"The 1 00 ' Wireless Magazine"

CIRCULATION LARGER THAN ALL OTHER RADIO MAGAZINES COMBINED

20 Cents RE%'DIO December 1921

Over 100 Illustrations Edited by H. GERNSBACK NEWAM. UA. T.01111. J r

"THE 1 00 ' WIRELESS MAGAZINE"

www.americanradiohistory.com CONTENTS

VOL. 2 FOR DECEMBER NO. 6

PAt,i PAM( Ideas- Seventh Spasm, The t ausc of Freak Messages, By Thos. W. Benson 367 By H. Gernsback 349 A Three -Tube Combination Radiophone The Eiffel Tower Radio Station 350 Transmitter and Receiver, By Robert L. Lacault 368 The Amateur Trans -Atlantic Feat, as Reported By Pierre II. Bouchcron 353 \ Shor¡ Wave Coupler, i Pocket Radio Receives Time Signals.... 354 By Geo. Mitchell 366,i

I Practical Receiver, \ The Spirit of Christmas, By Volney G. Mathison 355 By Erald A. Schivo 370

An International Radio Achievement 356 Raided by Radio, By Herbert \Varren Dodge 371 The Audios -Its Action and Applications, By Lee DeForest 358 Radio Digest 377

Comparison of Modulation Methods in Club Gossip 373 Radio Telephony.. By A. S. Blatterman 360

With the Amateurs 374 }iad;n T,3,!"., -.Reception 363

Junior Section 376 \ Method of Producing Musical or Other \edible Notes...By Victor If. Laughter 363 1.'ctiooary of Radio Tcrmc 37;

Awards of Portable Radio Prize Contest. 364 Junior Constructor 378

A New Land \Vire and Radio Trans- I- Want-To -knob 379 mitter of Photographs, By Umberto Bianchi 366 CorLespondencc from Readers... 380

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It A II I O NEWS Is publislrt on the 25111 of each month - at included... ALL accepted conlributions are paid for on publication. A 2:3 t. New York. There are 12 numbers per ye a . Suls rrip- spacial rato is paid for novel experiments: good photographs m,ompaning ti m price Is $2.00 a year in U. S. and possessions. ranurlaandr foreign them are highly desirable. merles. $2.50 a year. IT. S. coin as well asa U: S. Stamps accepted (no RADII() N E W S. Monthly. Entered as and -class matter .1 ac e Igu coins or lnrpsl Singlegle copies. 20 cents each. A sample copy will 6th, 1019. at the Post Ocoee at New York. N. Y., under the Act. or :fit grails on request. Checks and money orders should be drawn to March 3. 1397. Title registered U. S. Patent Office. Copyright. 1920. ty of EXI'EIIISIENl'$at PUBLISHING CO.. INC. If you should E. P. Co., Inc., New York. The Experimenter Publishing Co.. 233 btiSaI go your address notify us promptly. In order that copies be not mis- Street. N. Y., N. Y. The Contents of this magazine are copyrighted and c.( lost. No coplea sent after explralen. must not be reproduced without giving full credit to the publication. i communications and contributions to this Journal should be ad- RADIO NEWS is for sale at all newstands in the United 8tttes . to: Editor, RADIO NEWS, 233 Fulton Street. New York. and Canada: also at Brentanti s. 37 Avenue de l'Opera. Paris. tenir accepted contributions cannot be returned unless full postage has been Great Britain: Goriry. Parker & Gregg. 62 & SA, The Mall, Ealing, London. Publisht by EXPERIMENTER PUBLISHING CO , INC. 233 Fulton Street, New York City H. GERNSBACK, President S. GERNSBACK, Treasurer R. W. DE -MOTT, Secretary .0 -`!I \---1,.. v%= :»:.-- --

346

www.americanradiohistory.com An Amateur Copies POZ With the Connecticut Variable Condenser

An amateur in Southeastern New York says in a recent letter:. "I have purchased four of your CONNECTICUT Variable Condensers and it is possible to get better results with them than with the multiplate type of Variable. "I spent several weeks trying to get signals from the European stations. At first I was unstccessful. I bought one CONNECTICUT condenser for trial. It tuned the radio signals so sharply (and better than other variables) that I bought three others. Much to my expectation they did remarkably well and I was soon copying POZ and other European stations without much difficulty. "Hereafter I will use CONNECTICUT Variables in all my circuits as they are actually cheaper in the long.run and are far more efficient for radio receiving sets."

Your set will be a better one.with the CONNECTICUT Condenser. The instrument is set at .00i mfds., adjustable either higher or lower. There's a booklet with fill information waiting for you. Send for your copy.

CONNECTICUTCON '!ELECTRIC COMPANY . Meriden Connecticut

www.americanradiohistory.com Radio News for December, 1920

Now Dad -Hear the %nor "I can listen in on all the radio concerts now, Dad. Those Baldwin phones you bought me for Christmas are corkers. Just listen to that famous tenor singing over the wireless telephone. Every note records just as clearly as though it were a phonographic reproduction right here in our own home." Actually Baldy Phones reproduce in identically the same manner as do the high grade phonographs. In- stead of a heavy iron diaphragm, as in most phones, a selected grade of mica is used. This is much more susceptible to distortion and as a result responds more readily to the thousands of overtones and harmonics of the human voice or any musical instrument. Baldy's are the most sensitive phones in the world. This is attested to by the fact that the leading radio engineers, with every facility at their command for Slit. testing the audibility and sensitiveness of every make Wtun ü! of phone, choose Baldwin for their personal use.

Our new booklet will give you some interest- Study this \Ray photo of a ing facts about Baldwin Phones, in addition i atdwin earpiece and feu will see why they are world to prices. Ask your dealer for a copy. If he famed for their sensihiveness. can not supply you write direct, giving his name and address.

JOHN FIRTH & CO., Inc. 18 Broadway New York Sole Distributors of EIdriree Electrical Instruments holster Decremeter U. S. Bureau of Standard 1Vavemrter Navy Standard Lyden jars FOR LAND.SEA BALDY AIRAND IN THE ONES

www.americanradiohistory.com Radio News for December, 1920

Ilililll I

.1 w écoóôn ized Symbol of-Superior Pef rmance Our New Complete Receiving Equipment is Here and must be seen and used to be appreciated. Ask your dealer to show it to you. It is the most compact, convenient and efficient apparatus ever offered -only 5 °x5 "x7 ". Absolutely noiseless in operation, sensitive, reliable, scientific. An Excellent Gift How often have you marvelled at the mystery and wonder of "Wireless "? How often have you wished for a simple, reliable instrument complete that would bring the "magical messages of the air" right into your own home?

You need wish no longer. Produced by a nationally known manufacturer of commercial radio apparatus, the new Amrad Receiving Set admirably meets the wishes of those who have desired for so long to engage in wireless experimentation. Hear the Voices in the Air Easy to Set Up and Operate Year every large city there are now one or more The Amrad Receiving Set is not a "mechanical powerful wireless telephone stations. Speech toy." It is a high grade commercial product from anyone of these stations can be clearly bearing the Amrad stamp of quality. Yet any- heard with the Amrad Receiving Set a score or one who can use a few simple tools can within more miles away. Frequently, these stations give an hour erect his complete station and actually radio "concerts." By means of the Amrad Re- hear messages. Explanatory directions accom- ceiving Set you can easily hear these "concerts" pany each set. The operating is simplicity with surprising clearness though you are miles itself. Set the switch and detector adjustment distant and in the seclusicn of your own room. and then turn the control knob until the desired messages are audible and "tuned" to Radio telegraph messages, press reports, etc., maximum intensity. from commercial stations and ships several hundred miles away, as well as the constant in- The instrument is always ready for instant use. tercommunication of the amateur stations in your There are no batteries to charge or replace. The general vicinity can be heard any hour of the day. first cost is the last cost.

A Complete Unit in Our Established Policy of Standardized Design Receiver $25.00, Telephone Head Set $3.00, Antenna Equipment $12. Complete $40.00 Send for Descriptive Bulletin

Order from your nearest Amrad Dealer. His name was published in August Radio News. AMERICAN RADIO AND RESEARCH C9RPoITIoN 15 Park Row Address all Communications Factory and Laboratory New York to New York Office Medford Hillside, Mass.

www.americanradiohistory.com Radio News for December, 1920 A Practical Receiver By VOLNEY G. MATHISON

TI IE radio receiver illustrated here - with is one that 1 have recently designed and built with the idea in view of producing a strictly practical instrument, capable of covering all wavelengths in use today, either dampt or CW. This receiver affords an example of what can be done through a judicious selection of materials and a careful assembling of the various units. The materials and finished pieces of apparatus were selected from among the products 01 seven manufacturers and while in two or three instances the exact article desired was not to be had, nevertheless a quite satisfactory result has been obtained. As can be readily seen in the photographs, the receiver comprises a Loney - comb -coil tuning system, a vacuum tube detector and a two -step amplifier. The hookup employed is of the standard, to generative type, with one of the Loin comb -coils acting as at tickler in the detector plate-circuit. It is to be noted that no "master -switches" nor other switches of doubtful efficiency have been used in this instrument, nor have any pieces of apparatus been incorporated in it not actually This Receiver is Being Used Aboard One of the Shipping and, as May Board Fleet for "Snailin' the Press," necessary for best results. Be Imagined, the Ship's Complement Have Their Daily News Sheet Copied Front the II. S. A With But Direct The panel is tq x 24 inches and is of Little Regard as to What Part of the World the Vessel May Happen to Be, Ms inch bakelite, making a roomy and rigid mounting for the various units. The regular V.T. sockets tuning system needs but little explanation. are scrctred onto a Separate B- batteries are used for the small. bakelite shelf, which is attached to Audiotron The DeForest cariometer- switch above the the front detector and the VT -1 amplifier primary condenser on the lower left -hand of the panel with two brass bulbs. The detector battery contains twenty angle -pieces. This arrangement combines cells side of the panel serves to switch the con- the advantage and is adjustable in six steps by taps denser either in shunt or series with the of having the bulbs sup- taken to the switch on the upper center ported in a vertical position, of primary honeycomb -coil. The correspond- as is had with the panel. The amplifier battery is of 28 the usual back- mounting, together with the ing switch on the other side of the panel ready cells and is not adjustable. is wired to connect the detecting and am- accessibility of the horizontal front This receiver was sockets as are first designed with a plifying system of the instrument either to used in some instruments. back -mounting for the amplifier bulbs and the honeycomb-coil tuner receiver The degree of filament incandescence may the sockets of the be readily for this purpose may be no- itself, or to the two binding -posts adjacent, observed, eliminating filament - ticed on the bakelite shelf ammeters and the supporting the permitting the use of an external tuner mounting presents a detector B- battery. They are not con- for short waves, if very attractive appearance. The brass nected into desired. The Con- angle- pieces the circuit, however. necticut pull -switch below the inductance - are 2% by 2/ inches and The primary and similar ones may secondary condensers coil mounting is for shorting the tickler - be found in most any are both of .0ort5 M.F.. the grid condenser coil binding -posts it facili- hardware store. Those used on this re- is a balanced and the under ceiver were CE. .008, and the bridging tate the connection of an external tickler, nickeled in a plating shop, so condenser a balanced as to match the other units Chelsea, .0012. Due when using an outside tuner. on the panel. to the large primary condenser used, to- The two Corwin dials control grid and Another practical feature of this re- gether with the series- parallel switch in bridging condensers: above them are ceiver is the B- battery arrangement. Or- conjunction, only two primary honeycomb filament rheostats and A- battery switches. dinary, round flashlight cells are assembled inductance coils are found necessary to Two Federal amplifying transformers arc in a cardboard -lined, brass box, and the cover a range of from 1,800 to 23,000 me- mounted on the back of the panel between container then filled with hot paraffine wax. ters, one of about go milhenries and one the three telephone -jacks, which are of the The metal box is then placed on a warm of 125 milhenries (L-600 and L- 1250). For same make. The amplifier plug connec- stove and the wax brought to a boil, the secondary circuit two coils of the sane tion is worthy of note. The plug is con- thoroly removing all air pockets from size and a third one of 11 milhenries nected to two binding -posts on the tipper around the cells. This battery shows little (L -goo) are sufficient to cover a corre- right -hand side of the panel by a short deterioration with long standing and simi- sponding range of wave -lengths- An L-600 piece of silk- covered cord, making it pos- lar types built in the past have given fairly coil is used in the tickler circuit for almost sible to use any desired pair of receivers continuous service for as long as one year. all waves. without having to chop up the phone cord Renewal is quite easy, the wax being sim- Editor's Note: .Vo doubt there are many and attach a plug. ply melted out and the exhausted cells other professional operators who have con- re- structed effective Probably the most interesting feature of placed by fresh ones. The brass boxes are receiver units. Why not let others hear about it? Such this instrument is the manner in which mounted on bakelite shelves attached to experiences .should prove interesting to some the amplifier bulbs are mounted. . Two of the the back of the panel with brass brackets. .stay -al- homes. Fa^er/erne/ /iot/er -t0-

Schematic Circuit Diagram of the Hook -Up Used By Mr. Mathison in His Prac- tical Sea -Going Receiver Which He Employs on Ship - ladoau board.

www.americanradiohistory.com Radio News for December, 1920 An international Radio Achievement .11r..- Ilexandcrson /'resents e l'ape to a faint Body of Electrical and Radio Engineers of Striking and Far- Reaching Importance

naval power. When, on the other hand, years upon the field of radio communica- you send a radio message it reaches all tion has been a gradual growth and a na- parts of the world. Depending upon tural consequence of its general activities whether it has been sent in code or in in power engineering. The engineers spe- plain language, it may be a confidential cializing in alternating current technique }whale message or a press message in- were in a natural position to take up the tended for the world at large, but nobody problem of designing the alternators and can prevent the electromagnetic waves that transformers needed in the radio technique. carry the message from reaching their These differ front the one used in the destination. It is thus not exaggeration power technique principally in the fact to say that the emancipation of the human that the number of alternations per sec- spirit that was begun by the invention of ond is about one thousand times as great. the printing press has found its fulfilment This speeding up of the performance one in Radio Communication. Radio makes the thousand times involved many new prob- transmission of ideas from man to man lems but the most remarkable fact to re- and from nation to nation independent not cord is that the generally establisht prin- only of any frail material carrier such as ciples of the alternating current power a wile, but above all it renders such com- technique could be applied to the radio munication independent of brute force that technique almost without change. It meant might be used to isolate one part of the that the magnetic properties of iron which world from another. had been reduced to an exact science by These are the ideal aims which inspire Steinmetz thirty years ago had to be stud- the engineers engaged in the development ied again at radio frequencies but it was of the radio technique. This is also the found the Steinmetz laws of hysteresis, explanation why some of the foremost eddy currents and skin effect were as ac- lawyers, executives, financiers, officers and curate at two hundred thousand cycles per statesmen of this country have found in- second as at twenty -five cycles. centive in the human aspects of the radio It was furthermore found that the es- technique to devote a great deal of their tablished conceptions of phase displace- time and thought to its promotion and de- ment power factor leading and lagging Mr. Ernest F. W. Alesandar3on, Who Develop velopment on a world wide scale. currents were as applicable and useful in the High -Frequency Alternator Making Practical Long Distance Transmission Possible. The interest that is evidenced by all the high frequency as in the lower fre- concerned in this subject lias become much quency technique. more serious since it has been establisht It is true that radically different methods TTHAT radio has been developed to that the laws and forces with which we had to be devised for measuring. power fac- that phase, where the central sta- are dealing, are within the control of our tors of a fraction of one percent from the tion is as necessary and essential as knowledge, so that engineers can now pro- methods used for measuring power fac- t;te central electric power station ceed with the design of a radio communi- tor of 50 to too percent but the new meth- was pointed out by E. F. W. Alex- cation system with the same deliberate ac- ods of investigation verified the well known anderson, chief engineer of the Radio Cor- curacy as in the design of an electric principles. poration of America and consulting engi- power transmission from water fall to a The starting point of this development neer for the General Electric Company, in railroad. work was the time when Fessenden brought his paper read before members of the out the problem of generating alternating Radio Institute of America and the New A LOGICAL DEVELOPMENT currents for radio transmission. In doing York Electrical Society in joint meeting This audience is constituted of members so Fessenden realized that a practical solu- in New York City on November to. of a society of electric power and light en- ton of this problem could be worked out He broughi out how New York is the gineers as well as members of the Insti- only by an organization of specialists. natural communication center with Europe, so I shall tute of Radio Engineers; take SOME PROBLEMS OVERCOME South America and other parts of the the opportunity to trace the close connec- world and how this geographic facto[ tion which now exists between electric Some of the problems that presented would be utilized in the building of the power engineering and modern radio en- themselves in the evolution of the radio new high powered central radio station at gineering and will demonstrate as the spe- power plant were: Port Jefferson. Long Island. This station, cific subject of this paper, how the de- 1. The design of a dynamo- electric ma- to be the largest in the world, will be so velopment of the Central Station for radio chine or alternator generating electric constructed that the plant investment and communication is as logical and inevitable power in the form of alternating currents operating force may be used to the best as was the development of the central of frequencies one thousand times as great advantage at all times by shifting the electric power station. as those used for motors and lights. equipment from one service to another or The entry of the Corporation with which z. The development of magnetic ampli- combining them when long distance radio I have been connected for the last twenty fying devices capable of translating tele- is desired. MR. ALEXANDERSON'S PAPER Wireless achievements are often referred to as belonging in the realm of mystery and it is indeed wonderful that we are now able to speak with a voice that carries through empty space across the oceans. Whenever knowledge conquers a new force of nature for the use of humanity, it ceases to be a mystery but the pursuit of tin-- knowledge makes an even greater appeal t'. the imagination. The development of the steam engim was a triumph of the engineering art of the last century hut it was not the cngire itself but the steamship and the locomo- tive that interested humanity. The telephone and cables no less than the steam engine have introduced a new era in human affairs. They have, to a degree, conquered space and time, but only with certain serious limitations. An ocean cable runs only from one land- ing olace to another and it can be cut in tines of war: its use can he censored by Photograph of a Two -Unit Radio Station Employing Two 200 R.W. Alexanderson High Frognency its owners and controlled by military 0 nd Alternators.

www.americanradiohistory.com Radio . \'rws for December, 1920

find it, phone and telegraph currents into cor- a submarine and search for it, we liable contnuutication can be maintained is responding modulations of the high fre- and yet we arc told it is not so. about Soo times the length of the ether quency energy flowing from the power Does the little electron, as an individual. wave that is used. It may be more than a plant into the radiating antenna. take a leap of the aerial wires and after coincidence that the distance to which t. 3. The development of a regulator so devious paths find its home in the glass sound wave travels in air, and a wave sensitive as to hold the speed of an or- bulb on the other side of the ocean? Wr on the surface of water will travel before dinary induction motor constant within a arc also told that it does not. it fades out is also about Soo wave lengths. few hundred of one percent, this being If I knew what really does happen, acid "'The average wave length of sound of necessary in order to maintain the proper should I try to tell you, then sooner or spoken words is about one foot, and we phase relations in a load circuit working later somebody would chum that T was know that if we speak loud our voices will at one-third of one percent power factor altogether mistaken. Therefore, I will carry a distance of about Soo feet: The 4. Improvement of the tuning of the an- only try to tell you hot. I imagine that it exceptions to this rule that will occur to tenna so as to transform as large a part happens, wondering if any of voti will see anybody are also significant. We know process what as possible of the generated energy into the same mental picture of the distances voices will carry over a electromagnetic waves. that I see. lake in a quiet evening. We also know The realization of Fessenden's vision, We were once told by the physicists what extraordinary distances radio signals the radio power plant of today, became that all space was filled by a fine sub- will carry sometimes on a quiet night. thus the result of the combined effort of stance that was called ether, and that the These are exceptions that prove the rule leading electrical and mechanical engi- light and heat that radiated from the sun and the rule refers only to reliable com- neers. Among these, it is sufficient to men- was a wave motion in the ether. The munication tinder normal conditions. there is no tion W. L. R. Emmet the creator of the physicists now tell us that HOW RADIO TRAVELS giant electric power stations of today. ether, but still they say that light is a wave The radio power plant which resulted motion. Be this as it may, for the purposes A radio transmitting system is designed from this was shown to Marconi during a of visualizing what takes place in radio for the purpose of producing waves in the visit to Schenectady, and because of his in- transmission, it is convenient to cling to the ether which we call electromagnetic waves, terest in its perform- and for controlling the ance, it was transferred rite at which the to the Marconi Radio waves are produced, in Station in New Bruns- such a way that a train wick. of successive waves Here we had arrived will carry the meaning at a point where two of articulate speech or schools of engineering telegraphic code. If pursuing different aims we wish to send a with widely different message a long dis- modes of thought, had tance, we must select been brought before a a long wave. The dis- common problem. The tance to Europe is one had been thinking Sono kilometers. If this in terms of power fac- distance is to be tor kilowatts and phase bridged by 500 wave displacement, the other lengths, each wave in terms of wave length length must be at least decrements and tuning. Kt kilometers (six A third school of miles) or as it is knowledge was at that usually expressed a time brought into con- wave length of io,000 tact with this technique meters. and added new impetus We can produce to it. As soon as such water waves by rock- scientists as Coolidge ing a boat. If we rock and Langmuir began to a canoe we get a short study the remarkable wave, but if we rock little device invented a larger boat we get a by Lee DeForest and correspondingly longer known as the audion, wave. To rock the the foundation was boat requires energy, laid for the vacuum but in order to pro- tube technique which duce a wave of suit- has so profoundly in- able length, the energy fluenced the art of ra- must act through an dio communication. intermediate member ELECTRICITY NO which has suitable size LONGER A MYSTERY and proportions. These scientists tell In radio transmission us that electricity is the energy is fur- not the mysterious Schematic Arrangement of the Antennae Combination Which Will Be Installed at the Radio Central Station, Long Island, N. Y. nished by the high fre- power fluid that we quency power plant. may have imagined but in order to trans- flowing smoothly in form this energy into our wires but miniature planets of comets theory of the ether. waves there is required the intermediate of condensed material electricity of definite We are familiar with other forms of member which makes contacts with a large charge and mass shooting across a minia- wage motion-the air waves that carry volume of the medium which carries the ture universe inside of a glass bulb and around to our ears and the water waves heave motion. This medium is the ether following orbits that can be calculated as oit the ocean. Thus the carrier of the and corresponds to the water or the air accurately as the orbits of tae planets. radiated electric energy must not he lik- in the more familiar forms of wave mo- Keeping in mind the origin of the mod- ened to the flowing stream of water, or to tion. The member that transfers the en- ern art of radio communication in these the wind or to a pullet shot from a gun, ergy to the ether is the antenna. The three widely separate realms of knowledge, but likened to a wave in a uniform medium Craves used for trans -Atlantic communica- power engineering and elects physics, we where each particle of the medium oscil- tion are as a matter of fact to,000 meters may now proceed to examine the essential lates around a stationary base line while or longer. The antenna corresponds to the parts. We find then, -first, a modern elec- the wave rolls forward. hull of the rocking boat or the sounding tric power plant working at high frequen- The distance that a wave can travel board of the piano. cy second. a network of wires a mile before it fades out is proportional to its The analogy with water waves may be long, supported on tall masts: third, on length. We may therefore introduce the carried still further. The wave is a suc - the opposite side of the ocean a little idea of wave leitgth, which is the distance cessive displacement of the medium and glass bulb full of shooting stars. The front the crest of one wave to the next. the initial displacement produced by the question is: what does really happen? The long swells of the ocean travel for member acting upon the medium is pro- Does the electricity generated by our hundreds of miles, whereas a pebble portioned to its volume. The water dis- alternator emanate from the antenna and dropped on a still surface of water pro- placement of the boat corresponds to the flow in an undulating stream through the duces a ripple that fades away in a short effective volume of the antenna. The air nr through the water or through both? distance. maximum voltage at which the antenna if we search for it in an aeroplane, we Tn radio communication it has been ob- can be onerated corresponds to the maxi- find it, and if we submerse ourselves in served that the distance over which re- (Cm/tinned on page 382)

www.americanradiohistory.com Radio News for December. 1920 The Audion -Its Action and Some Recent Applications By LEE De FOREST, Ph. D., Sc. D. Part 3 An historical paper of unusual interest to the Radio (rater tity

pOPULAR attention has been rier -wave, a "band- filter," or combi- attracted to the success of the nation of several tuning elements recently announced applica- (inductance and capacity). This tion to line wires of wireless band -filter, then, is equally receptive methods of transmission, re- to any wave- frequency lying within ception and tuning, whereby multi- the prescribed limits, say 1,250 cycles plex telegraphy and telephony have on each side of the carrier -frequency, been made possible over wires al- but offers very high impedance to ail ready loaded down with their ordi- frequencies above or below the limits nary communication. The original of the band- frequencies. By eight ideas of such multiplex telephony such band -filter receiving circuits the date back to the early nineties, eight conversations are segregated, when John Stone, Hutin and Le- each delivered to its own proper blanc disclosed methods all involv- audion detector and sent out on its ing the same principle. that several own local telephone line. alternating currents of superaudio- But it is by no means necessary to frequency, each from a separate limit wired -wireless to the use of source, could be directed over the such low frequencies as we have been same wire or pair of wires, each be considering. Certain tests were re- modulated or controlled by its own cently carried out in Canada which microphone, or Morse key, and at proved conclusively that frequencies the receiving station each frequency as high as 5oo,000 per second can be taken off by its own properly tuned used over telephone lines. including circuit, and there retransformed into several miles of cable, without harm- its own original telephone or tele- ful attenuation. This demonstration graph current.. But none of these widens very greatly the range of fre- early investigators utilized at that quencies available for wired- wireless, time the all- necessary integrating de- with hope for a corresponding in- tector which was alone capable of crease in the number of conversa- retransforming the modulated high - tions, or telegraph communications, frequency wave- trains back into the which can be placed upon a single original audio - frequency currents. pair of wires, or group of pairs. Here again the wire telephone re. Moreover, with such high frequen- quirements had to await the advent cies (say from too,000 to ;oo.000 per of a radio -detector. Fig. 20. A Typical Two -Stage Audion Amplifier. second) the necessity for complicated band -filter receiving circuits van- WIRED WIRELESS telephone receiver. By this combination mul- ishes, with obvious attendant advantages. General (then Captain) George O. Squier tiplex telephony became at once a realized THE FUTURE in 1910 carried out certain experiments fact. Wired -wireless is the youngest of the which are destined to become classic as the But so long as a high -frequency alter- large family of methods for electrical com- new art of wired -wireless attains the impor- nator was required at each transmitter sta- munication of intelligence. He is indeed a tant commercial proportions to which it is tion the wired -wireless idea could not be- bold prophet who will today attempt to unquestionably destined. He, for the first come commercialized. Its first cost, the size foretell the limits of its application. That the time, used a constant, reliable source of un- and weight of it with its motor, its delicacy great saving in line costs, the vast multipli- dampt electric currents of high frequency of speed regulation, its limitation to rela- cation of available channels of long- distance for the transmitter, and an audion detector tively low frequencies, all made this impossi- comnnmicatinn which it makes possible will between each tuned receiving circuit and its ble. So again an important development was compelled to await the advent of the oscillating audion. Supplied from a common filament -lighting battery, a common "B" battery, or d. c. generator, any desired number of tiny alternating current generators, each driving its own easily tuned circuit, can now be assembled in a small central station. The grid of each oscillator is voice -controlled from its local telephone circuit, and as many high -frequency "carrier" wave- trains superimposed upon a single trunk line pair, as it may be feasible to use without interferences between the modulated frequencies of the several conversations. At present carrier frequencies ranging from 5,000 to 25,000 have been used com- mercially over a single pair of telephone wires, between Baltimore and Pittsburgh. A zone of frequencies of 2,500 is allotted to each conversation, which permits of eight simultaneous telephone conversations over the line, in addition to the usual "physical circuit" conversations. The constant frequency generated by each individual oscillion lies in the middle of each allotted zone of wave- frequencies, but the modulation of this "carrier wave" by the voice currents results in a wide band of frequencies (analo- gous to a spectrum band) on each side of the particular carrier -wave frequency. This Fig. 22. A Western Electric Bout le -Grid, means that at the receiving station it is Fig. 21. A 50 Watt Vacuum Tube Used in Pres. Double -Plate Vacuum Tube Used for Detection preferable to employ, instead of a circuit ant Day Power Work as Met in Radio Com- and Amplification. attuned to the single frequency of the car- munication.

www.americanradiohistory.com Radio !Veins for December, 1920

telegraphy, the principal agent in which was reported to be an instrument callett a 'valve,' a 'lamp,' or a 'tube.' This instrument seemed to have arisen suddenly into a predominant position among all the apparatus of the wireless experimenter and operator, and appeared to be of use in every corner of his outfit. The complete" - name of the instrument is the three -electrode thermionic vacuum tube. It must be emphasized that it is the three -electrode valve, and not the valve with two electrodes, that has been responsible for the over- Fig. 23 the old methods and appara- a throwing of tus. That it has been a veritable revolution Fig. 25 1 H.W. a Oscillion can he seen by comparing the common prac- Smaller Which tice in wireless telegraphy of 1914 with that Power Has of 1919. In 1914 practically all the most Tube Proved of a powerful transmitting stations in the world the Powerful generated waves by sparks and signals which KW. Maker were received at nearly all stations by means Óscillicn of Type Oscillations of crystal or magnetic detectors. The spark method of generating waves involved the use of very large antenna for spanning great distances; and at the receiving stations which wisht to listen to stations more than even 100 miles away very large aerial structures were customary. Hut if we look at the state of affairs today we find most of the high -power stations for long - distance transmission are 'continuous wave' stations; that is, they produce uniform un- interrupted waves instead of a series of short gushes made by sparks; while at the receiving end new modes of detecting these continuous waves appropriate to, and taking work profound change. in our present advantage of, their uniformity in character room, or even in a cupboard. In accomplish- methods of business, cal not be questioned. have been introduced. This is where the ing this the magnifications in use amount to Thus again it seems evident that the audion three- electrode tube, in various adaptations, several hundred thousandfold. All this is is destined to play a leading role in the enters the arena. Taken together, the im- the work of a thing which looks like an work of knitting more closely the people of provements at both ends of the span have ordinary electric light bulb with a few extra this land, and of all lands. made possible the use of smaller antenna pieces of metal in it-the three -electrode \ \'e have briefly recounted some of the at transmitting stations, and have almost re- tube." main achievements which the three -elec- moved the necessity for any antenna at all Years ago what physicist did not look at trode audion, or triode, has to its credit. at receiving stations. For example, under the simple, self -contained, noiseless incan- Let us now consider some of the possibili- reasonable weather conditions, it is quite descent lamp, consider it as an ideal source ties of its future. From its invention until easy to listen to the messages coming from of electromagnetic waves of a wide spec - 1912 it attracted an almost negligible inter- stations on the other side of the Atlantic by trum -of heat, visible, and ultra -violet ra- est in the scientific world. A year after the using a receiving circuit of which the recep- diation, and wonder why it should not be audion was first brought to the attention of tive clement is a small coil of wire, three made to generate also waves of any length? the engineers of the American Telegraph to four feet square. Thus, so far as receiv- Today that incandescent lamp, with the ad- and Telephone Company that corporation ing goes, it is possible to intercept all the dition of a metal plate and wire grid, has acquired exclusive license under all the au- great stations on one -half of the globe by become such a generator. Undampt llertz- dion patents for wire telephone purposes. means of apparatus contained wholly in one ien radiations of a few centimeters wave- Thereupon the research men of that length can be generated by audions organization initiated an elaborate specially designed to give minimum line of investigation of the device. capacity between the three electrodes which about that time began to in- and their lead -in wires. From these terest other scientists in America and short waves, representing alternating abroad. Prior to told not a dozen current frequencies of some hun- articles on the audion had appe:o,d dreds of millions, down to those of in scientific publications. Today it one or two per second, the electric - impossible to pick up a magazine de- wave spectrum afforded by the oscil- voted to physics or electric commu- lating audion is continuous. Con- nication without finding one or sev- sider this fact in connection with eral papers dealing with some of the almost infinite sensitivity of the what Dr. Eccles styles "the protean device as a detector, and its unlim- properties of the ubiquitous three ited power as a magnifier, or am- electrode tube." plifier, and one realizes something of Writing in the Radio Review Dr. the value of the three- electrode Eccles (who is affiliated with the vacuum tube to the physicist and the British Marconi Co.) says: "The inventor. To the former, however, most important single instrument in the keenest interest lies perhaps in modern wireless practice is the three - the audion itself, because there is no electrode thermionic vacuum valve. known piece of electrical apparatus for it enters into every main division linked so directly with the most re- of the subject -it plays a dominant cent work on the structure of mat- part in the veneration of oscillations, ter. A prominent British the physicist detection of signals, and in the has recently remarked: "Tt is prob- amplification of feeble voltages and able that there is no other sphere currents. Its arrival and develop- where research work has had sod, ment have, besides, helped greatly a combination of immediate practical toward the success of apparatus and value and intense theoretical interest." methods that might otherwise have Many an early experiment in tele- remained almost failures." graph transmission or reception by DR. ECCLES QUOTED wire or wireless, Inner since aban- Dr. Eccles has outlined the pres- doned as too limited in ranee, can ent status and forecast of the future today be revived het die great benefit of the audion so clearly that I am of man. Calculations have shown constrained to quote further his that with a littoral cable stretched words, as those of no unbiased ob- for fifty miles on each side of the server: "Daring the tear. hints Atlantic, and carrying some forty reached the civilian that a revolu- Fig. 24. A So-Coiled V.T. -21 and its Socket, a Tube Which Has amperes of 20 -cycle alternating cur - tion was taking the place in virelesr Been Much Used by U. S. Signal Corps. (Continued on loge 386)

www.americanradiohistory.com Radio News for December, 1920

THIS Department is open to all readers. It matters not whether subscribers or not. All photos are judged for best arrangement and efficiency of the apparatus, neatness of connections and general appearance. In order to increase the interest In this department, we make it a rule not to publish photographs of stations unaccompanied by a picture of the owner. We prefer dark photos to light ones. The prize winning pictures must be on prints not smaller than 5 x 7a. We cannot -*produce pictures smaller than 3% x 3g, ". All pictures must bear name and address written in ink on the back. A letter of not less than 100 words giving full description of the station, aerial equipment. etc.. must accompany the pictures. PRIZES: One first monthly prize of $5.0C. All other pictures publisht will be paid for at the rate of $2.00.

PAUL G. WATSON STATION This Month's Prize Winner

The transmitter is about the same as the first time my station was published, Mur- dcck condensers, transformer, etc. The antenna switch is home -made, I received several leters from amateurs in reference to my hearing stations on the Euro- Paul Wins the pean continent. At the present Five Berries time, since Because He installing the new set, BZR, BZQ, YN, Seems to NAT, NBA, NFL, VAL, NPZ, WSO, NDD Have a Well and NSS come in fine, on long sustained Planned waves and on spark have heard XDA, Mex- T r a n s- mitter as ico City, sending Spanish press. Well as P.e. I have found most amateur trouble with ceiver. Honeycomb coils to be in their not tuning accurately, and as arcs are very sharp, it is necessary to tune very sharply. As a suggestion a tuning record could be made, giving the size of the primary, secondary and tickler coils, the dial indication of the two condensers. and to give the positions of the coils three lines drawn at the This photograph is that of my amateu. home -made "honeycomb" coil receiver, and angles, approximately the same as the coils, set, which I enter in your amateur station home -made amplifier. A "feed back" or would be of great help in finding different contest. The picture you puldisht in a recent tickler circuit is used, for arc, giving fine statons and wevelengths. Let's hear from edition of your paper was the arrangement results. The amplifier as was mentioned solitcone who thinks as I do. of my staton until just a few weeks ago above, is home -made, but was designed after when the new apparatus was installed. The a standard amplifier and works very ef- PAUL G. WATSON, receiving set consists of a Deforest audion, fectively. 214 W. Barnard St., West Chester, Pa.

FRED MAHAFFEY, JR., STATION was is Fellows, what do you think of these two Cigna! - . My spark gap Rotor (Editor's Note: Fred telling the truth flashlights of my radio "studio" 5J1. It making, I should judge, about loco R.P.M. We have examined both the negative and will be readily seen that one of these is a with six teeth. I'm sending you the "freak" the print with a magnifying glass and can little out of the ordinary. Can you tell negative so that you may see that it ha; absolutely not detect any so- called trick how this came about? At the time this not been tampered with. photography. But how was it dotter Let's photograph was made, I was making the The photo shows that I am in the act of hear from you.) transmitting as may be noted from the flash of my spark. At the same time there seems to be emanating a series of dots and dashes from the confines of the sparking. This is no fake picture for the negative has not been retouched nor was the print touched up in any way. This incident opens up a little guess work on the part of other readers as to just how this stunt was accomplisht. Let our Editor have your guesses. My set consists of an Audion Detector and 2 stage amplifier of the Grebe Mfg., 54 kw. Thordarson transformer, Dubillier condenser, Murdock Oscillation transformer and Rotor. My aerial is 64' long, 45' high. and is composed of five No. 14 solid copper wires. My age is 13. and I attend the Y. M. C. A. Radio School. Am also a member of the Houston Radio Club and a very enthusiastic Boy Scout. Would be clad to hear from anyone to whom I can be of service. Or I should be glad to have anyone call me when they hear "SJI." Frontal View of F. M., Jr., Inventor of the New This Bird Claims the Camera Caught the Dots MAHAFFEY, JR., His Transmitter. FRED Way of Photographing Siena,e. He Admits the and Dashes as They Derarted IS Summers. How Comet 14 Fifth St., Houston Texas. Metbusalean Age of

www.americanradiohistory.com ` 374 Radio .V wtws for December, 1920 A

THIS Department is open to all readers. It matters not whether subscribers or not. All photos are judged for best arrangement and efficiency of the apparatus. neatness of connections and general appearance. In order to increase the interest in this department, we make it a rule not to publish photographs of stations unaccompanied by a picture of the owner. We prefer dark photos to light ones. The prize winning pictures must be on prints not smaller than 5 x 7 °. We cannot produce pictures smaller than 3i x 3/ ". All pictures must bear name and address written In ink on the back. A letter of not less than 100 words giving full description cf the station. aerial equipment. etc., must accompany the pictures. PFIZER: One first monthly prize of 35.00. All other pictures publisht will be paid for at the rate of $2.00.

PAUL G. WATSON STATION This Month's Prize Winner

'l'he transmitter is about the same as the list time my station was published, Mur- dock condensers, transformer, etc. The antenna switch is home -made, I received several leters from amateurs in ref- el ence to my hearing stations on the Euro- Paul Wins the pean continent. At the present time, since Five Berries Because He installing the new set, BZR, BZQ, YN, Seems to NAT, NBA, NFL, VAL, NPZ, WSO, NDD Have a Well and NSS come in fine, on long sustained P 1 a n n e d waves and on spark have heard RDA, Alex - T r a n s- mitter as ito City, sending Spanish press. Well as P.e- I have found most amateur trouble with ceiver. Honeycomb coils to be in their not tuning accurately, and as arcs are very sharp, it is necessary to tune very sharply. As a suggestion a tuning record could be made, giving the size of the primary, secondary and tickler coils, the dial indication of the two condensers. and to give the positions of the coils three lines drawn at the This photograph is that of my amateu: home -made "honeycomb" coil receiver, and angles, approximately the same as the coils, set, which I enter in your amateur station home-made amplifier. A "feed back" or would be of great help in finding different contest. The picture you publisht in a recent tickler circuit is used, for arc, giving fine statons and wevelengths. Let's hear from edition, of your paper was the arrangement results. The amplifier as was mentioned sotitcone who thinks as I do. of my stalon until just a few weeks ago above, is home -made, but was designed after when the new apparatus was installed. The a standard amplifier and works very ef- PAUL. G. WATSON, receiving set consists of a Deforest audion, fectively. 214 W. Barnard St., West Chester, Pa. FRED MAHAFFEY, JR., STATION Fellows, what do you think of these two signal - . My spark gap Rotor was (Editor's Note: Fred is telling the truth flashligl is of my radio "studio" 5J1. It making, I should judge, about 3,000 R.P.M. We have examined both the negative and will be readily seen that one of these is a with six teeth. I'm sending you the "freak" the print with a magnifying glass and can little out of the ordinary. Can your tell negative so that you may see that it has absolutely not detect any so-called trick how this came about? At the time this not been tampered with. photography. But how was it done? Let's photograph was made. ! was making the The photo shows that I am in the act of hear frent your.) transmitting as may be noted from the flash of my spark. At the same time there seems to be emanating a series of dots and dashes from the confines of the sparking. This is no fake picture for the negative has not been retouched nor was the print touched up in any way. This incident opens up a little guess work on the part of other readers as to just how this stunt was ac- compiisht. Let our Editor have your guesses. My set consists of an Audion Detector and 2 stage amplifier of the Grebe Mfg., IA kw. Thordarson transformer, Dubillier condenser, Murdock Oscillation transformer and Rotor. My aerial is 64' long, 45' high, and is composed of five No. 14 solid copper wires. My age is 13. and I attend the Y. M. C. A. Radio School. Am also a member of the Houston Radio Club and a very enthusiastic Boy Scout. Would be glad to hear from anyone to whom I can be of service. Or I should be glad to have anyone call me when they hear "5JL" Claims the Camera Caught the Do s Frontal View of F. M., Jr., Ieventar of the New This Bird FRED MAHAFFEY, JR., He Admits the and Dashes as They Departed His Transmitter. Way of Photographing Stems. How Comet 14 Fifth St., Houston Texas. Methusalean Age of 13 Summers.

www.americanradiohistory.com Radio X C res for December, 1920 LUE GOSSIP

ESSEX COUNTY RADIO ASSOCIATION the New England Navigation Company, to organize THE PHILADELPHIA AMATEUR RADIO The Beverly branch of the Essex County Radio and direct such a club. Boys and young men ASSOCIATION Association met at the Y. M. C. A. recently where throughout the city interested in wireless are in- Two meetings in November, 1920, were held by headquarters have been provided. President Es. vited to telephone or call at the Association build. the Philadelphia Amateur Radio Association, the tey was present and presented the club with their ing, so that a meeting of amateurs may be called first on Friday, November 5th and the ather on certificate of affiliation from. the American Radio early next week for the purpose of organization. Monday, November 15th. League Association. Pefinite plans were made for Mr. Willets has a thorough knowledge of his sub. On Friday, November 5th, two papers were read. the installation of wireless equipment. The branch ject and is able to instruct others. The first paper dealt with the construc:ion and can accommodate twenty -five members at present maintenance of storage batteries and was read by and is open for membership to any male person Mr. T. R. Cushman, of the Columbia Storage Bat- interested in radio. CLARK COLLEGE (WORCESTER, MASS.) tery Co. This paper was illustrated by lantern RADIO CLUB slides. UNION COLLEGE (SCHENECTADY, N. Y.) Clark College will greet Kalamazoo College in The other paper dealt with Regenerative Re- RADIO CLUB Michigan within two weeks by radio, providing the ceivers, with notes on regenerative reception. This The Radio Club of Union College in addition to plans of the two colleges do not go astray for the was read by Mr. 7. W. Wyncoop. These papers being of interest to those students who know radio clubs at both institutions have agreed to were very interesting and instructive. something of wireless, is attempting to be of bene- communicate by radio. The Clark club had its The second [meeting, Monday, November 15th, fit to those who as yet know nothing of the work first meeting of the year yesterday afternoon and was a sociable evening. All amateurs were in- but who wish to learn. The club has had several chose A. L. Parks as president. The radio set vited. Various types of wireless apparatus were lectures on wireless and is planning more. At is being set up. exhibited. There were discussions on interesting the present time wireless code classes have been radio subjects and experiences with circuits of formed to meet every afternoon at 4.30 o'clock. various kinds and unique hook -ups. New mem- -Radio Club, Union College, Schenectady, N. Y. bers were received. Visitors were welcomed and THE SENN RADIO CLUB radio associations were invited to send representa- TECH RADIO SOCIETY The Senn Radio Club was organized by a body tives who were asked to make themselves at home BOSTON of students March 17th, 1920, at the Nicholas at the meetings. The general public was also in- Novelty in advertising is the slogan of the Tech of Chicago, Ill. vited. Radio Society, which has adopted the scheme of Senn High School, by wireless to students as At the first meeting officers were elected and The Third District Convention will be held in furnishing correct time faculty adviser obtained, making the club an of. Philadelphia on February the 26th, 1921 -holding a means of increasing its membership. An ampli- ficial the fier with society's receiving organization of school. over during Sunday. Banquet tickets, $2.00. Boon, has been connected the The purpose of the Senn Radio Club is to the is set and placed in the student dining hall at Walker pro- Convention. Our business address 1902 time mote good fellowship to gain a better. knowledge N. 11th Street, Philadelphia, Pa. Memorial, so that when the Government of radio apparatus and to greater co- signal is picked up it may be heard throughout promote and operation among amateurs. the building. The signals start at 12.55 consist The meetings are held on the second and fourth MT. STERLING RADIO ASSOCIATION of dots every secone for five minutes except the Long skipped. At 10 Wednesdays of each school month. They are con- before the outbreak of the great World 29th and 65th to 59th, which are ducted by the president. War, several of the boys in Mt. Sterling became seconds before 1.00 o'clock the dots cease and on interested is given. The usual business is followed by a program. in wireless. They decided to put up the stroke of one a long dash This program is usually a talk by some student. a set together, just why we wanted to pit it upon The society's officers are H. P. Field president; a co- Webster, sec- Some discussion follows on radio science, alter the operative basis is not definitely known, but H. M. Lane, vice- president; F. D. formal adjuornment of the meeting. Those wish. the main reason was that not one of us knew any retary; W. C. Kohl. treasurer; standing commit- remain. too much R. C. A. Clarke ing code practice Communication with about the matter and though- that this tee. Il, L. R. Kurth, H. Shaw, other clubs is desired. Stanley E. Fey, president, would be a Good wav to shift some of the re- and Ansley Newmiai,. 5800 Glenwood Ave., Chicago, Ill. sponsibility for the success of it. That was before the war. The war came. So NOLA (NEW ORLEANS, LA,) RADIO CLUB did the Government's orders to dismantle. We December opened the season for the Nola Radio MORRIS COUNTY (N. J.) RADIO CLUB did. Just as soon as the war ended we again Club with a program combining entertainment and got the radio 'bud" as strong as ever in our instruction at the club headquarters in Chartres A meeting was held recently at the home of systems. This time we decided to put up a real Street. Officers of the organization are G. A. De Merritt E, Gregory on Pine Sreet, Morristown, set. As soon as possible our stuff was unpacked, Cortin, president; Theo Deiler, vice- president; T. N. J., at which the Morris County Radio Club seas and We found M. set up. that our apparatus had Preis, secretary and treasurer. -Nú(a Radio Club, organized. E. Gregory was elected President, grown sadly out of elate since we last had the Chartres Street, Neat Orleans, La. R. M. Lacey, Secretary, and M. \V. Kilso, Treas- privilege of using it. So the crystal gave way urer. to the audion and now the three stage amplifier SENECA (GENEVA, N. Y.) RADIO ASSN. The principal purpose of this Club is to better A standard 1.k.w. Thordarson transformer was The Seneca Radio Association, which was or- the condition of amateur radio in this vicinity purchased and the rest of the transmitting set agnized last fall, is about to re- comtnence its reg- and to act as a reliable link in a direct line of brought up to date. \ \-e have our aerial strung ular meetings. The faculty announces that the communication between cities. It is felt that with from the city's water tower directly leading to election of officers occurs in the near future, if an efficient organization of this character relay operating room. is our not at the first meeting. One of the features messages can be more promptly handled. It Our call is 9 -AHS and we would be glad to which is planned for the winter activities is a proposed to have at least one member stand watch test with other amateurs close to our station. We membership drive for the purpose of boosting the at an official station of the Club every evening have four of the numbers licensed as operators club. so that stations in other towns may be assured and thus have a man practically all the time. Many of the club mmebers are affiliated with of a good route through this vicinity. A word to Radio Clubs about our organizatiqn the American Radio Relay League, messages Another purpose of the Club is to co-operate individual radio would probably help them. Keep your member. will be transmitted, day or night, free of charge. with members in solving their ship town to say eight or ten or to where you The messages are relayed from one station to an. problems, also to gather together for the benefit knowledge can logically do good work. \\'hen there is a other until their destination is reached. Messages of the members such bits of news and great number in on a set there is sure to be therefore can be sent to practically any point in the as is of interest to the radio amateur, just a little indifference on the of some. At the meetings which for the present are held part United States. have This causes an unrest that is not good for study Tim purpose of the association is to develop at the homes of members, it is expected to or experimenting. Our plan is to assess each interest in amateur wireless and to have a point from time to time speakers of note, or other fea- member a fee that will entirely cover the ex- at which ito center and discuss the results of the tures of peculiar interest. should apply to the penses for the following month. It is then the various experiments which are daily being per- Those desiring membership duty of the secretary to collect the dues and pay formed. Secretary, R. M Lacey, 11 Mills Street, Morris. the bills. When any new apparatus is desired, Any person interested in the development of town, who will furnish blanks and explain neces- the question is brought up before the association wireless telegraphy or telephony are cordinly in. sary qualifications for admission. and it is voted upon. If passed, the secretary vited to attend the first meeting which promises A radio broadcast concerning the Club's activi- then proceeds to order it, and the cost is shared to be very entertaining. They will then have the ties will be sent out each evening at 7.30 sharp up among the members. opportunity of becoming a member if they do se. (Eastern Standard time) from one of the Club's We have experimented with practically every S LY desire. official stations which at present are and make of bulb, we have tested many couplers using Due to the illness of the president the date of 3 abg. bank wound coils and others. and would say in the opening meeting has not been definitely set- closing that we all enjoy RADIO NEws and Snenre tled. It will be announced in the near future. and Invention. Mount Sterling Radio . \- sociation, STATEN ISLAND RADIO CLUB Mt. Sterling, Ill. ELECTRIC CITY (SCRANTON, PA.) RADIO The radio amateurs of Staten Island have CLUB formed a radio club tinder the name of the Staten UNIVERSITY HIGH SCHOOL RADIO CLUB Meetings of the Electric City Radio Club, an Island Radio Club. This club started October 1. and has a membership of ten. It also has a code The C-niver.ity High School Radio Club was organization of local radio experimenters, will organized at the beginning of this semester at the be held during the w inter on Friday evenings at practice, and a club set which have given very good results. We are working on a wireless tele- University High School. Oakland, Calif., and held the Scranton Real Estate Building, 810 North its first meting in the Science Rooms of the Washington Avenue. phone at present which will be completed in the Sept. Persons desiring information about the club near future. Officers have been elected as follows: School. on 21. 1920. The following officers President. Geo. Gropp: Vice -president, H. Hitch- were elected: should communicate with the secretary. P. D. President. R. E. Calhoun- GFZ: McFarland, 802 Woodlawn Avenue. cock: Secretary, R. Stromberg; Treasurer, C. secretary, Hor- Barnes. Meetings are held every Thurdsay eve- ace Greer, OTTI radio engineer and chief operator, using. The club has been organized for the pur- Chas. Wilson, 6LE. Y. M. C. A. RADIO CLASS NEWPORT (R. L) pose of getting acquainted with the amateurs of The Faculty advisor is Mr. McCay, of the science Boys' Work Secretary Hobson has arranged to Staten Island and giving them a better knowledge department of the school. start a wireless class among the boys at the Young of the art. All other club. ay communicate The membership has been limited to 20, thus Men's Christian Association, having secured the with George Gropn. 24 OsgoodAve.,m Stapleton, affording each member a fine chance to study services of Gilson B. Willets, radio operator for Staten island, N. Y. (Continued on page 394)

www.americanradiohistory.com Radio News for December, 1920 RADIO DIGEST

CONDENSER ANTENNAE. NEW SYSTEM OF COMMERCIAL This edition is publisht by the United Experiments have recently been made at LICENSES ALMOST CERTAIN. S:atcs Naval Institute at Annapolis, Md., the Bureau of Standards upon a speical A conference held in Washington on and the price of the book is $1.so postpaid. type of antenna for transmission and re- November 12 under the chairmanship of ception of radio signals. The antenna con- Messrs. Alexander, Secretary of the De- DETERMINING AUSTRALIAN sists of a pair of metal plates. It is thus partment of Commerce, and Chamberlain, LONGITUDES BY RADIO similar to the ordinary antenna arrange- Commissioner of Navigation, as well as According to the Scientific American, ment, the wires of the ordinary antenna representatives of the American Steamship wireless signals are to be used in marking corresponding to one plate of the con- Association, the three large Radio Service out the boundary between South and 'u est denser antenna and the ground below the Companies, ,The United States Navy, the Australia, defined by Imperial Act as the wires corresponding to the other plate of Radio Inspection service, and the United 129th degree of longitude east of Green- the condenser antenna. When the lower Radio Telegraphers' Association and Ship- wich. It is proposed to determine the in- plate of the condenser antenna is on the ping Board. An interesting discussion con - itial point on the line by utilizing longitude ground, the two types are practically iden- cerning the value of changing the present signals from a high -power radio station tical. It is found, however, that raising system of licensing of radio men for a sys- located at some point between Greenwich the lower plate from the ground improves tem where an operator's period of service Observatory, in England, and Sydney Ob- the signals. This type of antenna has the would be a determining factor in the grade servatory, in Australia, the signals to be advantage that it is not subject to dis- of license he receives. It was unanimously received simultaneously at these points. turbances and irregularities produced by decided for the benefit of the entire service This undertaking will be the first step in a objects on the ground. to adopt this arrangement under the com- comprehensive scheme involving the re- The work done included the construction bined proposals made by The United Radie determination of the whole longitudinal ut various forms of condenser antenna and Telegraphers' Association and the Shipping system of Australia. A committee has

measurement of the capacity and other elec- Board. II The grade of ships upon which been appointed to carry out the work in trical properties. This type of antenna was these lie'me: kill I: valid is n matter for Australia, comprising the Government as- compared with coil antenna which are used tronomers of New South Wales, Victoria, as direction tinders. For the very short West Australia and South Australia, the wave lengths, such as are used in radio Commonwealth surveyor -general and the communication by amateurs, the condenser Radio Articles director of the Royal Australian Navy antenna gave more intense signals than the Radio Service. It has been ascertained coil antenna of the same general dimen- i i the December Issue that, under favorable conditions, signals sions. Compared with the ordinary anten- of Science and invention from Lyons can be successfully received in na with which a ground connection is used, Australia as well as at Greenwich, and sig- the condenser antenna is markedly free (Formerly Electrical Experimenter.) nals from other stations more symmetrical- fr.nn electrical disturbances. ly situated are also being tested. The co- The Kauen Radio Station. operation of the United States, as well as the British Government, has been invited. MODERN THEORY AND PRACTICE New Precision Condenser and IN RADIO COMMUNICATION. Waventeter. AMATEUR TRANSATLANTIC By Robinson and Holland. TELEPHONY A need having arisen for the instruction Secretary Baker's Son Radio En- The recent report received from a cf \lidshipmen in Radio, beyond that pre- thusiast. Scotch Radio Amateur in which he re- viously provided, the authors have under- ported having heard the station of Mr. taken the production of a text suitable for Ei.vcse Radio Station. Hugh Robinson located at Keyport, New that purpose. Transmitting Photographs Ra- Jersey, on October the 6th, 192o, received Their endeavor has been to provide a By dio. With Complete Diagram considerable notice from the newspapers as book containing all the information neces- well as the technical press of this country. for intend to of the Working Apparatus. -13y sary the student who does not Pierre H. Boucheron. and many are loath to believe that the feat specialize on radio, and at the same time to was actually accomplisht. produce a book which will serve as a basis However, the American amateur imme- for further study for the student who does diately wrote back to Mr. Benzie, asking for wish to specialize. The book is not in- Congress to decide and it is thought tha more complete details concerning just tended, however, for an instruction manual hecatise of more important matters, these whom he had heard and at what time. Mr. for a radio operator who lias little interest laws will not be passed during the shor Robinson has just received an answer in the how and why of his apparatus. session but will be left over to the regular which reads as follows: Requirements of time and space have scssior. Denntill Cottage, made it necessary to take for granted vari- Petcrculter, ous statements which would be derived ROBISON'S MANUAL OF RADIO Aberdeenshire, Scotland. mathematically, or explained in detail, in a -Voveetber I I, 1920. text dealing purely with fundamentals. TELEGRAPHY AND TELEPHONY. Dear Sir: These omissions are of such a nature that The Radio Manual presents, for the use / have Just received yours of October they may profitably be studied only by a of student operators and others, the ele- 25th, asking how i identified your station. student specializing on radio subjects. nientay principles of the art of radio teleg- It was as follows, as far as I can remem- To understand the work as presented, the raphy and telephony, together with descrip- ber. My friend Mr. Biller and 1 were at student should have a knowledge of ele- tions of apparatus commonly used. This our "dear" when we heard the carrier tear: mentary electricity and physics. volume is the fifth revision of the volume at a station and suspecting telephony, we This volume is publisht by the United originally written by Lieutenant (now Rear tuned with the results that the hone States Naval Institute, Annapolis. Md., and Admial) S. S. Robison, U. S. Navy, in "Roanin in the Gloamin'" cane in. Your 1907. in it is understood its price is $2.25 postpaid. Among those most prominent as- 8nisht by saying "2QR has been speaking," sisting in the various revisions have been repeated three times. So / looked up the Dr. L. W. Austin, Mr. G. H. Clark, Mr. G. calls and found your name and address SUBMARINE RADIO. E. Hanscom, Mr. J. A. Fried. Mr. C. J. and wrote to you thinking you would be The last annual report of the Bureau of I'ann&ll, Mr. W. S. Lemmon, Mr. A. Cross- interested. I will send fuller details later. Standards states that members of the Bu- ley, Mr. H. Pratt, Mr. R. A. Ballantine, and Hoping nest week 'we'll hear you again. reau's staff have developed very successful Lieutenant W. A. Eaton, U. S. Navy. The l'ours faithfully, methods of communicating with submerged fourtn and fifth revisions were made by GEORGE W. G. BENZIE. submarines by radio -telegraphy. With a Capte.in Tood and Commander Hooper. Altho this does not definitely settle the single -turn coil or loop attached to the out- The volume is exceptionally well adapted matter there would seem to he a strong side of the submarine, signals can be re- for instruction purposes, for it contains ele possibility that the Scotchman actually ceived as well when the vessel is submerged mcntary data of great value to the student. heard the Keyport, N. J., station which is as when it is at the surface. It is also A general review of facts relating to high known as 2 -QR. possible to transmit from a submerged sub- fregt.ency currents is given, and this is fol- This trans- Atlantic feat was certainly a marine a distance of 12 miles. Thus it be- lowed up by production, radiation, and de- most spectacular record for American comes possible for a slip and a submarine tection of ether waves. Sending and re- amateur radio and there now remains but to exchange recognition signals. A coil ceiving apparatus as well as continuous one thing to do and that is to repeat the aerial is a satisfactory direction finder when wave transmitters are described. The radio performance in the very near future where submerged and readily receives signals telephone, the radio compass ,and aircraft members of interested societies as well as transmitted thousands of miles, just the radio equipment are also considered. These other official witnesses could actually hear same as when used in the air. The navy being comparatively late editions to the ra- for themselves that such long distance has equipped its larger submarines with dio art, they should prove timely and of work is possible even with a comparatively this apparatus. -Scientific American. considerable benefit. small power amateur unit.

www.americanradiohistory.com Radio News for December, 1920 Raided By Radio In Which a Master Scientist -Criminal Is Caught By HERBERT WARREN DODGE

WITH a careful glance at the - - chess -board before him, Allen - - ¡ . Crosby threw the antenna switch _ f rI' sr r. sending position. He into the Tq I, i smiled happily as he slowly sent ,x;.,i I the symbol "D -to" into the ether. This ;

of his knight marked , last move, the placing ;á ` D to the square labeled to, had effectively - blocked his opponent's lone King and ended Ì the much- talked of "Chess Tournament by Radio" with Crosby the local champion. 6d Truly the San Francisco amateurs had been "chess -mad" during the past month. The fad, begun by a local Radio Club, had become so popular that a prize was offered to the best player at the game. Crosby had taken an active interest in the rather unusual method of playing the ancient game, and this, the last night of the tournament, had found him the undisputed victor. Acknowledging the congratulations he ''In One Corner of the Basement received from fellow-amateurs who had a Rather Uncommon Radio Trans- followed up the game, move by move with mitter Was Discovered." chess -boards before them, Crosby prepared t. to do some long- distance work, having several messages for the city of Seattle. Increasing power, Crosby gave the Seat- tle station a long call and informed the "g ZSX, g ZSX," he sent unfalteringly ord. As a member of this wireless organi- operator that he had some messages for and signed his own call, "get you o. k. zation, you are surely a progressive one him. The called station responded imme- Have you anything for me ?" and deserve to be congratulated," concluded diately and in a short time the business "Yes," replied the operator in Chicago President Terry as he handed Crosby the was completed. and thereupon sent Crosby a message to silver cup, the prize award of the Tour- An amateur in Oakland then broke in be delivered the next day. The man went nament. and told Crosby that he was being called on to say that Crosby's signals were loud "Thank you," mumbled Crosby, decidedly by Chicago, the operator in that city hav- and distinct except at times when he uneasy before the other members of the ing an urgent message for San Francisco. "faded" slightly and very little difficulty club as they gave him a rousing cheer. Crosby, listening a moment, heard the was encountered in copying him Arriving home late that evening Crosby feeble spark from the city in Illinois, but Crosby experienced the same fading out immediately called "g ZSX." Due to local was undecided whether to answer or not. phenomena of the signals from Chicago interference. however, it was some time Would his signals reach Chicago? But but received every word the operator sent, before he came in direct communication certainly they must have been heard in that and assured him that the message would with the Chicago station. With business- city otherwise the operator there would not be delivered early the next day and the like celerity Crosby transmitted the answer be calling him. Emphatically it was a long answer would be transmitted in the even- to the message of the evening before and jump from the city by the Golden Gate to ing. received the other operator's "o. k." the metropolis on Lake Michigan; Crosby's Crosby was not tìnisht io. the evening, previous record being to the state of though, and gave one of the New York \Vvoming. "Good for you, Crosby. that was certainly stations a call. Receiving no reply he Exultant, Crosby threw on the limit of a nice piece of long distance work you put tuned a trifle higher than the amateur wave his power and changed his rotary gap from over last night." It was the next evening and was surprised to hear a radio -telephone the usual low tone to one or much higher and the president of the radio club was working. It proved to be a phone station speed, the latter being more suitable for speaking. "You not only won the first in Pennsylvania conversing with a like sta- distance work because of its clear -cut, mu- prize in the Radio Chess Tournament, but tion in Ohio.. Both stations were fairly sical note. you also established another distance rec- audible. When they had concluded their conversation Crosby called the one in the Quaker state. "Hello, 6 XAD, how do you hear me out there ?" came back the voice of the operator in Pennsylvania in reply and told Crosby briefly the type of apparatus he was using to transmit the voice. Crosby replied and learned that he was loud at that station across the continent and they were only using two audion tubes to receive him! What a record achievement! Over 2,50o miles and on only one - half of a kilowatt! It seemed preposter- ous, yet it was a reality. He again sent out their call intending to ask them if they had any messages for San Francisco or vicinity but some local amateur with an extremely "broad" wave was "hamming" with another in Berkeley, causing too much interference to hear the far -away station. "The Government should make stringent laws pertaining to radio communication after ten o'clock." thought Crosby, "and allow only long distance operators to work." Finally the troublesome amateur ceased and the radio phone station was called once more. Upon throwing his switch into receiving "The Five Lay.Breakers Stared Into the Muzzles of Six Wicked -Looking Automatica and Slowly Crosby was aware of a low rumble in his Raised Their Arms." (Continued on page 413)

www.americanradiohistory.com 370 Radio News for December, 1920 Radio Bug-ology C ne of the Craft Sends In a Letter.

For this reason 1 am about to it is rather poor for C. W. reception. By describe the more unique parts merely substituting a good nerve tonic for of my station and some of the the vacuum the result will be an excellent little difficulties that I have transmitter bulb for tonic train transmis- overcome. In the first place, my sion. But let us continue. As I experi- aerial is of the well-known in- enced a good deal of difficulty in securing verted "O" type, made of a plate small enough to go into the tube I stranded doorbell wire. As the resorted to using a small china saucer, method of stranding is rather which gave gratifying results. Whenever original I shall deal with it more the bulb spilled over it spilled into the fully. When I purchased the saucer, and thus nothing was lost. CORK wire it was not stranded, but be- As everyone knows, while the bulb is in v.cuun UP TO MERE came stranded after I put it up operation, ions jump off the filament and FILLUHE'T To be more explicit, after I got gather on the plate, or rather saucer, which ono WITH it up the pulleys jammed and as soon gets all cluttered up with them. \Vhen HOLES yet I have been unable to get the this happens the tube should be uncorked to s O,)LATENG darned thing down. and the saucer taken out and washed in JH PLATE wane water. The other clay an unusually Nicely ch, what? stranded, large ion struck the saucer with such As for insulators, I at first velocity that it broke it. Due to the high used small pieces of brass rod. cost of china I have been careful to pre- but finding them rather unsatis- vent a repetition of this accident. Taking factory, I later discarded them last Saturday afternoon off I went out into ir, favor of short sections of the woods where I surrounded, and after broom handle. Efficiency at an a short struggle, captured a number of cost is my motto. small, square holes. After carefully chlo- I first took up wireless roforming these- I spent all Saturday night When binding wire. I experimented a good deal with them together with copper crystal detectors, but am now The result was not unlike fine mosquito netting. fastened as have using a vacuum tube of my own I this "grid," I filament. and design. The following are some christened it, around the now all thus eliminating of the crystals I have used - the ions are strained, galena. carborundum, radiocite, any which might be large enough to dam- zincitc, bornite, cerusite, hugmc- age the saucer. tite and settemalite, but I find In closing I would like to add this piece my new bulb to give the best of warning-don't use honeycomb coils results. with an audion. I did once and got stung. "AS I Experienced a Good Deal of Difficulty in Securing t This is how it happened. Two weeks ago Plate Small Enough to Go Into the Tube I Reported to This bulb, which is quite a de- I new coil, all the 'Use of a Small China Saucer." bought a nice honeycomb parture from basic principles fresh and dripping with honey. As soon as consists of a small glass tube, I got it home every blessed bec swarmed IHAVE been a wireless "ham" for open at one end, and carefully filled with out of my "B" battery and started to buzz is filled the open several years now and consequently vacuum. After the tube around the coil. Now a "B" battery is no cud tray be plugged up with a small cork good if all the bees have left it so I started have deal experience had a good of to keep the dust out, but this is not abso- to put them back, and in doing so I got It seems to one that if we old- timers lutely necessary. The vacuum is the same stung. Since then I have used duo-lateral would only tell each other about our kind Is is used for vacuum cleaners and coils and have had no further trouble with stations, our experiences, and our little may be purchased in liquid or powder form the bees. They sing nice duos! nearest store. I have found Hoping this may be of assistance to those and triumphs it might do a good at the drug trials the liquid vacuum to be rather unsatisfac- who contemplate building their own appa- the art in deal toward the advancement of tory, es it has a tendency to spill over un- ratus, I remain, undampt, amateur circles. less tte cork is in tight. Due also to its G. Rtnt.EAI:. V.T., (Echo answers. "It might -not. ") damping effect upon the incoming waves Chief Radio Eng., Toronto Lunatic Asylum. The Spirit of Christmas BSI ERALD A. SCHIVO

AMOMENTOUS problem confronted chairman had inquired for new business; the members of the Q S A Radio "this club is becoming more and more Club. wealth:- every meeting. We have a large Paul Knox, one of the fifty mem- sum in the treasury; more than we know bers which the association boasted what to do with. \Ve have the most satis- of, -.vas a very poor young man. The or- factory set in this city. A radio telephone ganization was aware of that fact. Knox is about to be donated by a large company. would accept no charity. He was quite So mut h for our wealth. popular. They listened intently to all sug- "There is a member of this club, he is gestions and motions he was wont to dis- not present tonight, who has accomplisht cuss. more fir us than any other member. As Insistent and distressing circumstances chairmt.n of the electrical committee all follcwed the wake of the young man. Both the interesting experiments which we had parents had died in an accident the day recently were due to him. He has worked before his graduation from grammar school. for the club heart and soul. Need 1 men He was left penniless. An aunt in mod- lion the name of this member? No, you erate circumstances argued that Knox must all know him." continue high school. Only with the prom- A whispered name which was intelligible ise that he be allowed to pay all expenses to everyone broke the silence. There was incurred after he graduated, did the hoy a sligh: stir as the members waited fen agree to finish with the upper school. He the speaker to continue. his year. was now in Junior "Paul Knox!" the speaker now shouted "Mr. Chairman." the nane. "Paul Knox is no doubt the "Mr. Clark." only mtmber we have who takes such great "Fellow members," the young man who "If I Only Had Such a Wonderful Set," He had asked for the floor was speaking: the (Continued on page 409) Sighed.

www.americanradiohistory.com Radio News for December, 1920

between CONSTRUCTION it in series with the ground lead, : -R p/ales o/receive.-. gok the ammeter and the earth. This set when For the construction of the set itself, a used in an open field gives good results bakelite or hard rubber panel Io" by 8/ with an inverted L single wire aerial about and about ìg" thick can be used as front So feet long and 7 feet high. Since a direc- panel, on which is fixed the ammeter which tional effect is obtained by this type of low is of the hot wire type and graduated from aerial it is advisable, if possible, to erect it zero to I ampere, the o.000s mfd. variable in the direction of the receiving station in condenser, the filament resistance, and the order to obtain the maximum intensity at 8 point switch of the loading coil and also the reception end. the twelve binding posts. Excellent results will be also secured ii Behind on a horizontal panel to x 6" are used with an amateur aerial having about fixed the three tubes and change -over 200 meters of natural wavelength. As will switch in the manner shown in Fig. 2 of be noted the same A and B batteries are the assembly drawing. Below and fixt on used for transmission and reception. Two the bottom plate are the two audio fre- switches make the necessary connections quency- transformers, the 2 mfd. fixed con- and automatically load the filament and denser which is connected across the B bat- plates with 4 volts and 40 volts respectively tery, the grid leak of the audion detector when receiving and 6 volts and 16o volts and the coils placed at right angles. The when transmitting. The voltage of 160 two coils are wound on wooden rods 1W" f volts can of course be changed and if a in diameter with No. 16 double cotton cov- direct current dynamo delivering a higher ered wire. The coil of the oscillating cir- Diagram of Connections When a D.C. Machine cuit is wound with 36 turns and a tap taken is Used Instead of a H.T. Battery for Trans- voltage is used, the range will be greatly mitting. increased. On the other hand, if lower at the nineteenth turn. The loading coil 6 voltage, about So or too volts is applied to wound with 42 turns is tapped every turns. the plates, the range will correspondingly a lathe by the amateur The constructional details the 8 poles himself or to order be reduced. of at an inexpensive change -over switch are clearly shown in price. THE FILTER CIRCUIT Fig. 2. A hard rubber strip fixt to the 8 In order to firmly fix the two panels and switches move them at the same time when the bottom plate together, they are screwed If a D.C. dynamo is used to supply the pushed on either side by means of the han- in two pieces of wood maintaining the com- high voltage to the plates for transmission, dle which appears in the center hole of the plete unit and allowing it to be used as a a filter circuit must be used and connected panel set or to be enclosed in a cabinet giv- in front panel. Each switch is provided with in place of the "B" battery as shown three switch points. The center ones being a neater appearance to this piece of ap- Fig. 3. ing dead points to cut out all connections paratus. The filter circuit is made of two choke and avoid short circuit of the batteries It is strongly recommended to make all coils composed of an iron core W" in di- when switching over from reception to wiring with No. 18 or 20 wire, the con- ameter and 3%" long wound with two transmission position. nections being straight. The set is very pounds of No. 26 double cotton covered The question of the contacts of this commercial like looking, and the contacts wire, and shunted by two fixed condensers change over switch being of great impor- being soldered the resistance of the circuits and I mfd. capacity each. tance, we recommend the use of three is reduced to minimum; a very important Using a B battery of 20o volts and a blades fixt together as shown and sliding factor in small power -c.w. sets. If two good ground connection made of a buried on the points. These blades are Cu: out in or more of these sets are built, the owners water pipe in a wet place, the antenna cur- a brass plate 1/48 of an inch thick. The will be delighted with the results obtained rent was 0.3 amperes. other parts of the switch can be made on with these portable apparatus. A Short Wave Coupler By GEO. MITCHELL

Here is a design for a short wave loose coupler which I do not think has been described in recent radio publications. A similar one is at present being used at my station and I find that it gives excellent results on wave -lengths tip to and including Soo meters. The accompanying photograph will give other amateurs an idea of what the completed instrument looks like. and I should be pleased to have others consider this design in future panel sets. This coupler may be mounted on a panel or cabinet as desired. The tubes are cardboard which may be procured from a gro- cer. The primary is about 3%" in diameter and 4" long. The secondary 3" or 3,/i" in diameter and 3%" long. This primary is wound with No. 24 S.C.C. wire tap every turn for the first twelve turns. Then tap every twelve turns for about ten taps. The secondary can be wound with No. 28 wire dividing it into about twelve taps. Solder all taps. also solder these taps to contracts. The primary is slightly longer than the secondary in order to allow for A Clever Idea to Fix a Loose Coupler on a Small Unit Panel. Even in a Cabinet it Saves Space. the wooden end of the primary. Turn or cut out of 34" white wood one end for primary and two for secondary. The secondary slides inside of the primary on two 5/32" brass rods fastened into the wooden See. bnaiy Ser lead_. ?ost end of the primary. By placing a narrow piece of fibre across the other two ends this will hold the coil firm. This also allows the secondary to be pulled out or pushed in at the same time turning the knob. This secondary will be tuned and coupled with the same movement of hand. By placing three small wooden or fibre blocks between primary end and panel enough space is allowed for connecting taps to contacts. The two primary leads can be connected to the two primary This Shows How the Secondary Slides Inside the Primary and How the Same Knob ii Used for switches and secondary leads to the bind- Coupling and Varying Number of Turne. ing posts on end of secondary.

www.americanradiohistory.com Radio _Yews for December, 1920

A Three Tube Combination Radiophone Transmitter and Receiver By ROBERT E. LACAULT

light cells: a range of ten miles has been easily obtained by the writer in experiments carried out in a field, using a low aerial. THE SPECIALCHANGE OVER SWITCH As will be noticed the new features in this set are the special change over switch which by a simple throw -over movement makes all the necessary connections, and the use of a simple oscillating circuit used for both transmission and reception. Of course. the three tubes being used for transmission, the use of three hard tubes is recommended, but any soft tube can be used as well, since only a small plate voltage is used. -The clearness of the speech will depend greatly upon the kind of microphone used. We found that a microphone filled with granulated carbon having consequently a greater number of points of contacts gave the best results. 'l'he diagram in Fig. f shows that it is Constructional Details of the General Change Over Switch, and Disposition of the Different Parts of connected the Set Inside the Cabinet. across a few turns of the grid circuit. The proper nttmber of turns will be found experimentally in the following TIII? great majority of the amateurs a two -step audio- frequency amplifier. Al- manner. The sending set being in work- possessing only a few vacuum tubes, most all the parts for this apparatus can ing order, the microphone is first connected will no doubt be interested in this be found in a well equippt laboratory and to about four turns of the grid coil as combination radiophone transmitter the only things to make are the special shown in the diagram. Then the filament and receiver for short waves, using change over switch and the two inductance current is turned on, and a watch or clock but three tubes. coils. The construction of these parts does placed against the microphone.-Listening- In fact, owing to the price of V.T.'s not present great difficulties and all ama- in a receiver placed nearby, it is then easy many an amateur cannot afford the con- teurs having a little common practice with to find the proper number of turns shunted struction of a radiophone, for if tubes arc working tools may easily build this inter- by the microphone which gives the loudest bottglt. it is mostly for amplification pur- esting piece of apparatus. reception of the beats of the clock or other poses. This set being very compact, may be used faint noises made near the microphone. Many of our voting "bugs" still use spark as a portable radiophone when placed in If no good results are obtained in this transmitters and do not realize that they a trunk with a 6 volt 20 ampere storage manner, owing to the resistance of the waste a great quantity of power to obtain battery and B Battery made of small flash- microphone used it is advisable to connect only a limited range, neither can they obtain such sharp tuning as obtained with C.W. telegraphy. Also the wonderful Ra- diophone experiments can he carried out Aavd/e ovny Jim/the/ and other innumerable experiments may be Tw/o//y made with vacuum tubes. some tr x. For this reason we recommend to beginning unatcurs that they read the books treating on the subject of audions, or the Junior Course nublisht in this magazine and. understanding the functioning of the ,.111111,111 audions they will take a greater interest in the branch of radio known as undampt NW 1 wave :elegraphy. 11111sIii Wit i only a small amount of power an s American amateur has succeeded in sending music and speech the Atlantic. across oi I _ This shows the possibility of undampt wave _- o _ transmission. 1111III!I111 In crtler to save space and money in the I, ronstr action of a portable set. the writer .anosmfd concei "ed the idea of using the same audions for transmission as well as for reception and the results obtained in the French mili- ,ii' UIIÚ UIII-°I1UI111UUUÌIIUUIiI tary service being most satisfactory, he II brings to the readers of RADIO \etts the ay data to build this short wave radiophone 2 Info, transmitter and receiver. rig./ In the transmitter the three tubes are used as oscillators. and in the receiver one Complete Diagram of a Combination Radio Phone Transmitter and Receiver: as Can Be Seen a is used as a detector and the other two as asocial Switch Makes All Necessary Connections.

www.americanradiohistory.com Radio News for December, 1920 Ideas- Seventh Spasm

s I pondered tonight the silences, All these and more lie within the walls size jolt from head to toes without trouble. fondling a triode with my thoughts of the common 'Tron tube; you have There you are, brother sufferers from meandering over the hills and val- but to harness these forces and turn them freckles, automobile corns and ches: con- leys of man's variegated endeav- loose to reap the fortunes hereby sowttd tusions from high waisted across coats. Get the ors, there came sweeping by my ingenuity. Ahem. aoparatus swinging at about a million a flood blinding and my mental horizon of a half light. In the wash of that flame there cycles per second, stand on the was born an idea that shall go roaring ground plate and apply the electrode in a down the canons of time to reveal to all manner described in the instructions that posterity the story of a full life. For there can be obtained from the manufacturers of within that tiny tube of glass with its cute high frequency outfits. The whole thing jiggers lay the secret of bigger and better is so simple it is a wonder it is not in lives, the spell to cast out all the demons common use even now. of disease, the withal to reach the pinnacle Every radio operator could connect a of health, strength and beauty. switch into his set so the apparatus could In the white heat of enthusiasm I be thrown from the aerial to a set of grabbed paper and crayon to emblazon on electrodes at any time. A shingle over the scrolls of immortality this wonderful the door offering their services as a Radio idea. But in all honesty let me add to also .lfechano- Therapist would bring those shin- bolster up the consumptive tendencies of ing dollars rolling in perhaps faster than a one -time healthy bank account. they roll out these days of the H. C. of L. Even my mind, trained and kept ready Ahem! Essentially This is s Radiophone Provided, of course, the L means living for breath -taking flights into the realm Hook-Up, But Benson's New (t) Idea is to Use and not loving. of wild imaginings cannot cover the wide it to Ours Everything From a Toothache to a Don't Stubborn Appendix. get the impression because you field opened to the experimenter and in- are fairly healthy that you have no need vestigator. All that is needed is a 'Tron for this device. Get one and try it on any tube and a regenerative receptor. Having seen that high frequency cur- and everything. No one to my kncwledge Far be it from me to cover in detail rents can accomplish many things, let us has tried the effects of harmless high fre- the chemical, physical and metaphysical see how we can get them out of a 'Tron quency currents on pearl- bearing oysters. effects of high frequency currents. Rather tube and into our ailing carcasses. Turn Then again how about trying these currents would I refer you to the thousands of ad- to any work on heterodyning and it will for cooking purposes. Place a steak be- vertisements gracing the back covers and be noted that there are several ways of tween the electrodes and shoot the stuff inside pages of our many magazines. obtaining currents at frequencies exceed- thru for awhile. The good, bad and indifferent sheets all ing a million cycles per second. There is It would be a man immune to ridicule do their share in spreading the propaganda the secret of getting the current which is who would dare place a limit on the pos- for the good of humanity and the health more apparent than real -I mean the se sibilities of this invention; yeah, I have of the world. There it will be found that cret. hopes of curing my brain storms with Violetta, the dancing Ray, is ever ready to By taking the simplest circuit and re- something similar. So let's go, dear read- bestow on you a wave of her glowing moving unnecessary apparatus, we will er, perfect the idea and there shall be wand and all things that mortals should have an arrangement similar to that shown stamping of medals and engraving of inherit but too often don't. There you in the illustration. The apparatus is es- names on the Rolls of Fame. Meanwhile, will see glowing health offered you, the sentially a radio 'ohone transmitter. We excuse me while I finish white - washing strength and vim of high power vitality ain't a'phoning just now so we connect an the cellar. Adieu. within your reach and the leadership and electrode to the aerial terminal and a metal respect that goes with beauty, sparkling plate to the ground terminal. By this (loth Asst. Ed. Note :-If there are any eyes and ruddy cheeks. The latter refers means we can shoot the juice thru any more like you in Philadelphia, Mr. Benson, particularly to the female of the species, convenient and willing sufferer to cure for we think something should be done by the yet I have seen many of the stronger ( ?1 all time their many ailments. Cut in all Health Department to protect the lives of sex who were not adverse to using fair the voltage the tube will stand, a hundred others from the scourge you seem to be means or foul to attain a similar end. honest -to- goodness volts will push a man suffering from.)

A Tone Amplifier*

The development of vacuum tube detect- modern radio station equippt with vacuum ors and amplifiers has shown clearly that tube amplifiers because the full advantages the days of the head receivers, so long as- of these cannot be realized without it. For sociated with radio, are numbered. Make- example, the distinguishability between vari- shift horns designed for a variety of pur- ous stations is increased by its use. When poses have been installed in isolated cases head receivers are worn clampt to the ears for rendering signals audible about the sta- the signals come out of them in a confused tion, but have not proven satisfactory either sort of way. The Amplifone separates them in point of appearance or efficiency. in much the same manner as the phonograph It has remained for this concern to brine separates the various instruments in an or- out the Amplifone, an instrument especially designed to meet the requirements of the radio station. This instrument comprises an especially sensitive telephone receiver and an amplifying chamber or horn in which the sound This Tone or Sound Antpltder Not Only Looks Business -Like But is a Distinct Improvement waves given off by the receiver are ampli- Over the Tiresome Head 'Phonos. fied. The horn is so shaped that the sound is thrown out horizontally at approximately the height of the operator's head when he is seated at the operating table. The surprising thing about it is that while loud signals can, of course, be heard at great dis- chestral record. For this reason the read- tai,ces. even relatively faint signals are read- ability of signals thru static or induction able when the operator is seated near the noises. which in some cases are not entirely instrument. Signals of medium strength preventable, is greatly increased, and at the are, of course, audible and readable any- same time the strain on the ears resulting where in the operating room. from wearin.e head receiver. from long The Amplifone is really a necessity in the periods is eliminated. Photographs by Courtesy of F. M. Doolittle Co

www.americanradiohistory.com Radio News for December, 1920 A New Land Wire and Radio Transmitter of Photographs* By UMBERTO BIANCHI

two boxes fitted with a small hole facing each other and on the same optical line in to / mp n"d phoe regard to the disc. The selenium cell is 4 then connected in the grid circuit of the audion. Fig. r gives the complete diagram IRad

www.americanradiohistory.com Radio News for December, 1920

SOMETHING TO TALK ABOUT AT LAST HLRE, indeed, is a really practical portable set which will readily lit in one's coat pocket ,mid which has been constructed witlu, -:.. the forethought and care of a highly jewelled catch. Needless to say it wins first price in our "Portable Ra- dio Price Contest." 14r. Armstrong has really accouplisht something worth talking about. He has shown an unusual amount of originality. which may bc noticed from the clever manner in which he varies the mutual inductance of the primary and secondary where he employs a telescopic arrangement similar to that of a fold- ing camera. Another original feature is the secondary variable condenser which emu ploys !wo aluminum plates separated by a dielectric of thin mica and where the capacity is either increased or decreased by simply varying the space between each plate tint a micrometer screw arrangement fitted directly to a Photograph of Mr. J. B. Armstrong Using Bis knob. Little Receiving Set With a Special Type of Cage Aerial. Not only that, but the most standard and up -to -date method of wiring, DETECTOR machine work and coil winding has been employed, for both the primary The operation of the galena detector used and secondary coils are wound in the with this set is as follows: By pressing efficient bank system. Photograph of the Pocket Radio Receiver. Note down on the hard rubber button S. the the Clever Arrangement of Coils and System of lever \V, will move downwards, raising Tic detector adjustment also shows Coupling. the other end carrying the bar R, to which originality and one must actually op- is soldered a helical spring of No. 32 bronze erate this set in order to be impress! with its effectiveness. rated. The pillar G. is '4" diameter with wire which rests on the crystal when the 24 pitch threads with keyway thruout lever W, is in horizontal position. A spring Rest assured that we are not over its length. A pin L, fits into this keyway C, causes the lever to remain in a horizon- enthusiastic in this instance, for we and prevents rotation of the lower plate tal position when no pressure is exerted on had the instrument sent to us in order wher the knob V, is turned to vary capac- S. It will now be understood that the idea that we observe for ourselves, just ity. hots roan in raising the bar R. and its contact spring, it was built. This young The bushing J, is threaded internally is to prevent scraping this delicate spring has not simply built a portable re- " -24 to engage with the pillar G, threads over the surface of the crystal when the ceiver. He has done more than that. at the lower end, and 6-32, to receive screw whole detector assembly is rotated about He carefully planned every detail D, st the Lipper end. This bushing J, also its axis, which is thru the center of the which entered into its construction. has a flange which hears on the similar supporting post. To obtain a new point of Judging from the forethought of even flange of the bushing K, on the lower face, adjustment on the galena, the bar R, is the most minute and unimportant de- and provides a stop for the circular scale U, also rotatable -about the ,screw, which se- tails, the builder must have spent (of hard rubber) and knob V, clamped on cures it to W. A tiny wire spring with hours, perhaps days, in designing the the upper tace by the screw D, and washer washers and a clamping nut cause this to various parts, which enter into the F. The ears of F fit into notches in the bc a friction joint insuring good contact make-up of the unit. Above all, every rubber knob V, and keep it from turning, between \V and R at all times. Brass 9'2" piece of material, be it rubber or while two pins E, forced into J, keep the thick was used for constructing W and R. metal, was milled and machined to washer proper from turning about J. The VARIABLE CONDENSER FIT to at almost astonishing degree washer F, has two holes which fit over the of accuracy. in toe The variable condenser used is of the fact, were both pins E, SO that by loosening screw D. the two plate variable -separation type with delighted and astotisht, at once, wife scare U, may be set for any separation of what Mr. mica dielectric H, .coos" thick. The plates Armstrong calls his "young (Continued on page 412) are of fig" aluminum, the lower being treasure," and so would you, fellow screwed to the flange on the threaded pil- amateurs, were you given the oppor ar G, while the upper one is held with tuaity to personally examine this in- 2 -56 flat head screws to the four pillars at teresting and above all efficient piece he corners. A hole in the center of this of workmanship. plate is large enough to give clearance to Briefly, this young man, has at last he spring X, which keeps the plates sepa- departed from the usual cut -ond- dried method of doing things. In other words, he has stepped out of the "beaten Path." Does this not suggest some ideas to others who are contemplating the building of receiving or transmitting apparatus? This time the editors received 53 entries and were much pleased to note that some really constructive workmanship was attempted in this second call. In fact, there were so many really good specimens that they have decided to publish several additional descriptions besides the price winners. These will be given honorable mention and will be published within due time in the pages of RADIO NEWS. The efforts of these young men will be paid for at our regular space rate upon publication. The photograph la a Top View of the Receiver Showing the Disposition cf the Various Switches, The Editors. In This. Little Box is a Complete Receiving S.t. While the Diagram Shows the Connections of Tho it s Small Enough to be Carried in the Same. Pocket.

www.americanradiohistory.com Radio News for December. 19'!i Awards of $100 Portable Radio Prize Contest First Prize Winner

Prize Winners First Prize, $50.00 in Gold Mr. J. Blanchard Armstrong, 15 Bradford Road, Newton Highlands, Mass.

Second Prize, $25.00 in Gold Mr. James L. McLaughlin, Box 288, Fairhaven, N. J. Third Prize, $xs.00 in Gold Mr. Robert I. Toran, 871 Cambridge Street, Cam- bridge, Mass. Fourth Prize, $xo.00 in Gold Mr. Raymond M. Moore, 252% N. Main Street, Tuc- son, Arizona.

to be very satisfactory, as a loud click is heard in the 'phones when a good adjustment is secured. The primary panel is fastened to the base by four friction hinges, P, which hold it in any position relative to the Full She View of Mr. J. Blanchard Armstrong's Portable Receiver, Showing the Variable Condenser secondary when raised or lowered by the With Mica Dielectric, Which Consista of Only 2 Plates. The Capacity is Varied by Changing the Distance Between These Plates. primary switch knob. The twenty-three switch points are secured by quarter -inch 2 -56 screws and may be obtained from .crews were used to hold all together. Clapp Eastham Co. The binding posts for parts and a post. A catch, B, was provided to hold the aerial ground are standard Honorable Mention cover down when the set is being carried shortened slightly to allow the cover to about, and velvet ribbon was glued the close down without interference. One Mr. William F. Marquardt, to binding post is connected to the begin- Chicago, Ill. edges of the cover to exclude the dust. A line grain polish for the entire case was ning of the primary winding; the other to a bent spring -brass strip tinder the nut Mr. Kenneth Richardson, obtained by rubbing down with emery cloth and oil. which secures the primary switch knob. Fort Lauderdale, Fla. By means of a 2 -56 set screw in the nut PRIMARY itself, the knob can be adjusted to turn Harold B. Dick, smoothly, without wobbling, and locked in Springfield, Mass. The primary core is turned from hard rubber and measures 2" outside diameter place. Phillip J. McManus, with a W' wall, and h" high. It has a SECONDARY C. Central Falls, R. I. three layer bank winding of No. 22 S. C. The secondary core is I jy" outside di- 166 turns) shellacked in place and tapped ameter with a /" wall, by %" high and Mr. Arthur L. Osborne, at every top turn (which makes every is fitted with a hard rubber disc which is Brooklyn, N. Y. three turns) by soldering a short length screwed to the base to secure the coil. of No. 22 bare copper wire to line no with The winding (bank) was four layers of the contact screws. This was accom- No. 26 S. S. C., tapped in eight places by plisht by cementing the wound primary the same method used for the primary. A Practical Pocket Receiving to the large panel and soldering the leads These taps should be of No. 36 S. S. C. to their respective turns in such a posi- bought down and shellacked to the out- Set line proper and along the base of the By J. tion as to tip with the contact side of the coil Blanchard Armstrong point screws. A soldering iron filed from set to a tiny connection block, where they TIIE case for this receiving set was No. 12 copper wire did the trick without are soldered to lugs secured by 2 -56 screws. made of hard rubber q%" x 3" charring the insulation of adjacent turns. (See photograph of set out of its case.) x 11" inside dimensions for The last contact point is left dead so that Another set of lugs have wires soldered the lower part, and qr/2" x 3" the aerial may be switched in or out to to them which go to the eight contacts on x ìo" for the cover. The top and test the detector adjustment. This method the small fixed panel, for tuning the sec- bottom are of %" liard rubber. 2 -56 of testing has been found by the writer ondary.

OCOpG 9 O o

. oG '1111 G zs G e O 4 !L O AN s 000

2--,ÿf--====-_ ' Ix' Constructional Details of Mr. F. B. Armstrong's Receiver, Showing Row the Variable Condenser and the Little Detector are Made. The Four Arms Supporting the Primary Allows a Very Loose Coupling When Extended.

www.americanradiohistory.com Radio News for December, 1920 Radio Taste Reception By ALFRED N. GOLDSMITH* and EDWARD T. DICKEYt

AN interesting paper was recently read at a meeting at the Institute of Radio Engineers, New York City, having to do with the reception of radio messages by means of taste. During ,the experiments two silver electrodes were employed which were separated by a piece of insulating material and so spaced that the tongue could be placed between the electrodes. Much information is disclosed concern- 4.:' ing the physiological effects of this method of reception upon the operator, as well as electro- chemical phenomena in connection with mouth electrodes. Altho the method does not preclude the possibility of abolishing the present sound method, it was pointed out during the dis- course that the results warranted further conditions investigation, as under certain General Circuit of the Method Employed by the Authors in Their Experiments on Taste Reception. this manner of reception would prove bene- ficent, such as in the case of airplane work where attendant noises make it extremely difficult for the radio operator to receive were made, using low potential direct cur- "Finally, the reception of actual signals signals of low audibility. rent and 6o -cycle alternating current to from an antenna was tried. It was found Fig. z, illustrated on this page, will serve ascertain the amount of energy and poten- possible by using four stages of amplifica- to rive a general idea of the circuit em- tial necessary for taste reception. tion to obtain taste sensations from all sig- ployed in tests described by the authors. "Tests were then made, using signals nals whose audibility was greater than 500 A general resumé of the method follows: from a buzzer source. By employing a in the detector circuit. "The purpose of this research was to two -stage transformer- coupled audio -fre- "The results obtained thus indicate that determine the feasibility of reception of quency amplifier it was possible to obta n from an electrical standpoint it is possible radio telegraphic signals by the sense of taste sensations from a signal having an to receive radio telegraphic signals by the taste. audibility of Soo in the detector circuit. sense of taste. When compared to the "Electrodes were made which could be The possible speed of transmission appeared sense of hearing or even of sight, however, placed against the tongue in such a way to be limited to a maximum of about ro the sense of taste is inferior as a means as to cause a taste sensation when a source words per minute because of the charac- for receiving intelligence." Data furnished of potential was connected to them. Tests teristics of the taste organs. by courtesy of I. R. E. *Director, Research Defartment, Radio Corpora- tion of America. tAssistant Research Engineer, Radio Corporation of .America. A Method of Producing Musical or Other Audible Notes BY VICTOR H. LAUGHTER

HE accompanying method relates to cuits associated with a middle circuit. The a means for the production of audible tertiary circuit is connected to a two step T tones. That every spoken word, mu- amplifier and receivers. The generating sical note or any audible tone produces a circuits are connected so as to oppose one certain vibratory effect is a well -known another, or 18o degrees out of phase. No fact. This vibratory action can be regis- current will flow in the middle circuit un- tered by various means, the best known der these conditions, but if either circuit being the phonographic method. becomes unbalanced a corresponding cur- (A) In radio telephony a wave is rad-- rent will flow in the middle circuit. Under ated which bears changes in the wave form the above conditions the circuit is ultra according to the words imprest on the sensitive to a capacity change. transmitter. This "change" usually occurs (C) Consider that we have a photograph in the form of an amplitude variation, al- of a certain series of spoken words as rep- tho in some cases the frequency is va- resented by Fig. r. A piece of tinfoil is ried to secure the same effect. A Minuit Ultra-Sensitive to Capacity Change. cut to correspond to the photograph. The A wave form modulated by speech is foil is pasted between two thin sheets of shown in Fig. r. As will be noted this insulating paper. The foil strip is so ar- consists of a h'gh frequency wave with rounds the wave components. The path of ranged that it can be rolled from one spool the amplitude varied according to the im- the envelope represents the variation caused to another. Two thin metal strips are so prest speech. A t imaginary envelope sur- by the spoken words. In radio telephone mounted that one rests underneat't the foil, reception one -half of this wave is lost by and the other is mounted above so that its rectification and the remaining half causes edge rests on the one underneath with the the desired reproduction in the telephone foil strip between. The metal strips are receivers. connected tip as the condenser of one of By means of an oscillog -aph connected the oscillation generating circuits The in- to a radio telephone set we can photo- sulated foil strip becomes the dielectric. A graph the radiated wave current. The re- small variable condenser is placed in the sultant will be a formation similar to Fig. o"nosite generating circuit. Adjust the r. Thus we have a record of the tones, foil strip by moving thru, until the low- the "hill and dale" of the phonographic est peak of the wavy line is between the record being represented by the imaginary two metal strips. Now adjust the variable envelope. So far as known no method ex- condenser and inductances until no tone is ists for reproducing this type of photo- heard in the receiver. If the foil strip is graphic record. A capacity variation moved it will vary the dielectric separating method is suggested. the metal strips thereby varying the ca- (B) The sensibility of certain types of pacity in a like manner. This variation P9. S vacuum tube circuits to a slight change in unbalances the circuit and results in a cur- capacity is well known. In Fig. 2 is shown rent flowing through the middle circuit of Illustrating a Wave Perm Modulated by speech, two independent oscillation generating cir- the same proportion.

www.americanradiohistory.com 362 Radio News for December, 1920 nitwit be expected that the grid modula- set of conditions at approximately the tion of case 3 would give superior results mid point of the characteristic curve of to these on the assumption that the output the amplifiers so that maximum amplifica- of the two tubes would be alternately in- tion is obtained (sec Fig. 9). In all of creased to maximum and then decreased w the present telegraph sets thus far de- nearly zero by swinging the grid potential veloped the input voltage is of relative at the modulating frequency; but when it large amplitude; it is in fact always so is remembered that the output cannot be large that the extremities of its oscillation increased above a certain maximum, it fig. /1 carry it well over the top and bottom flat wi -.l be seen that the results obtained by portions of the curve. this method place it at once on a par with Let us now consider what happens when the absorption methods. we attempt to apply this power amplifica- It must be remembered that the measure tion principle to the telephone case. The of the effect in the distant detector is the first method of doing this that occurs to value of the product AB of the carrier and us is to modulate the output of the master modulated component of received electro- oscillator and impress this modulated out- motive force, and this depends not upon e fig. /3 !D/ put on the amplifier, wherein it must be the relative energy components in the amplified and then radiated in its original transmitting antenna, but upon the cur- character from the antenna. Difficulties rents. That is, the A and B of the trans- n Fig. 12 Average Operation is in Center of at once arise, however. mitting antenna refer to current amplitudes Curve. While in Fig. 13a and Fig, 1.3b is Shown the Output Currents Under Two Given Con- Let us suppose that any scheme of modu- therein. Two tubes in parallel, therefore, ditions. lation is employed at the master oscillator while they may give twice the energy of and that the modulation is complete one, deliver only Vtimes as much current is present, altho in this particular case (shown in Fig. to). as a single tube, so that if complete modu- the speech was still quite intelligible. lation is obtained in cases t and 2 above, we may expect the conditions to be those AMPLIFICATION OF OSCILLATOR OUTPUT represented in Fig. 6. When increased output is desired it is most satisfactorily obtained by means of separately excited tubes. This method is '. exemplified by the circuits of several dif- fits 17 ferent sets now designed by the Signal ri As Compared to Fig. 16a the Envelope Curve nx-.. Should Be Increased to the Point Shown Sere. t,VW t gt t gq t\ t\,\ \,\ sr r Ir n 0. ki fg. ,g This modulation voltage is impresst Capon the amplifier of Fig. 8. The point on On This Curve is Plotted the Relation Between the characteristic curve about which ampli- the Fundamental Radio Constituent and Q. Plate E. This Oscillogram Record Shows the Result of Inadequate Filament Emission. fication takes place depends upon the grid current flowing thru the leak resistance. This in turn depends upon the amplitude Ir:spection of this figure shows that for Corps, for instance the pack set SCR-127. t00% modulation in both cases the con- of the impresst oscillation. Therefore, at These sets are, however, intended only for instants in the neighborhood of A (Fig. stant current or power modulation system telegraphing and it is found that certain is twice as good as the absorption modu- to) when the impresst voltage is small difficulties are encountered when attempt the grid current will be small and the oper- lation, or that 5o% modulation on the con- is made to adapt the circuits of these sets stant current system is equal in effect to ating point near zero grid potential, while complete modulation by absorption. Another with larger oscillation amplitude corre- way of looking at the matter is to note sponding~ to instants near B (Fig. to) a that four times as many oscillator tubes larger grid current will flow, making the are required to give the same result on grid more negative. Thus, during an audio the absorption method as on the power frequent modulation cycle the operating modulation method, when the latter gives point on the characteristic may vary be- complete modulation. If the latter gives tween I and 2 (Fig. Ira). The grid volt- 75% modulation, the absorption method age and plate current may then vary as requires three times as many oscillator shown in Fig. tr. The plate current varia- tubes. These conclusions cover in a broad tion will of course depend upon the shape way the comparison required between theso of the characteristic curve. For the condition shown the ultimate plate current two general systems of modulation. m' a' x' e. JO' will . There arc, however, certain practical have a form similar to that of Fie le rib, while if the characteristic curve were points that must not be lost sight of and moved bodily to the right the world unless due regard is taken of these it may Illustrating the Ratio of Effectiveness of Two result Specific Cases. he practically reversed as shown in Fig. not be so easily possible in every case to Tic: or if the cut -off and saturation effects correctl make the above statements. The were range practical limitations imposed refer to the to the telephone problem. A typical cir- more widely separated or the cuit is shown in Fig. & of operation (r -2) occurs more nearly in percentage modulation actually obtainable the curve wave by the two It is not difficult to The radio frequency voltage impresst center of the the plate methods. will approximate in Fig. Ird. get practically complete modulation by the on the multiple tube amplifier from the that shown diverting, or detuning method, low power master oscillator is sufficient to In any case, where the oscillation im- distortion. is sufficient tt positive presst on the amplifier of am- but usually a smaller variation is obtain drive the grids of the amplifiers plitude by the nun- absorption methods, such as so that current flows in the grid circuit. to pass over the ends of the char- grid and constant current modulation. This grid current passes through the leak acteristic curve distortion will result and is when resistance R and the voltage drop produced the original compleely modulated wave This always the case the electron will emerge from the amplifier com- emission of the vacuum tubes. particularl- therein is utilized to bias the grids of the with The amplitude of grid current plete modulation downward but only par- of the oscillator tube, is insufficient to give tubes. this modulation unward. This the increased output required on the posi- and hence of the bias voltage is controlled tial is illustrated modulation swine Another difficulty by adjusting the coupling condenser C and in Fig. T2 for the favorable case d ahoy,. tive where average operation is cen- is often found in the fact that the power the leak resistance R itself, hut in any case the at the ',u-i l.hlo from the microphone transmitter remains practically constant for any given ter of the curve. is too small to swing the grid po- The above discussion refers to tential to the required positive va l t te. operation with the bias voltage ob- In this case it is necessary to am- tained by a leak resistance. It plify the microphone output by holds, also, however. in its broad means of an additional tube. aspects for the case where a nega- Both of the above limitations re- tive grid battery is used. The only sult in radiation of the form shown difference is that in the latter case in Fig. 7 which is characterized both the bias voltage is held fixed regard- by distortion and incompleteness of less of the amplitude of oscillation. modulation. The oscillogram record This is obviously a more desirable Plate E shows the result of in- condition. In This Undesirable Case the Smooth Undistorted The as well as the com- adequate filament emission. The Curve Produced by Reduction of the Impresst quality modulation is much greater down- Voltage is 73% as Effective as the FlatToppt pleteness of the radiated modula- ward than it is upward. Distortion One. (Continued on page 3E8)

www.americanradiohistory.com Radio News for December, 1920 is complete. It is then Ye of the fundamental frequency term, and can, therefore. generally be ignored. Approximately, therefore, the receiving telephone current is -, t b.XAB i ; _ ;-_i (6) -t-,---¢.st è ; _ vz ;w t e .. Obviously it can be increased by increas- I ing either A or B -that is, either the con- \_% stant amplitude radio frequency carrier or the modulating componeut immaterially. Also, it appears that for a given value of fig. 7 the product AB the relative values of A More Interest- and B are of no importance: a large radio ing Curves frequency carrier weakly modulated will Having to dc With Various give the same detector response as a small- Types er radio term more completely of modulated. Modulation. / t , It is important to notice that for a given modulation amplitude B the response is in- I.4I-A e ?-A creased proportionally with increases in A, IIIII 1 I. ;1IIÌ1 i 1a i the carrier. The physical reason for this. i t of course, resides in the curvature of the t , , III' t t detector characteristic; the rectification is 1 ¡ made more efficient by the "riding" of the radio frequency c.m.f. on the detector. We note finally that what is desired for Absorption Modu/o/ion Constant Current Modu/o/ion good detector response is as large a value f os: /i/O /ors I oscillator of the product AB of the components of the transmitted wave as is possible. fig. 6 TRANSMITTER MODULATION We have to consider several methods for producing the modulated radiation just con- the effective value A of the carrier to the used W. E. Co. circuit and known as considered, keeping always in mind the re- A, of Fig. 3 above. stant current or power modulation. Grid quirement just stated that the product AB An exactly similar operational effect is modulation may also, under certain cir- shall be as large as possible; and that the obtained with modulation by detuning as cumstances, produce this type of radiation. measure of effectiveness of the modulated with a vacuum tube, microphone or con- On plate C is shown an oscillogram, taken radiation will therefore be indicated by the denser telephone shunting a part of the as described above, of the output of a value of this product as representative of oscillation circuit. telephone set modulated at Soo cycles by the components of transmitter antenna NON -ABSORPTION MODULATION the constant current method. It is seer.' current. This type of modulation is characterized that the modulation is very nearly equal DIVERTING, DETUNING OR ABSORPTION by the alternate increase and decrease of upward and downward. The oscillogrim MODULATION radio output above and below the value Plate D shows a case of grid modulation. There is some slight modulation upward A number of well known methods of normally supplied by the oscillator, and is modulation may be collectively illustrated in Figs. 4 and 5. in this case but most of it is downward handled un- is some distortion present. der the heading of absorption, diverting or When this type of modulation is most and there detuning modulation and all such methods effectively employed the output of the os- COMPARISON OF ABSORPTION AND NON - arc characterized by a reduction in an- ABSORPTION METHODS -GENERAL tenna current when the modulator is in In order to illustrate the real necessity operation below the value obtainable were for comparing the two general types of the modulating device removed. Fig. 3 modulation just defined let us take a con- shows the result of this type of modula- crete example. Suppose we have a cer- tion. tain given number of exactly similar vac- It is seen that although the oscillator is uum tubes, this number being limited by capable of supplying a radio frequency os- the amount of power available, or other cillation of amplitude At to the antenna engineering considerations. Suppose, to alone, the presence of the modulator and Plate C. Power Modulation at 500 Cycles. make the matter quite definite. that we the absorption therein reduces the effec- have two tubes. The question at once tive carrier amplitude to A, and the peak cillator which is normally At is equally arises "How shall we use these tubes so current never exceeds the maximum ob- increased and decreased, by the action of as to get the maximum modulated output, tainable front the oscillator. modulation as shown in Fig. 4. Frequent- i. e., the maximum value of the product Examples of absorption or diverting ly, however. the condition shown by Fig. 5 AB ?" Shall the use one of the tubes as modulation devices are those using the is obtained where the oscillator output is oscillator and one as modulator or both transmitter microphone directly in the os- caused to decrease more than it increases, as oscillators and modulate the total output cillating circuit thereby varying its resis- thus lowering the effective value of the of both? tance. or else inductively coupled with the radio frequency carrier (A,) to (A,) and The answer is not at once obvious. oscillating circuit: or the use of a three giving a less effective radiation (value of There are several ways in which the two electrode vacuum tube to absorb energy the product A,B1. More or less distortion tithes might be used under the above two in its plate circuit. the absorption being is also present. general schemes but broadly speaking we controlled by speech e- m.f.s. impressed in An example of this type of modulation may discard as obviously inferior all save its grid circuit. All such devices reduce is that obtained by the now extensively the following: T. One oscillator and one modulator with connections for constant current Typical modulation. Circuit Employed in the Signal Corps Pack Set for Radio Telegraph Operation. 2. Both tubes oscillating in parallel modulation by absorption of output. 3. Both tubes oscillating in Parallel modulation by impressing speech frequency on grids. At first sight it might appear that meth- Master Oscillator ods one and two would give exactly the same result. In the first case the output of the two tubes might be caused to vary by the absorption device between the total available output and zero with an average I1I1IiI--PQQ94- value eooal to one -half this variation: while in the second case, there would nor - Amaítier 11111110 .- -nil.- be half thr outnut of the Two tithes of rase r hue the action of the modulator I I tube would increase this output to double value and then decrease it to zero with the 4Q9QQ99 fig. B average the same as in the first case. It

www.americanradiohistory.com Radio News for December, 1920 Comparison of Modulation Methods in Radio Telephony By A. S. BLATTERMAN*

constant ampiitude (A) and another component of equal radio frequency but of varying amplitude (B sin pt). The signifi- Curren! cance of the quantities A and B will appear by inspection of Fig. t. Complete -{:-{- 1 modulation is obtained tchen A and iT Q =B ? under any condition the percentage modulation is B /A. For the sake of simplicity, as well as Yo/tage definiteness, let us assume that the receiv- Thes- jour ing detector is a vacuum tube connected Figures itep- in one of the usual circuits without a block- resent an Ex- ing condenser and leak in the fig. 2 planation of grid circuit. the Theory to We might equally well assume the use of be Considered a crystal detector: but in any case the de- in the Detec- tector action is to be considered as re- tion of a Modulated sulting front operation on a curved char- Sustained acteristic of the typical forni shown in Wave. Fig. 2. Such a characteristic as that illustrated may be represented by the power series ...... (2) wherein it may be shown that for the usual detectors and in particular the three clec- !rodc vacuum tube, terms beyond the sec- fig. 3 f/g. 4 ond may be neglected. The detected current can therefore be expressed as function of impresst voltage as i= b,c±b.,e' (3) T11E modulation of sustained waves veal three electrode vacuum tubes in par- In detection of the modulated wave for purposes of radio telephony has allel with their grids and filaments con- under consideration we have to substitute now assumed such an important nected together to form effectively a simle for e in this expression the value (t) place in the design of apparatus for cold anode. A zero line "a," Plate .\, was e = A Sin tut + B sin pt Sin aft this kind of communication that it first taken with the radio set inoperative. This gives very The radio set is desirable to clarify our conceptions was then caused to oscil- b. B' B' of ti .: various phenomena occurring in late without any modulation being applied. (A'+2AB Sin pt -cos 2 pt) some more useful circuits. Several The energy nicked in i=- -- of the then up and rectified 2 2 %cars with ago we had the arc and spark the vibrator circuit caused a deflection of + Radio Frequency terms (4) high power ^ranular carbon microphone.; the latter, giving the straight line "b," its in the oscillating circuits, and liquid nticro- displacement from zero line "a" being pro- This is the detected current. The only phonct. condenser telephones. etc. Today part of it effective in producing telephone the hivh frequency alternator, and much response is the variable audio frequency more extensively the three electrode vac- component uum vibe supply the energy for radio tele- bB phone equipment and the speech control 2 B may not only be affected by the previous -- (2i\ Sin pt -i- - cos 2 pt) arrangement of microphone, and other fac- a - 2 2 tors in the oscillation circuits, but the vac- Plates A and B. Curves Taken During Module. The effective value of this is uum tube itself may he employed in vari- tion Tests. h B ous wa' -s for molding or modulating the nortional to the amplitude of the radio P Idol) frequency carrier according to the frequency antenna oscillations. The oscil- Tl e V2A' -r (5) voice wave it is desired to transmit. lations were then modulated, causing their e =- methoc'.s for securing modulation are fast amplitude to alternately increase and de- is obviously one of becoming legion and the engineer is con- crease according to the curve the The second terns "c." In frequency "p" and has fronter by the necessity of selecting from case shown, was obtained both double the signal modulation when the modulation the gnat number available the ones which upward and downward, altho it was maximum amplitude are best suited to the particular problems far from being complete. For complete he has in hand. In all cases a large per- modulation the wavy line should have in- centage of modulation is desirable and creased to twice the average value "b" and good quality is not less important. decreased to the zero line "a" alternately. In ilis paper comparisons are made between various methods of modulation and DETECTOR RESPONSE TO MODU- conclusions are drawn with reference to LATED WAVES vacuum tube apparatus giving the compara- several types dis- Since the primary concern in the use of tive effectiveness of the modulated cusst. Not all of the known methods have transmissions (radio telephony) is been considered in detail, but because mane the value of detected telephone current, it is desirable of the systems suggested can be classified first of all to formulate the theory of the detection sus- under general headings such as absorption of a modulated tained wave. This, as will be seen, gives modulation. power modulation, etc.. a com- been made between several very fundamental information as to the parison has requirements general types of modulation which it is be- of transmitter characteristics. Consider the modulated voltage lieved will serve to make the entire discus- wave of Fie. r, which depicts a sustained wave of sion fairly complete. radin of in Several oscillograms of the modulation frequency periodicity varying obtained different circuit ar- amplitude at an audible frequency peri- artuallt with odicity- rangements appear in the course of this p. The vitiation of this wave is, paper. These were taken by coupling the oscillograph vibrator through a rectifier to e =(A +B Sin nt) sin tut the antenna of the telephone set as shown =i.\1 Sin on-1-(B Sin pt) Sin tut (r) Curves Met With in the Amplification of the in Fie. A. The rectifier consisted of sev- indicating a radin frequency component of Oscillator Output. Radia F' ,i,'rrr Cora .4lfred Vat/. N. f.

www.americanradiohistory.com Radio News for December, 1920

telegraphy, the principal agent in which was reported to be an instrument called a 'valve,' a 'lamp,' or a 'tube.' This instrument seemed to have arisen suddenly into a predominant position among all the apparatus of the wireless experimenter and operator, and appeared to be of use .j.t every . corner of his outfit. The comprete' ' name of the instrument is the three -electrode thermionic vacuum tube. It must be emphasized that it is the three -electrode valve, and not the valve with two electrodes, that has been responsible for the over- Fig. 23 throwing of the old methods and appara- a Fig. 25 1 tus. That it has been a veritable revolution E.W. a Oscillion can be seen by comparing the common prac- Smaller Which tice in wireless 1914 Has telegraphy of with that Power of 1919. In 1914 practically all the most Tube; Proved of a powerful transmitting stations in the world Powerful the generated waves by sparks and signals which t Maker E.W. of were received at nearly all stations by means Oscillion Oscillations of crystal or magnetic detectors. The spark Type method of generating waves involved the use of very large antennæ for spanning great distances; and at the receiving stations which wisht to listen to stations more than even 100 miles away very large aerial structures were customary. B'ut if we look at the state of affairs today we find most of the high -power stations for long - distance transmission are 'continuous wave' stations; that is, they produce uniform un- interrupted waves instead of a series of short gushes made by sparks; while at the receiving end new modes of detecting these continuous waves appropriate to, and taking work profound changes in our present advantage of, their uniformity in character room, or even in a cupboard. In accomplish- methods of business, cannot be questioned. have been introduced. This is where the ing this the magnifications in use amount to Thus again it seems evident that the audion three -electrode tube, in various adaptations, several hundred thousandfold. All this is is destined to play a leading rôle in the enters the arena. Taken together, the im- the work of a thing which looks like an work of knitting more closely the people of provements at both ends of the span have ordinary electric light bulb with a few extra this land, and of all lands. made possible the use of smaller antennæ pieces of metal in it-the three -electrode 11'e have briefly recounted some of the at transmitting stations, and have almost re- tube." main achievements which the three -elec- moved the necessity for any antenna at all Years ago what physicist did not look at trode audion, or triode, has to its credit. at receiving stations. For example, under the simple, self -contained, noiseless incan- Let us now consider some of the possibili- reasonable weather conditions, it is quite descent lamp, consider it as an ideal source ties of its future. From its invention until easy to listen to the messages coming from of electromagnetic waves of a wide spec - 1912 it attracted an almost negligible inter- stations on the other side of the Atlantic by trum-of heat, visible, and ultra -violet ra- est in the scientific world. A year after the using a receiving circuit of which the recep- diation, and wonder why it should not be audion was first brought to the attention of tive element is a small coil of wire, three made to generate also waves of any length? the engineers of the American Telegraph to four feet square. Thus, so far as receiv- Today that incandescent lamp, with the ad- and Telephone Company that corporation ing goes, it is possible to intercept all the dition of a metal plate and wire grid, has acquired exclusive license under all the au- great stations on one -half of the globe by become such a generator. - Undampt Hertz - dion patents for wire telephone purposes. means of apparatus contained wholly in one ien radiations of a few centimeters wave- Thereupon the research men of that length can be generated by audions organization initiated an elaborate specially designed to give minimum line of investigation of the device. capacity between the three electrodes which about that time began to in- and their lead -in wires. From these terest other scientists in America and short waves, representing alternating abroad. Prior to 1914 not a dozen current frequencies of some hun- articles on the audion had appeared dreds of millions. down to those of in scientific publications. Today it is one or two per second, the electric - impossible to pick tip a magazine de- wave spectrum afforded by the oscil- voted to physics or electric commu- lating audion is continuous. Con- nication without finding one or sev- sider this fact in connection with eral papers dealing with some of the almost infinite sensitivity of the what Dr. Eccles styles "the protean device as a detector. and its unlim- properties of the ubiquitous three ited power as a magnifier, or am- electrode tube." plifier. and one realizes something of Writing in the Radio Review Dr. the value of the three -electrode Eccles (who is affiliated with the vacuum tube to the physicist and the British Marconi Co.) says: "The inventor. To the former, however, most important single instrument in the keenest interest lies perhaps in modern wireless practice is the three - the audion itself, because there is no electrode thermionic vacuum valve. known piece of electrical apparatus for it enters into every main division linked so directly with the most re- of the subject-it plays a dominant cent work on the structure of mat- part in the generation of oscillations, ter. A prominent British physicist the detection of signals, and in the has recently remarked: "It is prob- amplification of feeble voltages and able that there is no other sphere currents. Its arrival and develop- where research work has had s el+ ment have, besides, helped greatly a combination of immediate practical toward the success of apparatus and value and intense theoretical interest. methods that might otherwise have Many an early experiment in tele- remained almost failures." graph transmission or reception by DR. ECCLES QUOTED wire or wireless, loner since ahan- Dr. Eccles has outlined the pres- doned as too limited in range, can ent status and forecast of the future today he revived to the great benefit of the auclion so clearly that I am of man. Calculations have shown constrained to quote further his that with a littoral cable stretched words, as those of an unbiased oh- for fifty miles on each side of the server: "During the war, hints Atlantic. and carrying some forty reached the civilian that a revolu- Fig. 24. A So- Called V T.-21 and its Socket, a Tube Which Has amperes of 20 -cvcle alternating cur - tion was taking place in wireless Been Much Used by the U. S. Signal Corps. (Continued on page 386)

www.americanradiohistory.com Radio News for December, 1920 375 '4'1\ ROY HAYNES STATION

Isere is my new receiving set which 1 have recently completed and which I A Madero and readers of our Effective Sta. thought might interest other tion You Have magazine, RADto NI:Ws. M r. Haynes. The set consists of detector and two step Wo Are Al- amplifier with ammeter on each tube. I ways Glad to Meet An Old - have installed a full set of honeycomb coils Timer. wired '_or the regulation tickler hook up and I secure excellent results with it. These coils are certainly there. By using the Magnavox sound amplifier apparatus I can hear all stations worth while, both dampt and undampt all over the room, and besides I get local radiophone music loud enough to dance by. in having Am an old timer the game, we amateurs have played our share in its l resu is compared to our long dis- started in the days of your pioneer maga my what progress. zinc. Modem Electric:. Then I had a sili- tance work of today. But then this radio ROY HAYNES, con detector and a one slide tuner, and oh, game has been a constantly rising art and 16939 S. May St., Chicago, Ill.

C_ W. COOLEY STATION DONALD ATHERTON STATION

It i; a pleasure to submit a photograph My aerial is 04 ft. long ,40 ft. high and I hare had i xcelleut rc_ults with my sta- of my station and also one of myself. My consists of Nos. 12 and 14 gauge areial wire tion, getting N. A. A. every night and noon set consists of the following, % K. V. A. spaced two feet apart. during the summer months when static is Thordarson Transformer, Thordarson Oil I have had fairly good results with the troublesome. The Great Lakes Naval Sta- imme-sed cnndencr. Murdock oscillation receiving set I have heard NAA. NAJ. tion and other large stations are also on my NAR. and NAT. As I have not tried for list. "dx." with the sending outfit I do not know how far I can send but I expect to cover Soo miles in the near future of the cold and crispy winter nights. W. COOLEY, 1336 19th St., Granite City, III.

ATHERTON STATION Here is a photo of my radio station and myself. By way of explanation, I may say the following: I am seventeen years of age and live on a farm. I made all the instrument except the condensers. receivers, clocks and switche' I have rigged up Cooley By Name But Not Cool When it Comes in my work shop, which He Lives On a Farm in Ioxa and He's Seventeen. to :he Fun He Gets Out of Amateur Radio. in the hog house. Farmer or City Dweller, They Have a Common My aerial is 150 feet long and 40 feet Stamping Ground in Radio. transformer, Murdock line protector, Mur- high at both ends. The outfit consists of a duck rotary spark gap and a Bunnell key. 4,000 meter loose coupled, loading coil, cab- I will be glad to furnish a complete dia- The receiving set consists mostly of De inet receiving outfit, two variable condens- gram of my station to any other amateur Forest Unit Panels and includes a one -step ers, four detectors, aereal switch, pair of interested. ampl.fier. I have two pairs of phones, one Murdock .2000 ohm receivers, twelve DONALD ATHERTON, Brandes the other Meteor. switches and automobile clock. Mt. Vernon. Iowa.

HENRY M. HARRIS STATION

The following is a description of my and transformer, three sections Murdock the end of a cabinet. All instruments are station: moulded condenser, Murdock rotary gap, mounted inside an oak cabinet All con- For transmitting I have % K. \Y. Pack- and Murdock O.T., which is mounted on nections are short and made with heavy copper ribbon. I have had excellent results with this set, and there isn't any noise to the gap. For receiving, the picture speaks for itself, as it were. Radio apparatus undamped receiver and loose coupler. Home made audion control panel, including two variable condensers. Two step amplifier, The Boys in and a set of Baldwin 'phones. I have Waco, Texas, since added a short wave regenerative set. Seem to Be I have no reason kick about the Going Strong to work With Their of this set except when local QRN is very Radio Stations bad. of Late. Pret- The aerial consists of two -foot poles ty Good Lay - 35 Out, "Hen." on the roof of a two -story building. To- tal heighth 65 feet. Six wires 2 feet apart, So feet long. Wishing you all the success in the world for your magazine I am, Yours for Radio. HENRY M. HARRIS, Waco, Texas, Box 427.

www.americanradiohistory.com Radio News for December, 1920

Junior Radio Course The Three Element Vacuum Tube

Flow of Current Flow of Electrons flectrons repulsed by the Grid.

NNW

Flow of Electrons Mdli- 1 ameter O O O

Flow of Current Fig. 2A -8 Fí9.2 -c

Here Are Three Simple Diagrams Which Will Readily Show You Three Basic Facts You Should Remember About the Operation of Vacuum Tubes. Note Well, How the Electrons Flow in a V.T. and the Role of the Grid and Plate. It Will be Noticed That the Current Flows "on" the Electrons Which Act as a Conductor.

N our last lesson we described the FUNCTION vacuum tube in a receiving circuit, it may principle of the vacuum tube, and the Now to study the functioning of the be used as a detector which is of the most first apparatus built along these lines, three electrode vacuum tubes, we will use sensitive type. \Ve shall therefore explain in other words, the Fleming valve. the hook -up shown in Fig. 2. As already its functioning as a detector. This time, we will speak of the three explained in the last lesson a plate- filament Since we know that changing the polar- electrod vacuum tube known as the audion, circuit is secured by the electrons travel - ity of the grid from positive to negative which is the present day adaptation. ing from the filament to the plate, since opens and closes the plate circuit, we can After many experiments, Dr. Lee de For- they are attracted by the plate positively easily accomplish this by means of the al- est conceived the idea of introducing an charged; and allows the current from the ternating current received in an aerial, as auxiliary electrod in the ordinary valve of battery B to flow in this circuit from the shown in Fig. 3A, and at the same time the Fleming type. Titis electrod placed be- plate to the filament as in Fig. 2A. Thus rectify this current for reception purposes. tween the filament and the plate is known the electrons act as a conductor. If we The receiving set which employs a crys- as the grid, and is composed of a little connect the grid to the common point O tal detector and a telephone receiver has solenoid surrounding the filament as shown including in the circuit a battery and a been described in a former lesson and rea- in Fig. t. It is sometimes made in the milliammetcr, as in Fig. 2b, it will be seen sons were given, why a telephone cannot shape of a ladder placed on both sides of that a current flows in the grid circuit be- respond to radio frequency oscillations. In the filament as in certain transmitting tubes, cause a certain number of electrons are order to mike the vacuum tube function but its rôle is the same in all cases. stoppt by the positively charged grid and properly at all times as a rectifier of oscil- allows the current of the battery Br to flow lations, you must introduce additiona' and in the circuit, in which case we have a grid - filament current. Now, if we change the polarïty of the grid, what will happen? In Fig 2c, the flow of electrons from the filament, when the grid is negative is repulsed, for in this case the electrons are negatively charged. since we know that two polarities of the same name repulse one another. There- fore, the current from the plate, having no electronic supnort to travel on, is then quite suddenly stoppt. One can understand from this explanation that the grid acts as an automatic in- terrupter. but since no mechanical parts are to be moved it has no inertia. and it can therefore open and close the circuit of the plate a tremendous number of times The Dispositi n of the Various Elements in a per second. as Well as the The Simplest Form of Receiver -By Compar - V.T. is Shown in This Figure THE THREE- ELEMENT VT AS A DETECTOR Representation of Three Elements V.T. as Used son With the Analogy the Functioning of a in diagrams. By properly connecting a three electrode V.T. detector is Easily Understood.

www.americanradiohistory.com Radio News for December, 1920 neces,ary appliances in the grid circuit. when open, represents the lighted filament. When nothing disturbs the water it flows These are the grid condenser and the grid It will be noticed, too, that the telephone continuously in the endless pipe providing leak Which you no doubt have already seen is shown in that circuit as a little tank hav- the faucet F representing the filament is described. In the case of Fig. 3A, when ing a side composed of a movable diafram open. connected to the main circuit. no oscillations are being received in the and WHEN OSCILLATIONS ARE RECEIVED grid circuit, the grid potential is therefore The cylinder having a movable diafram at a zero value and the result is that no top in the center of the diagram is the When we turn the crank W this causes current flows in the circuit; that is to say, grid condenser; while the safety valve on the piston C to move up and down within none of the electrons are stoppt by the the left is the grid leak, the grid itself be- the cylinder. Since this causes a suction grid but instead flow straight thru from ing represented by the faucet moved by and compression, it will operate the dia- the filament to the plate without internlp- the diafram of the cylinder. fram D and cause it to open and close the tion. The functioning of this apparatus repre- faucet G which in a radio circuit would When radio frequency currents are in- senting a VT detector may be explained to be the grid. It will be noticed that at each duced upon the grid circuit from the aerial, you as follows: down stroke of the piston a certain quan- is made first positive, then nega- tity of water will flow into the cylinder. the grid p tive, for only alternating current can pass This would be what would take place in a thru the condenser. When the grid is posi- router regular radio receiver which in that case when Rotery Pum," Nye would call the amount of current re- tive. electrons are drawn over it, but i filom2nt) it is negative, the electrons are repelled. (Battery) ceived from the aerial system. thus for each succeeding half oscillation Each stroke of the piston represents a electrons are drawn to the grid, placing a B' high frequency oscillation and you will condenser which is nega- charge in the grid Normo) Position a bioiram therefore understand that after a certain tive on the grid side. number of these strokes. the cylinder will Since an increasing negative charge on become filled with water in such a manner the grid acts to reduce the plate -to- filament as to force the diafram D to close the current, then, while a group of oscillations faucet G. This is also what would happen are rectified the telephone current is re- in a radio receiver system where after each duced, but the grid leak comes in to play 'Nate, 5upp13 wave train the condenser would become its rôle, which is to slowly discharge the - (Current charged and the grid having been made condenser and allow the grid and plate to Received) negative it will stop the flow of current come back to their normal state. These Seeen, Volve between the plate and filament. There- variations which occur at each wave train (6norLeok) fore. each time our water system moves up causes the diafram of the telephone re- and down the movable diaphragm T, which ceiver to vibrate. al Loose Coupler normally would be the telephone receiver, Altho this explanation is simple enough (Receiver) is forced to move back and forth in a simi- to be understood by most students we will lar manner. which oc- further illustrate the phenomena The safety valve of our system, which tube detector, by means curs in a vacuum in the case of a radio system would he the of a simple analogy. Movable Dolrom grid leak, permits the compresst water of ANALOGY the cylinder to run in the main water cir- Teltar;r, 'ece.^ -T In F-g. 3B, the endless water pipe P cuit. This same process occurs at each a radio receiver. represents the plate filament circuit. The wave train of rotary pump can be taken to be the B bat- Simple Ano!ogy Illustrating the Phenomeno, Li the next lesson we shall explain the tery. ami the faucet F is the filament which. Which Happens in a Vacuum Tube Detector vacuum tube used as an amplifier.

Dictionary of Technical Terms Used in Radio Telegraphy and Telephony*

Static i-rattswiner transformer hav- guying clownlead', etc. S. W. G.- British Standard \Vire Gauge. -.\ pow- ing no moving parts. Same as an In- Stratton -One layer of a number of ma- Swiss Covnnulator -One used in high duction Coil but without hammer break terials laid one on the top of the other. er sets, by means of which different series parallel, or parallel arrangement of in primary. The alternating current be- Strays -See X's, and see Static. the separate may be readily made ing sufficient to produce A.C. in secon- cord covered with rub- units Strop Insulator-A up in the condenser battery. dary. ber and vulcanized, having at each end Apparatus for readily connecting Stator -The stationary part of an induc- an eye fitted with a thimble and shackle. .Szitch- and disconnecting two wires. tion motor. .Stuffing Box hollow casting holding fixed to support -A Svl anite- Graphic Tellurium. A Crystal Stays -Ropes permanently asbestos rings through which tube of Guys. Rectifier. Tellurium in combination with a mast. Compare with Bradfield Insulator passes. a refers to width of gold and silver (Ag Au) Tee. Step -Of winding, Copper Sulphate. coils of drum armature. Also called Sulphate of Copper-See Synchronous Disc Discharger -One so ar- Pitch and Throw. '.In Step" refers to Sulphating -Lead sulphate working out to ranged that its electrodes approach, and two or more machines running in phase surface of plates of an accumulator in discharge takes place in syntony with the with each other. form of almost insoluble crystals, which alterations of the generator. The num- Step -Down Transformer -One which has are poor conductors and very difficult ber of studs is equal to number of poles cell many more turns of wire in the Pri- to remove. Caused by a discharged of generator which gives a spark at each When not very bad mary than in the Secondary, thereby in- being left inactive. half period or in other words a spark creasing Amperage and decreasing Volt - may be remedied by prolonged charging. frequency of twice the alternator. Sulphur -S. Brimstone. Pale yellow non- age. . Synehrondus Motor -One which runs per- Step -Lip Transformer -One in which Sec- metallic element. Excellent Insulator. fectly "in step." "phase." or synchronism ondary has many more turns of wire A.W. 37.83. S.G. 2.07. MIt. Pt. 239° F. with the supply alternating current. 3.8 than the Primáry, thereby increasing S.I.C. to 4.7. Synthesis -The building up of a complex Voltage at the expense of Amperage. Subpermanent .lfagnetisut- Partially per- compound from its component elements. Sticking of Coil Contacts -See Sparking manent magnetism. .Slaito,v and Syntonication -Two circuit, of Coil Contacts. Supplement- Amount necessary to be add- are said to he in syntony when they have Sl,raue Ralle,-y -.\ number of Secondary ed to an arc to produce two right angles, the same natural period of electrical os- Cells capable of being charged or dis- i. e., 18o degrees of a circle. cillation. charged at the same time through the Snsceptibilily -Ratio of intensity of mag- T. having its downleads field Aerial -One same circuit. A quantity of cells used netization produced in a body to the tapped off from the middle of the hori- as one. Also known as Accumulators. producing that magnetization. zontal span. Storage Cell- Secondary Cell or Accumu- Surface Resistivity-Resistance between the Tails -Name given to small iron wires lator. One which stores up electrical two opposite edges of a Cm Square of core Induction Coils. upon forming of energy m forni of chemical energy. Sec the surface film which is deposited Taw/rut -Line drawn perpendicular to end Secondary Cell. the material. of diameter passing through end of arc ebonite rods Sine part of diameter of Strain Red Insulators-Two Suversed -That and produced until it meets the other joined together by a link, one of which an arc not contained between Sine and has a zinc cone at one end. Used for Arc. (Continued mi page ait)

Tlti.. iiii.'íolnry ,cas sfart^.I in our March issue.

www.americanradiohistory.com Radio News for December, 1920 Junior Constructor A TUBE CUTTING DEVICE a brass strip bearing on the lower end of A SWITCH KNOB the plate assembly, cause much annoyance while being adjusted due to poor contact to the rotary plates thru the brass strip. This is often made evident by the scratching noise heard in the telephones. It can be easily remedied by soldering a short length of wire to the indicating arrow and then bending the wire in the form oc a spiral, bringing the free end to the proper binding post, as illustrated. Contributed by CHAS. BURSON.

Get Your Writer Friends to Save Ink Bottle AN EFFECTIVE COIL MOUNTING Corks -They Make Good Snobs, The mounting illustrated here is a very good one for the hand and machine wound Anyone desiring a number of switch knobs honeycomb coils having taps. and who has not the price to buy them can No dimensions of the length and the make very neat knobs himself. The knobs width of the base are given in this case are made from the corks of empty ink bot- A New and Effective Way of Using Old Safety as these will be governed by the diameter Razor Blades. tles. For a neat knob I used the cork and the width of the coil. shown as A. from a quart bottle of Hig- gins India Ink. I cut away the cork and sketch herewith shown is the method The removed the staple, this leaves a hole in the devised by the writer for cutting tubing for rubber variometers, etc. Thus far he has not found in which the bolt C is fastened. A one that would work any better or quicker. low fusion alloy may be used in fastening the It is simplicity itself, and needs very little bolt in place, most anything will do, explanation. The base "B" is made of any such as melted sulphur. After this has scrap piece of wood, the thickness of which cooled the switch arm D may be fastened is determined by the width you want your in place. tubing cut. If one piece is not thick enough, For smaller knobs smaller corks may be you can build it up in numerous ways that used instead. will suggest themselves. Contributed by "A" is a Gillette razor blade which has rounded ends as per the drawing and two FREDERICK H. GRAENING. holes as shown. The blade must be so placed that enough of the corners project to all way the carboard tubing go the thru METAL SHIELDS FOR C. W. and a little beyond to make a clean cut. It RECEPTION. is then fastened on with two short wood screws with washers under the heads, as the Set. 7itf. -sr' Amateurs now building cabinet sets had holes in the blade are fairly large. Two better start right by lining the back and holes are drilled in the remaining part of sides of their cabinets with fine metal mesh "B" to fasten the device to the work bench. wire, as illustrated in Fig. 1. This mesh This finishes the construction. w ire should be grounded. Amateurs who In operation, the tube, which should have, own panel sets can improve operation by and usually has, one end square, should be banking their panels with a similar wire placed on the bench as in the drawing, bear- mesh or metal plate, grounding it to a water ing against the block and the blade. The pipe or other convenient ground lead. Fig. operator pushes down on the top of the tube 2 shows a good method of accomplishing while rotating it, as the blade has a tendency ...... [cods !o rest of se %- - this. to turn up and make the cut uneven. Care must be taken that not too much of the Any Degree of Coupling Can Be Effected by Contributed by L. ZIMMERMAN. Changing the Position of the Coils to one corner of the blade extends, as it is very Another. thin, and will bend up as above mentioned. r You will find that once around will cut thin the ordinary run of tubes, while thicker The base is of 44" hardwood abolit I" tubes surrender to two turns. longer than the diameter of the coil and Contributed by wider than the, width of the coil. HOWARD C. STORCK. The support which holds the coil is cut out of wood and is as wide as the coil. It CONDENSER NOTE is cut to fit the coil as shown and secured to the base by two flat -headed brass screws Some makes cf variable condenser which as shown. The coil is glued to this. employ for connection to the rotary plates The "panelette" is of hard rubber of "Bakelite" Tf" or more thick. It is the same width of the base and as long as the diameter of the coil, and is secured to the base by two small round- headed brass screws. The switch is a DeForest small type. Contacts are " x % ". Binding posts are any of the small set screw type on the market today. If desired the coils may be completely 1 in and box thus made given a l-_ housed the lcree odicaie-- polish, making a fine looking piece of ap- Dy do{}eá lines paratus. They may be connected to the rest of Fig 2 the set by means of a flexible double con- e. ductor. Be Certain of Iroper Connection in Variables. Use These Shields to Prevent Interference A Little Hair Spiral Spring Does the Stunt. Contributed by CHAS. BURSON. Caused By Magnetic Disturbance in C.W. Work.

www.americanradiohistory.com Radio News for December, 1920

HIS Department is conducted for the benefit of our Radio Experimenter. We shall be glad to answer here questions for the benefit of all, but we ems only publish such matter of sufficient interest to all. T 1. This Department cannot answer more than three questions for each aurcepoudelit. 2. Only one side of the sheet should be written upon; all matter should be typewritten or else written in ink. No attention paid to penciled matter. 8. Sketches, diagrams, etc., must he on separate sheets. This Department does not answer questions by mail free of charge. 4. Our Editors will be glad to answer any letter at the rate of 25c for each question. If, however, questions entail considerable research work, lotit cote calculations, patent research, etc.. a special charge will be made. Before we answer such questions, correspondents will be informed as to the price charge. You will do the Editor a persnn:.l favor if you make your letter as brief as possible.

A SMALL AMATEUR LOOP Q. 2. Is this condenser neces- (128) Mr. P. B. Arnar, of sary for the successful operation Reykja'ik, Iceland, asks: Microphone of the set? A. 2. Yes, is use- Q. 1. What kind and what size this condenser the tuning oscillating of wire is best for a t Meter square ful for of the loop antenna This loop is to be circuit and cannot be dispensed used to receive wavelengths of with. about 6Do -1,800 Meters. Q. 3. Would the Skinderviken A. 1. We suggest that you use button make a suitable transmitter No. 20 Sare wire wound on insulat- for this radiophone? ing material and with tarns spaced A. 3. Yes, this microphone may about W. be used with this set with success. Q. 2. Could same be used for transmission? COMBINATION SENDING - A. 2. Yott may try the sane for RECEIV ING V.T. HOOK -UP transmission, but we do not think (133) Le Roy T. Rix asks: very good results will be obtained Q. 1. Will you please publish a with such an aerial using spark diagram showing the means of transmitter, owing to poor radiating quickly changing from sending to properties. receiving which could be used with Q. 3. Please give hook-up for Mr. Rumford's panel set published same. 0/33 in the July issue of RADIO News? A. 3. You will find a suitable A. t. You will find on this page hook -1In on this page. these A Hook -Up for Utilizing the Same Vacuum Tube for Both a diagram suitable for two Radiophone Transmission and Reception. A Switch Does functions. TRIANGULAR AERIAL the Trick. Q. 2. I -ioty much current will be ( I2.0) A. L. Iicyler, of Philadel- drawn from the B battery when phia, Pa. using this set for transmission? Q. I. Sends a diagram of his special instead of a hot wire altimeter in the aerial A. 2. The plate current may be from type of aerial which is a system of three circuit? about 30 to 4o milliamperes. aerials at ranged in a triangular spread, and A. 2, Yes, a little incandescent lamp may Q. 3. May I use a little dynamo deliver- asks what results could be secured with it? be used for this purpose, but when the cir- ing 150 volts to supply the current to the A. I. t\'e think that good results can be cuit is tuned, this lamp should be short cir- plates? obtained with the aerial you intend to ex- cuited by means of a switch, A. 3. Yes, this voltage would be effective periment with, but only three wires in each for this purpose, for the higher the volt- of the aerials will he sufficient, otherwise RECEIVING SET HOOK -UP age, the better results you will secure. your capacity will be too great. (131) Thos. K. Lewis, Albany. N. Y., asks: DUO -LATERAL VERSUS HONEY- TRANSMITTING VARIOMETER Q. t. What effect would shellac or COMB I 13o) S. Posen, Syracuse, New York, lacquer have on variable air condenser (t34) I.. R. Jewell, Kansas City, Mo., asks: plates? wants to know : Q. I. What arc the dimensions of coils A. r. This would increase the effective Q. r. May the duo-lateral coils be sub- and size of wires to use for a Telefunken capacity of the condenser. stituted for the regular honeycomb coils in type transmitting variometer suitable for a Q. 2. Will you please publish a good receiving set its ng the latter? one inch park coil set? diagram of a loose coupler for the set pub- A. T. Yes, t to duo -lateral coils may he A. t. To build such a variometer you lished on page 76 of the August. 1920, issue used without any alteration in the receiver may use No. t8 double cotton covered aire of RADIO News? and which pertained to providing they -Ire of the same inductance wound on an outside frame 4" by 3" and the article "Des ?gn of a Radio Receiyinv and that von make provision for mounting. 2%" long and an inside frame 3%" by 2" Set " (Continued one page 39.4) and 2" lor.g. In order to have gond insu- A. 2. You will find a suitable diagram lation. it is arlv'sahle to coat the frames on this page. and winding with shellac. Q. 3. Where may I find an article in Q. 2. Can a .mall Mazda bulb he used RADIO NEWS on winding an amplifier transformer? A. 3. For information on this subject we refer you to the book entitled "Design and Construction of Amplifying Transformers," by E. T. Jones, the price of which is 25e. and which is publisht by the Experimenter Pub. Co., New York City.

USE OF SKINDERVIKEN MICRO - FONE BUTTON (132) Jr. R. Roach, of Bronxville, N. Y., wishes to know: Q. T. Can you give me the size of the Seumndoiy variable condenser used in the simple radio- g ü Sporn yap Oa? phone circuit described in the July number A Simplified Hook -Up of the Loose Coupler of RADIO NF.ws, on page 21? Receiver Mentioned By Mr. Clement In the A. T. The capacity of this condenser is Suggested Hook -Ups Employed a Loop in a August Issue. about .ova; mfd. Transmitter Circuit.

www.americanradiohistory.com Radio Yews for Decenthrr, la' ?it CORRESPONDENCE FROM READERS WHY NOT LET V.T. MANUFAC- raises it above the dry or sordid and keeps of them are only funny because of their TURERS DO A LITTLE PRICE one interested to the end. And it seems to ridiculous attempt at humor! EXPLAINING? me that the sanie quality is strongly mani- 1 also beg to differ with you as to such Editor RADIO NEWS: fested in your alternate covers, namely one cover illustrations attracting the outsider to if the Editor will permit me I would of human interest. the game. If the skin of an apple made it like to add a few words on the subject If you change and make each cover one appear rotten, would you eat it? Of course, which Carl Masson has opened in the Oc- only of "RADIO" interest, you will have at even with the apple, outward appearances tober issue, namely "Why the High Cost least on disappointed reader in -so -far as are deceiving, at times, and such is the case of Audion Bulbs." the cover is concerned. with RADIO NEWS, for without doubt, it is It is a well -known fact that most of the I do not see how any radio man, especi- the premier publication among the radio bulbs manufactured in the United States ally one who has come up from the ranks, fraternity and we, the "radio fraternity" are are produced in quantity lots and the most starting as a "ham ", could decide to stop expressing our opinions freely because we up -to -date labor saving methods are used, taking RADIO NEws because he considers would like to feel proud of our publications thereby reducing the one item. labor, which the covers ridiculous. 1 should think it and do not wish the dignity that is justly is always a large factor in determining the would take something greater than that, due the art, offended in the manner under final selling price to a minimum. such as a consistent misstatement of facts criticism. Amateur radio has graduated The writer has recently returned from a or articles which would not interest the from something for the kiddies to play with considerable sojourn in Europe and while technical man. to real scientific experimenting. The out- in France purchased a quantity of Audion I think your comment on Mr. Maher's sider who notices our covers will pass them Bulbs of French manufacture, the same letter is very well taken, and I think many over as still a "kid's plaything." Most boys bulb that is used by the French and Bel- of your readers will think so too. of a "tinkering" talent, will naturally turn gium Governments. In no case was to Wishing your magazine a long continu- to radio. Its the older outsider we want retail price over 20 francs, which normally ance of its well -earned success, I am, especially to attract to the game. is $4.00, but actually was about $1.75 on JOHN B. DOWDEN, Now I don't wish this to be considered as account of the exchange condition. Glen Cove, V. a "knock," but simply as a friendly and in- These bulbs are practically all hand made, terested criticism, and let me add my sug- consequently the cost of labor is the largest SHALL WE MAKE IT A gestion to Mr. Maher's that our covers be item in the cost per unit. Labor in France BI- MONTHLY? more of a technical, business -like nature, is cheaper than in this country, but con- Editor R.tDIO NEWS: for instance, views of big high powered sta- sidering the greater amount of manual What do I think of RADIO News? Well, tions or up -to -date amateur installations, in labor involved in the making of the Frew I'llsay that it is a gosh -darn long time be- which we are all interested. Let the gen- bulbs and the increased wages paid the tween copies. \\'hv not issue it twice a eral outline of the cover stand -it is good - American worker, it is hard to understand month? It surely is the only magazine for hut substitute for the pictures. why the American bulb manufacturer the amateur and thirty days is a long time Sincere wishes for continued success of should charge almost double for their tu have to wait for it. RADIO NEWS, the best of its kind, from product. F. L WOOLSEY, L. M. DUNNAM, Some may say the difference is occa- San Francisco, Cal. 2375 Champlain St., N.\ \'., Apt. 301, sioned by the difference in the cost of ma- c/o The Associated Press, Star Bldg. terials in the two countries. In this con- Washington, D. C. to inquire what the FROM A 6r- YEAR -OLD "BUG." nection, I had reason Editor RADIO NEws: cost of a variety of raw materials was and SHOULD A RADIO MAN FALL IN material averages higher in Regarding the complaint of the radio in- found that raw structor of the K. of C. school, at Savanah, LOVE? cost in France than in the United States. Editor RADIO NEWS: know that the patent Ga., which appears on page 300 of your Of course we all November issue, please tell him to "tumble I read with considerable amusement the squabbles which the several patent holders letter of J. T. Maher in your November have to himself" and please don't discontinue and manufacturers have been having, your "human interest" issue concerning the cover on the Septem- very expensive and tve, the amateurs, pictures. been I'm a 6r-year -old ber RADIO NEWS. He seems to be under being unwillingly forced to pay the "bug" and am proud to are acknowledge that it was one of your covers the impression that "radio bug" is a cold, bills. sober- minded automaton with a soul utterly reduce price. The de- that caught me, and I can find something By why not the interesting in every one of them. I'm dead to the pleasant side of life, who pores mand, great as it is, will increase enor- over volumes of technical lore twenty -three can afraid there is something wrong with our monsly, because every amateur, who now friend's digesting outfit. hours of the day and spends the remaining only afford a 25c chunk of galena, will have hour dreaming of logarithms on a bed en- more bulbs. The greater quantities \\M. W. CRANE one or Terminal Hotel, Atlanta, Ga. tirely surrounded by scientific apparatus. Be- that are manufactured the smaller will be lieve me, the real radio bug is jus: as human the cost to the makers and the manufactur- and enjoys a joke as much as the next ers will still he making their profits with THANK YOU, MR. DUNNAM. fellow. You probably remember the old the result that everybody is satisfied. Pos- Editor RADIO NEWS: saying that "foo much radio and no jazz sibly the matter could be cleared up con- This is to be considered as a "bouquet - will make Jack a bonehead." This is par- siderably if the manufacturers did some brickbat," prompted by J. F. Maher's criti- ticularly true of radio bugs. I am sure, if explaining. cisms of cover illustrations of RADIO NEWS, I had nothing but dry scientific matter to and your frank invitation for opin- W. R. HOFFMAN. further read I would soon go crazy. Yet I think T Radio Operator on S. S. Sahoatao. ions along the same line. am just as "bugs" about radio as anyone. Charleston, S. C. Let me say that I, and I believe the ma- As to the September cover I thought it jority of your readers thoroughly agree with was as good or better than any cover I HE LIKES OUR COVERS Mr. Maher on the subject, both as to cover ever saw. Editor. RADIO News: illustrations and "genuine technical worth" I have become acquainted with quite a Regarding the letter signed by J. F. of the magazine, tho he may have been a number of amateurs and operators from Maher, in the November issue, relative to little less "blunt" in phrasing his views. both U. S. and Canada and so far have the cover of RADIO NEWS, it seems to me This would never have been written but for only met one who didn't have an exag- to he a difficult matter to understand such his letter, which struck me very forcibly gerated sense of humor and who did not criticism. due to the fact that I had already criti- relax once in a while to laugh and joke Since there is always an abundance of cised, and very emphatically, both mentally with his friends. This particular fellow excellent scientific matter between the cov- and to some of my radio associates, the was attending medical college and spent ers of each issue of your magazine, which cover illustrations of RADIO News, espe- most of his time slicing up dead bodies and is not "ridiculous" why object to the means cially the one made issue of by Mr. Maher, dissecting kidneys and livers. which proba- used to attract readers of such matter? the September number. They are decided- bly accounts for his melancholy disposi- I do not mean that I think the covers of ly "off color" and "out of tune," in my tion. I would like to tell you more of this your fine magazine are ever ridiculous in humble opinion, with the idea expresst by rare specimen, but I am afraid he might a strict sense, for if I did I would have the publication. read these lines and understand who I refer to agree with Mr. Maher. I think they are Furthermore, to the real "radio bug" ra- to. funny, but even if they could be termed dio is not "dry" reading by any means. If So, Mr. Maher thinks a bug should never ridiculous, do we not laugh at the ridicu- all, or the majority of enthusiasts are to be be so "vulgar" and "common' as to oscu- lous? And is a man who interests himself judged by myself, and I think I am of the late? But perhaps he never was young in reading technical matter supposed never typical variety, the fiction, "jokes" and hu- himself, in which case we will have to make to laugh? The better term for the covers man interest elements of the magazine are allowances. in question should be "humorous." passt over without a second glance, and Back in my home town are several hams The human interest which is apparent in every line of technical matter devoured who are very intimate friends of mine and the way you treat each subject is fine. it eagerly. As to the "jokes," the majority (Continued on page 408)

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www.americanradiohistory.com 382 Radio News for December, 1920 Play the Hawaiian Guitar Just Like the Hawaiians! Our method of teaching is so simple, plain and easy An International Radio that you begin on a piece with your first lesson. In half an hour you can play it We have reduced Achievement the necessary motions you learn to only four -and you acquire these (Continued from page 357) in a few minutes. Then it is only" a matter of practice to acquire the weird, fascinating tremolos, stacca- tos, slurs, and other effects that make this Instrument so delightful. mum angle to which the boat may be The Hawaiian Guitar plays rocked before it ships water. This is the any kind of music, both the air melody and the accompani- voltage at which the surrounding ment. Your tuition fee in- breaks down under the electrostatic pres- cludes a beautiful Hawaiian sure. In electrical units the displacement Guitar, all the necessary in the ether is expresst in anipere meters. picks and steel bar and 52 F as is complete lessons and pieces This is really a measure of volume of music. apparent from the consideration that the An Ideal Christmas Gift. t -- L- amperes charging current at the limiting Send Coupon NOW voltage is proportional to the two hori- Get Full Particulars FREE zontal dimensions. The third dintensio or the height appears directly in the prod- First Hawaiian Conservatory of Music, Inc. uct and is expressed in meters. 233 Broadway NEW YORK The height of the antenna is the most I am interested in the HAWAIIAN GUITAR. Please by which send complete information, special price Serer, etc., etc. expensive of the three dimensions we may create electric displacement in the NASE ether. The tendency in stations designed ADDRESS for greatest economy is therefore towards TOWN structures of moderate height and great

STATE 11 N. length, whereas, the tendency in the past, Please write name and address Clearly when dynamic efficiency was the principal consideration, was towards towers of great height. The unit of performance on the RADIO MEMORIZE old basis was kilowatts consumed by the 4 ; antenna. The unit on the new basis is APPARATUS CONTINENTAL CODE ether displacement. This modern measure 1ALMOSTtiINSTANTLY of antenna radiating capacity is the num- and SUPPLIES ber of ampere meters of ether displace- Save the man weary weeks n w spent pounding that can be produced at the voltage the Code into s your head with telegraph key. ment ROSE RADIO SUPPLY Memorize Code before using key and ubsequent which is limited by the breakdown of the 604 Gravier St.. New Orleans. La. progress trill be rapid. Get Wise. Ask for free air. copy "What They Say Aleut IL" Many report for Latest Catalog having memorized entire Cole In ONE NOTI: STATION ANTENNAE SYSTEM Send 10c and you can do the ¿ante. Amid the labyrinth of CENTRAL die Code in its ANC ...merino km Short cal The antennae of the stations of New al,Ihod is the straight path to quick suocese. Brunswick and Marion which are now used Complete Chart and full instructions in transatlantic service are each one smile FIFTY CENTS long. In the new radio central station which is being built by the Radio Corpora- C. IC. DODGE Long Island there will be ten or SIXES & SEVENS Nog 200 Mamaroneck. N. Y. tion on twelve antennae, each a titile and a quarter Save time and freight by getting your ap- long. This station is intended to com- paratus from us. We carry full MERAD The little matter of 10 cts. will brine you and RADISCO stocks. Order from their Pathfinder eight weeks on trial. The municate efficiently with all parts of the catalogs. Also DeFOREST. TRESCO, Pathfinder is illustrated weekly. pub - world. When very long distances are to MURDOCH, THORADSON and others. What li.

www.americanradiohistory.com Radio News for December, 1920 Paragon R. A. TEN

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www.americanradiohistory.com .E Radio News for December, 1920 Vg: ng:7FYJMVZ:-MWg:7J:.:VgVg'à`l'J:''M::.WMK::M l RADIO A :...,:NORM...:.:..v v v v' v v'. v'. Distributors of Relial A Schools, Colleges MERRY RADIO All Over XMAS TO ALL ! "PITTSCO" RWMUVIUM The Sign of Service! Why Not Let Us Prove It!

AMPLIFIERS DE FOREST (Duo Lateral Coils) Cont. CRYSTAL DETECTORS No BORE Grebe One step $25.00 DL- 250 " 50 No. DeForest $2 47.00 900 D -101 No. BORG Grebe Det. and one step DL- 2.45 No. 8854 Jove No. ROSIN Grebe two step 55.00 DL- 400 2.60 No. Y -875 Clapp- Eethem 5. No. BORD Grebe Del. and two step -5,00 DL- 500 2.75 No. proof) 2. 600 RPDB Grebe (Duet- F. D. PITTS CO.. BOSTON, MAI& DL- 3.05 No. P -1 Paragon (A dandy) 1. 750 DL- 3.30 F. D. PITTS CO., BOSTON, MASS. INTERNATIONAL AMPLIFIERS DL -1500 3.55 DL -1250 3.05 Na RTA -100A Dot. and one step $35.00 DL -1500 No. RTA -104 -A one step 26.00 4.10 GRID LEAKS 1'. I). PITTS CO., BOSTON, MASS. No. RTA -101. -A ,two step 42.50 No. MW -1 Marconi 1, 2. 3 or megohms $1. (Nd No. C -2l Chelsea Variable 35 to 5 magohms. 10 values 3. F. D. PITTS CO., BOSTON. MASS. ) DE FOREST COIL MOUNTINGS No. C -22 Chelsea Oscillator. makes any circuit oscillate 3. No, LC -100 with gears mounted $10.00 F. D. PITTS CO., BCSTON, MASS. AMPLIFYING TRANSFORMERS No. LC-101 with gears on wooden bue 13.Oo FIS No. No. A -2 Arme mounted $7.00 LC-301 with bue and pal. itch 15 (It No. A -2 Acme semi- mounted 5.00 No. 111.C.200 single coil mounting 2.00 LOOSE COUPLERS No. A -2 Acme unmounted 4.50 No. ULC -300 double coil mounting 4.80 No. ULC -400 triple No, A -1 Arnold 3500 meten $22. No. 166A, General Radio mounted 7,00 coil mounting 5.60 No, Eestham 5000 meten 14. No. ULC -100 Same as LC -100 1-673 Clapp No. 166A General Radio semi- mounted 5.25 but on panel 10.75 1500 meters 9. l'. D. PITTS No. 944 Murdock No. 166A General Radio unmounted 4.50 CO., BOSTON, MASS. No. REAS Grebe Variumeter- coapler. 1000 meten, No. 226 -W Federal 7.50 in cabinet 25. F. D. PITTS CO., BOSTON. MASS. DE FOREST UNIT PANEL UNITS F. D. l'ITTS CO., BOSTON. MASS. No. US -100 Pri. Cond. switch 32.50 AUDION CONTROL PANELS No US -200 Anti cap. switch 4.40 No. BORA Grebe. in cabinet $12.70 No. U -200 "A" Bat. switch and Tel. Jack. 3.25 METERS (Weston Model 301) No. RORR Grebe with tick. connections 17.011 No. U -300 "A" Bat switch and Tel. Jack.. Binding Model 301 0 -3 amperes flush $8.1 No. ZRD Clapp -Eutham (New type) 12.00 Model 301 0 -5 amperes flush 8.1 No. Y -1 Acme (latest model) 10.00 No- UD -100 Crystal detector 4.30 Model 301 0 -50 Volt flush 8.1 No. P -500 de Forest audion ultra- andion type with No. UR -100 Luellen tube receptacle 2.95 Model 301 0 -100 Mill-amperes flush 8.1 0i No. US -400 Three point switch 2.25 Model 301 0 -300 Nfilliamperes flash RI F. D. PITTS CO., BOSTON. MASS. No. OF -300 Filament rheostat 8.85 Model 801 0 -500 Milli- amperes flash 8.1 No. UCV -500 .0005 Mf. Var. Condenser 7.75 Model 301 0 -800 :Willi-amperes flush S. "B" BATTERIES No. U -100 .0005 Mf. Var. Condenser and variable F. D. PITTS CO., BOSTON. MASS. No. No. 7823 Standard 22.5 V.. small 01.511 0.50 No. 7825 Standard 22.5 V., large 2.65 No. U 1500 Bridging or stepping condenser 6. METERS No. 7850 Standard 22.5 V., variable 3.50 F. D. PITTS CO., BOSTON. MASS. (Hot Wire) No . 766 erready 2^_.5 V., large 3.50 No. 127 Gen. Radio flush 0.1 Amp 110.1 No. 127 Gen. Radio flush 0 -3 Amp 10.( No. 763 Everreedy 22.5 V., small e DE FOREST UNIT PANEL VERNIER No. 703 Escrready flashlight cells. set of 10. 45 V 3.50 No. 127 Gen. Radio Ouch 0 -10 Amp CONDENSERS No. 127 Gen. Radio flush 0 -5 Amp 10( STORAGE BATTERIES No. UCV -1500 .0015 MI. without vernier $14.90 No. 128 ]toller-Smith flush 0 -2.5 Amp 7f No. 128 -A Roller Smith with shunt to read up to No. BA -3 Harvard 8 -volt, 40 Amp. -Errs $17.85 No. UCV -1503 .0015 Ntf. with vernier 20.10 5 Amperes 7.7 No. -5 Harvard 8 -volt. No. UCV -1000 001 MI. without vernier 13.60 BE 80 Amp -Are 21.95 F. D. PITTS CO., BOSTON. MASS. No. BX-7 Harvard 6-volt. 80 Amp. -Bra 15.gó No- UCV -1003 .001 NH, with vernier 18.60 F. D. PITTS CO., BOSTON. SASS, F. D. PITTS CO., BOSTON, MASS. BUZZERS OMNIGRAPHS CONDENSERS (Variable Air) 2 No. 178 No. Omnigraph 15 dial machine $28.0 General Radio, Puretone $2.00 No. 366 Murdock .001 Mf. solid case 6 4.75 20.0 No. 77 Moir. High frequency 2.50 No. 2 -A OmnlgnMl ' dial machin No. 366 Ink. Murdock .001 Mf 4.25 Esta dials. each 0.5 No. 168 Century, high frequency 7.60 No. 367 ,001 Transparent case 4.75 No. -744 Murdock F. D. PITTS CO., BOSTON, MASS. Y Clapp-Eastham, high -tone 1.75 No. 388 Murdok 0005 Mf. mounted 3.75 F. D. PITTS CO., BOSTON, MASS. No. 368 Iot. Murdock .0005 Mf 8.25 No. Y -800 Clapp-Euotham Bal. type .0008 317 7.50 REGENERATIVE RECEIVERS DE FOREST (Duo Lateral Coils) No. Y -800-A Clupp-Eaetham Bal. type .001 MI 9.50 No. meter, tube -- control self DL- 25 $1.65 No. Y -30áB Clepp -Eotham Bal. type .0015 SU 11.50 contained.-1 Gre (`o 170-8 0 set 90.n DL- 35 1.70 Na 1 Chelsea .0012 m unted 5.00 No. CR -2 Grebe 170 -600 meten 51.0 DL- 50 1.76 No. 2 Chelsea .0006 mounted 4.50 No. CR -3 Grebe "Relay Special" 170 -800 meten 85.0 DL- 75 1.85 No. 9 Chelsea .0012 unmounted 4.50 No. CR -3A Grebe 170 -375 meters. the latest Grebe DL- 100 1.95 No. 4 Chelsea .0006 unmounted 4.00 eon wave receiver 45.5 DL- 15n 2.10 No. P -1 Connecticut .001 Mf 5.00 No GrebCR -4 ree170 -coo meters with series condenser DL- 200 2.20 F. D. PITTS CO., BOSTON, MASS. for fine tuning 65.0 Important -Every article listed sent to any part of the U. S. A. po» Service reaches all over the world ! Why not let it rea Catalog No. 22 just out 12 PARK SQUARE F. D. PITT Del

www.americanradiohistory.com Radio _V r s for December, 1920 PARATUS Radio Apparatus to A cid Experimenters o o MERRY e Fie World ! á g RADIO ! o XMAS TO "REMEMBER" o ALL! a 11 We carry an immense stock. O Let us fill your Xmas orders!

REGENERATIVE RECEIVERS Cont. INSULATORS TRANSFORMERS (Acme new type) a CR -6 Grebe 170 -000 meters. detector and two Electro,e Rail U'pe $0.40 Acme 250 Watt, mounted 316.0e step amplifier self contained. A complete set. Elettrose 4" strain type 0.50 Acme 250 Watt, unmounted 13.0,' Ideal for Wireless phono reception. A masterpiece.200.00 Electrons 10" strain type 1.00 Acme 500 Watt. mounted 22.00 a. CR -7 Grebe 500 -20000 motets. "Long w spe- Elettrose 16" strain type 1.50 Acme 500 Watt. unmounted 13.00 cial." A complete set. Ideal for long r wavwaves. Electron 22" strain type 3.00 Acme 1000 Watt, mounted Tt On A wonderful t F. D. PITTS CO., BOSTON, MASS. Acme 1000 Watt, unmounted 28. nee Ire him that Grebe pet for Xmas. An incomparable g1rl. F. D. PITTS CO., BOSTON. MASS. F. D. PITTS CO., BOSTON. MASS. GROUND EQUIPMENT No. Gtr 100 Amp. 600 V. Lightning switch. eeN- RHEOSTATS ladon type $4.50 TRANSFORMERS (For CW work) 4 wire per foot 0.10 214 Gen. Radio Bark No. G -2 No. Ground Acme 200 Watt, mounted 320.00 cots £'SSo No, G Porcelain cleats with screw complete for 200 a F -2 Paragon Back mie 1.73 -3 Acme Watt. unmounted 10.0o wire, each 0.19 Acme 50 15.00 r. It -1 Itemler Back wig mound Watt, mounted No. G-4 Ground clamp 0.25 Acme 50 Watt. unmounted 12.00 F -200 De FestForest Prooelaln 1.00 F. D. PITTS CO., BOSTON, MASS. F. D. PITTS CO., BOSTON. MASS. F. D. PITTS CO., BOSTON, MASS. CONDENSERS Trans. (Dubilier') TELEPHONES Type No. Watts. Volts. Cap. Price. JACKS a 55 Murdob 2000 ohms 14.0 D -100 250 10000 .007 319.00 No. 1423 -W Federal 2 circuit 51.0. 55 Murdocks 3000 ohms 5.50 D -101 500 14000 .007 30.00 No. 1422 -W Federal closed circuit 0.85 t uuies "Superior" 2000 duo+ 7.W D -102 1000 21000 .007 45 00 No. 1421 -W Federal open circuit 0.70 nodes "Trans- atlmuld' 2800 ohms 12.00 D -103 1000 25000 .007 50.00 No. WE-1 Western Elec. 2 circuit 0.90 den "Nary Tn., 32200 ohms 14.00 F. D. PITTS CO., BOSTON. MASS. No. W -2 Western Elect. open circuit ddwlns Typo C, Navy Standard 16.50 F. D. PITTS CO., BOSTON, MASS. ddwlns Type E. Super- sensitive "0 00 LINE PROTECTORS 2200 ohmshms Govt. standard 12.50 No. AM -888 Dubiller Up to I KW 34 00 ntury 3200 ohms Govt. standard 14.00 No. 453 Murdock Rod and fuse type 7.50 PLUGS awn 4000 ohms Imported, super -sensitive. double No. 452 Murdock Rod. fuse and condenser type. - 9.00 No. 1428 -W Federal Brass $2 0'. armature ^0 no F. D. PITTS CO.. ROSTON. MASS. No. 1420 -W Federal silver plated 2.50 F. D. PITTS CO BOSTON, MASS. No. WE-1 Western Elec. Brass 1.2ee KEYS F. D. PITTS CO., BOSTON. NASS. VACUUM TUBES No. 235 Murdock 30.70 No. 7943 Beeko, Practice type 1.50 0. If -1 Electron Relay 56 n^ No. 8650 Mascot. Up to Vs KW 3.00 DIALS e. M -2 Moorhead Amplifier 7,00 No. 7939 Standard. Up to 1 KW 4.00 No. PDA Grebe 4" 0 -100 $3.00 es M -3 Moorhead extra Trans hard, No. 10 7.50 No. PDB Grebe 4" 0 -50 s A -1 0n T -643 Clapp Fthem. Amps Audlotron Ó No. 3" 0 -100 2.50 F. D. CO., F. D. PITTS CO BOSTON, MASS. PDC Grebe PITTS BOSTON. MASS. No. PDD Grebe 3" 0 -50 SPARKGAPS (Plain) F. D. PITTS CO., BOSTON. MASS. VACUUM TUBE SOCKETS No. 440 Murdock 30.90 R -300 De Forest £1.50 No. 7750 Reeks, adjustable typa 1.40 . MW -1 Marconi 1.50 No. 7751 Mascot, Luge points 3.00 VARIOMETERS v 65 Murdoch 1.00 No. Y -656 Clapp Eastham. 1 KW 4.50 No. ZRV Clapp Eastham without dial $5 7 s 156 Gen. Radio 1.75 ROTARY TYPES No. ZRV -A Clapp Eastham with dial 6.50 R -400 Inverted type 2.,3 No. 143 Mfurdock 4000 R.P.M $18.50 No. ZRV-B Clapp Eastham veto- coupler 7.60 F. D. PITTS CO., BOSTON. MASS, No. 121 Klltren (Latest type) 26.00 No. ZRV -C Clapp Eastham dial only 1.:3n Bonwocd (Noiseless) 30.00 F. D. PITTS CO., BOSTON. MASS. WAVEMETERS Benwrod rotos. 8. 10 or 14 pt 3.00 wad Type D £0.50 BOOKS .Ó . 7.- 70422 Clapp Eastham 3000 Meters 2e.511 Thrdsoeron rotors 16n Practical Wireless. By Bucher 3=.- 174 Gen. Radio with hot wire galvanometer Murdock rotors. 3/16 or M° ahans 3.00 Erpeimenter's Manual. By Bucher 2.25 3000 matera 65.00 F. D. PITTS CO., BOSTON. SASS. Vacuum Tubes By Bucher ",Y6 F. D. PITTS CO., BOSTON. MASS. QUENCH GAPS How to Pass U. S. Exams By Bucher 0.73 now to Conduct Radio Club. By Bucher 0.75 ANTENNA WIRE Amtad 1 KW. Typo 341.50 Amred 55 KW. Type 24.50 Practical Wireless Stations. By Bucher 0.75 . F -1 7 strand No. 22 tinned copper per foot. ...50.0'', Amred 'd KW. Type 18.00 Radio Telephony. By Goldam' :th 2.50 5500 ft. or r, per foot 0.01 F. D. PITTS CO., BOSTON. MASS. Radio Inst. and Measurements 1.7.7. . F -2 7 strand No. 20 Phos. Bronze per foot 0.034 Elem. Prnc. of Wireless. By Bangay. 500 ft, or over per foot 0.02 TRANSFORMERS (Oscillation) Part 1 1.75 . 5 -3 7 strand No. 16 Phos. Bronze per foot No 424 Murdock 35.00 Part 2 1.75 (ship type) 0.03+_ No. P -1 Thordarson 12.00 Boa for 3,2% . F -4 Hard -drawn copper No. 14 (60 It to the No. TNL -100A International 18.50 Robinson's Manual of Wireless Tel 2.50 pmmd) per lb. 0.70 No. 7. -d52 Clapp Eastham 1 KW. size 20.00 Consolidated Call -book (new edition when Issued) 1.50 F. D. PITTS CO., ROSTON. MASS. F. D. PITTS CO.. BOSTON. MASS. F. D. PITTS CO.. BOSTON. MASS.

e prepaid or express prepaid. We want your business ! "Pittsco" you? If you want it for Xmas let "Pittsco" fill your orders. ten cents in stamps for it. C O., I n C. BOSTON, MASS., U. S. A.

www.americanradiohistory.com Radio News for December, 1920

(Continued from page 382) to another and combining it to meet vari- NOSTAT ous demands. New York is a natural communication "Cooquerer of Static" center and the service must extend to Eu- rope, South America and westward. An- other radio central station at Hawaii io CUTTING THE COST OF RADIO being equipped to serve as a relay for all points on the other side of the Pacific Ocean. NOSTAT ACOUSTIC TUNING CHAMBERS POSSIBILITIES OF TRANSATLANTIC RADIO. PHONY Identical in material, workmanship and design to our famous model While it is winter on the northern hemi- 4, but without, telephone, binaurals or base. Ready for use with sphere, the radiating power to Europe can your own receivers and the price -lower than that for which you be much reduced but this is the season could make them. when the South American traffic requires a maximum radiation because of summer conditions then existing on the southern hemisphere. The New York radio station $1o.m can then divert some of its radiating power For working through from the European to the South American circuits. There will also be daily fluctua- (QRN) or (QRM) The one piece of tions in traffic load which will occur at R a d i o equipment different hours due to the difference in geographic loneitude. Thus the peak load you can not afford to of European traffic will occur at different be without. times than the South American and West- ern traffic. The central station equipment For sale by COMPANY can be utilized so as to take advantage of NOSTAT this. 118 St. James Place The realization trans -Atlantic radio Brooklyn, N. Y of telephone for commercial purposes is another object of the Radio Central installation. Trans -Atlantic telephony will, no doubt, be a luxury for some time to come. The radiation intensity needed for telephony is much greater than for telegraphy, FACTORY GUARANTEED and a plant designed purely for telephony ALL SIZES might prove prohibitively expensive. How- ever, the flexibility of the radio central PROMPT GELIYERT where any number of antennae can be com- Polyphase Motors Hired Current Motors Single Phase Motors bined when desired to produce a more effi- a and IA..r. ,A. l'. 240 v. 110 or 220 , n1L., D. C., ,bunt wound. I 01. WW1 and sun R y . M. x111. pulley cient radiation will make an extra power- .In.IP'HI It.l'.M.. Cno,pkl+ ITAO 11.1. hart pulky Marling l,n Hm. Pull, ful transmitter available when needed. w.a $ 1/4 wym..iiMMlM r $28.50.50 . while the plant may be used in a more N. P. . $46.50 1/4 M. 28.50 1 50 economical way at other times for teleg- Cnarging Generators 1 $28.50 /4 t:;:::;,'"'"! $28 $66.50 /4 x r. i.e.ese.. mn $ raph. 1í 2 le;a .I.H . $46.50 1 H. P. $58.50 2 H. P. $86.50 , i k.M.nR 6 v. 10unp. n..H.wr $54.50 $19.50 1 P. $82.50 1/2 x P,ma.. .a.nxe. 3 H.P. 1 Isv..In.mp $26.50 $98,50 AE.r: Ge,.LRkm . $4.50 2 H. P. $124.50 40 v,6a06 $31.50 - xr o,.we.kevaH. H.P. 2 50 The Audion s $11650 Ne.uaer,.0 . $126 -Its Action no v, z!; amv. $31,50 3 H. P. $142.50 H.r.opw.l.e.u.. 1 H. P. aPrd,l c,mer $146.50 vehl0e5 $106.50 3 .Re xie.s e,,, and Some Applications I10v,5amp..$52.50 N. 18.50 Mele, . S P $ $188.50 12 amp. 40 v, - $52.50 ARO CENERATORS5 "'i' ( WRITE FOR OATAIOG. RARCAINS IN MOTORS Continued from page 359) Ilov,s!samp. $67.50 SPECIAL WASHING MACHINE MOTORS 40 v,25 smp...$67.50 relü HP.IIa11.0 $26.5° unv,lsamp. $116.50 1/4 S. P. 11AA R pM, rent, telegraphic communication by con- Cenpl.l,. cc.. NM .2 WWI 40 v.,50amp. $116.50 duction or leakage be RIONI.T BACK GUARANTEE currents should 110v,26amp. $156.50 llIr15,4b, o. St possible, using the audion as detector $ HIPPING TERMS: iuy.,,.5:55:pulie.iinsIiri 1l0v,50amp. $238.50 and amplifier. I venture to prophesy MANUFACTURERS' DISTRIBUTER that within a few years the tall towers and $116.50 CHAS. H. JOHNSTON, Bolls, West End, Pittsburgh, Pa. the atmospheric disturbances which have for two decades been esteemed necessary evils in transoceanic wireless signalling, will be re- garded with those sentiments which we now bestow upon the coherer and the spark. But more than this. Signalling by conduc- tion currents of relatively low frequency will soon be practiced thru the earth as well STUDY WIRELESS or as water; and we will find the antenna of the future thrust upside down, as into abandoned oil -well borings, and making contact LEARN TELEGRAPHY with deep semi- conducting strata, at points separated by a few miles ; the two inverted antenna of such a transmitter connected by Boylston St. STUDENTS an overhead power transmission line con- Cor, Washington Ener taining the alternating current generator BOSTON ANY TIME and signalling device; and a similar ar- 1 8 rangement for receiving. and Positions Guaranteed Then our wireless messages will go thru Results the earth's crust, or possibly by a more di- Best equipped Radio School in New England. There has rect path, and not around the earth's sur- 18 St. for over 18 years face, to be tangled up as at present with a been a Telegraph School at Boylston bewildering snarl of static ravellings. The Send for tree literature. audion amplifier stands ready to lead us back to the simpler methods of Morse and MASSACHUSETTS RADIO AND TELEGRAPH SCHOOL Lindsay, meritorious methods long ago Trl.Brorh 7168 G. R. Entwistle abandoned because of the lack of an electric ear of indefinitely great sensitiveness. (Continued on page 388)

www.americanradiohistory.com Radio News for December, 1920 397 `A N WIRELrC pT M The Demand for Good Wireless Operators Far Exceeds the Supply The New York Wireless Institute will make you an operator -AT HOME -in your spare time -quickly, easily and thoroughly. No previous training or experience required. Our Home Study Course has been prepared by Mr. L. R. Krumm, formerly Chef Radio Inspector, Bureau of Navigation, N. Y. He resigned last August to accept a position of still greater responsibility with one of the largest Commercial Radio Corporations in the United States. Radio experts able to impart their practical and technical knowledge to YOU in an easy to understand way will direct your entire Course. The graded lessons mailed you will prove so fascinating that you will be eager for the next one. The instruments furnished fret will make it as easy to learn the Code as it was to learn to talk. All you will hare to do is to listen. Big. Salaries Travel the World Over Wireless operators receive excellent salaries ranging from 8125 A Wireless Operator can visit all parts of the world and receive to $200 a month and it is only a stepping stone to better positions. fine and maintenance at the same time. Do you prefer a There is practically no limit to your earning power. Men who pay steady position without travel? There are many opportunities at but yesterday were Wireless Operators now holding positions or as Radio Engin.v.rs, Radio Inspectors, Radio Salesmen at salaries the numerous land stations or with the Commercial Wireless up to $5000 a y:nr. with the Steamship Companór. FREE Instruments and Text Books We furnish free to all students, during the Course,the wonderful receiving and sending set exactly as shown in the illustration. This set is not loaned, but given to all students completing the Course. One cell of dry battery all that is required. No additional wiring, aerials, etc., This wonderful Set for learning the Code furnished free with our Course. needed. The Transmitter shown is the celebrated Omnigraph used by several Departments of the U. S. Government and by the leading Universities. Colleges, Technical and Telegraph Schools throughout the U. S. and Canada. Start the Omnigraph, place the phone to your ear and this remarkable invention will send you Wireless Messages. the same as though you were receiving them through the air, from a Wireless Station hundreds of miles away. When you apply for your license, the U. S. Government will test you with the Omnigraph-the same model Omnigraph as we furnish W our students. Ask any U. S. Radio Inspector to verify this. Wireless Telephony Course FREE Post -Graduate Course We our institute an up -to -date and complete A one month's Post -Graduate Course. if you so desire, at one of have incorporated in the largest Wireless Schools in New York City. New York -the Course in Wireless Telephony. written by our Chief Instructor. Wonder City -the largest port in the World and the Headquarters Mr. i.. R. Krumm. This Course is also furnished free. of every leading Wireless and Steamship Company. The Department of Commerce of the U. S. Government recognising the value of the instruction furnished by us. allows all of our graduates a five -point credit in their examination for first-grade

litE U. S. SHIPPING BOARD will also testify as to the value of this instruction. America's Fastest Growing Wireless Institute Send for FREE Booklet There Must Be a Good Reason. Without obligating you in any way. send for our booklet "How to Become an Expert Wireless Operator " -it is free. Mail the coupon below, or postal or letter-but do it today. There Is- NEW YORK WIRELESS INSTITUTE, The Best Course in Theory available. Dept. 7, 258 Broadway New York City The Best Instruments obtainable. The Best Text Books and Diagrams on New York Wireless Institute Dept. 7, 258 Broadway. N. Y. City. the market. Send me, free of charge, your booklet "How to Become an Expert Wireless Operator," containing full particulars of your Course, in- Easy Payments cluding your Free Instrument offer. A small payment down will enroll you. We will make the pay- Name ments so easy that anyone ambitious to enter the fastest growing profession- Wireless -may do so. Address

City or Town State

www.americanradiohistory.com Radio News for December, 1920

(Continued from page 386) The future of radio signalling at sea lies R with the telephone rather than the telegraph. The simplicity, the reliability with which the '. medium of an utldampt wave- carrier, ideally suited for voice transmission, can now be had will rapidly limit the crudity and labo- riousness of the Morse code signalling between ships. Yet today scarcely the dawn of this new epoch has been seen. Vessel owners are today almost as skeptical regard- iii__ , , ing the practicability and utility of the radiophone as we pioneers found them toward r the wireless telegraph sixteen years ago! In the future during fogs at sea a short- r , . s _ y wave radio telephone will be used to prevent collisions, distances being determined (as well as direction) by conversation, whis- F`r tled signal or bell and a calibrated stop- watch. This service will be quite independ- F t , 1r' ß ! / , ent of the long -range wireless signalling. ;L 3" The new radio has also a wide field of use- fulness in telephoning between islands, thousands of which will never be linked by cable. Other useful fields await in sparsely peopled countries, between mines, oil wells, forest patrols, from express trains, etc. The future of aviation will be found linked with radio telephone, or a score of different purposes. Telephony by audion transmitter, receiver, and amplifier not only carries the complexes of human speech without distortion, but delivers them where human speech All Over the World ! itself is impossible otherwise -amid the From deafening motor and propeller noises of the It is extremely gratifying to us to note that our mail order service has of the globe. airplane, from one to five miles above the brought the patronage of radio men from every part earth. China, Ecuador, Costa Rica, New Zealand, Checko -Slovakia, Little imagination is required to depict Peru, Argentina, Spain, Santo Domingo, Netherlands, etc. new developments in radio telephone com- rc- munication, all of which have lain fallow Their patronage in itself, is significant of our SERVICE. For customers heretofore awaiting a simple lamp by which siding in far -away countries have no time for replacements or readjustments. one can speak instead of read. nor do they appreciate the necessity of being obliged to wait for their orders. So far as possible, every article ordered by mail is shipped the same day the order is received. We will appreciate the opportunity of extending this service to YOU. Comparison of Modu- Ter cents will bring "Bulletin 14" place your same on our mailing list, and pave the :,u. lation Methods in to satisfaction. Radio Telephony

ATLANTIC RADIO CO. i C ontinttrd from Aanr ; o_ INCORPORATED MAIN OFFICE: BRANCH: 887BROAD ST., 15 TEMPLE ST. BOSTON, 9, MASS. PORTLAND, ME. ;. "SHRAMCO This Shows How the OscillograDh Vibrator Was Coupled to the Set During the Testa. REO" tion may sometimes be improved by throt- tling ele- down the input from the master oscil- 6 -ohm Nickel- Chromium Resistance lator so that the operation is held more ment mounted on electrical asbestos makes nearly within the straight portion of the the ideal combination in a filament rheostat. characteristic curve of the amplifier. We Arranged for panel mounting by use of should be interested to know whether or locknut All metal parts brass. No sol- not this procedure is beneficial. As ex- dered connections. Spring Phosphor Bronze tremes, the two cases to be considered are: blade. Even regulation and smooth opera- (a) Strong impressi oscillation over tion. Complete with knob and pointer as entire characteristic; shown. Base dia. Overall height 2W. (b) Weaker impresst oscillation over "Licensed Under Marsh Patent 3" straight part of curve only. Shipping weight t lb. Will control 1 tubes. No. 811559." The output currents in the two cases are shown in Fig. 13a and r3b. Cat. No. 90- "SHRAMCO REO " -6 ohms - $2.00 each (Continued nn page 39o) CORRECTION NOTICE Special Resistance made to order Through a typographical error in the No- vember issue of RADIO NEWS, the adver- Send 5c in stamps for our catalog J. tisement of the Atlantic Radio Supplies Company of Newark, New Jersey, and the Pacific Radio Supplies Company of San Francisco. California. distributors for RADIO MFG. COMPANY Moorhead Laboratories, contained the SHOTTON wrong price for- the A -P VT Amplifier - P. O. Box No. 3 SCRANTON, PA. Oscillator. The price was shown as $6.00 whereas it should have been $7.00.

www.americanradiohistory.com Radio News for December, 1920

-andLicensed for use only in here itis! apparatus manufactured You have hoped for it. You have looked for it. You have by the De Forest Radio Td. & Tel. Co. asked for it. And here it is -a transmitting tube for telephone and telegraph C -W transmission, built right up to British and to French Government specifications. Capacity about 12.5 watts, and any number may be used in parallel -four, make telephone conversation possible over 25 miles, telegraph signals over 50 miles.

The plate of this transmitting tube By connecting the grid and plate is nickel, a special molybdenum grid together, the tube may be used as is provided and the high vacuum a rectifier for obtaining from an permits operation on plate poten- alternating current supply the tials of five hundred volts without high plate potential necessary for breakdown. the generator tube.

Adopted by the De Forest Radio Tel. & Tel. Co. as the standard transmitting 4 f tube in all De Forest sets of less than 3 2 k. w. capacity. Licensed under the De Forest Audion and Fleming patents. Other patents applied for and pending.

11 1 Atlantic Radio Supplies Co. Pacific Radio Supplies Co. Equipped with the SHAW 8 N. J. 638 St., San Francisco, Cal. standard four -prong Kirk Place, Newark, Mission hase. PRICE $7.50. Order from your dealer. Distributors for Moorhead Laboratories, Inc., Manufacturers of The A-P Trnitsmitting Tube

A Loose Coupler that WORKS For a Price at Which Everyone WONDERS

This instrument compares favorably with the high priced receiving transformers and has been built right all the way through. Not a cheap mail - order creation such as put out by some houses, but a loose -coupler that is guaranteed to work or money refunded.

Both primary and secondary are wound on non -shrinkable forms with the 1-G100-Loose Coupler, $0.00 best quality silk- covered pure copper wire. Interior so wired as to make short circuits impossible. The primary is encased in a hard wood cabinet and the base is also of hardwood-choice of mahogany, stained oak, or green finish. A FEW MORE BARGAINS All metal parts are heavily silver nickeled. No. 12 pure copper aerial wire per 100 feet $ .80 The loose -coupler tunes up to 2,500 meters in connection with the average Shipping weight 2 lbs. per 100 ft Carbon grain transmitter 1.00 aerial and is capable of very loose -coupling. Skindervicken transmitter button 10, Auditron adapter 1.75 No. LC-100 Loose Coupler-shipping weight 8 lbs. 1 B.W. sending key 8.00 Auditron tubes 6.00 Shipping weight on any of above, add 1 lb. $9.00 postage

Send 15e for our big illustrated catalog to showing scores of other bargains in radio apparatus. This amount may be deducted from your first order of $r 50 or over. High printing costs make free distribution impossible. ELECTRICAL SPECIALTY COMPANY Dept. R, 48 -50 So. Front St., Columbus, Ohio. Dept. R, 20 N. 9th St., Philadelphia, Pa. i

www.americanradiohistory.com Radio News for December, 1920

(Continued from page 388) The modulation envelope curve of case (a) contains a fundamental frequency term "Are You Working Distance ?" corresponding to the original modulating Get a Benwood Disc and Knock 'Em Dead frequency plus harmonic multiples of this frequency and also an invariable or steady The Merit of This Disc Has Proven Itself component which is the average value about which all the alternating components vary. This average value can be drawn, as in the figure, by making areas above and below it equal. The same sta:emettts apply to the non- distorted modulation of case (b) except that in this case the wave form contains only the original modulating frequency and no harmonics. In both cases, according to the theory already presented, the effect in the distant detector depends on the product of the average value A just mentioned and the amplitude of the fundamental frequency tent.' of the modulation envelope curve; i. e., on AB. We have, therefore, to cal- culate this product for the two cases presented. In case (a) the equation of the envelope Made in styles shown with 4, 8, to, and 14 sparking points. Drilled curve may be written in a Fourier's series to fit any size motor shaft. Outside diameter, 6 in.; width, 4 in. i= Aa +Ba Sin pt+Ca cos 2 pt -i-Da Sin 3 pt Points taper to A in. Extremely accurate to the hundredth part of +Ea COS 4 pt+ (7) inch. pow in use Line where the subscript (a) indicates that the an Hundreds up with the distance gang. coefficients refer to case (a). Order yours tcday- Immediate shipment. in case (b) the equation is Specify size of motor shaft when ordering i = Ab + Bb Sin pt (8) Price Prepaid $8.00 We are interested in the relative values of the products AbBb and AaBa, in the BEN WOOD stationery electrodes consisting of wide copper elec- two cases under different conditions. Evalu- trodes and highly polished knob in conjunction with above disc ating the coefficients of the Fourier's series gives a clear beautiful note. in the( usual way we get Price Prepaid $2.00 per set Aa Ç2'r -2 cos 9,-4- 90 Sin 9r)i. (9) 2," 111111 "Try Our THE BEN WOOD CO., INC. "You Will t f 11 Service" Cor. 13th and Olive Sts., St. Louis, mo. Like tt" Ba -- 9 -. -Tr % Sin ter j .... (to) * 2 The significance of M and o, are shown in the Figure 13a, as is also Ba. As will be seen 9, indicates the point in the cycle where the flat portion of the characteristic curve is reached. In Fig. 13b the maximum or peak am- WHY THE Q.R.M.? plitude (Ab +Bb) is obviously equal to Use UNDAMPED WAVE transmission. Now made possible by the M (1 + Sin 9,) (it) `MIDGET" motor generator uait, designed for that VACUUM TUBE of yours The two products which we have to compare are therefore seen to be l0Y 1 AaBa= -{2r -2 cos 0, +(r -29,) Sin 9,) z !, 9,-! - i/2 Sin 29r (12) and M' AbBb = - (i + Sin 9,)'....(13) 4 The values of these two products are plotted for different values of 9, on Fig. 14 where it is seen that the formet is larger than the latter for all values of 9 except 9, = go °, where the two become A equal. This result is what might have "Midget" Motor Generator Unit Stated installed on your radiophone ELIMINATES cumbersome transformers and rectifiers. been expected. non- mathematically, No induction hum. CONSTANT VOLTAGE. Efficient operation. Self regulating. No it means that reducing the radio frequency starting device or field rheostat necessary. MOUNTED ANY PLACE. back of panel. amplitude ii pressed on the amplifier so in cabinet, under table. AMPLY SUPPLIES THREE VACUUM TUBES. as to keep the operation on the straight MOTOR -Universal wound. Operates satisfactorily on A.C. or D.C. -110 or 220 volts. GENERATOR -Shunt wound. 15 watts capacity at 275 volts D.C. portion of the characteristic. while obvi- DIIIENSIONS -3,!- x 4" x 1154 ". Net weight 9% lbs. ously improving the quality of the modula- Both machines mounted on common cast iron base, coupled together by means of flexible tion, reduces the net modulated antenna insulating coupling, allowing quiet operation and perfect alignment. energy. This reduction is greater the F. O. B. CHICAGO, ILL. $42.35 smaller the value of 9,. that is the greater Can be shipped via Parcel Post the portion of the cycle which embraces Our "HYLO" Motor Generator unit, supplying both FILAMENT CURRENT and the horizontal flat part of the curve, and PLATE CURRENT, thus eliminating the possibility of a DEAD STORAGE BATTERY is nil when the peak of the cycle just at a critical moment made in capacities up to 100 watts at 500 volts. The "STANDARD" Motor Generator unit made in capacities of 50, 100 and 175 watts reaches the flat part of the curve (9. =g0°). at 500 volts. The ratio of the effectiveness in the two AbBh RAY-DI-CO. cases is shown on Fig. r4; it is 2653 -A N. Clark St., (Not Inc.) Chicago, III. AaBa and is seen to be never worse than 7, %. (Confitn(ed on page 392)

www.americanradiohistory.com Radio News for December. 19ßu 3:91

Off V42" RADIO TELEMEGAFONE A Sound Amplifier of Unique Electrical Design

WHEN USED WITH A SUITABLE AMPLIFIER THE VOL- UME OF SIGNAL SOUND IS ENORMOUS. TOO GREAT Connect "A A" lv TO BE ADEQUATELY MEASURED OR ESTIMATED. your Amplifier and "B B" la a 6 Volt NOT a lia ttcry. MAGNAVOX Telemegafones are made by attaching horn to a radio telephone receiver, and must not be confused with other so- called "loud- speakers." IT'S ALL IN THE MAGNAVOX ELECTRO- DYNAMIC PRINCIPLE -PROTECTED BY BASIC PA- TENTS.

Write for Bulletin No. 21020A

The Magnavox Company Oakland, California

cEkt, Your Duo Lateral Wound Coils A Are Ready " SERVIMUS" JUST a word of explanation: Our first advertise- THAT was up till a short while ago. Now we have ment caused such an upheaval in radio circles that succeeded in doubling our productive capacity, and we were swamped with inquiries. Indeed, one large Duo- Lateral Coils are available to everyone in the manufacturer of radio apparatus immediately placed radio field. We can make prompt shipments from ' his contract with us, taking over our entire output. stock. Your DUO - LATERAL COILS are ready to As a result, we were obliged to turn down orders. to be shipped the moment your order is received

lifinilinil imum REMEMBER: DUO- LATERAL COILS are recog- 0 - "' nized for: ,,:,, :. .a -.

nil I I !i I Ij t i. Lower natural period. ti- Z=- -- -"' A z. Lower high-frequency resistance. 3. Very low distributed capacity.

- ~ : s, 4. - ' = Lower direct current resistance. ---<.,..... -°- g. Higher self - inductance. -_ - 6. Mechanically stronger. Bulletin P -IR, containir.g valuable engineering data, constants and prices of numerous sizes of Duo -Lateral Coils, covering practically every wave -length used, is yours for the asking. TO DEALERS: OUR DISCOUNTS ARE GENEROUS PACENT ELECTRIC COMPANY, Inc. We now represent the WIRELESS IMPROVEMENT CO. excusively Representing: A. H. Gr °be & Co., Dubilier Condenser Co., Electrical Products Mfg. Co., Richter -Schottler Co.. H. W. Sullivan of London. Rawson Elec. Inst. Co., and others. 150 NASSAU STREET Telephone Beekman 5810 NEW YORK CITY

www.americanradiohistory.com Radio News for December, 1920

(Continued from page 39o) In Fig. is is shown this worst condition. The smooth undistorted curve produced by reduction of the impressed voltage is CHELSEA 73% as effective as the flat- topped one. The ratio curve of Fig. 34 gives an in- VariableCondensers dication of the permissable overrunning on to the flat part of the curve. If a total Lo° - of is cut off from the peak of the wave (Die -Cast Type) the loss in signal strength at the receiver No. 1. -.0011 m.f. mounted.. $5.00 occasioned by reducing the amplifier input No. 2.-.0006 m.f. mounted.. $4.50 voltage so as to give undistorted modula- i 3.-.0011 m.f. unmounted $4.50 tion would only be 9 %, hardly noticeable, No.No. 4. -.0006 m.f. unmounted $4.00 and probably advantageous because of the Top, bottom and knob are absence of distortion. 0\1, Referring to Fig. 13 or Fig. 15, it will genuine bakelite, shaft of be understood that the radio frequency steel running in bronze bear - oscillations are cut off equally (usually) _ ings, adjustable tension on at top and bottom iving distortion. These movable plates, large scale distorted (flattened) radio oscillations con- Condenser No.3 tain components at the fundamental radio reading in hundredths, high frequency and harmonic multiples of this c: ¡.acuv, amply separated and accurately spaced plates. frequency. The antenna, being tuned, re- Unmounted types will fit any panel and are equipped with sponds only to the fundamental constitu- counterweight. ent, and the amplitude of this depends upon how much of the cycle is cut off at top VARIABLE GRID LEAK and bottom. Obviously the amplitude of the envelope curve over the fundamental Permits the selection of the proper leak R radio frequency will exceed that shown resistance regarcless of the type or tube, or in Fig. 13a or Fig. 15a. Fig. 15c shows its use as detector, amplifier or oscillator. one of the radio frequency cycles with time a 54 Ten steps give range from to 5 meg- et axis expanded. Cut -off occurs at angle Br. ohms. Genuine bakelite base and knob. o If there were no inflection in the charac- All our apparatus embodies the highest ®* ® G. teristic curve this radio oscillation would degree of mechanical construction, electri- reach the value Q corresponding to grid cal efficiency, and good appearance. ,. voltage Eq. Owing to the saturation, 1-ow- Pr:mediate Delizer;,- Bulletin sent upon request -r ever, it can only reach the value T. The ' 11116 óf110 if Purchase Chelsea Apparatus from amplitude of the constituent of fundamen- by your dealer PRICE $3.00 tal is given 15 FIFTH STREET S--- Q Sin'Ode -L CHELSEA RADIO CO. CHELSEA, MASS. Manufacturers of Radio Apparatus and Moulders of Bakelite Pin 0, Sin Ode± N r /Q Sin' 0C10 (14) rr0, =2 T- ( 1 B, -i- Sin 29, ..(1:) a Sin e, 2 TUNING TRANSFORMERS. r T T Immediate deliveries while they last. -Q Sin-' -- /lO'-T' (16) ,r Q 0'-/ PRICE Occillogram Obtained When Grid Modulation Is and Used in a Radiophone. Equation (16) shows how the amplitude of the fundamental radio frequency con- QUALITY stituent of plate current, which is the fre- All meta'. work brass. quency selected by the antenna, varies with Green silk windings. different values of Q. Q is obviously directly proportional to the amplitude of impressed grid voltage. As the grid voltage Manufacturer's Prices increases from zero, the value of S is Direct from Manufacturer to you. You save 30 to 40% paid dealers. equal to Q, and increases therefore in di- Both instruments mahogany finish. rect proportion. This holds from Q = o to Q T. Beyond the point where Q T 18 inches ABSOLUTELY GUARANTEED. = = Range 140 to 3500 meters Base the variation of S with Q is given by (i6). Secondaries, divided into 12 parts. If this latter variation differs from that for Primary Dead the region Q = o to Q = T there will be end switch. distortion. Oa Fig. 16 is plotted the rela- 18 single taps, 16 tion between the fundamental radio con- spaced taps made stituent and Q. It is seen that as soon for most sensitive as the oscillation exceeds the saturation adjustment pos- value T, distortion takes place. The fun- sible. damental of the radio oscillation continues Panel heavy hard to increase slightly however as the im- rubber 9/32 ". pressed grid voltage (or Q) increases, ap- All metal work proaching a value 27% greater than the nickel plated. saturation value T. as Q increases indefi- Green silk nitely. For the case shown in Fig. _5a winding. (Q = 2T) which is about the limit in These transformers are the equivalent or superior to any practical cases. the peak amplitude of the similar instruments on he market. Money back after 3 days if not satisfied as represented. envelope curve for the fundamental radio frequency constituent should be increased G. M. PROUDFOOT, 361 East Ohio St., Chicago, Ill. above that shown in Fig. 15a by 22 %, giving the envelope curve of Fig. t7.

www.americanradiohistory.com Radio Nc,s for December, 1920 393

For Perfect Signals and Solid Comfort Wear Brandes Matched Tone Receivers We were satisfied when uc accomplished the mechanical per. which come in contact with the wearer's head, and the head band fiction of our receivers to such a litht degree for we realized, and cannot catch the hair even when adjustments are made on the head. every professional knows, that lightness and comfort are almost ns Other metal parts are nickel plated brass, making the head band necessary as the perfectly matched tone for which Brandes Receivers absolutely rust proof. Our new head band is the strongest and are famous. lightest of its kind on the market. We have now equipped our receivers with an improved head Our receivers are now equipped with new style conducting cords band made to fit may size head and instantaneously adjustable, which indicate the polarity of the receivers. This eliminates any Check nuts hold the adjustment. The new head band is more dur- danger of demagnetizing the receivers when used in connection. with able and lighter in weight. It is made of Galvanized Piano Wire. Vacuum Valve Detectors. r^ unucd with ,.tong] y "Aim) Khaki. There are no metal parts

Yuhtríor-Luau filma, fight 1.1 "'lcatr.: i iantie- -'.900 Ohms. weight 11 "Navy TI- lw- 3. 200 Ohms, weight P omple:o with head band and polarity complete with head band and t aleto with head band and pal:wits Indicating cord. Peleo $9.00. polarity indicating cord. Price $12.00. indicating cord. Price $14.00.

Give yourself a Christmas present. Order any pair of our re. distance and comfort than what you are using, return them to us, try them for 10 days in comparison with the phones you and back contes your money immediately and without questi.m. hamre eow. If they aren't better receivers for clearness, sensitiveness, Send 5c for Catalogue G C. BRANDES, Inc., Room 823, 32 Union Square, New York City. WIRELESS RECEIVER SPECIALISTS

"The Greatest Radio Catalog in the World -"The Universal Verdict of Tens of Thousands of Radio Amateurs DUCK'S No. 14 Big 200 Page Wireless Catalog Announcing Permanent Reductions on 3 of our most popular Radio Instruments The demand last month for our Navy l'ypc, Arlington, and No. 7721 Recei ring Transformers at the greatly reduced prices convinced us that with large quantity production. because of the exceedingly att racl i cc prices on these instruments, we ontinue to maintain these 1,.e prices. 1 \ a therefore announce the following permanent reductims on these instrument -. FINS so Navy Type Reteiviq Transformer, Fenner Peke 517.50. New Price 521.95 Ne. !HI lopped Type Minim Raeeiviet Trustless', Regular Price $15.11. New Price 511.95 No. MI Receiving TranIgsser, Regular Price titI. New Price 57.50 Send your or.it- ttm,..diat: /p jar your ;ó.i, nj Na.;

Improved Arlington Receiving Transformer, Regular Price $15.00 , New Price, Only $11.95 The secondary on our new type Arlington i- divided into three sections, with two dead end switches. ANYTHING3¿i eliminating dead end effect and harmonics and ELECTRICAL. giving greater selectivity. The end support is \ similar to that un our Navy, permitting a looser coupling. The base and pri- rt mary end pieces have a spline to prevent warping or damage --We Sen only Cooda+ ' Q in transit. This feature ss also on our Navy. It is a ' and Merit mod's J , p'.:wW i4:4- eáÌPf beautifully finished instni h in rnt. e 7 _ ir s r (^ Improved Type Sayville e' A.:, °.. Rotary Gap Embodies the 1 y-- JJ jl 1.. (, latest and best features In Spark Gap / IlJ(t( 1)ìi, Construction Our New '1)pe Sayville Rotary Gap is. we believe. Lai TREMENDOUS CHRISTMAS STOCKS - In advance of any rotay gap on the market within a range a I,u.ine:: or fettleunprecedented minute eer 'lose With nothing of tawi eo the price. It is the final development the war. many different made shocrt of miserable service from our many ties In our experimental Radio Labo- ratory. It fulfills every requirement of the Ideal rotas fit of sttpply. and any other u unusual gal. It is neat and attractive in appearance; simple and conditions eeoutend with. we. found It impossible. durable in construction; a wonderful up a comparatively short ago, to give the possesses tor: has to a cast aluminum rotary wheel. beautifully every Semite one orders for which we always enlnycd polished; Melt part is in perfect alignment; Were Is n rabbling of ]Melt a and n'hlrh was our We a repel ton. pride rotor; produces and mamtabts a clear and deliberately curtailed our advertising. beeaw.. we pure 500-cret to: Is Instantaneous it action; permits of no dragging et get catalogs printed fast enough and be- odd not the spark: has contacts ] of tempered flat copper want a of business w of proper cause wo did not volume and width, and removable, handle. Wo are now abbe length easily quickly and Inex- could not expeditiously pensively renewable; the stationary contacts aro adjustable wonderful service thousands to guarantee the that to any length.- $27,50 of patrons reeeived for many years before the com- ntell,ment of tito war. THE WILLIAM B. DUCK COMPANY, 231 -233 Superior Street, TOLEDO, OHIO.

www.americanradiohistory.com 394 Radio News for December, 1920

Club Gossip (Continued front page 373)

If they don't know what you radio. Code practice is given on Monday, Thurs- want for Christmas, show them day, and Wednesday noons, by the chief operator our Catalog and suggest a or his assistant, Justin Toles, 6CF. The Club is making plans for :m excursion to the Moorhead Laboratories in the near future. All further doings of the Club will be made known thru these GIFT BOND columns. Russell E. Calhoun, 2436 Dwight Way. Good for Cash Purchases Berkeley, Calif. at any time in our Big SOUTH JERSEY RADIO ASSOCIATION The South Jersey Radio Association is EA last on its pre -war footing. WIRELESS DEPT. At our last meeting on October 19th, we had fifty enthusiasts present. Great spirit was shown. We had a mighty interesting talk by Mr. Mexlin, 3GW, on a simple radio tlephone that really works and does not cost much to construct. The Association, in order to advertise itself more, furnisht Collingswood, X. J. with the election returns. We have installed a two-step ampli fier. Our operators received the returns which were flasht from the station to a large screen in the street by projection apparatus. It was a great stunt. The people appreciated it and no longer make a fuss when we blow the lights now and then. Four years ago we pulled the same trick and put it all over the telegraph. At the head of the technical committee we have Mr. j Donald Haig, manager of the Inde- pendent Wireless Company. You can rest assured the staff is a good one. Collingswood, K, J. is our headquarters. Men from all parts of south jersey flock there on the third Thursdays of the month. Why don't you join the happy throng? We ill make it worth your while. Write to Edward B. Patterson, 92 W. Walnut Ave.. Merchantville, N. J, HOOSIER RADIO LEAGUE The Hoosier Radio League was organized in Kokomo, Indiana on September 15, 1920. The purpose of the League, as stated in the coratltu. tion, is "to study. obey and assist in enforcing the United States Government laws and regulations relative to amateur radio communication. and to furnish an easy means of exchanging ideas concerning radio among amateurs." The League is planning to purchase a radiophone transmitter which will he used to give public concerts and entertainments. As the name implies, membership is open to anyone in Indiana who is interested in radio, and is not restricted to local amateurs. At the first meeting the following officers were elected: Kenneth Schneid-rman. (SRL) president; Georre Machin, (SEE) vice-president: Ervin Mid- dleton treasurer: Walter Lanterman, secretary: and Ralph Schwartz, corresponding secretary. Tell Them That You Want an Examinations will be given and members will be classed according to their ehility to answer the questions. The questions will follow the general outline of the Government examinations. .0 as to ai" members who desire to do so in passing ex- ACME aminations for licenses. Meetings of the League are held every Wednes- day at the Y. M. C. A. in Kokomo, and arynne Detector and Amplifier interested in radio is cordially invited to attend. Applications for membership will be received by SRL or by W. F. Lanterman, 746 So. Armstrong for St., Kokomo, Indiana. All communications to the should he addresst to the latter. Christmas League

The ACME AMPLIFIER contains an A -2 Ampli- ACME I Want to Know fying Transformer, tube socket, filament rheostat, rheostat (Continued front page 379) dial, finished oak box, engraved bakelite 'panel and nickel plated binding posts plainly marked. AMATEUR ANTENNA FOR The ACME DETECTOR is the same size as the Ampli- SENDING fier and has a condenser and grid leak in place of the Acme (135) Paul Crouch, of Gresham, O., asks: Amplifying Transformer. Q. t. Will you please publish in your I- Want -To -Know page the dimensions for what would be an ideal amateur transmitting antenna? Leading Dealers Have Stocked TheselUnits A. t. A good amateur transmitting an- for the Christmas Rush tenna may be planned as follows: Four phosphor bronze or aluminum wire No. 14, 8o feet long, 40 feet high, with a lead -in of Small enough to go into a Christmas stocking 25 feet and an effective ground will make a good aerial. The wire should be fixt to 8 foot spreaders at each end. 25 Windsor Street, ACME APPARATUS COMPANY p Cambridge 39, Mass. "LITZ" OR LITZENDRAHT WIRE Transformer and Radio Engineers and Manufacturers (136) Wilfred T. King, Memphis, Ten- nessee, asks the following: (Continued on page 396)

www.americanradiohistory.com Radio News for December lo;o 311.3

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Variometer complete with Tube Control Panel $12.00 Radion Receiving Trans - knob and dial $6.5c One Stage Amplifier Panel 18.0o former $14.00 Without knob or dial 5.75 Two Stage Amplifier Panel 40.00 Detector and Amplifier Variocouplers of same gen- Amplifyng Transformer.. 6.5o Tubes 5.00 eral construction 7.5o Amplifying Transformer without panel 4.00 Rheostat only 1.20 Our advertisements are not filled with superlatives but our products will be found fully equal to the best and are backed by a reputation of thirteen years of continuous manufacture. Complete Catalogs 6c Stamps Order from your dealer and remember it will pay you to insist on apparatus manufactured by CLAPP -EASTHAM COMPANY 120 Main Street, Cambridge, Mass.

A NEW RADIO PRODUCTION Turney Spider Web Inductance EMBODIED IN A SMALL UNIT

COILS This unit con. A BETTER twins three Tnr- compact, efficient l__ -- _------ney Spider-web short wave coil set. STATEMENT REASON inductance coils Two movable There i s n o magnetic lank- and one station- .\. age in coupling. ary. There are Tie coils being six b i n d i n g More Bat, the entire inductance magnetic area posts permitting * a ' r of the coil is most any type *,40 IP / -i' available. of circuit to be used. The door O .r 1 % L'., The wire runs as shown in cut 'Ir" Less parallel a I( for are capable of ' Ej ' aw . distributed O I greater distance p Ili very line adjust. .' capacity ar.d crosses itself leas fre- meat and stay if ; s.W. gcently t h a n where they are any coil known. placed. W i t h -: two condensers Ls There being no .0005 and .001 Lower high interior m a g mf, it will re- netic field or air frequency core, high fre. spend to wave resistance lengths, 175 quency resat- to Illustration Mona /root of rehu idt removed an ,e is reduced 400 meters and to a minimum. giveglue Pending results Dimensions. 454 x 5 x 114 each as you PRICE, $6.00 have never had Occupies The calla are so before. The best $6.00 worth of Radio you ever saw. thin that three Full information on request. less of them occupy lane than ° " °- I L, c, iodine - quarter inch. Eugene T. Turney Laboratories Coil Frame Radio Hill, Holmes, New York

www.americanradiohistory.com 396' Radio News for December. 1920

(Continued from page 394)

Q. 1. What kind of wire is "Litz" wire and where may I obtain it? ti {, HOOK 'ER TO YER BULB A. T. "Litz," otherwise known as Litzen- draht wire, is a stranded wire composed of in the World for a great number of fine insulated wires The Most Wonderful Tuner $10.00 twisted together. We suggest that you write to the Beldon Mfg. Co., 23d St. and '/-- Add Parcel Post -Coils only, - - - - 6.00 West End Ave., Chicago, Ill., and to the Doubleday -Hill Electric Co., 715 12th St., About four months no I purchased one of your mysterious 20.000 meter tuners. And today ant copying Washington, D. C., who manufacture this POZ-YN- xPM- 11IU17- LC31-1DO -OUI. Haven't had much time to sit in but the bat part to tell you about this black box is 'het all this foreign avid comes In on a 35 fL aerial 35 It high on one end and 20fí type of wire. on the other end. I'm always ready to recommend the black box instead of any other inductance made. Q. 2 If I cannot obtain this, what may I (Signed) ERNEST F. SCHWACH, best substitute for it? 1637 Parkaide Ave.. Chien°, BL A. 2. If not obtainable. some ordinary silk covered wire can be substituted but at KNOCKED DOWN AND ASSEMBLED CONDENSERS a disadvantage. The "Litz" wire has very \\Tlch kind do you Irma. Made for panel mounting er and send us his name If he cannot supply you little high frequency resistance, and of and are complete with scale pointer and mob. Used Canadian amateurs buy from local dealers or write all over the world now and still going strong No us for nearest dealer. Formica tope and bases. course gives better results in receiving sys- C.O.D. orders. Add parcel post. Buy from your deal- )forable plates are screwed on and not clamped. tems where the received energy is always so small. II plate knocked down $1.8o Are and 2.25 Q. 3. the coils marked inductive 21 plate knocked down regenerative in a short wave receiver moved 41 plate knocked down 3.20 from one another? 11 plate assembled 2.75 A. 3. Yes, it is necessary to have a va- 21 a= plate assembled 3.25 riable coupling between these two coils. 4x plate assembled 4.25 - ! and the primary. Sold by your dealer or á. -- LICENSE REQUIRED FOR RADIO- TRESCO- Davenport, Iowa PHONE Be a sport and send 5c for our Catalog. Foreign orders solicited. Canadian Amateurs buy (137) Gordon A. Cooke, Providence, from Canadian Dealers. All products licensed under Armstrong Patents. R. I., asks: Q. r. Please give hook -up of radiophone using one Marconi vacuum tube. A. 1. You will find suitable hook -up and PARAGON $1.75 AUDIOTRON ADAPTOR information on page 2r of the July, 1920, POST Consists of standard 4 -prong base issue of RADIO NEWS. wih b anppordng T,nr'reatpra° °ae Q. 2. Does the require IIIIIIIIU,nglp RHEOSTAT PAID permha so a tube rtsag Government the O,m positionto eh filament willwiu not bag licensing of radio telephone stations and 11 For back 02 panel table and touch grid. mounting. stn in. dia. c $1.75 Postpaid radio telephone apparatus? In the case of ohms, Par amps. ax.,.ì ,t Improved Standard YT Sod), El the latter, would I have to pass the code / De Forest CV500A Variable Electron Relay (fmE $0 (1e knob test to obtain my license? Condenser A-P Amplifier VT LSE 1444). E7 poi A few $4.00 A. 2. Yes, you must pass the code test cit.at. 44 VOLT VARIABLE of io words per minute even if you do not stO General Radio Not B . BATTERY f: W I r e Ammeters (flush intend to send by means of the key. Thin type) $7.75 $3.60 is required by the government laws. (Plus Postage on 4 lbs.) Complete in handy wooden case Q. 3. What does the abbreviation C.W. FOOTFPER t ith adjustable phosphor bronz stand for? ANTENNA WIRE lc °Jigy" Connocbrx Better Nan No. _52 7 strands, copper, tinned to prevent corrosion. weakens. ely Oit A. 3. The letters C.W. mean continuous Include Postage on 15 lbs. per 100 fL unit weakens prematurely. I. waves, i. c.. undampt waves. Lightning Switch, 100 amp.. 600 volt E6.00 be removed and replaced. Young & McCombs Rotary Gap 15.00 thereby not impairing the toil Action ' du Key. .¢ S \ \'. N.P 10 voltage-making this the bat bat- Mesas Standard WifelessWireless Key 3.00 value the in Chelsea Oscillator 3.00 sto4.4V \' renewal units alwaysarways m NO AGE LIMIT FOR AMATEURS Chelsea Grid Leak 3.00 stock. Y., 90c each, or $3.10 per 10, plus (138) Walter Stackler, Jamaica. N. 4 ]h >. postage wishes to know: O. T. Must a person be a certain age to HONEYCOMB COIL ADAPTORS obtain a Government amateur sending $1.50 PER PAIR license. and if so what age? - to poste of a Murdock Condenser A. T. The Radio Communication Laws -Insert H-C Coll-making a Tuning IIn1tUnit. Ibo Units of the United States do not state any par- make a Loose Couple. a third makes a Tickler Coll One makes a first class wavemeter. ticular age for the obtaining of an amateur license. A license will be issued to anyone ST. who is qualified by examination. RADIO EQUIPMENT CO.,630 "th FLOORN BOSTON, 11, MASS. INSTALLING THE LIGHTNING SWITCH (13g) L. S. Cole, Logan, Utah: asks: O. t. Should the aerial lead -in and the R Supersensitive ground wires be insulated wires? A. I. The aerial lead-in only needs to be insulated when passing thru the wall and KLAUS Apparatus down to the station. The ground wire may consist of a bare wire or copper strip. for every requirement. Let us design Q. 2. Should the lightning switch be and equip your Radio Laboratory. placed inside' or outside the house? A. 2. To make an effective protection WATCH this space next month for against lightning, the switch must be placed I details of our 6 -volt 6o ampere storage outside the house with as short and effect- Battery and dealers who carry them. ive a ground as may be possible. Q. 3. Please publish a buzzer transmit- Amateurs, Dealers, Radio Clubs, ting hook -up. Schools, the most advanced designs in A. 3. On page 30 of the July, tgt9, issue of RADIO AMATEUR NEWS you will find a modern Wireless Apparatus are in- suitable buzzer transmitting hook-up with Distribatorb for Grebe, De Forest, eluded in the Klaus line. necessary data for its construction. Moorhead, Amrad, Murdock, Atnco, Acme, Redisco, Tresco, C.E. etc. Let Us Serve You MR. PHILIP J. McMANUS KLAUS RADIO CO., EUREKA, ILL. Let us have your proper address, Phil. We wrote you recently and the letter came back.

www.americanradiohistory.com Radio News for December. 1920

The Babe Ruth of Radio ou can knock home runs into the long distance field every night in We year fs ith the dh pendable

Type CR -3A Short -Wave Regenerative Receiver and Vacuum Tube Unit

This little outfit is a wonder. Complete and up -to- the -minute in every detail, its wave -length range runs up to 35o meters. It is built ir. conformity with our usual superior standards to fulfill the nee-1 for a mode- rately- priced regenerative receiver. The CR -3A includes a variable antenna circuit, continuously variable grid and plate circuits, a specially designed coupling circuit and a standard vacuum -tube mounting with a grid cone..cnser and leakage element. All binding posts are conveniently located on the front of the panel. The price, $45.50, is within the reach of all. Be sure to ask your dealer about the CR -3A. GREBE RADIO apparatus is licensed under the original Armstrong and Marconi patents. Central Radin Institute, Independence, Mo. Klaus Radio Company, Eureka, Ill. Continental I2a11io and Electric Corp., New Work. Manhattan Electrical Supply Co., New York, Chiccg, St I....c Detroit Electrical Co., Detroit, Mich. r.eo. J. Meyberg Co.. San Francisco, Cal. Doubleday) l ill Electric Co.. Pittsburgh, Pa, Pacent Electric Co., Inc.. New York Cuy. Electrical Specialty Co., Columbus, Ohio. P. D. Pitts Co.. Inc., Boston, Mass. Holt Electric Utilities Co., Jacksonville, Fla. Philadlephia School of Wireless Telegraphy, Ph ladelpuia, l'... Hurlburt Still Electrical Co., Met-Aim, Texa. Western Radio Electric Co., Los Angeles, Cal. Kelly and l'l:i!lip -, Itwokq -r, :.. Y. A. H. GREBE & CO., Inc., 72 Van Wyck Blvd., Richmond Hill, N. Y.

N.sMt hNNNNNINMyYMy^'>'° - a MittlhMhhMNMNhr,Nh!hh Christmas Suggestions for the Radio Amateur

PI.:T Ile Forest Ladin Apparatus C on your t hristmas list. t'et ',at new apparatus you need as a present. Here are three instruments of typical Deforest high quality which will make your station more modem and greatly increase its operating efficiency. Our Catalogue "D" illustrates and describes a lot more apparatus you'll be glad to know about. Fend 10 cents in stamps and get Type T -200 Type P -300 Combination your copy now, in time to make Multi -Wave Tuner Audion UltrAudion and your selection before Christ nn. - Responds to any wave length; One-Step Amplifier P -200 DE RADIO 150 to 25,000 meters. Contains Type FOREST Specially designed to fill a triple adjustable coil mountings; real Two -Step Amplifier TEL. & TEL. CO. need for an instrument of titis The newest development in .Am- Inventors and Manufacturers of \'ernier primary and secondary kind in the average amateur plifier design, combining compact- High Grade Radio Apparatus tuning condensers; primary con- station. When used in con- ness and extreme etiicienO inopert nection with the -200 Lion. Amplifies the pincer about Ir, 1401 Sedgwick Ave., New York City denser switch; all mounted on T Tuner shown here, it completes a re- times. Panel (middy .movable: engraved Bakelite panel and in ll pansa ce. ,ih!e. Cabinet size LEE DE FOREST, Inc. ceiver of unequaled efficiency. 1 214 x (a X14. Price (without handsome cabinet, size 13 x 18 x Cabinet size 12% x 8% x 4 %. tubes btu including "0" battery) Western Distributors Each $70.50 451 Third St. San Francisco, Cal. 12 %. Price (without coils) $85.00 Price (without tubes). ,$75.00 \. !V\\hyshl hMt1NNNl¡,MMyMNhNbfs`

www.americanradiohistory.com 398 Radio News for December, 1920

Re- Enameling Wire For Homes, Offices, Factories, Farms By Francis McCartin, Jr. The radio amateur who has constructed a Navy Type Loose Coupler, or a long Complete Wall Set loading coil will no doubt recall the trouble had in trying to properly insulate an enameled wire once the original covering Magneto Telephone has been removed. This was one of the Western Electric Type problems that confronted me when I made THIS is a complete commercial telephone sta- my coupler, and after using good energy tion. They were bought from telephone ex- in calling upon the saints to help make the changes who put in Central battery types. Slightly insulating tape stay, I set out to find some- used but guaranteed to be in At working order. thing that would take it's place, and at the The cabinet is of polished oak, piano finish, within same time do a better job. which is contained the powerful magneto, the 300 After many experiments with all kinds Ohm polarized ringer, an induction coil. The of adhesives I finally struck upon this idea: magneto is exceptionally efficient, being of the Why not try and re- enamel the wire? This two bar type with brass gear transmission. The is what I did, and it can't be beat. The extra sensitive microphone, mouthpiece and two following is the solution: gongs are mounted on the front of the cabinet, As each tap is taken from the coil, it t giving the entire instrument that desirable appear- soldered with a good quality of silver sol- ance of compactness and efficiency. Guaranteed to der, this is done, by making the required work over 20 miles. The telephone receiver is a number of turns on the cylinder scraping double poled one, and has a hard rubber case. the wire where the tap is to be made, then Seven binding posts are provided for connections. unwind two turns, fastening the remainder The instrument is one which we can offer with pride to our patrons at a of the wire to the tube with a thumb tack ridiculously low price. It is unobtainable anywhere else at less than $15.00 so as it will not unwind. If silver solder and is an instrument unequaled in value for the price we ask. Size ..v' is is ail11 x 10 x 8 in. used it only necessary that the wire be clean, then dip the connection into the Long Distance Telephone Set -One station-Shipping weight, 15 lbs...... $7.00 solder, and allow to cool. If lead is use' Two stations- Shipping weight, 25 lbs ...... $1$.00 it is necessary that the connection be treat- Send Cc in stamps for our hip 80 pape Wireless and Electrical Catalog No. 28. ed with a saturated solution of muriatic acid, that is place a solution of muriatic The Electro Importing Company acid and zinc before the solder is applied if lead is used see that the connection ie 231 Fulton Street, New York properly cleaned of all the acid, then apply a good coat of enamel or varnish to P. bare spots on the wire. When this is done light your alcohol torch (if you have none your druggist can supply you at a cost 01 UNIVERSAL COIL about fifty cents) take the wire in both hands so that the joint is in the center. and M/IOUNTING PLUGS pass it thur the flame. When this is done for the first time, a flame will be seen. Take it from the torch flame, and blow the fire out, then return it to the light, taking care that you don't burn the wire, work it thru the flame from one side to the other, as fast as you can for about ten seconds, make ing sure that you enter the air on both sides of the torch. This gives a cooling effect to the enamel, and at the same time protects the wire from getting too hot and Make Your Own Mountings running the solder from the connection. With These Corwin Plugs If these directions are followed you will find that all the bare wire has Seen cov- Suitable for Radisco and ered, and while it will not be as smooth as All Hand -Wound Coils the original insulation, it will have as good NY amateur can easily make smooth running mount. an insulating quality. and the wire will be ings with these CORWIN Plugs. They are accur- as good a conductor, and have no chance A ately designed, carefully made, and conform to the of a short. I have used this system on a inflexible Corwin standard of high quality materials. The be beat. pins will not have to be bent or filed to fit, as every one Navy Type Coupler and it can't is accurate to exceedingly close limits. Fiole and pin are After finishing the first tap, rewind the of standard spacing to fit Coil Mountings now available. two turns, and continue with the balance These plugs are one more example of CORWIN prod. urta that fill the amateur's needs exactly. Fitting commit. of the coil. ions to Corcin Dials. Can be supplied as illustrated only. DO NOT FORGET TO CLEAN YOUR CONNECTION IF YOU USE LEAD Price 80 cents postpaid. SOLDER? OR THE ENAMEL \WILL NOT STAY. A. H. CORWIN & COMPANY 4 West Park Street Newark, N. J. A GRAIN FINISH FOR A PANEL I found that the following method of giving a panel a finish somewhat like hake- VACUUM TUBE CONTROL UNIT lite is very successful. Type MW First the panel is made to fit the cabinet. then all holes must be drilled. Purchase some Adapted to any modern hook -up. Best appearing emery cloth and about one tablespoonful and highest type Vacuum Control Unit at the price of pure olive oil. and work by the follow- in the market. ing process. Place the panel so that the Grained formica panel, Grid condenser and bottom is towards the worker, spill some 554" x 6g ", lettered in leak mounted in back of the olive oil on the surface cf the panel white, graduated rheostat of panel and so wired and smear it evenly. Procure a small block dial, variable plate con- that it can be adapted of wood and tack the emery cloth around trol. Tube socket (stand- to any modern hook- it. Take the emery block and pull away ard 4 prong). up. Price $10 and towards you with an even pressure till Mende in 8. A. a is obtained. WRITE for descriptive Booklet MW. Sent free on request. Panel poet 0. all marks are gone and grain Immediate shipment. I found that the method just described THE MIDWEST RADIO CO., 3423 Dury Ave., CINCINNATI, O. works best on fiber panels. Contributed by EDWARD RUTH.

www.americanradiohistory.com Radio News for December, 1920

II!u00U1 uWH!NUUUII!!ommlll!W!!uull!oau!uYNlu; RADIO -CRAFT RECEIVING INSTRUMENTS WILL BE INSTANTLY APPRECIATED BY THOSE WHO KNOW AND DEMAND THE BEST. A Short Wave Re- generative tuner n with wave length n range from 125 to o 550 meters. u $65.00 Price n under Marconi and Licensed c Armstrong Patents Radio -Craft Price List n Detector $15.00 i Detector and one stage amplifier 45.00 Detector and two stage g amplifier 70.00 FOR SALE BY Two Stage Amplifier 50.00 Atlantis Radio (o.. Boston. Mass. Philadelphia School or Wireless Teleg- Short Wave regenera- Continental Radio & Electric Corp.. raphy, Philadelphia. l'a. m N. tive tuner 85.00 New York City Radio Distributing Co.. Newark. J. Tidwell Bros.. Richmond, Va. Rudolph Schmidt & Co., Rochester. Combination Short and F. S. Katzenbach & Co., Trenton, N. Y. Long wave tuner 145.00 N. J. Southwest Radio Supply Co.. Dallas. . Supply Co., New Testis. Varionteters, each 0.00 Manhattan Electrical York City. Jos. M. Zomoiskt & Co., Baltimore, McCarthy Bros. & Fool. Buffalo, N. Y. Md. RADIO -CRAFT CO., Inc. Brooklyn, New York Perfection in Radio Instruments Jobbers' Inquiries Incited

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Entire Satisfaction t 11 is what our customers say. ARE YOU GETTING ENTIRE SATISFAC- TION from condensers you have purchased elsewhere? IF NOT, we are sure you will be pleased with what we are offering, because, we manufacture only the BEST. 43 4300 All we ask is GIVE US A TRIAL. This month we wish to announce a NEW MODEL of VARIABLE CONDENSER, which will be known as SERIES "T". It is of the same general construction as our SERIES "S" condenser, but is built of heavier material, the aluminum plates being die stamped from 1/32" hard rolled stock. The spacers are also of heavier stock, and the general assembly insures a very rigid instrument. At the present time we are unable to fill orders for the SERIES "S" condenser, as we cannot obtain materials, but can ship the NEW SERIES "T" or the SERIES "L" condenser from stock. SERIES "T ". PRICES SERIES "L ". No. 20 2 plate Vernier. $2.00 No. 2300 23 plate, .00075 $6.00 No. 70 7 plate, approx. .0001 m f $2.35 No. 4300 43 plate, .0013 $8.03 No. 130 13 `r .0002 mi. $2.75 No. 6300 63 plate, .002 $10.00 No. 170 17 " .0003 m f $3.15 Include postage for two pounds. No. 230 23 CA " .0005 m f $3.60 Prices include knob and pointer and mounting No. 310 31 .0007 m.f. $4.30 screws. Specify whether brass or nickel pointer No.430 43 " .001 m.f. $5.25 and screws, and thickness of your panel. No. 630 63 " " .0015 m f $7.50 Either style of condenser, fitted with indicating dial Include postage for one pound to your city. at additional cost of 75c. THE WIRELESS SHOP 511 West Washington St. A. J. EDGCOMB Los Angeles, Cal.

www.americanradiohistory.com Radio News for December, 1920

Theory of the Fading of Signals By Michael D. Lyons Are You Buying "B" Batteries That Are Giving Service ? At all times since Marconi first listened TRY THE ONE ILLUSTRATED in on a winter night the radio periodicals of WHICH WE GUARANTEE, the United States have had occasional ref- _/ erences to the subject of fading of radio ii - SMALL SIZE$2.40 $1.10 signals. EVEREADY No. 786 $8.40 The Detroit Radio Association has SMALL SIZE $2.00 been for some time discussing that phe- nomenon at the regular bi- weekly meetings \\ SPECIAL STORAGE and some of the members have been making iA' BATTERIES notes. The subject seemed so big and Q)` , MARRO, 4V 100 Amp. - -- $15,00 interesting that they thought they would MARRO, BV 40 Amp.. ..$18,00 do well by discussing it at the regu- ` MARRO, 8V 80 Amp ....$20.00 lar meetings. Many interesting theories were advanced to for A discount to all RADIO CLUB account the phenom- ~ members enon. Anything from Martian signals and ELECTRO Martian radio power plant inductions to movements of the ether were at length and seriously propounded by long -winded amateurs with the imagination of a Baron Mun- chausen or a ham with his first piece of galena. By far the best theory advanced brought into light old Sol. OSCILLATION TRANSFORMER to the right has The sun's terrific explosions, earthquakes sufficient inductance to radiate up to 325 meters - (or is it sun -quakes ?) and sun spots per- Çl, LL sells for $5.00 - haps are causing the havoc with long dis- Send for anything in the Radio Line. \= tance transmission. The movements of al- WE HAVE IT most unimaginable masses of heavy highly - heated gases may be causing the flow of surface currents on the sun which large AMERICAN ELECTRO TECHNICAL APPLIANCE CO. currents might in turn be setting up enor- 235 Fulton Street, Dept. R New York mous magnetic forces which in turn ionize our air, affect our compasses, and cause the Aurora Borealis. Prof. Taylor in a recent number of the "Scientific American" in treating of the probable connection between sun spots and the Aurora Borealis points out that the sun spots have been of _ NOW'S THE TIME extraordinary size and frequency this last to drop a hint to Dad about that Christmas present! Why not make your selection winter as have been the Aurorae Boreales. from this list -we promise "Immediate Delivery" on every item. If you don't see The experience of the vast majority of the what you want here look over our list published last month. Give us your business i -we'll give you SERVICE you will like. amateurs that the writer has spoken to on the subject has been that they have never Grebe Apparatus ClappEastham before known such a winter in their entire CR -3 Relay Brreirer 565.00 \-arlometers 56.50 ' experience as this last one. Signals Control Panel 15.00 \'arlo- Couplers 7.50 2 Stage Antpltter 45.00 Antenna Swith 12.50 faded in such a manner as to amaze Dee & 2 Stage Amplifier 75.00 Boston Rey 7.50 the oldest veteran operators. There is no Power Transformers Rheostats doubt on this point. Would not this seem Acme 250, mounted 18.00 Porcelain Base 1.00 Acme 500. mounted 22.00 Paragon Panel 1.75 I to point to a connection between sun spots Acme 1000, mounted $3.00 General Radio Panel 2.50 and terrestrial magnetic and electrical oper- C. W. Trans formers Modulation Transformers ations? Acme 50 Watt. mounted 15.00 Acme, fully mounted 7.00 radio Aria 200 Wan, mounted 20.00 Acme, sera- mounted 5.00 If the sun does affect communica- Jacks & NUM tions it would seem that it would affect long Federal OMn Circuit Jack .70 Oscillation Transformers Federal Closed Circuit Jack 1.00 International Radio 16.75 distance stations most in the day time which Federal Telephone Plug 2.00 Murdock 5 ou it certainly does. Not that the sun spots Western Electric Plug 1.20 Books exert much influence then and cause New Apparatus Practical wireless Tel 2.25 Weston esisteeters, 500 volt sale, Wireless Exp. Manual 2.25 freaking but operators all claim that the with Resistances 21125 Rectifier Tubes suns intense light ionizes our atmosphere W. E. Transmitters-low resistance for Electrodynes-500 Volts 7.00 the Phones-complete with mount- DeForesteForest Type -500 Volta 7.00 and thereby causes atmosphere to absorb Mg bracket SAO radio waves. However, at night the light Storagege Batteries -8 Volt, 10 A. H.- Amrad Apparatus - Guannteed 1 year 17.50 Wductioere, 130 -230 M 8.50 from the sun can cause no ionization of our Posner Tubes for C. W. 500 Volts. 35 Induction coils, 6 Volt 35.50 - air but what is to prevent the magnetic Watts- standard base 15.00 Duplex Detector Stand 6.50 storms on the sun from affecting Icing dis- Send for Bulletin u and illustrated catalogs- they're free. tance terrestrial communications. What is to prevent these same irregular tho mas- CHICAGO RADIO APPARATUS CO. sive displays on the sun from affecting our 8900 South Michigan Avenue CHICAGO. ILLINOIS compasses? What about the Aurorae Bo- reales? Does the effect of the sun affect our weather ? Some scientists answer yes to the last question. They are now carrying S6.00 Pont Pahl on tests and observing the sun spots to ERAdicate Your Detector Troubles prove it. oco Buy a New Era V. T. Control Panel or one -step amplifier The writer, having no access to observa- Oc with or without a cabinet. tions of the sun at present, cares not so -O The NEW ERA Panel is made of genuine bakellte. measuring 314 x 614 inches, much about answering such questions but mapped with a modern V. T. Socket, filament rheostat. nickle-plated binding posts. plug and jack high voltage adjustment, and a arid condenser with leak. about getting some one else interested. If These attractive Instruments wired with No. 14 wire. and mounted on substan- this is done this article will have accom- tial light oak bases will add to the appearance of any operator's instryment table whether he be board ship or in his own radio shack. Its small size makes it plisht its end and the Detroit Radio Assoc. convenient for the ship operator or for u e in a portable set. will feel that it has added another star to -O - When mounted in a cabinet. the Panel and oak base are so arranged u to slidn In o lit, thus allowing inspection of wiring or removal of tube. the banner of Yankee amateurs. The following prices apply for a limited time only. MICHAEL D. LYONS, Type ID Detector Panel with high voltage variation 56.00 P. P. Inst., Class Type IA One Step Amplifier without high voltage variation 12.00 P. P. Sec'v D. R. A., Radio -theory Type IOC Detector Panel mounted in hand -rubbed oak cabinet 9.00 P. P. Tech., ex- commercial, etc. TYPO PAC Amplifier panel mounted hand- rubbed oak cabinet 15.00 P. P. All types supplied without tubes or batteries. High voltage batteries, suitable for this panel can be supplied at moderate cost. Des.wipl ive circular on application. YOUR FUTURE The Eastern Radio Company 929 D Street, N. W., Washington, D. C. Don't let anyone tell you there is no great future in radio. It is something more than a pastime or plaything. Furthermore Insure your copy reaching you each month. Subscribe to Radio News - there is plenty of room in the field for real $2.00 a year. Experimenter Publishing Co., 236 -A Fulton St., N. Y. C. live enthusiasts who desire to make it a life work.

www.americanradiohistory.com Radio A.c.cs for December, 1920

A VARIABLE GRID LEAK. In using a grid leak with my VT I find Storage Battery Cells it frequently necessary to vary it. The For FILAMENT Lighting or method of adding or erasing a pencil line EXPERIMENTAL WORK drawn between two binding posts was too Just the thing for Radio enthusiasts. slow and uncertain, so I devised the vari- Thew cells are Ink. z x:de and can be able leak shown in the accompanying dia- Imd singly or In sit. "f i or 'no., at lhr i o' mire of gram. "L" is a square rod with one end $4.00 per cell filed round to fit into the large binding plus transportation post "A." . \n ordinary slider "C," such -less than half the price they would cost you elsewhere. as is used on tuners, fits on this rod, the l We bought lien, at i low figure and are piss- Piece ing them along in von a smallmall margin 0' spring contact sliding along the pencil line An Old Binding Post, a of Square Rod profit In ulve you the benefit of our bargain. and Slider and a Lead Pencil Line are the Es- "D." This line may be of India ink and sentials Here. DON'T MISS will then be more permanent. Two binding THIS BIG OPPORTUNITY In stock op of b0urrles. Bnpply is Um II posts "E" are screwed into the base and We guarantee all cell. and sill replave hope this may help some amateurs both- chat are not as represented. connected to the post "A" and the line "D." ered with their grid leaks. Addr ., all request, to respectively. Contact with the line is made Contributed by T & R ELECTRIC CO. by a washer held down on the line by the 840 Waterman Ave. Detroit, Mich. ,crew, as shown in the drawing. I P. F. FAULKNER, JR. MORE MILES PER DOLLAR

A Few Features of the Cockaday Amplifier

Small and Compact Type DA -1 Rugged Construction Detector and Single Designed and perfected by compe- Stage Amplifier tent engineers in well equipped $45.00 Research Laboratories With the New 50°,; Louder Signals Filament Temperature Does not "Howl" Greater operating efficiency Indicator Write for Information L. M. COCKADAY & CO. DEPT. C 2674 BAILEY AVE. NEW YORK

11111.1.11111,1111. III Mk.

THE Broadway Subway or 5th Ave. Buss num- I low the G. A. got the Best ber 3, will take you to 181st St. and St. Nich- Iplanning apparatus to be developed for experimental use, the olas Ave., from which it is only three blocks men behind the G. A. Company believed that it was possible up to the G. A. Store. to design radio equipment which would have that precision of detail and nicety of workmanship which distinguishes the instrument maker's products.

F. \. D. ANDREA stood out head and shoulders above any other instrument maker in the United States. The man under whose direction were. built the Kolster decremeter, and the Bureau of Stand - ards wavemetcr-his skill was distinctive. Going into the manufacture of experimental equipment, he set out to find the organization most familiar with the requirements of experimenters. THAT the G. A. and Frank A. D. Andrea should combine efforts was natural. The first product of the combined efforts is the FADA TRIODE DETECTOR, an audion control -panel 5 by 7 ins., on a cabinet

I r ins. deep. The panel carries a FADA rheostat, telephone jack which opens the filament when the plug is removed, and binding posts. Behind, is a socket and G. A. grid leak condenser, with space in the cabinet for t large or 4 small B batteries. Workmanship and operation are such as to be expected of FADA and the G. A. The price is $57.50. The same panel, on a cabinet 3% ins. deep, is $15.5o. LI\IITED time prevented an illustration of this set, but you can see it at the larger radio stores, or order it direct. Usual G. A discounts to Dca'ers.

570 N. West New York 184th Street City The General Apparatus Company, Inc.

www.americanradiohistory.com 402 Radio News for December, 1920

Sparks From the Radio World A NEW RADIO STATION A new wireless station at Siasconset, Try This Sensitive Nantucket Island, Mass., has been opened by the International Radio Telegraph Com- Radio Head Set pany. The site is an historic one, from a wireless standpoint, for temporary stations . It is equipped with non -conducting spool heads and slotted have been located here ever since the begin- pole tips which eliminate eddy current losses. Furthermore nings of wireless, but permanent, commer- all operating parts of these cial service is now establisht at this point. This new station, which is the fifth to be STROMBERG- CARLSON opened by the company, is now the nearest Head Sets one on the Atlantic Coast for vessels com- Radio ing from Europe. Its working radius is are housed in dust and moisture -proof more than 25o miles by day, and l,000 miles aluminum cases. Have adjustments by night. It has direct cable connections for temperature variations. Strongly with Wood's Hole and is thus in touch with the entire country. constructed; very sensitive for use on Current for operating this plant is ob- shore or aboard ship. tained from a storage battery which is charged when necessary by means of a Bulletin 1206R gives full generator driven by a gasoline engine. The particulars. Write Today. This sample set will be sent upon receipt of $12. transmitter is of the spark -gap type, of 2 cord 6 -toot alsture -proof Kw capacity and is equippt for operating Stromberg-Carlson Tel. Mfg. Co. attached. For mercial radiom servi.. on either a quenched spark gap or a rotary ROCHESTER, Mprivateoney refunded ll not satisfied. synchronous spark gap. The frequency of N. Y. the radio motor -generator set is soo cycles with a sparking rate of r,000 per second. The current in the antennae circuit for 2 h Kw input is 15 amperes. The receiver is adapted for either dampt or undampt waves over a range of wave lengths of from 300 to 3,000 meters. The radio call for this station is \\'SC. Land line charges will be computed from Wood's Hole. SOMETHING NEW IN RADIO RECEIVING SETS Mr. L. R. Krumm, for many years Chief 1eREYNRAD" PRODUCTS Radio Inspector, U. S. Department of Commerce stationed in New York City, A complete multi -wave tuner and audion detector, combined in the neatest unit on and during the war Lieutenant Colonel Sig- the market. Primary condenser, (series, shunt nal Corps, of the staff of the Chief Signal or out), secondary condenser, stopping con- Officer, A. E. F., and in charge of the radio denser, and grid condenser give the very operations A. E. F., is now associated with closest adjustment obtainable. The battery connections are in rear of cabinet doing away the International Radio Telegraph Corn - with clutter of binding posts usually found on oany as Superintendent of Marine Installa- the front panel. tions and assisting in the establishment of Cabinets are of hand finished mahogany, the new activities in which this company panel of grade K7í bakelite. has entered since becoming affiliated with Price of Cabinet 355.00 the Westinghouse Electric & Manufactur- With Bulb pí0.00 ing Company. Set of three four -inch Bakelite coils with plug mounting make expensive short wave regener- Mr. C. W. Horn, recently in charge of ative sets unnecessary, when used in conjunc- the sales of the Navy Surplus Indio ma- tion with this receiving unit. terial and formerly Lieutenant. J. G. U. S. Two stage audio frequency amplifier, to Navy, during which term of service he match receiving cabinet, complete with bulbs. installed radio compass stations for the Price $55.00 Navy on the Atlantic Coast, is now with A series of short wave tuners and receiving this company in the technical section of sets from $10.00 to 385.00. the Marine Installations. Immediate Delivery 'til types of audion bulbs. \\-hat is believed to be a record in radio 'ione Amplifying transformers 35A0 operation was accomplished on September the New A. R. Co. Variable Condenser .001 MF with Dial and Knob 57.25 17th and 24th by operator Chester Under- - complete stock of De Forest Apparatus. hill in the New London, Conn., station of Catalogue and Bulletins sent on request for Oc in stamps. Correspondence solicited. the International Radio Telegraph Com- pany. On the first named date he received REYNOLDS RADIO SPECIALTY COMPANY 74 messages averaging is words each in 729 So. Prospect Street, Colorado Springs, Colorado one hour and one minute and on the second date received exactly 75 messages of the same length in one hour flat, between 6.25 and 7.25 P. M. These messages were Audion Control Unit only $15.00 received over a distance averaging 125 Tue K. & G. Wireless Supply Co., in its efforts to place technically cor- miles and were mostly in foreign languages, net and reliable wireless apparatus well within the price reach of critA- Italian. French, which at amateurs, announces its new Auction Control Unit. Tu-pe Al. This and Dutch, makes unit is absolutely reliable and can be used with e ray known circuit. the feat additionally noteworthy. I is designed and built for exacting service. it combines the very latest ideas in design with the best of material and workmanship. The cabinet, ", has a highly polished mahogany finish and with Its well OPERATOR'S REPORTS WANTED aysa6nted battente panel will add much to the attractlraroes of your sta- ON LOWENSTEIN SYSTEM r unit contains these Instruments: vacuum tube locket (for stand- rd 4-prong tube). filament rheostat 110 ohms) ugrid condenser. grid leak. The Lowenstein Radio Company, Inc., and filament switch. Panel has binding posts. suitably engraved in white. have manufactured a number of radio trans- mr secondary, tickler. phones. and filament battery. Whole back of cabinet swings open on hinges and thus permits rosy insertion of tube and mitting sets for the U. S. Navy, which have batteries and plete inspection of the interior. Efficiency guaranteed. bcen in service on American ships for some or money encoded. time. Being desirous of hearing from the Price $15.00, without tube or batteries. If your dealer can't supply you, order direct. Dealers: Write for proposition. operators who have used a Lowenstein set, it would to a pleasure to hear from them. K. & G. WIRELESS SUPPLY CO. What they want is honest criticism from the Dept. 16B, 152 Chambers Street New York City man on the job, so that we may be guided by his experience in our future work. We shall be glad to hear from any operator who ' A welcome addition to your library. Send $2.00 plus postage today and your copy of bound i volume No. of 1 of Radio Amateur News will come forward by return mail. has used one of our sets. Experimenter Publishing Company 236a Fulton Street. New York City Address this publication.

www.americanradiohistory.com Radio News for December, 1920

A SWINGING PLATE CONDENSER There have been many varieties of small capacity variable air condensers illustrat:d in the magazines for use in radio receiving sets. The following is a description of one which the writer has found to be very satisfactory either as a grid stopping condenser or as a shunt condenser across the secondary of the tuning transformer. It is also different from any he has seen de- sribed. Learn Telegraphy The material required to build this condenser is as follows: two sheets of metal (Wireless or Morse) (non -magnetic), the size depending upon the maximum capacity desired of it two The EASIEST, QUICKEST, small brass hinges, two binding posts, two CHEAPEST WAY small wood spools, one foot of No. 18 spring brass wire, 7" of ill x " brass strip, 6" of A"" brass rod, an indicating dile with pointer and turning handle, one AT HOME strip of hardwood Y. x 2" and as long as the metal plates, to - %rr flat head brass In Half the Usual Time wood screws, and 2 - " fiat head brass wood screws. Begin the work of soldering the two hinges to the moving plate (C), along with / WITH THE OMNIGRAPH a short piece of flexible wire (L) and a / stiff short brass strip (J) on the opposite / "Just Listen -The Omnigraph will do the teaching" edge. In the fixed plate (B) drill four / / The Omnigraph is an Automatic holes with counter sinks for the %" brass / Transmitter that teaches you both the wood screws. Also solder a short piece Wireless and Morse Codes, at home, without any expense except the of wire on the opposite side of the plate to /i cost of the machine itself. Merely connect to battery and your Buzzer, that which will face (Cl. Now fasten (B) / or Buzzer and Head Phones, to Sounder to the side of the cabinet in the position / or your and the Omnigraph desired. Give both plates a coat of shellac will send unlimited messages by the hour, at any speed you desire. so that when they are mounted they will / not form a short circuit when they touch. USED BY THE U. S. Next take the strip of hardwood (0) and e. T GOVERNMENT on it mount the two binding posts. Fasten / The Omnigraph is used by the the wire from plate (B) to one of them / Government in testing all appli- cants applying for a Radio / / License. It is also used exten- / sively by the large Universities. / / Colleges and Telegraph Schools / throughout the Country for teaching Wireless and Morse. / Hundreds of the Army's skilled /i / operators who served during the / / war learned with the Omnigraph. / Let The OMNIGRAPH Teach You Wireless / Quite an Idea, Fellowa. Takes Up More Room For a few dollars you can have a complete You'll be surprised how quickly you will attain Than Some But Its Easy to Construct. outfit that will make you an experienced speed. Even if you are already an operator : / operator in the shortest possible time. No the Omnigraph will help you. It will make hard, laborious work -just learn by listening. you more proficient, more accurate and more / in The Omnigraph is adjustable so you can start confident. Thousands of Omnigraphs are in and then fasten the strip the positio.. / receiving shown in the drawing. This will now / messages slowly, gradually increas use today and thousands of operators owe / ing the speed as you become proficient. their suns to them. permit the plate (C) to be placed in posi- / tion opposite to (B). The flexible lead / Write for Free Catalog from (C) may now be fastened to the / r The Omnigraph Mfg. Co. / Send for a catalog today, showing the 3 differ. 26 F Cortlandt St., second binding post. ent models, $12.00 to $28.00. Every Omnigraph The condenser proper is now complete. / is sold with the absolute guarantee that you New York City The controlling device will next be con- must be satisfied or your money back for the Gentlemen:- asking. Mail the coupon today -the catalog structed. Bend the strip of 7 x I / will come to you by return mail. As per your ad in Ramo NEWS please mail brass into the "U" shape as shown at (D1. me your free catalog of Omnigraphs. Drill holes for screws to fasten it to the /i back of the cabinet and holes for the ?s" The Omnigraph Mfg. Co. Name spindle. Also drill a hole thru the panel 26 F. Cortlandt St., New York City I about 7" from the corner and at a height Address such that the top of the spool will be on a 4 xCINNIMIIMMICl City State level with (J). Now secure (D) to the panel, pass the spindle with dial (G) and handle (H) attached thru it, slip a piece A Simple Radiophone Operating on "B" Batteries of coiled spring brass (E) over the end, Out of our largo stock of genuine double dia- In re ent articles in the "R. N." and other men double life And loons we have carefully se magazines. These same tubes as is well known then the spool, and then another coiled b +led rind n limitai n mber of tubes which surpass others now the market as detectors spring (D), and finally pass the spindle incorporated In andd oscillators receiving purposes. - "R" batteries of ihmatisfadory tubes replaced free of charge. thru the second hole in (R). The spool been described Price $6.00 each. should fit the spindle tightly, and the THE KEHLER RADIO LABORATORIES, 901 springs should press against the spool and W. 1st. St., Dept. R. Abelene, Kansas back of the panel with sufficient force to old the plate (C) at any point against the pull of a rubber band (R). Dependable A new Tuner and a new Short Wave Set have joined the It still remains to connect the above con - DEPENDABLE FAMILY t:olling device to the condenser. Secure Radio one end of a string to the spool (M) and Catalogue Mailed for l0 Cents in Stamps the other to (J). To (J) also fasten a DORON BROTHERS ELECTRICAL COMPANY small rubber band. Pass this band behind Apparatus the spool (F) and fasten below it with Hamilton, Ohio. sufficient tension to hold plate (C) against (B) when there is no tension on the string. Add to your Salary -Make extra Pin Money. The advantages of this condenser are MONEY f o r You Start a lucrative business of your own. that it is easy to construct and requires Spend an hour each day taking subscriptions for the "Radio News." We'll pay you well and you'll enjoy the work. Write for full particulars. Circulation Dept., RADIO NEWS, 238A Fulton Bt., only material that is to be found in any New York City. workshop.

www.americanradiohistory.com 404 Radio News for December, 1920

KEY CONTACT LOGIC. By Sheldon Trent Most of us are intimately acquainted with one or more of a pesky branch of animals, called by the "hams" a sticky key. This A $25,000 Catalog Free most troublesome instrument usually makes its presence known in the middle of your most important message. When this hap -. Nothing like it ever published. It positively will do your heart pens, the most experienced of us "sine" off with a couple of . - .... and then wait un- good to feast your eyes on this wonderful book. It is a real Experi- til the key feels generous enough to cool off, menters' book, full of photographs, bargains and surprises. The finest but the majority of us keep on pounding the ether and, incidentally, making more mis- lines of WIRELESS INSTRUMENTS & SUPPLIES are shown, takes than there are words in the message. together with a full line of SCIENTIFIC INSTRUMENTS, COM- Perhaps it would amaze some that a key can be fixt up without sticky contacts for PLETE LABORATORIES, CHEMICALS, SUPPLIES & GLASS- two thin dimes and some hard solder. The WARE. It is a veritable mine for the Wireless, Chemical and Gen- first thing to do is to fish up the old practice set you bought when you were young eral Experimenter to delve in and discover things he has long desired and foolish and remove the key from it. but could not find. In short, friends, it's impossible to describe this The contacts of this are usually very small, being supported as in Fig. 1. They may be wonderful book. The edition is LIMITED. Send rz cents (refunded clipped or filed off with ease; one contact on order of $1.50) for YOUR copy TO -DAY, to the being forced into the key lever proper, and the other into an insulated, brass block in the framework of the key. The surfaces of Palmers Electrical Equipment Co., Palmers, Minn the key, Fig. 1 -a and b, should be filed thoroly-. Two bright dimes should be procured and hard solder applied to both MASTER WIRELESS APPARATUS PRICED RIGHT Representatives for: Ace, Amrad, Acme, Murdock, Doron Bros.. Burgess, Moorhead, etc.

Fiy.1. WIRELESS and Kindred Science Revolutionized ! Whether or not you believe in the present electromagnetic and valve theory of wireless, you should read my book Fi .2. "Revolutionary Theories In \Vireless ", and I believe you will agree with me that electromagnetic waves are not the domi- Don't Use Too Soft a Solder In this Cue, As nating cause for wireless transmission and that we have no Otherwise Contacts May Loosen When Heated. valve or rectifying detectors in use at present. After you read this book you will under - many of the mysteries of gravitation, life. the dimes and the filed surfaces of the key. ,tand wireless and witeless apparatus from magnetism, electricity, light, chemistry, and Now heat the places where solder is applied a different angle than you have ever read kindred science. and press the dimes onto the lever before. The only book in print advancing and Get on the right track in your study and framework of the key (Figs. 1 and the conductive theory of wireless transmis- experiments in wireless. -a b). don, the valveless theory of detectors, the If the dimes are uneven and dc not hit new attractive of electricity, etc. I have been highly complimented on my book theory by The Experimenter Publishing Co., he squarely, heat thoroly and press firmly Among the many new ideas advanced are International Society of Radiolsts, Josephf on the handle. If there is only a slight thermo- coherers, thereto -microphones, vacuum Branch Publishing Co., and others. discrepancy, filing may be resorted to. Be microphones, electrostatic receiver, earth Above bound in full cloth, has 200 primary and secondary battery, improved book is careful that you don't get any soldering pages, 72 illustrations, and 129 intensely in- flux on the faces of the dimes. electrolytic interrupters, how to fly by man. teresting articles on science and describing ual power and secret cf soaring. by the Summers' theory all the most used If the key has renewable contacts, Fig. 2 This book will doubtless prove the key to wireless Apparatus. -a and b, bolts may be soldered onto the dimes and then screwed onto the key as in Eventually you will study, teach, and experiment by the Sum- Fig. 2 -C. This method of applying solder mers theory, why not now? Book sent postpaid ripou the to both surfaces works unusually well, es- receipt of $2.50. Address, pecially in this case. FRANK E. SUMMERS Memphis, Mo., U. S. A. Keys usually heat up because too much current is passed thru and broken, but SPECIAL PRICES TO DEALERS IN BOOKS 1 with dime contacts 110 volts A. C. may be broken with not a spark. An exceedingly handsome instrument may be made if the key is mounted on a marble base with strip MARKO BATTERIES XX BAKELITE brass connections. 4 V. 40 A. 11. ..IJst $I0.7a.-Our ]'rice. $10.00 7/32" thick, 12" wide. per inch in length.... 23e G V. 00 A. H....tist 220.00....Oar Price, $18.50 Short wave set panels, 8^ x 18^ x 3/16" at...$3.75 PARKIN VARIABLE CONDENSERS 'G.A." FIXED DISCARDED RUBBER STAMP Unit only. $1.50. with knob. settle, etc. $2,00 Grid. 35c. Grid leak- Condenser, 50o. Phone 35o HANDLES CARDBOARD TUBING Postage extra on all orders. Did any of you "bugs" ever try using ans 4" , liamet ers at. per foot 25c Circular for stamp. sawed off handles of old rubber stamps as A. K. LAING, RADIO SUPPL ES, Pelham Manor, N. Y. knobs on indicators, tickler coils. scales. etc.? I rounded up all obsolete ones I could find at the office and found them 10,000 Printed - quite useful. Advance Notice All Sold Out Contributed by WM. W. CRANE. Our new line of STANDAannorn THE SECOND EDITION OF THE LECTURE ON THE RESONANT RADIa SPEC1.1tines will be ready CONSOLIDATED RADIO CALL BOOK TRANSMITTER within a few days. Send for A highly instructive and mighty inter- our New Bulletin 152D. tras completely after It published.pu o The Third Edition' will esting lecture was given to members of the be out sometime in December. Watch for the Radio Club of America on November 26, WIRELESS EQUIPMENT announcement of the n edition and be sure to COMPANY, Inc. copy before they are an gone. 1920, at 3 p. m., Columbia University, by Mr. Walter A. Lemmon, who described 188.190 Greenwich St. New York CONSOLIDATED RADIO CALL BOOK CO. application to 43. Park Row New York City his invention and its spark and Vacuum Tube work.

www.americanradiohistory.com Radio .\'cars for December, 1920

AN IMPROVEMENT IN ROTARY SPARK GAPS The Corwin Mail Order Service By L. uroexIE li. ilr:N15E THERE are thousands of rotary spark The wonderful success resulting from the inauguration of our Mailing depart - gaps in use, also as many owners who ment on a small scale, and the courteous replies, after the delivery of goods. are looking for some cheap and reliable way to increase the number discharges congratulating us on our promptness and accuracy in tilling orders, has re- of across the gap per secondwithout increas- .ultcd in our forming the Corwin Service. ing the number of electrodes or speed. In the following article the writer will de- Ilcre you can buy ally radio instrument manufactured by old and reliable houses. scribe a cheap and tried way of rebuilding Our immense stock enables us to serve you the clay we receive your order. any rotary spark gap so that it will give the same service as one revolving at twice VARIABLE CONDENSERS VACUUM TUBES its speed, the result being that a sharper 6.00 It. Co., .001 56.25 Electron Relay wave may be transmitted. O. Co.. .0005 5.00 VT Amplifier, 1 Ib ... 7.00 7.510 o Kith N. 17 DIM, :u111 51.00. VT extra liard The first thing rebuilding a n unlock tre 4.75 to do when Murdock il:7 ROTARY SWITCHES rotary spark gap is to remove one of the 5lurdoek ms 't Clapp-I:n.Olam. No. ID 1.00 900 ,...11 stationary electrode mountings, unless there claro -Ees hart Clapp-Ea:Akaln. No. DOA .35 000A 9,50 is not room enough below the rotor "R" ClaPP-Flastliam Our lion. No. 1 Clapp- Easll,aul 90011 11.50 40 Our ()on. No. 2 .51 for the special stationary electrode "B" 01111 Shipping weight 15umple10 dial. Postage 5 cents. one pound. shown in the drawing. Or for some reason or other a notch cannot be cut into the GRID CONDENSERS CORWIN DIALS ltml:mo, postage 3c .35 No. 60, 3 In 7' hase, thereby giving the electrode plenty No. 07, 3 In.. veldt knob 1.30 of room for vertical motion, the motor ANTENNA SWITCHES No. Ge, 3% in 1.111 No. 05. 371, vean I.:0 Slunluek. :1 rands 4.50 In.. knob must then be raised by placing a block of ti app- rustbam, 10 grounds 1".50 Postpaid. bakelite, formica or even wood under it. OSCILLATION TRANSFORMERS RECEIVERS Itadiuo. Na 5 15.00 Murdock. No. 55. 2000 ohm 4.510 Via express. collect only. Murdock. No. 35. 3000 ohm 5.50 Brandes Superior 7.00 RADIO CRAFT PRODUCTS Baldwin 0 1r.511 Ile:cet,r 15.00 Baldwin F. Improve,) 20.00 Two-Step Amplifier 50.00 Itrownlle New 12.00 Detector and One Stop 45.00 Shipping weight, 2 lbs. Desolar ami Two SRI, 70.00 Postage paid. CONTACT POINTS CT -No. 1. brass. 110001 'B" BATTERIES CP-No. 4, brass. doyen .3.5 Mauls..... No. I. 2 lbs 1.5C CP-No. 5 nlekle plaid .J:. Radise, N0. 5. 5 lbs -.65 rosira id. Eeerraily Storage Batten. prices on apiIll , cation. VARIOMETERS RadLsco. No. 1 C.W. TUSKA APPARATUS Radisco, No. ID ' x 131 Coll. 2 lbs 3 pounds. 132 loll. 2 lbs 10.00 10:1 Coil. 3 Ins 1 ".50 170 FIJI.. S 11 1600 VARIO-COUPLER Rullse0 No. 2 AERIAL WIRE Radlsco No. 2D 7x2! Tinned Copper. 3 pounds. 100 feet, 2 lbs 1.25 200 feel. 1 110 2.40 LOOSE COUPLERS 300 feel. S II 6.00 Clapp- Eastham Radton 14.00 5lunhck. 344 9.00 AMPLIFYING TRANSFORMERS G pounds. A. R. Co., 1 N 5 00 Federal, 1 Ib 7.50 GROUND OUTFIT Switch. A Simple Improvement Gap. JACKS AND PLUGS Consists of SPOT 500 Amp. 25 for Your Rotary Federal l'Owel Circuit .05 feet No. 4 Wire. Clamp and Cleats. pre- It Surprised Mr. Henke With its Effecuq less. Federal linen Circuit .70 paid 7.00 Federal Rouble Circuit 1.00 Federal Plug 2.00 VT SOCKETS Postpaid. Murdock 1.0n Also, both stationary electrode mountings Radio Service Double 3.00 and must made longer or one ALL RADISCO COILS and WIrclos Press Radio Service Triple 4.0o "A" "C" be Rooks. Shipping weight I pound. might be mounted upon a small block of the same material as used for raising the motor. The other must be made or bent, All orders for apparatus not listed as postpaid must be accompanied IT post- so that when the stationary electrode "C" charges. will be just between the rotor electrodes age "J" and "K," the rotor electrode "D" will SEND TEN CENTS FOR CATALOG be exactly in the center of the stationary electrode "B "; this is all clearly shown in the drawing. A. H. CORWIN & COMPANY The electrode "B" may be made of zinc and is as thick as the diameter of the rotor Dept. B2, 4 West Park Street. \ewark, New Jersey. electrodes, the width is the same as the distance from the center of one electrode of the rotor to the center of the next, the length may be 1 inch or more, as it depends mostly upon the type of gap used. The slot cut in the center is 3/16 of an Write to our nearest branch for inch wide. Canadian The support "L" may be made of the Price List "B" of Radio ,l pparatus, same material as that of the base; it has A m a e u r s Supplies and Publications. a 3/16 -inch hole put into it for a bolt of t the same size. also a washer and a hard rubber knob threaded to fit the bolt. This assembly holds the electrode "B" tightly in Scientific Experimenter Limited place. The same binding posts are used, Dominion Bldg., Confederation Life 111.11' 03 King St.. F.., altho Vancouver, B. C. Winnipeg, Man. Toronto. Ont. the connections must be changed around a Arcade Bldg.. Vadistwo Electric Q,., Board of rade. bit; the stationary electrodes "A" and "C" Halifax, N. S. 94 Germain Street St. John's,TN'ft'd being connected together to one binding St. John, N. B. Head Office, Show Rooms, post, while the electrode "B" connection 11 St. Sacrament St. MONTREAL, QUEBEC 33 McGill College Avenue goes directly to the other post. When the high- tension current flows into the electrode "A" it jumps across the gap A $2.00 bill will bring you interesting reading and worth while ideas for many into "E," then it passes thru to "D" and months to come. Bound volume No. r of Radio Amateur News, $2.00 plus postage. it then jumps the gap to the electrode "B." Experimenter Publishing Company, 236a Fulton Street, New York City. The rotor moving in a clockwise direction,

www.americanradiohistory.com .4O6 Radio News for December, 1920

and when it has made 1/16 revolution the electrode "J" will come opposite the electrode "C," which, being connected to the electrode "A," will pass a current thru PRICE REDUCTION OF into "J," then to "K" and again jump the gap between it and the electrode "B," The next spark will pass between "A" and "D" and "K" and "B." This cycle of operation HOT WIRE AMMETERS is repeated twenty times per second with a gap having eight rotor electrodes and revolving 4,500 revolutions per minute. FOR C -W STATIONS In the ordinary gap each rotor electrode is used only twice per revolution, but in a gap rebuilt, as explained above, each is used four times per revolution. Thus the Type 127 Hot Wire Meter $ 7r.7í5 discharges are twice as frequent as in an ordinary gap. Every CM station should have a radiation ammeter. Our Type 127 hot wire meters If it is desired to know the are well adapted for purpose, number of this and for the measurement of filament currents, either discharges per second with a AC or DC. They are also suitable for measuring pulsating currents such as are obtained rebuilt gap, from rectifiers. Increased production has enabled us to reduce the price of these well the following formula may be used: known meters to $7.75. Supplied in a variety of ranges and for either flush or front -of. Number of discharges per second = board mounting, EX RX2 Where E = the number of WHILE FIXING YOUR ATTENTION ON YOUR TRANSMITTER 60 rotor electrodes and R= the number of DO NOT NEGLECT revolutions of rotor per minute. For example, if the revolutions per minute are 4,500 YOUR RECEIVER 5 and there are eight rotor electrodes, there will be 72,000 discharges a minute, or 1,200 Our 4 Step Inductors have solved the re- a second. ceiving coil problem. The wide range of each Where the ordinary gap with the coil reduces the number required to cover x1 same number of electrodes and speed would wide working ranges. No auxiliary mounting ÿ only produce 600 discharges per second. required. No terminal blocks to work loose. Try this on your rotary spark gap and you will be surprised with the results se- Attractive Efficient Reliable 1 cured from this simple improvement. PRICE $6.00 EACH FLICKERLESS LIGHTS Send for Bulletin 901:: I recently found a way to keep on the Type 226 4 Step Inductor good side of the neighbors and the world in general. I put my rotary in a sound- GENERAL RADIO COMPANY JY0/11 to ftey tire/if Massachusetts Avenue and Windsor Street TOP V/fw Cambridge 39 Massachúsetts !t 11111111111111 1 ..\...... \ .\..\.. mitCxxxicswomissamerzaimemMissal 4 0J

to eeseiter Here's How to Hook Up Your Radio t_ to trnmf His Lights Used to Flicker So Badly That the Neighbors Sent in Numerous Complaints to the Service Audion Control Panel "Juice Foundry" to Put a Muzzle on Him, Just hook up your Radio Service panel as this .,. - diagram shows. You will get a new idea of efficiency in radio apparatus at an amateur's proof box and made a little device which price. Dercriptior- Machined bakelite panel 6" takes all the flicker out of the lights. x 31/2", navy standard socket and rheostat - Now this idea of mine was to use a re- mounted on hard wood base; metal parts nickel .+v plated. Thoroughly tested and guaranteed to lay- which closed the power circuit of the work fully as well as any more expensive panel. O transformer on the downstroke and closed so an equalizing circuit on the up stroke. A Opr-furf a, small magnetic operating on two dry cells ,! The well -made, eor thru a telegraph key supplies the motive lii? business - 1 i k e n roo or panel at an ama- force to the relay arm. An adjustable con- teur's price! ' RonwSiry -- - tact point is located on each side of the awsax awr so may be regu- -S 11 arm that the gap closely Type YKr lated. The whole is mounted on a fiber a Pr ce $7.00 _.,.r.,, . Ill base 3" by 2" and provided with suitable In binding posts, two for the battery circuit Schedule of Prices on VT Sockets and three for the power circuit. The con- 't , Single Tube bench Type S2- (for and experimental tact points are made of /4"TT silver and have use) 1.75 %z microfarad condensers shunted across Type 83- Double Tube (for amplifier use) 9.00 Type 64- Triple Tube (for detector and two -stage them. amplifier or three -stage amplifier use) 4.00 This relay is quiet in operation and gives Type 830 -Combination Grid -Leak Condenser .50 a snappy break. Since scarcely any spark- 4 ing is noticeable it has little chance to stick. New Single Socket The adjustable reactance used as an equal- c. Spun aluminum izer was built of 200 turns of No. 20 wire 40 socket - machined on a laminated core 2" square with a tap q bakelite base 2%" taken in the middle at too turns, this gives square. Heavy - r phosphor bronze it a regulation of % to K. W. which is the c o n t act springs. capacity of my Thordarson trans--`ornter; Metal Carts, nickel when using this system use a change -over plated. , 4 .... switch with a third blade to break the power Type S 10 - Price $1.10'Iry -,? circuit while receiving as the equalizers use stunt works dealers or considerable current. This out All leading by mail from well in practice. taking all the "flicker" out RADIO SERVICE & MFG. CO. of the lights. Of course, the lights grow L. I., New dim when the load is thrown on but the Lynbrook, York objectionable flicker is entirely eliminated. Contributed by RICHARD J. VOIGHT.

www.americanradiohistory.com Rodio News for December, 1920

Radio Operating in the "Miniature Navy" By Charles J. O'Shea ACME APPARATUS For the benefit of those who are not familiar tcith the term Aliniature Navy, I vi ill make it known that I refer to the RADIO TRANSFORMERS United States Coast Guard. It has gained this title because while in size it is not so large as our regular navy, AMPLIFYING the uniform, pay, allowances, discipline and in fact every detail is carried out as in the TRANSFORMERS big "outfit," i. e., the I.T. S. Navy. In time of peace it functions under the Treasury Department. The secretary of this MODULATION department at present Mr. Houston is the 3 TRANSFORMERS ranking officer: with the declaration of war 4f however. it automatically becomes part of PLIFYING the regular navy. TRAMER jjTy C. W. POWER Its duties are highly important to ship-. its CO TRANSFORMERS ping, answering SOS calls being one of ,,ME APPARATUS the destruction of MA55. specialties, then comes eAMeFIDGE derelicts, floating mines and other menaces FILAMENT HEATING to navigation. During the storms which swept the Atlantic Coast last winter one TRANSFORMERS cutter alone saved over a million dollars' worth of shipping. When icebergs start breaking off up north, CONDENSERS AMPLIFIERS TELEPHONE usually during the months of April, May TRANSFORMERS and June, the cutters stationed at Boston DETECTORS and New York go to the Grand Banks on IN HENRY CHOKE COILS what is termed an "Ice Patrol" which is a trip which all hands dread. This consists SPECIAL TRANSFORMERS of about a month's cruising around in the most desolate place in the world where warm sunny weather is unknown, a thick Send for a Copy of Our Manual fcg is continuous and worst of all there of Wireless Telegraphy, M12 is no place for "liberty." This patrol is kept as a preventative to another Titanic To secure satisfactory re- disaster. Its upkeep is maintained by several sults in radio communica- governments while the United States sup- tion, absolute perfection in plies the vessels and part of the money. It material and workmanship, is on these cruises that the radio operator, both electrically and me- without whom the patrol would be useless, chanically. is essential. These gets corns on his fingers from broadcasting conditions obtain in all the iceberg reports. The movements of ties_ material we offer for sale. Imp are watched with eagle eyes so as We have on the press a to warn trans -Atlantic shipping when ap- manual and catalog covering proaching this vicinity. practically the entire field. During the summer months the cutters It will be ready for distribution within the next few lay tip for repairs and the crew secures a tviceks. \\'e make a charge of 25 cents for it, give a well earned rest and "leaves" are granted coupon receipt, which coupon receipt is good for 25 generously. The cutters, however, even rents en a future order. during the off season are always ready to It will contain 20o pages, size 6 by 9 in. profusely illustrated, printed on hull respond to an occasional distress call which grade paper with cover in two colors. may occur during the calm months. One of the latest duties this service has acquired is to enforce the prohibition law, to pre - RADIO EXPERTS AT ALL OF OUR STORES vent liquor from being smuggled from foreign countries. This promises to hold in store excitement aplenty. MANHATTAN ELECTRICAL SUPPLY CO., lac. The motto of this service is "Semper 17 Park Place 110 W. 42nd St. 127 W. 125th St. 1Pastes" and is well lived up to for when NEW YORK me least expects, orders come from the Division Commander that is some vessel CHICAGO, do S. Wells Street ST. disabled and in a short time the cutter is LOUIS. tio6 Pine Street speeding to her assistance the "black gang" SAN FRANCISCO OFFICE, 604 Mission Street firing at top speed, the deck hands pre- paring the towing hawser and "sparks" is p uII1111111111111111m extremely busy trying to establish com- ,.. ,.. munication thru the mass of harbor QRM to obtain latest information for the This New Tuner "skipper." Any radio operator who desires experi- Gets the Big Stations e lcc, sea service and excitement combined Without Loading Coils this branch of service holds forth great :utiactions for him. The period of enlist - Another letter says: "Your nient is for one year and is admirably suited New Long Wave Tuner brings in for a commercial operator who has just re- all the big stations fine. No load - ceived a license and lacks practical experi- ing coils. There is practically no ence, At the end of a year he will find him- interference whatever from un- self well informed about "J" tubes, audion wanted stations. Signals come in bulbs, amplifiers, radio compass and tele- louder than is possible with the phone sets with which he is in daily con- old type instruments used for the tact. big stations." Usually three operators are carried Send 2 -cent stamp for bulletin tir aboard a cruising cutter. This affords a shouting new short and long line opportunity for practice and exchange reave tuners. of personal experiences in the wireless game and prepares an "op" to re enter civil life Colby's Telegraph School capable of filling a much better position AUBURN, N. Y. than at the time of his enlistment. i:i.www.americanradiohistory.com Radio News for December, 19W

A Surprise Party a la Radio- phone A surprise party and radio dance was held recently at the home of ;,Ir. Joseph A. fiere It Is! Fried at Flushing, L. I., which was rather novel in its character. Lattice Wound Music was transmitted from the radio station owned by E. J. Simon which was Variometers. located at 40th Street and Broadway, N. Y., and the distance to the home of Mr. Fried was approximately 15 miles, air line. This station was loaned for the occasion to the Especially De- De Forest Radio Telephone and Telegraph Company. The transmitter was a standard signed to Improve t -KW. radio telephone developed by Mr. L. C. F. Horle. the Short Wave The receiving station consisted of a portable receiver having a wavelength range Regenerative Circuit. from 170 to 3,000 meters. This was a home- TYPE 19 made affair made by Mr. Pacent. This 12 is and Type a complete unit, and consists of receiver is equipped with a detector and Realizing the need of a neat, compact 7 on 4 , a 4 , inch BattrBake- highly efficient Variometer for the modern lite Panel.Panel, incasedmessed iníg a mahogany finished two -stage audio frequency amplifier and receiving set, we have produced one which cabinet.con t. Fo ca binding posts side. d so very efficient thruout its entire range. we feel will meet these requirements.4 connections can be made on styany dard Both The telephoning was done at 1260 meters Type T is assembled ready for panel mount. types are fob, with a standard 3-inch panel is and altho there was considerable leeway in ' -inch hole drilled in your dial and knob, makingmakíag a very attractive tn- all thatShat is accessary to mount. strument. wavelength range, considerable interference PRICES Charges Prepaid PRICES Charges Prepaid was noticed from the Brooklyn Navy Yard Type 7G. (For Grid Circuits) $7.50 Type 12G. (For Grid Circuits) $12.50 which was forever going with the broad Type 7P. (For Plate Circuits) 7.50 Type 12P. (For Plate Circuits) 12.50 spark transmitter which they are using. Attractive Proposition to Dealers After having a little trouble in toning out the undesired signals, a point was finally A. W. HALLBAUER located where the interference was at a minimum and the music came in very well. :°' ' ° ^" 1001 N. Lockwood Ave., ` "" "'' "'! CHICAGO, ILL. I"' '1 he receiving station was located at the top floor of the house from where two wires ran to the living room downstairs. 1Iere a Magnavox was connected and while !'J', the music was not very loud, it was loud enough for eight or ten couples to dance without difficulty. To the surprise of the assembled guests, the apparatus worked and NO LIMIT We received the music without the need of faking the entire matter. The possibilities of experiments with Among the folks who contributed to the undamped [rave circuits are unlimited. success of this twentieth century surprise There are all kinds of circuits to try, party, were some well -known radio engi- tests to make, observations to record. neers and experimenters. A reporter dis- C. W. Transmitters, telephone, tele- guised as a radio bug noticed several good graph, or buzzer modulated, can be looking young men who suspiciously re- made with tubes ranging in size from sembled the following: Mr. Joseph A. the small ones, operating on B batteries, Fried, Mr. L. C. F. Horle, Mr. E. V. Amy, to the big fellows, which require motor generators Mr. George E. Burghardt. Mr. George J. or transformers and rectifiers. Eltz, and Mr. Louis G. Pacent. ANY CIRCUIT Correspondence from Tuska equipment -inductances, filters, meters and other instruments -will fit right in because they are Readers designed that way. Universal in design, low in price, they are made for the experimenters who are doing things. II !:now warm summer nights they that on Five cents in stamps will bring you the C. D. pur- Tuska catalog, an illustrated price list, but a are wont to abandon their scientific not suits and to play the lover for a few brief handy book of information and diagrams. hours. And really, a radio bug makes a good one! My friend "T.S.O." will tell THE C. D. TUSKA COMPANY yott so and maybe he will write aad express his opinion when he reads this. HARTFORD -2, CONN. However, let us hear what the other bugs have to say about this. ...,1IIIIII!III811IIIIIIIiIliü H. F. SHOEMAKER, S.S. Winona, c/o Lock Postoffire, Sault Ste. Marie, Ont., Canada. IMMEDIATE DELIVERIES LEADING MANUFACTURERS' PRODUCTS CONCERNING DE FOREST PLANT FIRE WESTERN RADIO ELECTRIC COMPANY No doubt many of our readers noticed ESTABLISHED recent announcements in various news- "FOR BETTER SERVICE TO THE WESTERNER" papers describing the fire which took place at the De Forest Radio Telegraph & Tele- 550 South Flower Street Los Angeles, Cal. phone Co., New York. Most of the statements asserted that the plant was completely destroyed with a damage of $goo, - QST 000. These reports were erroneous. The HOLY BUCKWHEAT ! ! QST ANNOUNCEMENT machine shop is practically intact. All of LOOK AT THIS We are now carrying a complete line of the departments, with the exception of the COMPLETE RECEIVING SETS sending and receiving apparats. All Oscillion Department, are now in operation standard makes. Our catalog will be at is $9.00 up your disposal by December 15th. Watch and within six weeks it expected that the send 5e for catalogs for our January ad in this magazine. entire plant to be operating in even better S. G. RADIO CO. DAVID KILLOCH COMPANY condition than before. 644 East 15th St. B'klyn, N. Y. 57 Murray Street New York, N. Y. The loss, which totaled about $ao.oco.eo. i i is fully covered by insurance.

.www.americanradiohistory.com Radio .Vent's for Dcecml-rr, 1910

The Spirit of Christmas RADIO CORPORATION OF AMERICA S interest in our club. .\il his spare time is RAD I OTRO N devoted to our advancement. I-ic loves a THE rapidly increasing demand for the Radio Corpora- radio set as our chairman loves his -." 's new VACUUM TUBES indicates conclusively :\ scowl from that individual interrupted that the field appreciates QUALITY manufacture. the speaker. Only an organization possessed of the facilities of the LAMP Proceed," said the president now smil- FACTORIES of the GENERAL ELECTRICCOXIPANY ing. Unruffled, the young mat again broke could produce RADIOTkONS in the quantities we have forth in voluble speech. ordered, and assure a un ii'orm product. "To Paul Knox a real radio set would RADIOTRONS are made by novel and refined methods of be as a dollars." The eulogist was million under the supervision of experts of ysars of experi- quite capable of exaggeration. "What has manufacture ence in the manufacture of incandescent lamps. They are de- he in the tvay of a set ? Nothing worth laid down by the engineers of the Why? You know. signed after specifications mentioning. all Knox's Electric Company's Research Laboratories the will him to at- General - aunt not allow work while pioneers in the development of Pliotrons. tending school and yet she gives him no earned an en- pocket money. Except, yes, she gives hint RADIOTRON U. V. 200 has already was developed specifically for the radio the dues for this club. God knows how n viable repuruiun. It rf amateur. Economy demanded a tube which would prove sen- she does it. Fellows. a deserving young Radionroa U. V. 200 would "stay would work front a single standard man has for six months been a member sitive, put," Price $5.00 which, could be sold at atair of the Q S A. \\That are we intending to plate battery, and nureover, 18 volts on the plate do in order to pay hint for the enormous prier. U. V. 200 requires from to 221= current isapproximateiy benefits we have derived because of that for best results. 'he normal filament V. 200 works tvondei s in cas - membership ?" one ampere. KA1)IOTRON U. t amplifying circuits for ntagnifs ing the Several voices greeted the question. The cale tone -frequency tube receiving sets, although it speaker wished to answer his own ques- : telephone currents in vacuum tions. was designed primarily as a detector. "Wait a minute. I will tell you. Christ- RADiOTRON U. V. 201 is an exceptional tube of the mas is approaching. Why not present PLIO'I'RON type, newly designed, :rad intended for detec- Knox with a complete wireless outfit.? He tion, and for radio -:rad toue- trequrney amplifie: tien. It is would he the happiest fellow in the city. the proper tube for complex amplifying circuits, where bulbs normal The club can %cell afford it. i make a mo- requiring a nlininmm of adjustment are desired. The tion that Paul Knox, for reasons already plate voltage is 40. One 1 Bred volts may be used with in- stated, shall be given a Christmas present, creased amplification. a complete wireless set." The speaker sat Eacll of the above tubes has unique characteristics, and both down triumphantly as at least thirty mem- should be a part of every wireless receiving station. bers eecnnded the motion. AMATEURS - DEALERS - JOBBERS The chairman banged the table for order. The Radio Corporati,n, In, in manufacture a number of vacuum tube accvssories Gradually the murmur of voices subsided. of novel de,itn. New mmplif, i'.. trawl,.rmrr> de >irned pecial'.) for k,%DIO l IONS "No need. fellows," the ocean. manufacture. Turre are several >urprim> in>tore. and o,w draie"wit! president make their pplication to represent us at once. "ti, put the notion to a vote but to follow Price $6.50 the rules all in favor say Aye." Radiotron V. V. 22011 , $5.00 \ clamorous yell resounded from the Radiotron U. V. 2111 . 6.50 walls, of the meeting room. Standard Tube Sockets . 1.50 "Now we shall discuss the motion. The Grid Leaks, Mounted . 1.25 .75 question is: twill Paul Knox accept the Grid Leak Units Only . present Remember the time we tried to Grid Leak Mounting . .50 exempt hint from dues and failed? Iic lnterv: lve Transformers 7.511 caller! it charity." Standard Grid Leak Burgess "B" Batteries . 3.50 The members stared at one another. tuiles are covered by patents dated Several suggestions were offered. The The Radio Corporation's November 7th, 1905, J:umary 15th, 1907, and February I sth, chairman listened to all of them. 1911S, as well as by other patents issued and pending. Tubes "i am afraid." he said, "Knox will be- licensed for amateur and experimental use only. Any other come aware of our motive in offering him Standard Var aunt Tube Socket use will constitute an infringement. a present. T fear he will decline to accept Ile might consider it as he dial the dues." elddrees all otter¡ and inquiries to: "Mr. Chairman." DEPARTMENT "Mr. Clark." SALES DIVISION, COMMERCIAL The originator of the motion rose from AMERICA his chair. "T have thought bat RADIO CORPORATION OF this over 233 Broadway, New York City wished to h(ar what the other fellows had to say. There is only one way Knox may be enticed to accept the present. He must believe he has earned it. T will outline my plan." BrieIly the speaker unfolded a neat little plot. When he had concluded there was silence Then loud applause greeted him. PLATE BATTERIES For TWO DOLLARS you A second motion was made and carried get a 22!_ volt battery made of live 4I_ volt flashlight batteries, the best obtainable. The soldering Is with i5 inch brass strip, and the positive and negative unanimously. Five minutes later the meet - terminals are of the same, drilled for bolt and nut connectons. No wires to break. Hun- 111e adjourned. Everyone was sworn to dreds of Jersey users boost this combination to the skies. secrecy. Nevertheless the events of the last These batteries are made to last half hour were discusst in whispered con - sultation. You can tap in on the voltage by means of a clip which we provide. in couples and groups the mem- Mail orders should be accompanied by money order. Reference, Merchants' & Manufacturers' bers left the club room. National Bank, Newark, N. J. The following week, in front of the larg- Shipments parcel post paid anywhere in U. S. est radio supply firm in the city. Pant Are you making Knox surveyed the various your own regenerative set? Black fiber pa. el Q3 00 instruments for SPECIAL 7 x 20 x ., just the right size for a Paragon. price W sale. it was the day before Christmas. The shining apparatus clustered among ECONOMY RADIO SUPPLIES COMPANY, 232 Sanford St., East Orange, N. elaborate decorations dazzled h'm with DON'T forget the Eatteries. Ask 2A1JM. 2AXH. 2APA, 2GF. 2H0. They use them.

their resplendent settings. He eyed one set II .111 11111 lovingly. "If T only had such a wonderful set." he HAVE YOU SOMETHING TO SELL OR EXCHANGE' sighed. "The price, let me see. Ry Jove' A classified ad in Radio News will reach 40,000 at a cost of only 4 (Continued on page 411) cents a word. Try one in the next issue!

www.americanradiohistory.com Radio News for December, 1920

It contains the following 44 chemicals: Alum Al_(SO.),. (NH,),SO, Antimony (powdered) (Sb) Ammonium Aqua (NH, +H2O) Ammonium Carbonate (NH,), CO, AmmoniumChlc ride (NH,CI ) Ammonium Sulphate -The Joy of Father and Bor" (NH,), SO, Barium Chloride (BaCI,) Boric Acid (H,BO,) Brimstone (Sulphur) (S) Calcium Chloride (CeCI,) Calcium Oxide (CaO) Calcium Sulphate (CaSO,2H.0) Chemical Laboratory Charcoal (Carbon) (C) Chloride of Zinc (ZnCI -) Copper We present herewith to our friends our new E. I. Co. Chemical Labora- Ferrous Sulphate (FeSO,) tory which contains Ferrous Sulphide (FeS) real chemicals and apparata to perform real chemi- Glycerol (Glycerine) cal experiments. This outfit is not a toy, put up merely to amuse, C,,Hs(OH)s but Hydrochloric Acid (HO) a practical laboratory set, with all the chemicals, apparata and reagents Iodine (I) necessary to perform real Iron Chloride FeCI,) work and to teach the beginner all the secrets Iron Oxide (Fe..O,) of inorganic chemistry. With this outfit we give free a book contain- Lead Acetate ßb (C2H,O2)2 Litmus Paper ing a Treatise in Elementary Chemistry, useful data and recipes, and Magnesium Carbonate too instructive and (MgCO,) amusing experiments. Manganese Dioxide (MnO21 Mercury (Quicksilver) (Hg) Nickel Chloride (NiCI,) DESCRIPTION OF THE OUTFIT Oxalic Acid (k,C,O,) Sodium Bicarbonate The outfit consists of forty -four (44) Chemicals all A good part of the book is devoted to 'Weights and (NeHCO,) C. P. (chemical pure) put up in appropriate wooden Measures. ll:e Metric System, the English system Sodium Borate ,NaBO2) bores, glass bottles, and hermetically closed jars. The and the U. S. System are fully explained. Sodium Carbonate (Na..CO,) acids are put up in glass bottles, with ground-in glass stoppers and there is Sodium Chloride (Ned) a sufficient quantity of chemicals The following tables are furnished: Symbols and Sodium Nitrate (NaNO,) supplied (mostly one to two ounces) enough to make dozens Atomic weights of the Elements; Measures of',\'eights, Sodium Phosphate of experiments with each. See list of Chemi- Volume. Capacity and Length; Per Cent solutions: (Na2HPO,) cal: herewith. Conversion of Measure expressed in parts; poisons Sodium Sulphate (Na.3O,) 'he apparata furnished are all of the best obtainable Sodium and their antidotes; Techni.:ai and common name of Sulphite (Na_SO,) make and of standard laboratory size and shape. A chemical substances; Formulas for Cleaning various Stannous Chloride the 17 (SnC1,1 list of pieces of apparata furnished with this substances, etc., etc. Sulphate of Nickel (NiSO,) outfit is printed also herewith. Sulphate of Zinc (ZnSO,) The Instruction Book is a real Chemistry Course Sulphuric Acid (H,SO,) for the Beginner. Some of the Contents r Divi- Among the 100 Experiments are: Tin (Granulated) (Sn) sion of Matter: This is a Treatise on Elementary Zinc (Metal) (Zn) Zinc Chemistry and deals with the theory of the Me- How to make chemical tricks; How to make invisihl Carbonate (ZnCO,) melts, Molecules and Atoms. etc. Chemcaal Nomen- and magic inks: How to t -t flour; How to test soil: clature: This explains in simple language the deri- How to Make Chlorine Gas and smoke (German \'a The following apparata vation of the chemical names of the elements and Gas): How to bleach cloth and flowers. How to pro- are furnished: their compounds. There is a chapter on Laboratory duce Oxygen and Hydrogen: How to make chemical One Standard Washbottle Oparations: Glass Working; First Aid; Fire Ex- colors: How to test Acids and Alkalies and hundreds One Alcohol Lamp tinguishers: Experimenters' Aphorisms, etc. of interesting hints and formulas. One Conical Glass Measure One Erlenmeyer Flask The Price is $6.75 Shipping Weight 10 lbs. ',Can be shipped by Express only One Glass Funnel One Delivery Tube Six Assorted Test -Tubes One Test -Tube Holder Ten Sheets of Filter Paper One Glass Dropper THE ELECTRO IMPORTING CO., Mfrs. One Spoon Measure Glass Tubing TRADEMARK 236 -A FULTON STREET, NEW YORK CITY TRADE MARK One book containing Trea- tise on Elementary Chemis- try and 100 CI-arnica! Ex- THE LIVEST CATALOG IN AMERICA" periments to be performed ELECTRO IMPORTING CO. with this outfit. Our big nets electrical cyclopedia No. 23 is waiting for 234 -A Fulton Street. New York City you. Positively the most complete Wireless and elec. I enclose herewith 10 cents In stamps or soil. to send me your latest trical catalog in today. SO Pages, 300 corer Yost sits, for hich please print Big dins described. tracions, 200 instruments and apparatus. etc. Big C)clopeadl Catalog tNo. 23 as "Treatise on Wireless Telegraphy." 20 FREE cmi- NAME pons for our 160 -page FREE Wireless Course in 20 ADDRESS lessons. FREE Cyclopedia No. 23 measures 630. STATE n. N. 12-20 \\'eight 54 lb. Beautiful stiff covers.

www.americanradiohistory.com Radio News for December, 1920 411

(Continued from page 409) They are giving it away. What's this " In his enthusiasm over the beautiful cab- Build your own apparatus inet radio receiving set, he had failed to read the sign above it. For a moment he was puzzled, then surprised, the surprise Use Parts turned to gratitude. The members of the Q S A Radio Club did not reckon with ('- the quick thinking powers of Knox. He understood their motive immediately. All prices post paid. Reliable dealers "Some club," thought the gratified young Catalog sent for Sc. wanted. matt. "If I could only return the gift in some way. What a fine way for the boys to present me with the set." He read the notice again: To Paul Knox. Winner first prize. in smaller letters followed: A meeting of the board of directors of the Q S A Radio Club. six months ago, voted out one hun. dred dollars to be presented in the form of Type 103 Panel Switch a receiving set to the member who accom Type 101 PanelLSwitch A tary panel switch which I plished the most for the organization. The and efficient rotary timible pole and double throw` A beautiful 102 Will change meeting remained a secret. No member switch for n.. Furnished Type Panel Switch variable condo Is, general from series ro parallel. etc. was in two sixes. I" radius brase A compound switch consisting of radius aware of the prize to be offered. The two electrically Independent brass finish 75e. Nickel finish 40c. Nickel finish 50c. finish 65e. best man wins. was given without wurhe noel with e Service brass 50o. Irié 1%" radius finish knobs. , Inc" radius brass finish encouragement of any kind. Nickel finish 60e. $1.10. Nickel finish 51.25. Knox was happy. Christmas would be bright for him after all. He walked erect. he inhaled the fragrance of holly branches which decorated many a store. Happiness was everywhere, he joined into it. Thu° the members of the Q S A Radio Club die, something to be proud of for a long time to come.

Tyre 121 Rheostat Dictionary of Radio Type 104 Panel Switch Suitable for table or hark of panel mounting. sas turned altt- A complete unit for back or panel ease, convenient binding Terms amounting. Tito latest and 11 best posta and ohmi n..glance It in rotors paoel srip4les. Better with all off and all on positions. (Continued from page 377) looking. n efficient and easier Long and q cei l designed ,o mount r Complete with Type Insure un,nb running and poslliee eteitoet. only occupies 116 Dial and 6 contacts 62.25. space 2" in tiare, on your panel. Complete with 116 Type Dial and Type 116 No. 121A with Type 116 Dial diameter, called Secant. passing through II contacts 52.50. Indicating Dials 52.50. Ne. 1218 with Knob and end of arc. Of polished hard rubber accurate- Pointer 51.75. other ly engraved. filled with brilliant Tangent Gahm-One so called because the white, furnished complete with strength of currents passt thru it are to knob and hushing to fit 3/16" shaft. fir sense n -50 or 100' each other as the Tangent of the resp,h scale 9-100. 2" diameter 51.25. ive deflections. See Galvanometer. 3" diameter 51.50. Tangent of Anale-Is tangent of arc measuring or contained in that angle. It Is Cotan of Complement. Tapper -Similar to electric bell but so arranged that hammer gently taps coherer and thus decoheres filings after passage of each incoming oscillation. Type 14B Rotary Disk Telefunkcn- German system of Radioteleg- Tho same style rotor as used on raphy. Translated into English is "Spark our famous belt driven cap, only with bakelile renter and brass Telegraphy," or, more literally, "Far or bushing to fit your motor shaft distant Spark." Distinctive features are Suo is 455" diem. said 9/16" Type 5A Variometer Quenched Spark and De- thick. This rotor being light its Electro -lytic and perfectly Variocoupler Rotor State from wilco: Vaninmeter balanced will give il- tector. excellent results on any small A carefully turned hardwood lustlustrated. rated. maym as form for the secondary cells easily hem un Telegraph -Any apparatus for transmitting 111011 speed motor. Matoate sloe of of on panel ua wish. Ware etc. Sine is 357" shaft when ordering. No. 14B length in rage circuit intelligence from one point to another at Inarlocouplen,diameter and 2" wide. No. 101 with ,.Ills Inseries Rotary Disk 56.00. Rotor 51.00. thl,,nt 175 -450 a distance. Literally, "writing at a dis- meters. No. SA Variometer 513. tance." Generally used in conjunction with the Morse Code. Telegraph Naut-Nautical mile of 2,029 THE WILCOX LABORATORIES, INC. yards or 1.1528 statute miles. LANSING "Manufacturers" MICHIGAN Telephone -An instrument having a disc of soft iron, diaphragm, held over and near to an electroma "_mt \chose windings are such that very weak electric currents, whether direct or unidirectional impulses, We Will Surprise You will cause disc to be attracted. Attrac- tion and retraction of this diaphragm pro- Christmas ducing audible sound waves. Speaki'1 at a distance literally. Introductory Offer Telephone Condenser condenser of tin- -A UNTIL JAN. foil and mica, variable by a plug, which 1st, ONLY eft is used for putting telephones in most Less Tube and Batteries, 25 star complete sensitive condition. description send statap at Tellurium. Tc -Semi- metallic rare element once for circulars. having a silver -white color with a metal- RTS instruments Found and backed by a reputation lic lustre. in small crystals which guarantees quality and satisfaction. in combination with various metals. Is \'err brittle. The crystals are used as a RADIO TESTING STATION rectifier. A.W. 126.6. S.G.6.27. Mlt. Pt. BINGHAMTON, N. Y. 4 :2 °F. See Graphic Tellurium. Nagva- cite and Sylvanite. Temperature Co- efficient- Increase in unit READ the CLASSIFIED resistance per unit increase of tempera- ADVERTISEMENTS on PAGES ture. 420-422. YOU'LL FIND MANY GOOD THINGS (Continued of nest page) THERE. I

www.americanradiohistory.com 412 Radio News for December, 1920

eeeeeeee5e eeeeeNImcISxNVtISsCISIVWrWxNNee%1CIIC Temporary MfaRuet -One losing its magnetism after source of supply is with- drawn. Most electro- magnets are tem- GIVE HIM THE WORLD porary. Telegraphy, Radio -The art of sending and AS A CHRISTMAS GIFT receiving radiograms. Telephony, Radio-The art of sending and receiving radiophones. Even though that "kid" of yours may have good Tesla Coil--An oscillation transformer for radio apparatus, the ad- producing high potential discharges from dition of the super- oscillations of low potential. Somewhat efficient C. R. L. Para- similar to gon Regenerative Re- ordinary transformer though ceiver will open up a much more heavily insulated, and has 5 new world to him, Ama- ends of secondary connected to a con- teur and commercial sta- denser which discharges across a spark tions all over the country will "come in" as gap. thus increasing rapidity of oscilla- loud as he now hears tions which then pass into a second in- locals. duction coil. This second coil has no iron core. The C. R. L. Paragon, Thermal Detector -One depending upon with t t s tremendous amplification factor and the heating of a fine wire by the passing extreme electrical ef- oscillations. See Barretter. t'. R. L. Paragon Reg. Receiver ficiency, combined with Thermo Electricity- Electricity produced mechanical perfection by heating two and convenience, makes the ideal Christmas present -and you can be sure that it will different metals, placed be appreciates -BIIT be sure that you get the genuine C. R. L. product. Look for our end to end at their junction. See Ther- name on the instrument. The genuine C. R. L. Paragon is used in almost all long distance mopile. stations throughout the country. Thermopile -A chain of two different me- Price F. O. B. Chicago, $65.00 tals arranged alternately, which. upon be- Licensed under Armstrong patents. ing heated at the alternate joints. pro- Stela( p- epara.,mu mode for Xmas deli: cries, rf rite f, r Ir descriptive bn cretin. duces an electric current. In combination with a delicate galvanometer forms CHICAGO RADIO LABORATORY a senstive thermometer. Thimble metal ring, though sometimes 1316 Carmen Avenue. 5525 Sheridan Road. (Testing Station IZN) CHICAGO. ILL., U. A -A S. heart- shaped, with a groove round its eeeeeeeeeeeeeeeeeeeeeeCex .ew.ewee7pGVAX CJCSC.% eceeeeee 001, circumference to receive rope spliced round it.

Awards of Portable DO YOU KNOW Radio Prize Contest that the ACE Type B 2 -step (Continued from page 365) Amplifyer will give you 450 the condenser plates. This feature permit times amplification of signal? the condenser to be variable between any Price, $20.00, ready to wire. two values of its entire range. For general Diagram furnished. work, the scale should read maximum when the plates arc as close as possible giving a zero so low that it does not increase We appreciably the amount of secondary in manufacture and handle ductance. This condenser has a somewhat complete lines of Radip in- greater capacity than a 17 -plate Murdock struments and accessories. CONNECTIONS The 'phone tips connect with stiff spring brass strips when pushed into two holes in the front of the case. (See photograph Write for Catalog. showing front view.) One of these spring clips (the right hand one), .is held by the "You may pay more but you screw which fastens the crystal (a De- - can't buy better." forest mounted galena crystal) to the small panel. The other clip is held to the small panel by screws A. The rest of the hook- up is as follows: THE PRECISION EQUIPMENT COMPANY From detector post to one condenser pillar; front condenser bushing K to left 2437 Gilbert Ave. Dept. A Cincinnati, Ohio 'phone clip (held by A) to secondary switch arm ; from beginning of secondary winding to one condenser pillar. This system of connections reduces to a minimum the amount of connecting wire. A small fixed REAL RADIO APPARATUS condenser may be connected across the Headquarters for srebe Appvatua m 'phone clips and placed beneath the vari- Distributors -De Forest, Murdock, Grebe, Philadelphia ocrrltorr. able condenser as suggested at M, altho Clapp Eastham Apparatus. Perfection this will not increase the strength of very Tuners and Condensers. Benwood Rotar? weak signals. Coils, Better Quenched, Honey Comb "B' PRACTICAL USE Batteries. - In one of the accompanying photographs Phila., "Radisco Agency" is being in School in the set used connection with a The First Wireless America. collapsible coil aerial consisting of 5o turns Established 1911 of No. t6 bare copper wire spaced one inch Day and Evening Cl . apart. The coil is one foot square, the turns Correspondence C ours e being supported by silk fish line. PHILADELPHIA SCHOOL OF When making use of a fifty foot antenna, TELEGRAPHY this set will tune to six hundred meters WIRELESS with the secondary condenser at zero. Parkway Bldg., Broad and Cherry Streets Cape Race, Brooklyn, Norfolk, Miami and scores of other commercial stations, as well as amateur stations in the first three dis- WHETHER YOU ARE IN THE MARKET TO BUY OR SELL. THE tricts, have already been heard in the short CLASSIFIED COLUMNS OF RADIO NEWS WILL GET RESULTS FOR time since the set was completed. using the YOU. TRY THEM. co ft. aerial.

www.americanradiohistory.com Radio News for December, I 92

Raided By Radio PSST-zip (Continued front page 371) GR2R-2zZ SST-TtCK rt-M-f-Nj ,tll.s' - THERE'S receivers which gradually increased until saVAwK it became a roar. Then abruptly th strange sound ceased and all was quiet *!)nm)7 Glancing at the clock he saw that it wa- just twenty -eight minutes past eleven. The radiophone station had nothing fo NO USE San Francisco so Crosby stoppt for th night, promising to call the Penusylvaniat when he had secured a radiogram for Phil adelphia or thereabouts. The following evening fount( Crosby in an attempt to "raise" the radiophone again, TALKING ! but in this he was not successful. N., doubt it was due to the atmospheric conditions that made it impossible. Not knowing what to do he finally de- When it comes to coils for that set you're building. cided to send out a general call to all amateurs inviting some one to play a game you will want HONEYCOMB COILS-they'll sure make of "chess." Even though the contest was ended he felt certain that he would find the lil' signals trickle down your antenna like a ton of an eager opponent. In this he was right brick. Each and was soon engaged in a game with an earful will be a lump of pleasure. amateur in Burlingame. "L-15," sent his opponent, and Crosby And our price list is a " accordingly moved the man marked L to sure cure for "howling -just space 15. take a slant at it, and then let us know how many. At the conclusion of the game, Crosby being an easy winner, another unsuccessful attempt was made to get in communication with the station near the Atlantic. PRICE LIST "All in the weather, I suppose," Crosby complained regretfully to himself. "and I Turns Price Turn, Price have three messages for him too," he added Unmounted Unmounted ruefully. "Guess I'll have to let them lay How- over unless Chicago will take them." 25 $ .50 300 $ .85 ever, the operator at that city could not b, heard. 35 .50 400 .go Again, as on the previous night, Crosby 50 .Úo 500 1.00 heard the low rumble which gradually increased in tone until it became a terrific 75 .6o 600 1.15 roar in the receivers. It sounded as if it roo .65 1.35 emanated from the very center of the earth. 75o so unusual was it. The hands of the 150 .70 1000 1.6o chock again pointed to t 1 :28! The same 200' -75 1250 2.00 time as the evening before! Was it ordinary atmospheric distur- 250 .80 1500 2.50 bances? No; Crosby was sure that it was not. Never in all his experience as a radio operator had he heard such a queer sound Any of the above sizes will be sent postpaid to all in his receivers. It reminded him of the rumble of a caged monster. What on points in the United States upon receipt of remittance. earth could it be and why should the same identical sound occur two nights in suc- To avoid delay or possible loss remit only by Postal cession at the same time by the clock? Money Order. The thought of interplanctarian radio entered his mind but he quickly discharged this impossibility. Fifty million miles was no joke as several American scientists had found out when they tried to erect huge COTO -COIL CO. PROVIDENCE, R. I. radin receptors to attempt to receive the signals from the other planets, Mars for instance. No: the strange rumblings were not caused by the Martians or their neighbors, he was certain of that, but what caused the INSTRUMENTS unearthly signals in his receivers? He did Always Reliable not know but meant to find out. Bunnell

The next morning's paper had an ac- JOVE DETECTOR count of how, for the last two nights two Handiest, Handsomest, Best local police stations were wrecked under Sample by Mail, $2.00 decidedly queer circumstances, in each case killing several men. Tested Galena Crystal, 25c Spectators had said that the buildings we are distributors of the Standard Electric Novelty Co.'s Type B "Cyclone" Audion Batteries. had first seemed to totter on their founda- Also of De Forest and all the leading manufacturers tions, then with a slight "puff" the walls of High Chase Wireless Apparatus. Send stamp for PATENT) blew outward as if a terrible explosion had (0/120AN new edition 42RN Catalog. occurred within. Both station houses had been reduced to débris in the same manner J. H. BUNNELL & CO., 32 Park Place, New York and both nt the saine time, n :28 n. m. Allen Crosby gazed up from the paper in his hand with a frightened look upon his face. Bound Volume No. 1, Radio Amateur News, 12 it ies. July, 1019 -June, 19211. itac ',ivety Twenty -eight minutes past eleven," he Nouml Only $2.00 plus postage. A mon valuable asset to your library. Order today. -epeated slowly, "could it be by any chance

www.americanradiohistory.com 41.4 Radio News ¡or December, 1920

that those rumblings in my phones hat anything to do with this ?" It was a question open to debate, and the more he thought of it, the more cer- RACINE WISCONSIN tain he was that the two were connected offers ill some unexplained way. Thinking it would be to his advantage to visit the scene of last night's wreck, he immediately di( RADIO so in search of information. After spend- LETTERGRAMS ing an hour or more in the vicinity of the to the devastation he discovered something beneath the ruins which caused him to utter RADIO AMATEUR an exclamation. THE "ILLINOIS" RIABLE CONDENSER Quickly hurrying home he at once begar A Standard form Telegram The Condenser with "Star Spring" Tension on the solving of the mystery, as he teal Blank especially designed for Am- MADE RIGHT -STAYS RIGHT almost certain that he was on the rigl: ateur use, showing wavelength, Hard Rolled Aluminum Plates track. relaying station, type of trans- These condensers are made by s watch me- mitter, etc. chanic schooled in accurate workmanship. Per- He first constructed a large frame upon sonally we will need no introduction to Amateurs which he wound wire. Although rather - Prices - who have "listened In" for "time" and "weather" $0.20 per pad of 100 from crude, it would serve its purpose as 9. ZS. "loop" antenna. Upon the completion of $2.00 per thousand Three Styles: No. 1. Panel; No. 2. Open Type as shown; No. 3. Fully Encased. Anti Profiteer. this instrument he suspended it from the Prices on larger quantities on application Less than pre -war prices. Fully assembled and ceiling of his 'radio room and connected it tested. to his set in lieu of his regular aerial. He RADIOFORM PRINTERS Style No. 1 No. I No. 3 Stoney back if not 207 Bldg. Racine,;Wis, 43 Plates. $3.50 $4.50 44.72 satisfied. Just turn was greatly pleased to find that with this Baker 23 Plate.. 2 75 3.75 4.00 condenser within 10 improvised loop he could locate any trans- 13 Plates. 2.25 9.25 9.50 days by Insured P.P. mitting station by simply rotating the coil. Sent Prepaid on Receipt of Price. Knowing the location several ama- Except: Pacific Slates, Alaska, Hawaii, Philip- of pines and Canal Zone, add 10e. Canada add 25e. teurs in the vicinity he found that the in- Foreign Orders other RADIO ALM,ATIE,URS than Canada not solicited. strument pointed to their exact locality. Judge for yourself what kind of RADIO NOTE : Above Prices Effective November 1st, 1920. With this "Radio Compass" it would to equipment you shall purchase, bitt remem. The "ILLINOIS" is rapidly adding to the num- easy to determine the location of tut( ber that any piece that you ,elect can be ber of Its friends. The bouquets they Bing only strange signals, and when this was learnt( procured from us at a saving to >au pro- spur us to still more careful work, and more rigid vided it is dependable and efficient in oper- inspection- It la a matter of pride that among the the secret of the destruction of the police ation. thousands of instruments sent out, not a single stations would also be solved. We will be glad to build equipment of complaint has been received of bad condition. That evening he did no transmitting but special design to meet your requirements This may possibly be because every instrument is if you can not find what you desire in subjected to the scrutiny of the "old man's" waited patiently for the mysterious signals. eyeglass. standard equipment. Let us hear from you. Again at t t :28 the strange rumblings oc- We want your name and address so that Now we will take you into our confidence, and obtained location of we will be able to keep in touch with you, tell you the reason for the above slight change in curred and Crosby the by moving coil about. and we will send you descriptive b.illetins price. We know more about manufacturing costs the sender the of new apparatus together with our price list. than we did when we started. Then, there have Upon a map of San Francisco, Crosby been sharp advances in the cost of materials; in Northern Radio Laboratory some cases nearly 100 per cent. drew an arrow in the general direction of Speciolirts in Radio Apppmrotay Again the difference in the price of the various the source of the radio signals. Seven 111 Main Street Clyde,LOhio. sizes and styles were originally based almost en- blocks due west of his home was a large tirely on the difference in material. Experience hill, from the top of which the Pacific has shown that as the number of plates increases, the labor of assembling and adjusting increases Ocean, the Bay, and neighboring territory in n much greater ratio. For this reason the for miles around could be seen. slight advance we make in the new list is In the hill larger units; the smallest remaining unchanged. The mysterious sender was on this as in a -line to- Radio Service Patent is pending on the "Star Spring" feature, the compass pointed dead which has been very valuable. The action of this ward the summit! spring produces an unvarying friction that holds With this information Crosby left the Station the "rotor" in any position to which it may be set, and at the same time automatically centers house, first having learned from the tele- Complete facilities for panel engraving the plates in relation to each other, and prevents phone central that another police house was and model work for the experimenter. any of "endahake." possibility wrecked at II :28! This was conclusive' Expert workmanship at prices arna- The plates are in proper relation by construc- The maker of the strange rumblings was tion, and will remain so, obviating any necessity tours will be glad to secure. of readjustment. Once right, always right. Once the one who had ruined three police sta- mounted on your panel. there is one thing that tions in San Francisco. Watch for our next months can depend an no entof "FADA" you upon to never gire you trouble. Since the Fire of 1906, the top of this Radio Specialties We again thank our friends for their letters of hill had been uninhabited. The only struc- generous appreciation. remaining being a dilapidated two Kindly note: We Issue no Catalog. and make ture FRANK A. D. ANDREA no "trade discounts ". We set our prices at the story house, once used for an observatory 1882 Jerome Ave. lowest limit, and leave the "middle man" out for but long -since abandoned because of the Bronx, New York the sole benefit of the "consumer ", numerous fogs of San Francisco. G. F. Johnson, 625 Black Ave., Springfield, Ill. Toward this place Crosby made his war without delay. It was a moonlit night ani two white masts could be discerned rising from the roof of both ends of the house. Radio Engineering Principles Suspended between them was a wireless By Lauer and Brown aerial! Crosby was not greatly astonished 300 pages Price $3.65 postpaid as he was on the look -out for just such a This is one of the latest radio book? and covers the vacuum tube in a com- thing. prehensive manner. Crawling close to one of the lower win- Experimental Wireless Stations Learners "HYTONE" dows Crosby peered into the lighted base- By P. Edelman ment. Five men were inside sitting about 892 pages Price $3.15 Postpaid a rickety table with an oil lamp illuminat- An excellent book for the begin or KEY AND BUZZER SETS Covers both ing the room. One of the men was speak - advanced experimenter. n, With Code and Instructions. radio telegraph and telephon.. Easily tuned buzzer (2 adjusting screws), ing and Crosby with his ear close to the What books do you need) silver contacts. window pane distinguished every word. BROS. "Well, that make three of them," SWANSON PRICE S1.75 Technical Book Service man within said with a chuckle, "and an- Dept. B., 186 No. LaSalle St.. Chicago WITH FLAT SPRING KEY 51 25 other scheduled for to- morrow night." Buzzers, unmounted 50.50 At this the rest of the men laughed and Lever keys unmounted 1.00 one of the others spoke. High grade lever type sending key, "Come on, let's get some work done to- Bakelite base and knob 1.50 night," said the man, evidently their leader . RADIO APPARATUS Amateur Radio Builders Handbook, as he picked up the lamp and advanced to Raw ma. price 1.00 built to your specifications. by R. U. Clark, 3rd; the other end of the basement. tented and parts. Machine work done for experimenters. Get my prices before (AU postpaid) Crosby changing his position saw the man with the lamp raise a trap -door in the buying elsewhere. CO. floor and the next moment the five men A. C. PENFIELD AJAX ELECTRIC PA. Palmer St. Cambridge. 33, Mass, were out of sight and the lower part of CONNEAUTVILLE, the house was in darkness,

www.americanradiohistory.com Radio News for December, 1920

At the Post Office Building early the next morning Crosby related his story to the Chief of the Secret Service. He told how he had used the Radio Compass in locating the men and repeated the conversation he had heard the evening before at the window of the deserted house. - To the Something New best of his ability he described the men in the house, at which the Secret Service officer broke in with an exclamation. "Why, that's the most notorious gang of and ! counterfeiters side the different this of Rockies!" said the man excitedly. "They're wanted in a dozen cities thruout the United States. There is a reward of $5,000 for FOR their capture! Here," he said as he drew out five small photographs from his desk, "is that them ?" RADIO MEN f' "Yes," replied Crosby, "it's them beyond a doubt. But why should they wreck out police stations? I don't understand that WIXICO COIL MOUNTING part of it." (Pm. "rriird for) "I haven't the slightest idea unless they CHEAPEST -QUICKEST arc atraid of being captured by our local SIMPLE -MOST EFFICIENT police and are taking precautions by ruin- DURABLE- ANTI -CAPACITY ing the station houses, with hopes of kill - POSITIVE ACTION ing officers." NO MOVING PARTS At eleven o'clock that evening ten op- ADJUSTABLE eratives of the Secret Service surrounded COILS LOCKED IN PLACE the house on the hill while five more with NO WIRES Crosby entered the house from the main floor. "They're all in the basement," whispered one of the detectives and silently the men Introducing a plug and mounting for radio coils that solves the lattice made their way to the lower regions of the coil problem for amateurs who are looking for a mounting for their house. unmounted coils. The raiding party paused before the Coils may be changed in less than half the time necessary with other door leading to the room where the coun- mountings. terfeiters were and listened a moment. Voices could be heard on the other side Coils lock in mounting when swung to vary coupling. I- landle on coil of the door. strap provides most convenient means of operating coils. "Hands up!" commanded one of the detectives as the door was suddenly flung Mounting. anti -capacity, all metal parts brass nickel plated; Formica open and the party tiled through into the panel, hardwood base room. "Hurry up, reach for the ceiling!" The five law- breakers stared into the Plugs of durable black composition, anti -capacity. Take any size muzzles of six wicked -looking automatics lattice coil. raised they and slowly their arms. When Plugs furnished with strap. were all handcuffed and led to a waiting autobomile for transportation to a safe keeping place, the Secret Service men and Crosby searched the building. Under the Write for particulars ! floor of the basement was a large room with apparatus for making counterfeit money and a stock of counterfeit bank- Table type mounting $8.00 notes was found near -by. Panel type mounting 6.09 Crosby was more interested, however, in {, '(I-,f Plug with strap .60 the method the men used to wreck the po- d Knob, or handle .Os lice stations. In one corner of the basement a radio outfit was discovered. In- (t Discount to Dealers stead of the ordinary transmitting apparatus, in its place was a large cabinet with many switches. surmounted by a huge pointer. Wireless Instrument Co. Later at the city prison where the crimi- nals were placed, the leader of the gang, Cincinnati, O. one Dr. Ilemmingway, made a complete P. O. Box 669 explanation of the apparatus found in the . corner of the basement. "Yes, I invented the Ray Projector," he said, "and it served its purpose well. We had already wrecked three police stations, our object in this being to diminish the force as much as the could in order to escape capture. The fourth was to be 777 wrecked tonight. when you came. As long / $12.00 7777 as the game is up I may as well tell you That is the erice Which puts at EV- lta.A it Type the principle of my invention. "D" Audion control Unit at your service. May be "When I desire to wreck a building I used with Audio.Tron or tubes equipped with standard base. manipulate the until pointer it points in the 45.V. "B" Battery tapped for above Panel $2.75 exact spot of the building to be ruined. extra. Other EV -RA -LAB bargains as follows: Of course the building must have a wire- Single less antenna on it. Then using an enor Stage Amplifier, $22.50 Two Stage Amplifier, 40.00 moils current a powerful ray is directed Det. and Single Stage Amp. 32.50 toward this antenna. Previously. however. Dot. and Two Stage Amp. 50.00 a box of high explosive is placed in series REAL SERVICE on Acme, with the lead -in of the aerial near the ap- Radisco, Tresco Chel- sea, Brandes, Firth,, De Forest, Grebe, and Murdock paratus. That being the work of my men apparatus. who planted the box under the very nose Dealers we have a very attractive proposition for yen. of the police. Sem,' police force, T must ca P EVANSVILLE RADIO LABORATORY 1.103 5. Third Street 'Rut what happens when the rays strike EVANSVILLE, IND. the explosive ?" queried Crosby.

www.americanradiohistory.com 11(; Radio -News for December. 192(

"A terrific gas is formed which, being so the building 1921 Bulletin Under Preparation -Listing Now powerful, causes to totter, then Developments. Send for Yours Now. IF YOU ARE A with a sudden puff the gas expands and pushes the sides out of the building. Bu, "SORALA99 Stands for the right how did I become discovered ?" Quality- Price- Service Licensed "At eleven twenty-eight for the past A Trial Will Convince You Government three evenings," began Crosby, "I heard NEED WE SAY MORE;? THE uNUCLEUS" it a logical bcgiming for strange rumblings in the receivers of my 536. a practical. up-to -date radio set and when I learned that the local Transportation Charger WIRELESS PHONE Amateur Radio Operator police stations were being wrecked at the Allowed Until Jan. l Place your order :now same time to the minute, I connected the It consists of the following instrumenb assembled on a Grained Bakelite Panel, 9'<" x 9'< ". you should take pride in the fact_ two occurrences. When I searched the with Mlssioned Oak Base. The great increase in the number of ruins of one of the wrecks I came upon an General Radio Mot Who Ammeter-in 0 -1. 0 -2': box, and 0.5 Amp. Readings. New Price. 57.75. government licenses held means bet- antenna and a small fractured steel Special Radio Microphone Transmitter. 54. ter radio in the future. then by means of a Radio Compass I dis- TYPO J 57 Plate Current Mllliammeter In 0 -IC0 covered your location." 0.300. and 0.500 M.A. Scale Readings. Type CSU -11 Balanced Variable Condenser. Some few nights later Crosby was in Bakelite Insulation, and 41,2" Silver Plated Navy Show that you stand for communication with the radio telephone in Standard Dial: Shielding the Circuit from False Capacity Effects 57.00 Pennsylvania again. 6 185 Large Insulated B:nding Post, "Congratulations!" began the voice of See Photo in Nov. Raaio -News BETTER RADIO the operator in the east. "We have heard The above are essential to a practical by wearing one of the emblems illus- all about you back here. The papers say 'phone, but may be purchased separately. you are the most progressive amateur in tf desired. trated below. Type J 0 -500 Voltmeter $18.0C !" America Type J 0 -3 and 0.5 Ammeters 7.0' "Thanks. OM," Crosby flashed across the Electrodyne Rectifier Tubes 7.00 continent, "how about a little game of De Forest Buzer Radiophone 135.00 Radio Chess ?" Paragon RA -10 Regenerative Tuner 85.00 New Adjustable Honeycomb Coil Adaptor .15 Separate Plugs and Tacks, Panel The Amateur Trans - Mounting, net .35 Agllelre Relay Atlantic Feat McEleeela VT'S REPAIRED, $4 (Continued from page . Cash .Must Accompany Order. Park'Carefully Somerville Radio: Laboratory k. I1! HEATH ST., tOMERVILLE,'IS, MASS. tt hiól Mein The cniblem is exactly like above cut. It One of the most important factors is constructed of 14Karat gold plate with a prompted this body of men to this action blue enameled edge, producing a beautiful is due to the fact that the Radio Club o! effect. A truly artistic button that you America has for some time past been con- will be proud to wear. sidering the award of a substantial cash Prices (Postpaid) prize to the first experimenter who effect- Canadian Amateurs ively bridged the Atlantic by means of Emblem coat button $1.00 BUY your Radio Apparatus 14 -karat gold filled ring, 20 year radio telegraphy or telephony with amateur guarantee 8.76 apparatus and on amateur wavelength and in CANADA 14 -karat solid gold ring 9.50 regulations. $ $ $ $ $ $ Special prices to radio clubs when It would certainly be more convincing to and save ordered in quantities. the radio fraternity at large if in the very Murdocks No. 55 Phones near future the feat were again repeated It 2000 Ohm $6.00 Co. other actual workings of the apparatus in- 3000 Ohm 7.23 Milton Specialty volved. This may prove more difficult than 1.35 Two offices: Rheostats panel mounting realized owing to the fàet that the reported Series Parallel Switches. .75 Box 34, Columbus Ohio transmission was probably due to a freak Contact Points, per doz. .30 Box 11, Philadelphia, Pa. condition where atmospheric and other natural elements were exactly suitable for long Radisco Agents distance work at that particular moment. Mr. Fansler recently wrote the following Tresco Condensers letter to Mr. Robinson which would infer that it was Mr. Robinson who was heard Our new Catalogue is ready, SURPRISE YOURSELF in Scotland. send 5e to cover postage. Norota; Heights, Conn. THE VIMY SUPPLY CO. FOR CHRISTMAS November in, 1920. 567 College Street and Start rile New Year with your table Dear Mr. Robinson: full of apparatus neatly installed in one / wart to congratulate you on wc'ltat ap- TORONTO, ONT. of our famous Drawer Bottom Blank pears to be the first trans- Atlantic amateur Cabinets. transmission. When I saw the article in If the value, quality, workmanship the New York "Times" I thought that and finish of cur Cabinets don't stir there might be a possibility that he had LEARN WIRELESS prise you, nothing ever will. heard me transmitting to yon as tite record at the largest radio school We are now in position to make mentioned is one that I used every evening in the Central States. not Modem complete equipment. almost immediate shipments. lt's during the first part of October; also the Experienced instructors. Dor- to late -write for our bulletin No. 101 mitory in connection. Stu- at once. mention of 400 watts indicated the output dents mar expenses If of my motor -generator of my set, and I necessary. Write today for We also wish to take this means of have mentioning in catalogue and full informa- extending to our many customers and been that fact all broad- nt. friends, the Compliments of the Season casting. However, I phoned .br. Bouche- CENTRAL RA010 SCHOOL - rih you all a Merry Chr'stmas ron vestcrday and he said that you were IPNpa4saq, Me and a happy and Prosperous Ness Year. working on the afternoon of the 6111 while I teas not -that, I remember--which seems Penn. Radio to fir- the responsibility on von. Of course. it's freak, but it's great stuff just the saute. TELEGRAPHY Apparatus Co. What are you going to try for (text? Mos- 'Both Morse and Wireless and RAILWAY ACCOUNTING cAG,ov cow!' Hope to get Inv set rigged up again taught thoroughly and quickly. Big salaries now paid 03\., Dept. RND. Great opportunities for advancement. Ou est and largest nest week with some power. l'ui going to echo.* established 46 years. Endorsed by Telegraph. Rail way, Radio. and s Aa Reading Pa. t officials. low- Put in a KW. 2000 volt generator. opportunities earn vrnmentv portion R'- free s FA.\'SLER. 00o-cs tNSrlrurc D sines aalearuea, me. Altho a personal trio by the writer to Kcyport and an interview with Mr. Rob- inson failed to disclose much more than is already known concerning this incident. i VACUUM -TUBES REPAIRED Bought he hopes, nevertheless, to shortly he in Five -Dial Omnigraphs Marconi -Moorhead- Audiotrons - a position to present readers more defi- at highest prices. Write for prices, _ Four Dollars Each, Postage Paid - nite facts rnncernine this marvelous feat Standard Grid Leaks, $1.25; Bases, 60e; stating what you have and how which probably r,ean< another laurel to i and Sockets, $1.00. long it has been used. E.L.D., 1312 amateur radin of. America. THE DALTON LABORATORY Ed. Nate . -At montent ni pouter to press T'e Cc. Dalton and B elvidereSts., Boston,17, Mass. Belmont St. N. W.. \ \7ashington, D.C. reir'ed a copy rl the .Scotch n m ateue's answer. This s on the Radio DicestPace 272.

www.americanradiohistory.com Radio .\'oins for December, 1920

TEI,. BACK BAY The Eiffel Tower 5 64 Radio Station TE R

Fig. 1. Schematic Arrangement of the Actual Antenna Supported by the Fanions Eiffel Tower.

Such is tut future of the Eiffel Tower. After being one of the first powerful sta- CERTAINLY WE HAVE A -P VTs tions in the world; after having rendered great services during the war, it will work during peace time towards the improve- Immediate Deliveries ment of the new technic which is called radiotelegraphy. A -P Electron Relay Detector 16 00 Museum and well equipped laboratory. this station which has been and will be use- A -P VT Amplifier Tube 7.00 ltd to the whole world, that is owing to ach its time signals, has really a great rôle among the powerful stations of the world. A -P Transmitter Bulbs :tt ss 7.50h It owes it especially to the reason that it is not a commercial enterprise and that the FOR prominent scientists working under Gen- WRITE RADIO CATALOG No. 2 eral ierrie s management are not looking Mail orders promptly attended to for profit but only for progress of the radio art. DOUBLEDAY- HILL ELECTRIC COMPANY A HARD ONE 715 12th Street N. W. RADIO DEPT. -Desk B 719 -21 Liberty Ave. Radio Shark: "Ask inc any question WASHINGTON, D. C. PITTSBURGH, PA. concerning wireless and i will answer it." Humorous Radio Bug: "How many A welcome addition to your library! Send $2.00 plue postage today and your copy of bound meters does the gas ratan work on ? "- volume No. 1 of Radio Amateur News will come forward by return mail. Experimenter Publishing Company 286s. Clarence T. Mayer. Fulton Street. New York City I

www.americanradiohistory.com d1S Radio Xews for December, 1920 RADIO COMPASS STATIONS AT SAN FRANCISCO BAY Join the 3000 By Phil Vernon Mail Us For some time the United States Navy Mutual Purchasers Department has had in operation, on the Your Radio Wants Atlantic Coast, radio directional compass Each 22y, V. "B" Battery $1.25 Right now 3000 amateurs are stations. The purpose of these stations is RORK Detector ....17.00 saving money, getting quick deliver- to aid navigators to ascertain the bearings Grid Condenser .35 ies and sharing in liberal credit divi- of their vessels when entering a port; par- Stopping Condenser .35 in when is im- RORE Amplifier 25.00 dends, by combining their purchases. ticularly foggy weather, it Grebe CR3 Special possible to accurately determine true posi- 85.00 The Mutual Purchasers are large Corwin Dials 1.30 tion by observation. Radlaeo Coils - enough to secure big quantity dis- Several months ago, the Naval Com- LRD 40 $0.70 LED 175 1,15 counts, and powerful enough to in- munication Service commissioned four ra- LRD 100 0.95 LRD 550..... 1.65 sist on immediate deliveries. The dio compass LRD 325 1.40 LRD 1200.... 2.65 stations at the entrance to LED 750 $2.00 following prices on Storage Batteries San Francisco Bay, California. These sta- are fair examples of the savings, Tap Coils - tions are located respectively at Point LED 325 3 1.70 LED 750..3.. 2.30 shared by our members. Reyes (NLG), Bird Island (NLD), Point LED 1200 S.. 2.90 Montara (NLH), and Farallon Islands Coll centers plain Pair .25 Coil mounting for Kadin(' Coils.... 6.00 SPECIAL STORAGE BATTERY OFFER ( NPI). Add to Battery prices 5% tear ta.r. file aerials at these compass stations arc DeForest Coils (DL) .t -I 4 volt 20 -10 amp. Marko 97.3í No. 25 $1.65 No. 400 2.60 .t9 4 volt 40 -GO amp. Marko 10.13 of rectangular loop type, with six insu- No. 96 1.7C No. 500 2.75 .t -:t 6 volt 20 -10 amp. Marko 10.45 lated wires around a frame about 4x3x2 No. 50 1.75 No. 600 9,05 Supply of abore special filament lighting No. 75 LSE No. 750 hatter :es limited. Orders will be shipped feet; and they are movable for direction. 8.30 immediately. The No. 100 1.95 No. 1000 3.51 .t 6 volt 40 -60 amp. Marko 19.05 base of the aerial loop shaft re- No. 150 2.10 No. 1250 3.81 A 5 a volt 60-a0 atop. Marko 24.00 volves on a table. A pointer on the loop No. 250 2.3C No. 1500 4.1C A.a G volt SO -up soap. Marko 20.2: shaft is lixt to register true bearing on a No. 800 2.4E Every new member adds to the buyiue dial that is set to the local meridian. This Send 10c for catalog. ewer of the association. Send stamp today dial, graduated in degrees from o to 360, for enrollment and complete information. is fixed on the table. Thus, when these Open Evenings Until 9:30 P.M. stations hear a ship radio calling MUTUAL PURCHASERS ASS'N. operator KELLY & PHILLIPS "Q -T -E" (which means "where am I "), 312 Flatbush Avenue, Brooklyn, N. 2 -4 Stone St. Dept. RA Nevi York Y. it is an easy matter for them to advise Telephone Sterling 2380 him the bearing. This information is given to him by all of the above stations simultaneously. Then the navigator. on his chart. assumes the position of his vessel to _uI11f11111111II11IlII11lIIIlIIIIIIIIIIIIIIIIIIIIIIII_ be the center of the small triangle or fix Materials and Parts of any three of these directional bearings, allowing for a slight error of one or more UT-T=MAItKS new set you are of the stations. NAUTICAL ACADEMY for that The bearings are given on Boo meters wave -length, so traffic. we that commercial Mti lt1 O RIAC L building, have it. which is on boo meters. will not he inter- fered with; and all vessels that desire to Brass sheet, round and square make use of this service have been re- NEW °- ^ -r' BOSTON rods, sheet aluminum, fibre, quested to retune their sets to Soo meters. Offers a thorough course in bakelite and hard rubber cut to Vessels have also been instructed to use all branches of wireless teleg- size, machine and wood screws, maximum power, broad coupling. and low raphy. Radio Operators Barr. decrement, when ascertaining bear- at the start $125.00 per month, points. their and first class board, etc., free. binding points, switch ings by means of these radio compass sta- knobs, insulators, switches, all Our school prepares you for tions. your license in three to four types; variable and fixed con- There is no charge for this valuable serv- months. Positions guaranteed densors, and card board tubing. ice. All the Naval Communication Service to first grade licensed opera- asks is that navigators check hack on course tors. Murdock, Acme, Tresco, Bun- line the hearings ftirnisht Ify' the indi- Day and evening classes. nell, Parkin, Morehead and vidual stations absolute fix when is de Nautical Academy 1804 E Burgess products in stock, and termined by buoys. lightships. or light- established we can give you the service houses. and that a short report stating the CAPTAIN F. E. UTTMARK. Principal = good or bad results of the radii compass P. you want. Our new catalogue bearings be mailed to the District Com- Write, call or phone for illustrated = sent for five cents, which will munication Superintendent's office at S- booklet. _ be refunded on first order for Francisco as soon as practicable. one dollar or over. This service is especially valuable for 8 STATE ST., NEW YORK, N. Y. vessels approaching San Francisco Harbor. Paring Battery Park, A'. where low. thick fog not infrequently Y. Try us on your next order makes the passage dangerous. At the pres- Telephone, Bowling Green 8079 ent time no attempt is to be made to guide Keystone Radio Co. vessels throtteh the Golden Gate and into UTTMARK'S for Nautical Education Drawer 307 - Greenville, Pa, the harbor by means of the radio compass hearings. The intention is simply to assist 5lIIIl11111111I1111111111111111111111111111111111111a navigators. during thick weather, to locate the lightship. which is anchored seven miles outside. if this experiment proves RADIO CLUB PINS successful. further improvements, it is Audion Control and hoped, will eventually enable these radio Special folder of designs and paces compass stations to actually guide vessels Amplifier Panels to reg'-1ar school pin and riadditionng catalog free request. Bo sure through the narrow, mile -wide Golden Gate Neat, Efficient, Low Priced to see these newnumbers .+hichw ill and into San Francisco harbor. even when Send stamp for circular or Se for catalog put new life in your club the weather conditions are most adverse. Meld Arts Co.. Derr. II, Rsehesler. N Y. 20th CENTURY RADIO CO., Greenville, Pa. RAILROAD INSTALLS RADIO The Nashville, Chattanooga & St Louis Railway has installed a radio sta- STANDARD RADIO EQUIPMENT tion at Tullahoma, Tennessee, for com- AGENTS FOR ROLLER -SMITH COMPANY MURDOCK FEDERAL TEL. munication between this city and Gun- BRANDES AMERICAN RADIO Manufacturers of tersville, Ala. A mast ninety feet high BURGESS . AUDIO IRON. GREBE CHICAGO RADIO LAB. Electrical Measuring Instruments has been erected in the rear of the Trad- BENW00D SPEC. DUBILIER ers Bank and another on top of the build- DE- FOREST TRESCO AND OTHERS Meters and Circuit Breakers ing. office U. of I. SUPPLY STORE, Inc. The operator's will be located 1127.29.31 SOUTH WRIGHT STREET 15 Barclay Street New York, N. Y. in the railway i-ompanv'c -suite of rooms CHAMPAIGN. ILLINOIS on the second floor of the bante building.

www.americanradiohistory.com Radio News for December, 1920

!!II!IIIIIItlhI11II1IIl1I111II111IIII11111I1111lllllllllllllllllllllllllhl111111 1a!'"' " .

Instruction Book

A WATISE ON EIFINENTnf+, EEEC'RKITY 1.17 IEO Electrical Experiments 10 4/11111110 .110 A Sample of What You Can Do With This Outfit

"sir lop a Etertrir Sops" This illustration, do front -

a I tzholegrupb, tl> cry n, in he ltteatsloath. with he Boy's Electric Toys: Elec- tric t'mudal.nn. Electric 'Tc Ittral III CIRO IMPORTING CO. Current ST new 'OM v as litertrl.-tb'm'retnr iIauetol r al aka Slmee rise ftat l, permit us to slaw the hcOettd. ,.r is that can he erfo need with u micrfnl eluart The outfit contains Ile separate pieces of material and 21 pieces of finished articles ready to use at once. Ae the fiis,) material the following parts are Included: Chromic salts for battery, lamp socket, biotic , wire (Iwo different lengthst, a battle nl iron rulings, three spo0 l. of u arb,nt-r. Iluantlty of t stein. germs. flexible and bases, glass plate. Pm smut pier, binding posts, lnscrew-driver. etc., etc. The instruction lack Is so clear that anyonea can make the apparatus without trouble, and iosfites a section of Ilie i taken up with the fundamentals of elec- triclty to moomiot the layman`TwithIl all important facts in electrlelty In a simple mmn, tee guest roe satisfaction, C 'eke ' over ell of for unfit Is 1{x9x2a'. Shipping weight, T uis. r No. 2002 "The Boy's Electric Toys." outfit as described E6a75 IMMEDIATE SHIPMENTS The " Electro" Radiotone HIGH FREQUENCY SILENT TEST BUZZER This umtrumrnt g. ces a wontierful high pitched NIFNt'AI. NOTE lu tir receivers. impossible to obain with the ordinary test . Tho RADIO. rom: is bulls along entirely new unes: it. is NOT buzzer. r uetrmged in some manner. 'to.filtraryrt itAD111T(,NE has , single line steel retest iiltratillg al a remarkably high speed. adiuslnl to ,Ot rOlclentt tlfrequency at the factory. Ilan) -Over tantarta arc soit to make the instrument last practically forever. E l'es, the RADI(1Tt1Ni: Is SILENT. In fact, it is oz silent that ) 1 1 1 1 1 1 1 1 1 St place your ear o u top o: 0it to hear beautiful musket note. L its You will he astounded at the wonderfully clear. X cycle note. s ml.ug slg1rply iii your ...Pliers. To l learn the cades. Were 1a absolutely aothins P like It. 11'illt the rdiobme a key and 1010 1,11 :11111 ANY fine Icam.ers set is had. Two more such sets t in series will afford f -ure E r Intrnomnnineellon tsork. Weight I lb, No. Otto IT, I m a. descrlbrtl.. Cart 51.50 R IMMEDIATE SHIPMENTS M Take a dollar bill I Send it wist Your addresr to E the Electro Innoing 2ß1a Fulton St., New York, and by return mail you TN receive your No. 2002

ETII F. ROY'S ELECTRIC 'TOY'S' contait s enottgl . material To MARE AND COMPLETE OVER TWENTY-FIVE DIFFEREN'I RELECTRICAL APPARATUS without any other tools, except a s wdriver furnished with th- outfit The hog contains the following Scomplete instruments and apparatus which are already assembled: SRINDERVIKEN TRANSMITTER Modem'. chromic plunge battery. compass -galvanometer, solenoid, tele- BUTTON phonr electric lamp. Enough 1 r iou. parts, wire, etc., alt furnishedt b1 retake the following apparatus: Electromagnet, electric cannon, magnetic pictures, dancing spiral. electric hammer. galvanometer, voltmeter, hook for telephone re The "Electro" Codophone (Patents Pending) !ceiver, condenser, sensitive microphone, short distance wireless tele- What this remarkable phone, test storage battery, shocking coil, complete telegraph set. instrument is and electric riveting machine, electric buzzer, dancing fishes, singing tale. tle $1.50 phone, mysterious dancing man. eletcric jumping jack, magnetic 'l' t 5.'1.:Irrt ni ' geometric figures, rheostat, erratic pendulum, electric butter ^y. Codophone thermo electric motor, visual telegraph, etc.. etc. cri' the t nt modemy. titi Thin dog, not br . exbarest the list, but a great many nice, 'ItiI/` imitate apparatus can he built Tactually and effectually le note e deaM In n sit With the instruction) hook which we furnish, one hundred expert ,eke'. TLc A men is that can he made with this tit lit arec listed, nearly all of these hr. alpedw n , i 1g illustrated with superb illustrations. No other materials, goods m with a ham, f supplies any the hood that are necessary to perform of one hundred experiment- round can hear ' to make any of the 25 apparatus. Everything can he conitructe I the and accomplished by means of this outfit, two hands, and a screw -driver. room, n Ir there I.Nd'Mgl- No. 199J ofIrai other noise. lin . "The Livest Catalog in THAT'S NOT ALL. r tightening the r p. nine America" ill.. lord, softestm-i ninthly, up to Me loudest and highest .,rtioniug óoulbl n,n big. I lapedla No, 23 1, walling you ow ebsirical for had In a few seconds.Ì.. l'. oi tinily the ltmost t tupfer,' Wireless and electriealT catalog in print FOR INTERCOMMUNICATION - Tsang dry cells for each (ore, two today. Rig "Treatise on 20 PRIN: co'ipu,- rio luscii Weeks. Telegraphy." when t .acrd With o o wire and return earl be used for our I6p -pat FREE Wireless (ourse In 20 lessons. Codfphiees ground, for inter ,. ratlmt between u t fous, self mile apart - a 000001 er gras n sea us ear mi4o outfit alone replevy, the oüi`fnshiorlrd learner's telegraph set. consisting C ------w and ELECTRO IMPORTING COMPANY "Eteetro'' Codophone la a hmultutm. Well made Instrument. bol prof. and 231A Fulton St.. New York City I milt for heard wnrk. tomme: are of hard silver if, Melt in diameter, that will I enclose henni it h le re:ito in stamps r In for which tilinte send in outlast the Instrument. _ purr latest lycli e'tlm Catalog No. 23 as descriibed, There Is also it neat rode chart and full direct lues enabling any intelligent tountaunt; man or girl to learn the codes within 30 days, practising mfr -hall hour .t sees 0lxrx' an' 3 x 2z,o, whipping weight. 2 Ibs. Nn. 1999, Ter 75 NAME "Eleetri' Codophone a. d.rlhrd. c..undrlr 52G

11yDnt. =¢ 231A FULTON STREET STATE. i2 _n I ELECTRO IMPORTING CO., NEW YORK

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i, OPPORTUNITY AD -LETS Follow these advertisements every month, Reliable advertisers from all over the country offer you their most attractive spy. cials in these columns. T' Classified advertising rate four cents a word for each insertion. Ten per peat discount for 6 issues, 20 per cent discount for 12 issues. Name and address must be included at the above rate. Cash should. accompany all classified advertisements unless placed i by an accredited advertising agency. No, advertisement for less than 10 words accepted. ïl Objectionable or misleading advertisements not accepted. Advertisements for the February issue must reach us not later than 1. January 10. iE THE CIRCULATION OF RADIO NEWS IS OVER 40,000 EXPERIMENTER PUBLISHING CO., INC., 233 and 236 Fulton Street. New York. N. Y. i ,treAri trt7l'rturslt t iflhmtì tltr ivIlr4/ iTreliYYIfYYirsiDVirsittrg1YY,iviVireireit YETYfrilit.iri . silfacifferisilliffixiVir, Aeronautics. Business Opportunities. Electrical Supplies and Appliances. Propelldrs tor Aeroplane Propulsion, small pro- 25e Coin brings household n1Ceity and whole. Water Locating by Mlanstield's wafer tinder is pellers for motorcycle driven snow and ice sleds, sale price. Wonderful seller. Lafave, 134 W. interesting and profitable. Particulars from Ed- road speedsters and hydroplanes. 5 ft. diameter, Park St., Watertown, N. Y. win Mansfield & Co., 94 Victoria Road, New $12, others in proportion. hub mountings, bear- Substantial Manufacturing Corporation wants Brighton, England. ings, sprockets, and countershafts complete. Have capable men to establish branch and manage sales. Storage Batteries, etc. Illue Ford and for auction filaments, full scale Prints for building melt; $300 to $2,000 necessary. Will allow ex- Guaranteed two years. 6 V. 40 -60 amperes, $16: Motorcycle driven sleighs. Crawford Motor and penses to Baltimore as explained. Address Mr. G V. 60 -S0 amperes, $19. Immediate delivery-. 'r3 Aeroplane \Ifgr., 142 South Rampart St., New Clemmter, 603 N. Eutaw St., Baltimore, Mtl. Dealers wanted. William Schick, 0723 Cooper Orleans. La. Turn Your Spare Time into money for that Ave., Brooklyn, N. Y. Boys Make a Model Aeroplane that Fly. Will apparatus . you want. Start a profitable, perma- Easily made at small cost. Write for circular. nent home business. Steady weekly income. No Aero Shop. 05$t.. Hurlbut Ave., Detroit, Mich. investment but your brains and spare time. Posi- Formulas Build the Latest Aeroplane Models. Exact tively no soliciting agency proposition. Write You May Have Been epernnentiug for year, duplicates of those in use today. Accurate models today. Address Opportunity, Box 175, Fredonia, to make common solder stick to aluminum, but that fly are built from \Vading River scale draw- N. Y. their is a harmless product that will do it. For- ings. Our n catalog completely illustrating each mula, $1. 1) Smith. 593 5th St., Oakland, Calif. individual modelc curtains 52 pages of live information and 24' of the latest models, also a full Agents Wanted. line of supplies for Model Building. Send 16c Agents Oro Into Permanent Business N cal Health. for your copy. \ \'ading River Mfg. Co., 672 H tal reqired. Should net $2500 to $5000 first year. Tobacco or Snuff Habit Cured or o pay: $I Itoanlivay. Brooklyn. N. Y. Guaranteed products needed in every home. Re- if cured. Remedy sent on trial. Superba Co., peat sales -big profits. Old established concerti SII, Baltimore, Md. whose products are knew-in everywhere. \I any make (omobiles Pyorrhea i RigF s Discase- Bieedine or Swollen sales of $40 to $75 per day. Practical sales Gums) -hundreds have been helped by our suc- Six Gold Initials for your auto. 25e. inn. helps, advertising matter furnished. Sample outfit cessful home treatment. Purifying, healing, pre- lafave, 134 W. Park St., Watertown, N. Y. free. Write today. W. T. Rawleigh Co., $09 ventative. Full month's treatment, consisting of Liberty St., Freeport, Ill. a very beneficial massage paste and an antiseptic American Made Toys. Make and Sell Your Own Goods. Formulas by tooth.eleansing paste to be used in glace of your Expert Chemists. Manufacturing Processes and ordinary detnrifice, together with full directions for Home woraers tad An Opportunity Secrets. Write for Formula Cha- for treatment, $1 postpaid. Or wiite for free and on large scale to stake Trade Catalog. scale manufacturers pin Mystic Company, Washington, D. C. Booklet "R," Pyorem 111g. Co.. 439 Seventh St.. American Metal Toys. Army, Navy, Machine Brooklyn, N. Y. Gum -, Cantons, Warships, Indians. Cowboys, Reliable Agents and Deaiers anted in every Get Conscious Wild Animals, Whistles. Bird. Whistles, Re- city in Iowa, Nebraska, Kansas, m Missouri. State Well- evolution the new Science. ligious designs and other toys and novelties. qualifications. Splendid proh,o, ittou for right men. Makes super -health, super- energy. and dynamic industrious have Central Radio Company. Inc.. Independence, Mc. courageous and personal. Detail free. Alois P. Greatest chance for people to Swabcdat No. an independent business. Enormous demand for 5356 Berkeley Building, 19 West cheap toys offers unlimited field and great future 44th St., New York City, N. Y. all over States and foreign countries. Ex- Help Wanted. perience, o ols not necessary. Hundreds and Detectives Earn Big Money. Excellent oppor- Miscellaneous. more mader et:mplete per hour. Casting forms, nvtity. Travel. Great demand everywhere. Fas complete outfit from $3.00 up. We buy these dilating work- Experience unnecessary. Particu- Sportsmen- Trained beagles, rabbit, fox, coon, goods paying used prices. Attractive price, of. lars free. Write, American Detective System, skunk. squirrel and oppossum dogs, bird dogs, pet ¡erred for painted goods. A strictly business 1008 Broadway, New York, N. Y. and farm dogs, swine, rabbits, pigeons, pheasants, proposition. No one need apply unless he means goats, 100 varieties of blooded stock. Circulars Be a Mirror Expert. $3 -flu a day; stare t nu business. and information furnished free. 10e. Violet Hill Kennels, York, Pa. Booklet home at first: no capital; we train, start you We have no sales agents and we warn against Electrical Tattooing Machine. 53, 55 ands: imitations. Soldier making and silvering mirrors, French method. worthless and cheap Toy Free W. R. Derr, Pres., 579 Decatur Catalog for stamps. J. H. Temke, 1019 Vine, Manufacturing Co., 32 Union prospectus. Square. New York. St., Brooklyn, N. Y. hap.. Cincinnati, Ohio. Boys a collection propaganda issued Stop Daily Grind. Start ilvering mirrors, auto -Start of Books. during the war: sets 50c. and 5c. Loren Hurd, headlights, tableware, etc. - Plans free. Clarence Madison, Minn. The Amateur Etoctrician. Pocket size, 20c Sprinkle, Dept. 48, Marion, Indiana. Big Mail Free! Just send your Mama W. E. (coin). Joe Tillberg, Proctor, Vermont Wanted -Picture play writers. Big pay. Ns Fitzpatrick. Box 722, Chicago, - Illinois. Four Books. Seer A. C. Emmerich, Nativity, perience unnecessary. Best course how to write Egypt, Cana. 20c. Klein Co., Brandon, Minn. and sell plays. Prepaid $1. Address Studios, Here. Fellows. is good smoking at postilar S36 Carpenter Ave., Oak Park, Ill. prices. Pure tobacco. positively no randy or dope. Your Opportunities have come at last. Secrets In twelve -ounce packages. Home grown. 70 cents. $1. Guaranteed. Walter Stine, Ashland, Armature Winders make big money. We wi.l Granulated smoking, 65 cents. hurley smoking Pexposed,a., R. D. No. 1. train you for this interesting profession in 3 to 6 and chewing. 65 cents. Postpaid te second zone. The Vest Pocket Lawyer. in plain lauguag... months, and will find you a good paying job Samples on request. \looredale MacLaren, New Will answer any question. 112 legal forms. Cloth while you are learning, so that you can earn your City, Rockland County, New York, 82 miles from binding. 335 pages, $1.50. Money back if not way. Write for special proposition. State age New York City. satisfied. Hazzard Company, Box 1, Vanderveer and education. School of Engineering, Dept. R -62, 373 Broadway, Milwaukee, inVis. Kentucky's Extra Fine chewing and smoking Park, Brooklyn, N. Y. tobacco for sale. aged in bulk, hand prepared and Subscription Agents-Rest magazine proms,. Earn $25 Weekly, spare time, writing for news- in twist. ready for use, nice. rich and mellow. tion. Make big money. Write for particulars. papers, magazines. Experience unnecessary; de- Satisfaction guaranteed. Order quick before it Concordia Magazine, 9 -A Water St., York, Pa. tails free. Press Syndicate, 5665, St. Louis, Mo. is all gone: 8 pounds, $6.80 postpaid. Reference. We Buy and Sell back issues of Radio Amateur Learn Drafting. Draftsmen snake good money. 1st National Bank here, Bartiwell, Ky, News and Electrical Experimenter. Boston Maga- Take up this interesting profession. but be sure you zine Exchange. 109 Mountfort St., Boston, Mass. get your training in a real Engineering Institution Novelties. Card and in a school which will give you a good well Be An Expert Player. For full informa. learning the business. Novelties. tricks. puzzles, jokes. Wireless ap- tion consult the Encyclopedia of Games. Price paid position while you are Write today for special offer to limited number of peralus. Send four cents in stamps for catalog. urepaid 50 cents. J. R. Kerr. P. O. Box 291, Radio Specialty & Novelty Co., 6243 Station St., Brooklyn. N. Y. ambitious young men. School of Engineering, Dept. R -63, 373 Broadway, Milwaukee, Wis. Dept. B, Pittsburgh, Pa. Special Service Magazine published monthly to Motion Picture Show, with stage appearance, help you make money. Plans, schemes and ideas. screen and continuous pictures. 50e. Rempe, Stamp brings descriptive circular. J. R. Kerr, Instruction 2827 Myrtle St.. Oaklad, Calif. O. Box 291, Brooklyn, N. Y. P. Before Taking Any Electrical or en.tineering Genuine Indian Baskets. Wholesale catalogue. How to Make Wireless Sending Apparatus. course, write for details of our special "Earn- Marion Gilhams, Highland Springs. California. 100 pages -SS illustrations. Written and pub- Your-Way" proposition. Our wonderful plan of lished entirely for the wireless enthusiast who placing students in part-time positions makes it wants to make his own radio apparatus. Con- easy for you to become an Electrical Expert or Office Devices. tains more information on "how to make it" Electrical Engineer. Courses in Electrical En- We Buy for Cash. Rebuild and Sell for about than any other hook we know of. Paper bound. gineering, Practical Electricity, Armature Winding, half new price, multigraplts, addressing machines, 85c. postpaid. Experimenter Publishing Co., Book Starting and Ignition, Radio and Drafting. Learn duplicators. etc. Don't he misled by firms in- Dept., 230 -A Fulton St.. New York City. one of these interesting professions in our big fringing on our name. \Ve are the original Office How to Make Wireless Receiving Apparatus. laboratories. Thorough intensive training under a Device Company, 154\.soots[ Randolph. Chicago. 100 pages-90 illustrations. Only strictly modern staff of 90 electrical experts. Pleasant surround- ,,..,....,...... ,,..,,..., radio apparatus are described in this book and ings. Fraternity House where you can live at cost the illustrations and descriptions are so clear sports, athletics, boating. Write for big free post- Phonographs. and simple that no trouble will be experienced in paid illustrated llbook. State age and education Build Your Own Phonograph. Big saving. making the instruments. Paper covered, 35c. ad w ll i you the course for which you Blue prints. parts price list. instructions free. postpaid. Experimenter Publishing Co., Bonk are best fitted. School of Engineering, Dept. R -61. Associated Phonograph Co., Dept. R -N, Cincin- Dept., 236 -A Fulton St., New York City. 373 Broadway, Milwaukee. Wis. nati.

www.americanradiohistory.com Radio News for December, 1920 Printing. (Wireless-Continued.) (Wireless-Continued.) Amateur Apparatus bought or motile in LOU Name Varus, leatherette ease. i3t'. Agent. A Real Buy. DeForest Type '1200 tuner. St; All daily. Information, Wolf, Marconi Valve, Class 1, $0, Clapp Eastham Type cordance with The Radio Buyers' and Builers 5u, profit. $6.00 Handbook invariably re -sells very profitably. Study Orsk J. Station E, Philadelphia. %RD audios panel, $11. This apparatus is AI, never used. Wireless. Box 353, Calais, Maine. my June and July display advertisements in Q. 2000 Gummed Labels I x 2. s1.23. (."rest Label S. T., sec why, and get your copy now. R. Clark, prices. Other sizes and styles. Simplex For Sale-Ltrose coupler: Jove detector D: Barnes Ind., Newton, \lass. House, 3253 North Herndon Street. Chicago. Forest detector, Conn. V. condenser, Murdock phones No. 55, 3000 ohms. Grid Condensers prepaid anywhere, <.:,u each. 9.000 Two Color labels, $1.25. Irvin J. Wolf, Fixed Cond., ]lurdock Century buzzer, key. Roger Shaw, Concord, Mass. Ingenious invention makes it possible to hermet- Station E, Philadelphia. ically seal very small capacitances io very small Tressa Long and Short wave tuners reduced i compartments. Not exposed to chacecs of armes Attorneys. price from $15 to $10. Type CS Regenerative phere. 100% efficiency performance test. Works Patent tuner, effective range, approx. 150 to 500 meters. It !reds with any type tube. Crescent City Radio Com- Minions Spent Annually for ideas. Type AS, effective range, 000 to 5,000 meters, Department and profit. Write to- U., P. O. Box 1104. New Or- acted. latent yours Type BS, effective range, 3,500 to 20,000 meters. lpany,eans, I.a. day for free 1, tk- tell IIo i , yourself, wavelenth. Send for circular. Robert Sagebiel, t;. how to invent, ideas wanted, (tow r e help you i W. Second St., Dayton, Ohio. Listen to 'em Buzz In. IL -\. l'In oo c sell, etc. :fol Patent Dept., Amerient, Industries, dessers, 40c; Grid condensers, 40e; Grid.leak con- Inc., Nashiegton. It. C. Radio Paper. Radio telegram blanks for veur densers, 60e. We carry all standard stock. Vacuum station -for delivering messages and for station tubes a specialty. French bulbs, $20. The ('oast file. This is the last word of efficiency tor super. Radio Distributing Co., 301 Second Ave., Asbury Patents For Sale nsitiVe receiving sets. Blanks well printed on good Park, N. J. for use grade of telegram paper. Hundred sheets per pad. Patent Pencil Lighting Attachment. Our Special for This Month. This n u!h w today for a supply of these forms day u, night; lease for royalty. Jerrell Bennett, Send your order are making a special offer on Chelsea Apparatus. make perating a toape vi tar. Texas. and install a system that will and for one month we area making an otter of cash, or send your order Patent for Sale. \lost educanou.,' to.. On: pleasure. Enclose M. O. or i less than list prices and all goods fully guar- and blanks will eke shipped collect. Price: One wheel r roe on between single h ,rizoalu : anteed and will be shipped by insured hundred, twenty cents; $2.00 per thousand. Spe- o pf J ly this post paid. We handle all the best grades of radio cord or rope. Patented the twentieth Radioform Printers, 207 year. Hey iro Somata, Gyl Chestnut St., Yakima, cial prices on quantities. apparatus and in practically make shipment the . Wisconsin. \\inch. Baker Bldg.. ltac :ne, same day the order is received. Radio Mail rder 2222 o,,"",,,,..,""',,.',,,,.., .,.,,,,',,.,",,,,,,,,.,,,."., '.. Prepaid to You. One each of the lull, wine: Supply Co., 533 \ \'est End Ave.. New York City. l'inofogrepity DeForest Honeycombs, L -50, $1.30; L -3110, $1.35; N. Y. $3.20. Western \ou gil it here. L.400, $2; L -11100, $2.70; L15UU, DeForest Radiophone Transmitter :old radio You Wallt Best Results. set, type ('1\'.534, tesfitat4., ('riots "i'c up. 1Vill not fade. Send for price Electric head apparatir,. ]tare bargains. Pine phosphor bronze list. Iliad, Wareham, \lass. ohms, $9; Amarad duplex detector, type C, $1.50, aerial wire cheap. 120 Christie St.. Ridgefield Wireless, Box 353, Calais, Maine. Park. N. J. Photo Silk, liow to Print Pictures ott. Booklet. Duly $2.50. Prepared photo silk per package only Grid Condenser that will kn nek 'em cold- Cat Sale- -Slightly est.] wi rrlss goods. Stamp for 52.oe. F. Irsa, Elizabeth, N. J. you beat this? Complete mounted grid condenser list. G. M. Scheib, 6r243 Station St., Pittshnrgh, for 30e, with our usual guarantee of 'Money back Pa. if not satisfied." Amateurs- try us once and you Navy Couolers, $11: \arionierer-.. $ Ampli. Rubber Stamps. will try again. Postage 3e. I.ive sire agents fors, $35: Regenerative sets, $411; transfnnners. Rubber Stamps Made to Order. Ni taddo0 wanted. Radio Testing Station, Binghamton, sockets, tubes. switches. knobs. binding posts and C lllll patty, Zanesville. Ohio. p:. ts. Sets madeade to order. Jerome Ha as, 2011 lllll Radio Phonists Attention. High voltage gem A t l:un ie Ave.. Atlantic City. N. J. Song Poems. trat,rs. We supply these motor generator set" Bakelite Tubes and Panels, all leugrlt -, ,L arne- Ill various capacities, esptciall'y designed for tens 3 /16 2,4e is Anything in music, -rite t., Wm. E. thick, square inch, switch pints If it also low powered rotary con - 8/32 3c. Giles Music Studio. Blanchard. Wash. radio phone work, with nut DeForest self cleaning switches; erters, dynantotors. fractional II. P. motors other radio apparatus. Meade 4akelire Radin Ap- Song Writer's Manual and Guide t no free. and storage batteries. We are in a position to paratus, 975 Putnam Ave.. Brooklyn. N. Y. Contains valuable instructions :und advise. Sub. solve your generator problems and supply tim- Just Off the Press. Design and Construction suugiawn,s for examina ' . Vn t. will furnish mit idness; to fill your rettoiremeets. We also 1 a v of Audios Amplifying Transformers (Radin and opt right and facilitate publication or sale. the standard RAY -DI -CO phone sets complete. Gaiety Bldg., New Audio -Frequency Types). By Edward T. Jones, tKnickerbocker Studios, 311 IA. furnish guy part thereof. In fact, if it is York. late Associate Editor Radio Amateur News. The radio equipment of any kind, or a set of your transformers shown in this book have never been own design. write stating your wants and described in print before and have usually been Scenery for Hire. become acquainted an with our service. R:\Y- considered a manufacturer's secret. The designs D1.CO (not Inc.), 2033 .1. N. Clark St., Chicago. arc very rugged and simple. A hook that every Collapsible Scenery to, au pint s. Ameba III. t; sin, Philadelphia, l'a. radio "Lug" sleuth' have. Written so you will Slate Panels for That New Set. This

www.americanradiohistory.com 422 Radio News - for December, 1920 (Exchange-Continued.) (Exchange-Continued.) (Exchange-Continued.) For Sale -Audiotron, $8.00: 1" ,park coil, SS.in: Wanted -Two barnt -out \" l's must have good Look -Electro Dynamo, Ten IYollars. 'twenty 3,000 -meter receiving transformer, $9; key, $1; plate and grid. Will pay cash for first reasonable thousand meter tuner, Eight Dollars. Two thou- Pancake tuning coil, $2; 2 -cell bicycle lamp, $3; offer. Thos. Pillsbury, Enid, Oklahoma. sand meter coupler, Four Dollars. Omnigraph, 3 lbs. No. 27 magnet wire, $2.50; wire 4x4 logy Set of Hawkins' Electrical Guides, never used, No. 2, 30 dials, Fifteen Dollars. D. C. Kerr, Ragnar Westuran, $2.50. And others. 102 17th $S postpaid. Howard Osborn, 340 Peach St., Vine. Woodstock, Ontario, Canada. St.. Cloquet, Minn. land, N. J. For Sale -German two -step Telefunken sub For Sale --3.000 -meter Navy type loose coupler. Will Exchange chemical laboratory for wirele s mariste type amplifier. Described in December, All bakelite. Nearly new, $20. Washington High sending apparatus. Lists exchanged. W. D. 1919 RADIO NEWS, page 271. Natalish,-'68 West School Radio Club, Washington, Penna, Myers, Vandergrifr, Pa. 56th St., New York City. Telephone Circle 658. Wanted -half- kilowatt sending condenser, rifle Vibroplex Bug -Brand ew, never. used ,in Cabinet-Grebe CR -3 in conjunction with new actual work. Sell for $12. Need cash imme- audion detector and two -stage audio frequency as part or all cash. Ralph Underwood, Agra, amplifying Kansas. diately. John Mrowca, Cove Hall, Harvard, Cann. cabinet. First $95 money order takes bridge, Mass, both, including tubes. G. N. Garrison, East Or- For Sale -Two Western Electric V. r 2 -- ange. New Jersey. ammeter, 1,4- Hilowatt Acme Transformer, $15.00. Jack $12 each. MiliAmmeter, $9; hot wire Moore, 6015 Ross Ave., Dallas, Texas. sockets For Sale- Regenerative set, audion detector and receivers, $42. Chemical set, $16. Modula ion transformer, $5.50; variable acondens- Selling Out -DeForest coils LL 1500 at $2.75; Charles Jones, Irvine Ave Sharon, Pa. er, $3.75; 2 rheostats, $.75 each; mineral de- LL -100 at $1.35, and condensers CV -1000, $6: tector, $1.50. This goods used one hour for CV -1500, $8; Tron panel and bulb, $10; 15 dial Wanted -Automatic 3000 coupler, pistols, revolvers, rifles, radio telephony. Sidney Sussman, 2917 Jamaica (Continental) Omnigraph, $18; -meter shotguns, any condition- Natalish, Stockbridge, Ave., Richmond Hill, I. I. $4. Harold Jones, Ferndale, Wash. Mass. Portable wave rgeneratiye set, (Cabinet) short For Sale -1'ypc 94 long wave receiver. 12 V. 100 Amp. Willard Battery, $15;vo;t- $35. Miller, 33 Windsor Place, Brooklyn, ,N, Y. 300 to meter 0-90. ammeter 25.0 -175 with lamp, $13. Edi- 18,000 meters, practically new-, Price, $25. Wal- son phonograph (cylinder), $0. Philip Stout, DeForest Unit Panel Type receiving set, with ter Bone, Box 709, Carneyville, Wyo. Knoxville, Tenn. complete set of coils mostly Litz from L-25 to L.1500; -0015 and .001 Vernier condensers, Galena Will Swap Pope motorcycle twin. in good con- 2 Duplex Varlo- Absolutely New Variometer, R( detector and audion socket with change -over dition. motors, generators, etc., for screw cutting oupler. RC'1 coupler, made by Universal Radio lathe with chuck and countershaft. Write, Mignon switch, hest triple coil mounting, rheostat and no giving Co. and RCL4S receiving outfit (special). tentimneter, condenser switch, telephone all specifications. Correll, Thorn St., Chicago and 2 fixed primary Spark gap, 14" spark coil Murdock and plug, etc. A $H0 set Address Heights, III. E. 12S Pleasant Ave.. lick for $75. condensers. Donald Sharp, C. F. Allen, Box 1504, Providence, R. I. Hamburg. N. Y Columbia code teaching records; cost eight, will For Sale -Knapp Dynamotor, two variable con. sell for five dollars. Good as new, L. E. Felker, All for $8; 33 Wireless Age. 20 \Vireless World, densers in cabinet, Brandes Trans -Atlantic phones. Madison, Maine. S QST, Year Book, Call Book, Bishop's handbook, Enlarging camera, developing film tank, Remler Moving Picture Navy Manual, Arlington coupler. $0. John V. T. socket. For particulars, address R. L. Len - Machine, "Provers No. 5". with- Smith, 3650 Marvine, Philadelphia. hart, Hamburg, Pa. out lens, excellent condition, will sell or exchange, $50. An opportunity, address David Forde, Jr For Sale- P Soo DeForest ludion control panel. Sell-14" telescope. magnifies 12 x. 55.50. 2523 So. Garnet St., So. Philadelphia, Penna. $18. 20'c off on DeForest honeycomb coils, L-25 Albert Kauzmann, 100 Hamilton Ave., New to L -400. Howard Strong, Smethport, Pa. Rochelle, New York. Sell -E. I. Co. Vario Selective ennoler. $6.50. Radioson Electrolytic detector, $5. All brand new, radio wanted. Bargaln- 4-K.W. panel transmitter, S35: 2 Mur- Used Commercial equipment sections. Navy Duluth. never used. H. Friend, Sand Springs, Okla. State description. prices, first letter. Address dock Kohnitz, Radio. Radio. 103 Bowen. Independence, Missouri. For Sale- DeForest receiving set and oilier an. Bargain -Ducks a NvN. coupler. Never paratus. Nearly new. Stamp for list. sell used, works perfectly. Worth For Sale- Complete amateur radio station. Get Will " $27.50, sell, $17, Mich. separate and cheap- Eldred Flail, Village Hall, no less. Jay Edmondson, Milton, Iowa. my list. Harold Schulz, Cheboygan. Solvay, N. Y. For Sale -Arnold Navy type 30on.meter eounler, Let's Swap! Buy! Sell! \\'hat'ye gat' - The Complete Radio Station 9 LA for Sale-- little used, $14; Marconi VT -1, Si, H. B. Dick, Whatdyc nt? Dime quarterly. Swap Bulletin. Ilargain- lK.\\'. transmitter, 94 -K.W. transformer, 40 Westernview St., Springfield, Mass. New YorkDetroit. Audio-Tron and one-step amplifier; spark and arc p to 20,000 meters, Write at once, L. A. Why Not Buy a good automobile generator ana For Sale -The Radio Apparatus Co. Type 94 charge your and your friends' receiver, 18,000 meters, complete with Hendricks and F. S. Fritts. Wakeeney. Kansas, storage batteries? long wave We have a number wing necillating inductance and control cabinet, of generators. All O. K., For Sale- Two-stage amplifiers without cabinet. mechanically and electrically. Correll, Thorn St., complete with tube. A -1 condition, $50: 1 K.W. bakelite mountings. nickel finish. $37. Guaranteed Chicago Heights, Ill. Thordarson transformer, $20. Roy E. Slayer, 308 perfect or money refunded. H. Geibel, 1457 N. Monroe St.. Kalamazoo, Michigan. 28th St., Philadelphia. Pa. For Salo -One complete receiving et; one audiotron cabinet with double filament Get a Real Storage Battery -"Iron -Clad Exide" -meter bulb, $15. For Sale -40011 C'lann.Eastmmn coupler. Also No. 7 American model builder set complete cells, 150 amp. hours, $10 each; Edison cells, 150 $10:.001 mitt. Universal variable condenser, $2.50: with condi- motor, $15. William Davis, jr., 231 Stanley amp. hours, $7.50 each. All in excellent E. I. "Radiocite" detector with mineral, $1. Write Ave., ('anon City, Colo. tion. New 20 -amp. rectifier tube, $15; 4-H.P. G G. Greeno 137 Glen St.. Cl. ns Falls. N. Y. steam engine and boiler. $15; steam turbine. $8. For Sale -A, A.P. V.T. tube, amplifier oscilla piano slaver. A. R. Sl artana, 615 N. Washington St., Balti- Exchange -Mahogany ,celim tor, has burned 100 hours, $5 postpaid. A. S. more. Mtl. make. with music rolls, cost $200, for complete Decrees, Hartford, Mich. wireless sending outfit. Faulkner, 349 Summer Sending and Receiving Station for sale. 4K.W. St., Paterson. N. 1. Complete. all most new. one and a half inch Thordarson type "It" transformer; Thordarson spark coil set sale. Swan- Dc Forest P 300 auction tilt rand inn ampli for Write John E. Codman, Os. trap- former; 6 sections 8 by 10 glass plate 4116 Spruce St., Philadelphia. Pa, condenser. Quick break rotary. Murdock line fier, T -200 Multi -wave tuner, twelve honeycomb protector. ('IappEastham antenna switch. Duck's coils 1,25 -L -1500, two tubes, Baldwin amplifying For Sale-Wireless apparatus about two weeks Navy coupler. Mignon type RW3 undatnpea re- phones -plug attached. "Electro" radiotone and old. Write for list. Joseph Christman, Eaton, ceiver Brandes phones. Every instrument guar- complete aerial, four ires. stranded. about 100 x Ohio.

70, . =ix -foot lead -in, high grade insulators, lead -in anteed. Certified check for $170 takes all. 1 Must Sell-Beautifully R \W3 guaranteed perfect, $75. Radio insulator, 600 -volt lightning switch, cable, etc. mounted and wired and Mignon absolutely complete sixteen panel SDB, 727 Williamsport, Nest-never been used. Worth $240. First certi- DeForest unit Arch St.. Pa. set at fied $190 gets it, boxed, delivered. F. O B. Home great sacrifice. Never used. For particu- Bell -Pine. long model 11-flat cornet. $16; Omni- City School, Home City, Alabama. (Long Island lars write A. Boscow, 395 East 16th St., North, graph. $11.50. ('rystaloi detector, $3.60; Radio- P. 0.1 Portland, Oregon. son detector. never used, $3. Write for partial. lars. Stanley Reed, Lennon, Mich. For Sale -Murdock loose coupler. $5.00. Carl For Sale --3 DeForest type CV500 variable ccn- Staugaard, 4531 N. Rockwell St., Chicago, Ill, densers, each $2.50; 2 Connecticut new type varia- Bargain -Radio apparatus never used and back bles, each 52.50; 600V 100A ground switch, $1.50; numbers of the Electrical Esperimenter. Send For Sale -From Station 2N.W. (see photo in Murdock 55 'headset, 2000 ohms, $2. Everything stamps for list. _John. Rakosy, 331 E. 80th St., September Q.S.T.) 1 new Grebe CR7 receiver, C. O. D. J. K. Brennan, Eolia, Mo. New York. N. ,i. $110; 1 Magnavox telemegaphone, new, $45; 1 Rotary converter, excellent condition, 220v d. c. For Sale- (hnnigraph No. 2. Ir.. A -1 condition. Bargain s-New' DeForest honeycomb coils: to 15nv a. c. at a current value of 10 amps., $115. Save money. Complete with dials and instructions, L -25; two L50: ío250: two L -500: three L -1500. 1 new remote control automatic starter, Marconi $12. H. W. Brady, 546 Bosart Ave In- with three -plug unit panel, $20. Arnold variable type. $20; t Weston A. C. voltmeter, 0 -150 volts dianapolis, Indiana. fine case .001, rúgged construction, mahogany 7" face hack of board mount, 1 Roller Smith A. C. Omnigraph Wanted (Cost $151, for $c. :,n. "Superior' Brandes photnes, 0.10 -Quote lowest price. Bow- meter, amps. 7" face back of board mount, ers, 531 Madison St., Brooklyn, Y. $5.50. Many other instruments- E. G. Baier, new condition, each $20; both mounted on black N. 253 Ninth St.. Brooklyn, N. Y. mik panel with supports. $40. 1 Type Tl Thor- For Sale -Loose coupler. range 400 miles. $12. darson transformer type) $15. All Francis Bailey, Sale Pottstown, Navy up!rr, (old 4-K.W., 23 Harvard St Worcester, Mass. For -1 type the above absolutely guaranteed. Act quickly, the new, $20, 2 -panel type, variable con- co-t for $17. above are really being sacrificed. am leaving the .22- Calibre Remington Takedown rifle: Duplex 75 -ohm phone, with head- I densers. $3 each; one States. You to pay all transportation charges. Orchestra Snore Drum. Want high grade re- band and cord. $1.30: 65 chemicals, test tubes, ceiving Letters serewv i. Ralph Brooke Austrian, cabinet. Alnustrou, 5774 8th St., Muskegon, graduate, and other chemical apparatus, all for 694 Mich. Broadway..n New York City. $10. Radio keys, $1.25 each. Murdock phones. $4: loading coil, SO. Numerous other radio and Genuine "Juniter" Aerial Wire. Seven strand. Sale -Small Crystaloi detector, $1..0; I" spark electrical apparatos. Send for list. Alfred Mihs- Number 22 solid copper. 100% conductivity, coil, $4; 2 Leyden jars, 1% pint, $1.50; 400n 1% v chik. Freehold. N. J. cents per foot. $12 per thousand. No C. O. D. s. R.P.M. Universal motor, A.C. or D.C.. $5; 15 per thousand. Send a unit crystal detector, $2: 10 coils No. 36 S.S.C. Sale Duck improved receiving transformer. pounds postage. Also -$15 limited supply of seven strand So, 22 tinned, copper. 500 feet to coil, $1 each. Chas. Whartenby, $9: $2.50 detector, $1.50; 17 plate variable, $3.50. 801 VI'. suitable receiving aerials. 1 cent per foot. Elm, Enid. Okla. 700 -meter cabinet set, including de. for Also oupler, Lee A. Bates. 8 Moen St., Worcester, tector, fixed condenser, phones and aerial wire, Mass. For Bale -- Regenerative receiver, auctions and $7, -i t spark coil. 81.30: condenser, 5.50; Want to Buy-Baldwin type "E" or "F" aerial complete, $40: K. & D. motor, $2.50; Mesco spark gut, $.$0. Write Edward Srntm.m, .ir- phones and omnigraph, Alex Serna, Lehigh, 10-volt dynamo, $3. E. Trachsler, 14 Chestnut St., canum, 01110. Okla. Paterson. N. J.

Exchange or Sell -Indian motorcycle, one cylin 1 Murdock 1500 -meter loose coupler. $10.00; For Sale or Ezohange- -Pair Brandes phones, der. 4 H. P. engine is in excellent condition. for 1 Bunneil's mascot 23 plate condenser. $4. Com- 3200, $10, or exchange for Packard or Thordarson high class receiving outfit with. V. T. or sell for municate with F. R. Summerville, 28 Orchard l,- kilowatt. Dehert, 867 McPherson St., Brooklyn, $45.00. Ralph Petranek, Muscoda, \Vis. Place. Ridgewood, N. J. N. Y. Will Sell- Chemicals and chemical, electrical, Sale Quick -Audiotron bakelite control panel, For Sale -Arnold Navy type loose coupler worth and wireless apparatus. Send 5 cents for par- $5: 4.K.W. Blitzen transformer, $8. Carmi Mil- $23. sell for $15. Arthur Miller, 235 W. 110th ticulars. Karl Petersnn, Weldon, Illinois. ler, Spring Valley, Illinois St New York City, N. Y.

www.americanradiohistory.com Radio News for December, 1920

of magazine subscriptions expire this month! With tremendous advance of paper prices and labor it is certain that nea^ly all magazines will advance their Millions subscription prices at least from 25% to 50 %. BY ORDERING NOW YOU WILL SAVE BIG MONEY. In announcing these wonderful prices it is with the absolute knowledge that our readers are offered the lowest prices for standard Magazines that it is possible to obtain anywhere. Only by special arrangement with the publishers are these prices possible, but to take advantage of them. Magazine you must act quickly. Don't delay, do it now. This offer is so good that of necessity it must be limited in time. Direct From Just think of buying standard Magazines at reduced prices in time for Xmas Presents, and they certainly make ideal Their Own gifts being a constant reminder for a whole year of a con- siderate friend. Just glance over our wonderful prices, and see Office to You. how we enable one dollar to bring yob. two dollars' worth, and then make up your list. When sending your order, don't forget to state where magazines are to be sent. But be sure /ou do It now. To- morrow means you may forget and lose this wonderful opportunity. quoted are for eubsetlbera In U. S. A. only, Canadian and Foreign subscriptions require additional postage.

BIG SPECIAL TO Radio News $2.00 Radio News "WIRELESS BUGS" &merlcan 6.00 Our Prhe Wireless Ag.' Reg. E'tentaitvemrlay Engineering 2.00 Illustrate.' World Prim Our 9.75 lind:o News $2.0f Regular Price $10.00 Regular Price Radio News Radin News Wireless 2.511 stadio News A.lnerudml Prie $2.00 Everybody's St. Nielolas U. 5 T Boy's Lite 2.00 Engineering 2.00 Qs Delineator 5 Itegrlla- Price Wireless World Ilu..dol0 2.75 Regular Price $4.00 Regular Price hullo News $2.0 Housewife 1.00 Regular Price $14.25 Radio New; Today's Radio News $2.00 Popular Science Radio News $2.0 Itegula- Price $3 0 ti 1,0.0 & Inventi 3.00 American 3Iagnxhe 2.30 Women's ilene I'om- Itadlo News $2.00 Regular 2.0( Popular Selene., 3.00 l'rirc 55.00 PanIon Silence & Inrrnthm 3.00 Rail :o 'Sows Wireless Age Si:::2.50 Our Price Resoles l'-ire $6.5, Regular Price $8.00 Silents & Inveennnn 3.00 6.75 Regular Price 57.50 Radio News S2 gr . Our Price SP. al e i Wireless World (lnudoto 2.75 "'Wit b 1 SpNciall llri. 4.50 Club (Radio Nlib NewsI Iterilar Prier $4.75 Msugaxine Price Mngnzinr Pelee SO Admllture $4.00 $5.75 40 Motor Boating 2.00 3.75 50 Amer :e:nl 2.50 4.25 60 Mntnrv's sumo.. ... 3.00 4.75 35 1107's Ufa 2.00 3.50 17 Ste(' all's Magazine 1.50 2.50 :u Iloy's MaWS1na 2.00 3.50 30 M;{9urds 3laltaxiue .. 1.65 3.25 70 turtary 4.00 5.25 70 (Piling 400 5.25

35 Christian herald 2.00 3.50 20 Pathfinder - 1.00 2.75 SO Cosmopolitan 4.00 5.75 50 Pictorial 3evlew 3.00 4.25 100 Country Idee 1100 6.75 60 Popular Science 3.00 4.75 70 Current Opinion 4.00 5.25 70 St. Nirbolas 4.00 5.25 $0 Delineator 2.50 4.25 120 Ssirnti.L. Auavlean.... 6.00 7.75 40 Designer .... 2.00 3 75 SO Srrllno-r's 4.00 5.75 Eversiws s 2.75 4.50 00 System 3.00 4.75 :511 Eitide (for Music Invers) 2.00 3.50 15 Today's liotls ssiHe .. - 1.00 2.50 50 Fled had Streun; 2.50 4.25 45 Wireless Ago 2.50 4.00 illustraIed t'arld 3.00 4.50 40 Womarí s Dome P..o 00 lfh eery Dige.e 4.00 3.75 hellion 2.00 375 SO Melrolndlau 3.00 4.75 SO World's Pork 4.00 5.75 37 Moslem Prisealn 2.00 3.60 50 Youth's CamP.udnu ... 2.50 4.25 GO Motor 3.00 475

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www.americanradiohistory.com s Radio News for December, 1920 Three Radisco Features One distinct feature of Radisco Service is the close co- operativeness of each individual Radisco instrument with the other, and the strength of signal derived from such contact is marvelous. The other two are the Radisco Variometer and Coupler described below. It is impossible to go wrong when you use them together. Radisco Variometer Like all other Radisco products it has been produced to anticipate and supply the demand for a good short wave instrument, qualified to stand the acid tests of radio work, and built at a price consistent with the cost of manufacture, which has always been a Radisco characteristic. For the radio man who desires an instrument of this character, our Variomet r makes a distinct appeal. It is made in one size and of one quality, the bes:. The extreme dimensions are 434" high. 3" wide. F" deep and the shaft is f %" brass, just the right size to fit the number 09 dial; forms are carefully turned from thoroughly seasoned wood and snbstantial brass bearings provide'.. The price is strictly an innovation and shoulc appeal to the most conservative. No. I Variometer $7.00 No. ID Variometer with dial $8.50 Shipping weight 3 pounds

Radisco Coupler Specially designed for use with No. 1 Variometer The stationary winding consists of 37 turns in groups cf six turn- :nd single turns. Strength and high insulation insured by use of Bakelite cubing. Brass bearings support thoroughly seasoned wooden ball; brass shaft of standard size to fit the No. 97 Corwin dial projects far enough for Coupler to be readily mounted. The whole instrument is finished off on a neatly varnished wooden base. No. 2 Coupler (as illustrated) $8.50 No. 2D Coupler with dial $9.75 Shipping weight 3 pounds The agents listed below carry all Radisco products and they will be glad to consult with you on the new Radisco Coupler ALBANY, N. Y. LOS ANGELES, CALIF. PORTLAND, ME. Shotton Radio Mfg. Co., The Wireless Shop, Atlantic Radio Co., 8 Market St. Sir W. Washington St. 35 Temple St. ASHEVILLE, N. C. Hi -Grade Wireless Instrument NEW ORLEANS, LA. PITTSBURG, PA. Co. Rose Radio Supply, Radio Electric Co., 604 Gravier St. 3807 Fifth Ave. BALTIMORE, MD. Radio Engineering Co., NEWARK, N. J. SEATTLE, WASH. 614 No. Calvert St. A. H. Corwin & Co., Northwest Radie Service Co., 6o9 Ave. BEINVILLE, QUEBEC, CAN. 4 West Park Street Fourth Radio Mfg. Canadian Co. SCRANTON, PA. BOSTON, MASS. NEWCASTLE, PA. Radio Mfg. Co., Shctton Mfg. Co., Atlantic Radio Co., Pennsylvania Wireless P. O. Box 3, 507 Ave. "8HA" 88 Broad Street Florence Branch 8 Kingsbury St., BROOKLYN, N. Y. Jamestown, N. Y. Kelly & Philips, OMAHA, NEBRASKA 312 Flatbush Ave. O -B Radio Supply Co., ST. LOUIS, MO. 406 Brown Building CHICAGO, ILL. The Benwood Co., Inc., 13th Olive Streets Chicago Radio Laboratories, PHILADELPHIA, PA. and 1316 Carmen Ave. Philadelphia School of Wireless TORONTO, ONT., CAN. EUREKA, ILL. Telegraphy, The Vimy Supply Co., Klaus Radio Co., Broad and Cherry Streets 567 College Street Branch, Peoria. Ill. KANSAS CITY, MO. PROVIDENCE, R. I. WICHITA, KAN. McCreary Radio Supply, Rhode Island Elec. Equip. Co. The Cosradio Co., 4th & Delaware Sts. 45 Washington Street 1725 Fairmount Ave. Reoponsible Dealers: Write for interesting sales proposition on Radisco apparatus If none of the above agencies are in your vicinity, or do not give you the desired information on Radisco Apparatus, communicate with

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