notch in the base is provided for thecord of the phone, which may be simplytaken out of a head set and replaced whendesired.

To This Horn May be Attached Any Type ofTelephone Receiver. It Gives a Great BoardAmplification When a Good Phone is Used laConjunction With it and With an AmplifierMakes Signals That Are Readable Over a

Large Area.

The complete instrument is made of brassand is either coated with black enamel, ornickel plated. Its shape gives to this soundamplifier very good amplifying propertiesand compared with another well-known ap-paratus, has proved to be equally efficientwhen a Baldwin receiver was inserted inthe base. Of course, an amplifier is neededin connection with the receiving set in orderto have a sufficient volume of sound pro-duced by the telephone receiver, but forstrong signals the instrument may be usedwith a detector tube only.'

in 1922 by Riley -Klotz Mfg. Co.

MULTI -1 tJRPOSE Bike Radio, consists of a solid-

state AM radio, headlight and signal horn.Fits on handlebar of bicycle and comes with 2flashlight batteries, bracket, screws and in-structions. Unique and useful for bike rides

perfect for beach, camping, picnics,sporting events, etc. Easy locking devicepermits user to install or remove in seconds,yet makes theft difficulty. Shipping weight8 pounds, shipping size 13 X 9 X 6 inches.

Comes post paid. Send $19.95 to Coe Enter-prises, Dept. 1026, Box 259, Coe Drive,Mesquite, Texas 75149.

10 The HORN SPEAKER,.... 9820 Silver Meadow Drive, Dallas, Texas 75217

EDISON PERFECTING THE PHONOGRAPH.

SHOP TLKI recently tried again to come

up with a viable substitute for01A's that would require no setmodification and work in most settube positions with a minimum ofincompatability. Enclosed is aschematic of a common active de-vice with a few added passive de-vices. It draws 25MA filamentcurrent at K volts and has a MUof 8. I have directly plugged itinto RF, audio output, and de-tector sockets in my FreshmanMasterpiece. The device is knownas a 6C4.

Seriously, though, there werea few problems in some of the RFapplications; but I feel that alittle alteration of the high re-sistance grid resistors would al-leviate that. These alterationsare probably necesitated by thefact that the 6C4 does not havea filamentary cathode. In anOlA or /10 the cathode is dis-tributed along the filament; inmy CKT the cathode is electricallyat the center. The cathode resis-tors should not be made largerthan specified in order to pro-tect the antique tubes (if used)from drawing excessive filamentcurrent. 27 ohms should be con-sidered maximum. Used at K voltsthe 6C4 should have very longrtlament lifte. Also, the CKT issmall enough to be enclosed in anOlA or similar bulb, if one canget into it.

Mike StosichBolling Brook, IL

rRFl Í6U6

1 II

MFMAN

5-MEG

R 0606

ALL RFCOiLSWITCNES AND Sw ARE GANGED C325LOAF T63 F2 CLASSA .02- O

42 wSu.WLI<2 I0,C roLE

'2000 TONE

C ONiROL

2 MC 100

n,I ,,M I.o.. «.rT EDODMMFt,DEOIE

The new column "Shop Talk"is designed to shorten the let-ter column and give space toreaders who want to give otherstheir ideas and experienceswithout writing a regular art-icle. May we hear from you?

PET WAVE.607 a,,óTNi:..

25000COWS

1-D01

(r_s_nn-.soo

Cl 200,0,0C2 002.M4C3 .001 -MC

t02606

FT,25 KC

,3000 DNMS_ O bMC

7 Ñ250. 000

45

05C 3ICOR $CAT-

RECEPTJON

tF3606

The MATTHEWS'Talk about innovation and ad-

vanced design being the main interestof classic set collectors, then theMatthews Challenger will occupy a topshelf in a room full of classicradios. And it was developed for usein 1934.

Every customer for the MatthewsChallenger was given a questionaireto fill out so that A. C. Matthewscould custom build the radio for aparticular location. The tunerchassis was quadruple chromium plat-ed and the customer's name was in-cluded on the dial along with anyother words the owner might wish.

The receiver covered from 13 to560 meters and extended to 10 to 2100meters when required. Of course thenovelity of the set is the incor-poration of two different I.F. unitsin effort to use 3 stages of Z.F. am-plification without introducing tubenoise, hiss or instability.

In the future we hope to have theprice of this set, information aboutits builder, present owners, etc.

Information from Radio Craft forNovember 1934

Diagram of 14 tube all -wave "Double.Superhet."

0ET2605C 26.67

ICT600 AC

CÁEOUNENCv"TER

.EAT-OSC -_SWTCN

LL6

so

THE DOUBLE SPEED KEY.This hey requires but one-half the motions

of the ordinary key, and these are made by asidewise rocking motion of the hand, veryeasily acquired, which insures the operator notbeing affected with cramp. It Is simple andinexpensive.

M°° 5.oKKKNMS...,.,.

50000.45'

3Q000 ÍlPWMS,

lA0 0,0,C

IMF

DESCRIPTION.The Key Lever moves in a horizontal direc-

tion, standing normally between the two points,but not in contact with either. The knobshould not be gripped, but allowed free playbetween thumb and finger. It Is operated byan easily acquired sidewise rocking motion ofthe hand, and as contact is made in either di-rection. only about one-half the ordinary mo-tions are required in forming signals. For in-stance, the word "Philadelphia" with the or-dinary key requires 64 movements of the hand,32 down and 32 up¡ whereas with the DoubleSpeed Key, only 33 movements of the hand arenecessary. Because of the horizontal motionbeing more natural, and easy than the oldmethod, and owing to the fewer movements re-quired, this key is bound to become the lead-ing telegraph key.

We sell these keys in two styles.Style W has an adjustable spring tension for lever.Style G has tension of lever fixed at best point. -

These keys are now made only in legless or top connection form adaptedto be fastened by wood screws to table or by machine screws to portablebase.

Each key is provided with wood screws; each portable base is providedwith machine screws.No. 58X76. Style \V-Double Speed Key i200No. 58X78. Style ('T --Double Speed Key - 1.80No. 58X79. Portable Base only .50No. 5SXSO. Wedge and Cord only .80

21ST/,2wFrom catalog; Nos. 6 of The J. J. Duck Co., 1913

The HORN SPEAKER 9820 Silber Meadow Drive, Dallas, Texas 75217

WANTED11

CLASSIFIED ADS

ww. z.: 1144 Tim sw.ensti.... lows 1....LHL/0LEb3.1104.40LISa.a0a/00.30

L454.15480aao4.10LSOL155.20844

MSC.PHONOGRAPH COLLECTORS, join the Amer-

ican Phonograph Society. Receive thequarterly Journal and four Newslet-ters. Receive free reprints and ster-eoscopic phonograph cards. For moreinformation send 100 stamp. For one

year membership, send $6.50. The Am-erican Phonograph Society, P.O. Boa5046, Berkeley cá 94705.

WILL DUPLICATE exactly, the mutilatedpanel for your antique radio. Sendsketch or rubbing for quotation, orwill trade for antique radios ofequal value. Norman A. Parsons,22 Forest St., Branford CT 06405.

WE BUY, SELL, REPAIR older radios.Tubes for nearly all radios and TVsever made, old radio books and

schematics $2.00. C. Church, Haddam,

Conn. 06438.

FOR SALE OR TRADESPEAKER GRILLE CLOTH, fine, silky,20's - 30's style fabric from an oldwarehouse. Nice, unobtrusive wovenpattern (reversible) in muted goldand dark brown. Nothing like theheavy, coarse stuff they sell today.24" wide, $4.00/yard. A yard willdo about 6 Philco Baby Grands. Pleaseadd 25¢ for mailing. SASE for sample.Warren Dewey, 5021 Ambrose Ave., LosAngeles, CA 90027.

COLLECTORS: Binaural records (sep-erate tracks) used $4.00, new ;6.00.Rekokut turntable, Rystensis motor3/sp 137.00 cost $129.00. McIntosh30W amp ;55.00. Telegraph -keys,

sounders, meters and old tubes. RCAWireless Specialty Co. Faradon con-denser Model 1803, 000025, 115.00.Al Dayes, Rt.l, Box 206, WhitewaterCA 92282.

FOR SALE: Wireless Specialty Ear-phones...excellent condition..$50.00.Also available, other early phones,telegraph tape register, relays,switches & sounders.Amrad Spark Coil 4125.00.R. Matson, 388 Concord Rd., Bedford,Mass. 01730, 617-663-3877.

FOR SALE: Emerson radio, 1930'smodel DS365, mint condition; 12"speaker, excellent tone; 17 X 11X 11 cabinet by Ingraham, Briston,Conn. Best offer. La Placa, 53-

49 97 St., Queens, N.Y. 11368.

NEW, Robert Gelatt's book about thehistory of the phonograph, The Fab-ulous Phonograph, out of print price

17711, damaged 15.00. THE HORNSPEAKER, Box 12, Eleberg TX 75145.

FOR SALE OR TRADE

FOR SALE: Operadio portable 6 -tubes

battery, front 12-3/4 X 17-1/2 X9-1/2" original good condition

$75.00. Sue Covey, 316 Panhandle,

Denton TX 76201. Pho: 817 387-

'1473 after 5.

FOR SALE OR TRADE, BY LOT OR PIECE:Weston #692 Oscilator, plug in coils,all bands; Weston #772 SupersenativeAwalysen, accessories, manual; NRIRC testor #111; Feiler electronicStethoscope #TS -3. Need: Crosely ##124 chasis and speaker. Dick Scham-berger, 1975 Hertel Ave., Buffalo,N. Y. 14214.

CLOTH COVERED POWER CORD, new 2 -con-ductor cord as used on AC sets of thetwenties, thirties, forties. Fromold stock, limited quantity. In brownor gold, 25¢/foot. Please add 50¢for mailing. Warren Dewey, 5021 Ame.brose Ave., Los Angeles CA 90027.

HORN PHONOGRAPHS, grind organs, etc,etc. Bought & sold. Send "2.00 re-fundable for large illustrated list.S. Leonard, P.O. Box 28, Little Neck,New York 11363.

WD11 Adaptors, use UX199, 120, VT24.No wiring changes, Radiola III'sbattery hook up included °`5.25 pp.,2 for M9.25. Keith Parry, 17557Horace St., Granada Hills CA 91344.

FOR TRADE: Loose Couplers. 1912 Clapp -Eastman, 1912 Marconi, Adams MorganNavy Type 1915. Trade for wirelessequipment equal value. Guy Martin,

P. O. Box A, Azusa CA 91702.

FOR SAIE: 34 issues of Modern Elec-trics and Electrical Experimenter.SASE for list. Robert C. Campbell,2175 S.E. Pine, Hillsboro OR 97123.

FOR SALE: Collection of antique

Radios. Send SASE for list. PaulGiganti, 2429 San Carlos Ave., SanCarlos, Calif. 94070.

FOR SALE: Rubber stamp with your

name and address plus AK Radio and

speaker 5'3.00 pp. James Fred, P.O.

42, Roseville IN 46065.

MiscellaneousDON'T DIE without a WILL:Blank will form protects your family.Only 92.00 guaranteed. Order todaylCOE Enterprises, Box 259, 75 Coe Dr.,Mesquite, Texas 75149.

WANTED: Radio News magazines 1925March, May, June,- July, August,October and December.Popular Radio magazine, 1926 December.Electronic Digest magazines 1972 -January and February issue.J. Albert Warren, Box 279, ChurchSt., Waverly PA 18471.

WANTED: AK 33 parts, grid leak,power cable, small trimmer capknob, AK service manual. AlsoPhilco model 70 parts, 4 knobs,tuning dial, escutcheon plate.Lawrence R. Moser, 5925 W. FloridaAve., Lakewood, Colo. 80226.

WANTED: Magnetic pick-up for model61 Wurlitzer table model Jukt Box.Just the electronic parts or thewhole arm, or parts machine withgood pick-up arm. Ira Dueltgen,4126 N.E. 105#h, Portland, Oregon

97220. Phone, 503 254-4430.

HELP: Would Like MICHIGAN RADIONRC-2, two tube regenitive ingood shape, will pay very goodprice or trade. Thanks, DelHambly, 8910 NW Lovejoy, Portland,Oregon 97229.

WANTED: Interstage transformer forAK47 single 26 to PP 71A in workingcondition. In can or to fit can2-1/8 diameter by 3 inches long.G. E. Frater, Pennsylvania Ave.,Paoli, PA 19301.

WANTED: Crystal sets, battery andelectric radios and televisions Mfg.before 1935. Need all related items.Will buy one set or complete collect-ion. Young, 11 Willow Court, Totowa,N. J. 07512.

WANTED: Riders Radio Perpetual troubleshooters manuals Vols. 17, 18, 24, 25,26, 27, index. E. H. Scott & McMurdoSilver radios. State type, conditionand price. J. E. Cunningham, 23W675 Ardmore, Roselle, Ill. 60172.

WANTED: Speaker cone and Antenna for

RCA Radiola 18. Please send infor-mation and asking price to John W.Heiser, 38895 Dodge Park Road,Sterling Heights, Mich. 48077.

WANTED: Board for AK Breadboardmodel 10- 30" by 10". Ronald F.Hill, 386 Roosevelt Ave., Lynd-hurst, N. J. 07071.

WANTED: AK speaker, part #181000for an AK radio Mod. 85. E. A.

Thompson, Rt. 8, Box 474, Florence,Alabama 35630.

WANTED: WATCH CASE TYPE VOLTMETERS,Watchcase style earphones. H. Mon -

2:11.47;76W Hui Kelu St., Kaneohe,

WANTED: Jewell panel meter 0-5 VDCto fit 2 9/16" hole. Will buy ortrade Modern Electrics and ElectricalExperimenter. Don Rnotts, 3158 N. E.Azalea, Hillsboro OR 97123.

Q' PO

STS IL

LC

TN

OiIG

s I PUE

TT

IIiCT

n(AIIC

aPE

WIT

EfiC

TaO

NIC

a I PUE

TT

[I.EC

TaO

SICs

E

TU

BE

S &

DIA

GR

AM

SP

UE

TT

ELE

CT

RO

NIC

S

PUT

T E

LE

CT

RO

NIC

S1 PU

ET

TELELTaCNIcs 1 PIRTT EIECTROEIC.

LIST

t;0. 11

3008 AB

STO

N D

RIV

EM

ESQ

UIT

E, T

EX

AS

75149

ROW

(1)

TO ORDER:

1/1EV11 OJ.M.fEpOW

MUST BE MAD&

(2)

Please state whether new or used tubes are

desired and whether a half-price used tube

is desired when a new tube Is out of stock.

REFUNDS are mailed with your invutce for

out-ofstock tubes, or when, by customer

reorient, a used tube la substituted for an

out -of -stock new tube.

(31

All order. are shipped parcel post - no

C.O.D.

INCLUDE 15% POR POSTAGE AND

HANDLING.

INSURANCE ELATES ARE 30j for

orders under $50.00.

TEXAS RESIDENTS

ADD 5% STATE SALES TAX.

MINIMUM ORDER $3.00

TABLE 1.

86020180

07224

Uí22737

56

U1245

71A

866

PERRYMAN

H3131I3.

PA224

SPEED

TT-- $3.

ACE '24 $4.

OLD-STYLE GLASS ENVELOPE TUBES

all are used

thoroughly tested.

CUNNINC.:AM

4. ITZ17

3. C327

3.

3. CZ332

3.

3.

56

3.

4.5. NATIONAL

4.

(NEONMIT13.

91224

4.

245

4.

SILVERTUNE

227

$3.

2)2

43.

SYLVANIA

Sí551

$3.

KEN RAD

01245 i4.

56 $3.

MAJESTIC

24

14.

G27

3.

G27S

4.

0359

4.

CROSLEY

56$3.

TUNG SOL

14

11.

PHILCO

34

14,

73.

337

3.6

3.

4645

4.

UNKNOWN

BRA: D

24 3.

2227

3.

245

3.

TABLE 2.I SPECIALS I

NEW TUBES:

itiTiotron:

Cunningham 01350 used $5.

07227 $5.

Western Electric 2050 used $6.

Cunningham:

Westerr. Electric 212E used

15.

0327 $5.

Arcturas 56 (clue ruse) used $5. 01371.A 17.

Cardon 0444 used $4.

01345 }b

C347

85.

MAJESTIC - New In Original

Eveready:

Cartons:

ER551 $4.

GUS

G4S

2A6

287

127

0275

G31

0255

15.

4.3.

3.

4.

4.

4.

4.

607

13.

607

3.

6E7

3.

4681

5.

C46A1S

5.

0625

4.

NOTE

IF YOU DO NOT SEE A TUBE

WHICH YOU SEEK LISTED,

SEND US A SELF-ADJRESSED

STAMPED ENVELOPE.

WE

MAT BE ABLE TO RECOMMEND

A SOURCE OF SUPPLY.

TABLE 5.

BALLAST TUBES

43.00 (nee)

1E1, 33AG, 042, K36A, K5SC, K55D, 62A,

KBOB, K900, K920, 100-37, 100-70, 100-

77, 100-79, 160A, 165-1., 200R, 200R-4,

250R, 2500-4, 300R, 305-1A, 50A-2,

1155H0, 6-1, 3H-7, 70-11, 2014, 214,

CR260-1.5, CR1;300-8, CAA.

SCH

EM

AT

IC D

IAG

RA

M SE

RV

ICE

r'Me Can furnish schematic diagrams

technical data on almost any ratio

from 1920 to 1954 from our library of

original manufacturers service oats.

Send a self-addressed stamped envelope

and $1.50 per radio set.

This offer

is limited to five photocopied pages.

Ifthe data on your Bet exceeds five

pages We sill send you a quºte.

SEND A SELF' ADD,ZESSEI3 STAMPED ENVELOPE

FOR A COPY CF CUR CLASSIC RADIO NE'IIS-

LET1'ER.

(E.H. Scott & McMurdo Silver).

de offer free technical advise for e

self addressed stamped encelope or you

may call J.W.Y. Puett before 10100 PM

Central Daylight time PLEASE.

Cell -

a/c 214 - 279-8309.

ALL TUBES ARE THOROUGHLI TESTED on a mutual conductance tube

checker before shipment. CUSTOé±ER SATISFACTION GUARANTEEp -- If

you are not satisfied with your order for any reason, tubee may

be returned within ten days for refund or replacement with ex-

ception of tubes which are shorted or have open filaments.

It

will be assumed that returned tubes with open filaments or shorts

were damaged in shipment.

Shipping damage claims will be handled

promptly through the poet office on insured orders.

Puett Elect-

ronics assumes no liability for orders which are not insured, and

no liability beyond that which is covered by postal insurance.

IN TABLE 3,

THE SYMBOL n INDICATES TH4T A TURK IS AVAILABLE

NEW 1';D THE SYMBOL u

IND

ICA

TE

STHAT THE TUBE IS AVAILABLE USED.

TABLE 3.

OLDER TYPE -NUMBER

TU

BE

S -prices listed for new tubes

used tube. are half new price

0lA3

114

115

.A6

1A7

1E4

185

105

106

117

1D5

108

1E5

1E'1

14

104

105

106

1H4

1415

1H6

1LA4

1116

1184

14::5

1106

17.05

1LE3

1L7)

1.105

1184

11N5

1115

1P5

1Q5

17213

2/4

2A5

216

287

306

31"

3Q5

586

504

574

514

514

513

574

unnuu

nuu

DUu

nuu

nuuuu

nu

DU

nnu

n:,

nnnu

nnnu

nunu

nunu

nunuu

nu

nunnnuu

nu

nu

nu

nu

nu

nunu

4.

3.

O.3.

3.

2.

3.

3.

3.4.

4.4.

3.

3.

3.

3.

3.2.

3.

3.

2.

3.

3.

3.

3.

4.

3.

4.4.

3.

3.

3.

3.

3.

2.

4.5.4.3.

3.

3.

3.

3.

2.

2.2.

2.2.

2.

2.

2.

2.

523

526/3

644

645

616

617

648

6B4

685

686

687

688

615

607

6C8

606

607

6E6

6E7

675

676

677

678

606

óHó

625

627

628

685

686

6E7

6K8

615

616

617

615

616

617

6P5

607

6R7

697

638

677

618

606

607

676

677

676

624

nu

nunnu

nnuwnu

nuTU

nu

nuTUTUTU

nnu

nu

nunu

munununu

TU

nunuu

nu

nu

nuDU

nu.

nu

TU

nu

nunu

DU

nuTU

nu

TU

nu

nu

nununu

2.

2.

3.

4.

3.3.

4.

3.

4.4.

A.L.3.

3.

3.

3. 33.

3.

3.

3.3.

5.

3.X.

3.

3.

3.

3.

3.

3.

3.

3.

3.

3.3.

3.3.

3.

3.

3.

3.

3.

3.

2.

3.

4.

2.

3.

2.

2.

6215

714

715

716

717

718

7177

7107

7117

784

785

786

787

788

7C5

7C6

7C7

7156

7E7

777

778

707

787

727

7K7

7L7

717

707

757

797

777

716

727

714

7Z4

1217

1218

1287

1288

1205

1218

1275

1225

1227

1287

1288

12Q7

1283

1414

1417

1485

1486

1488

nu

nu

nu

nu

nununuu

nu

nu

nuu

nuDUunuu

nu

nu

nuunu

nu

nunuDU

nuu

nu

TUTUu

nunu

nnu

nunu

nu

nuu

n

unnu

3.

3.

3.

3.

3.

).

3.

3.

3.3.

3.

3.

3.

3.

3.

3.

3.

3.

3.

3.

3.

3.

3.

3.

3.

3.

3.

3.

3.

3.

3.

7.

3.

3.

3.

3.

3.

3.

3.

3.

3.

3.3.

3.

3.

3.

3.

3.

3.

3.

3.

3.

3.

14C5

n14C7

n1477

n1478

n

1487

n1427

nu

1417

n

1407

nu

1417

n

1417

n15

u19

nu

241

nu

2516

n

2517

nu

2586

u2506

u

2516

nu

25Su

2525

nu

25E6

nu

26

nu

2616

n

2647

nu

71

nu

28U7

nu

30

ell

31

nu

32

n

3216

u3217

n

33

n

34

nu

35

nu

3574

u3523

nu

36

u

37

hu

38

nu

39

nu

41

nu

42

nu

43

nu

44

nu

45

u

46

nu

47

nu

48

n

49

n

50A5

nu

5306

n

5016

nu

51

hu

3.

3.

3.

3.

3.

3.

3.

3.

3.

3.

5.3.

3.:

3.

3.2.

3.2.

2.

,4.3.3.

3.

3.

3.

3.

3.2.

3.

3.

3.

3.

2.2.

3.

3.

3.

3.

3.

3.3.

3.

4.

L.55.

4.2.

2.

3.

3.

55

e

13.

56

nu

3.

57

nu

3.

58

u3.

59

n3.

70/7 n

3.

7017 nu

.3.

75

nu

3.

76

nu

3.

77

nu

3.

,8

nu

3.

79

nu

3.

80nu

2.81

u5.

62

u3.

437

n3.

84

nu

3.

85

nu

3.

89

n'

3.

117-

L7

nu $4.

117-

Z6

nu

13.

90O2 n

3.

9003 n

3.

VT52

u4.

ZZB

n3.

XXFM

u3.

XII

nu

3.

AliDITION:

215

n14.

605

n13.

10/7Ta25 $4.

22

u }5.

6N4 u

8}}

0004 n $4.

53 nu

}146n

3.

1620 u

j.

IN TABLE 4, THE SYMBOL n IIUICATES THAT A TUBE IS AVA LABLE

NEW AND THE SYMBOL u INDICATES THAT THE TUBE IS AVAILABLE USED.

TABLE 4.

MORE f1SL®IT TUBE TYPES - pricee

Iletsd for naw tubes

used tubee are half new price

012

n0A3

u

O8)

uOC3

nu

003

nu

074

n

024

nu

1Lp

nu.

1L6

o1R5

nu

134

n

195

nu

114

nu

115

nu

115

nu

2C26

u212

n3A4

nu

315

nu

318

n

3154

nu

384

nu

374

nu

6184

nu

6AB7

m1

64C5

nu

6107

nu

OMnu

6115

nu

6117

n

6105

nu

2.

2.

2.

2,

2.3.

3.

4.5.

2,

1.

.2,

2.

2.

2.

3.

3.

2.

2.

3.

2.

2.2.

2.

2.

2.

3.

2,

2.

2.

2.

6176

nu

6/U6

nu

6/76

nu

6816

nu

68E6

nu

6BJ6

nu

6C4

nu

6J6

nu

6S4

n

6517

nu

6987

nu

6507

nu

69D7

nu

6375

n

6977

n

6307

nu6387

nu

6327

nu

6317

nu

6917

a+

6317

nu

63Q7

nu

6917

nu

6397

nu

69U7

n

6977

n

61 6

nu

614

nu

615

nu

675

u677

u

2.

2.

2.

2.

2.

2.

2,

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2.

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2.

2.

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1.

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2.

12115

nu

1216

nu

121176 nu

12177

u121U6 nu

12AU7 nu

12176 nu

12846 nu

12B16 nu

1216

nu

12517 nu

12907 n

12975 n

12577 n

12307 nu

12SH7 n

12927 nu

12917 nu

12917

no12317 nu

12907

nu12387 nu

1276

nu

1216

n

1214

nu.

1918

nu

35

nu

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nu

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nu

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nu

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35Z5

nu

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nu

4085

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n

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5077

nu

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117-

24

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nu

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n

884

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1635

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2051 nu

5686 n

5691 n

CE-

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u

5749

u

5751 nu ,2.

5814 n

5879 n

5881

u

5992 n

6080

u

6842 n

6973 n

7193

u

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re -

105 n

$2,

YN-150 nu $2. 3.2.

2.

2.3.

3,

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4.

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From Radio Broadcast, June 1924