Radio News for June, 1921 849

PP' CIRCULATION LARGER THAN ALL OTHER RADIO MAGAZINES COMBINED

20 Cents June 1921 Over 100 Illustrations Edited by H. GERNSBACK

"THE 100% WIRELESS MAGAZ!Nir ;

www.americanradiohistory.com CUNNINGHAM

po wER TUBES Type C -302 Demand 5 watt output Cunningham Tubes Price $8.00 The Name is etched on the Tube

C W TELEGRAPHY AND TELEPHONY WITH CUNNINGHAM TRANS- MITTER TUBES OFFERS THE ADVANTAGES OF COMPACTNESS - RELIABILITY - LONG RANGE - LOW POWER - SHARP TUNING TH A NSMITTFR TI JBE SPECIFICATIONS Output Filament Plate Conservative Delivery Model Rating Amps.p Volts Voltage Price Date C 302 5 watts 2.35 7.5 350 -400 $8.00 immediate C 303 5o watts 6.5 io. r000 30.00 Mar. 10th C 304 250 watts 15. 12. 4000 Max. II o.00 Mar. 10th Price of C 303 -C 304 fob. New York or San Francisco C 302 is mounted on the standard four prong receiving tube base. The larger tubes have special bases.

TNNIlvr'" A POWER TUBES are the latest product of the great Research Laboratory of the General Electric Co. The trade mark GE is the guarantee of their quality. Each tube is built to most rigid specifications. The output ratings are extremely conservative and in actual test deliver greatly in ex cess of their rated outputs. I GENERAL ELECTRIC QUALITY PLUS CUNNINGHAM SERVICE Address All Communications to TRADING AS AUDIOTRON MFG. COMPANY i 35 MONTGOMERY STREET SAN FRANCISCO, CALIF.

www.americanradiohistory.com Radio News for June, 1921 849

No. 766 Eveready Wireless Station Battery. No. 763 Eveready Airplane Standardized for use in U. S. Navy Wireless Battery. Standardized for use in U. S. Signal Corps Aviation Section

Four points of superiority in Eveready B No. 766 Wireless Receiving Battery Long Life have always wanted a -due to high quality of materials and refinement of VOU process better dry battery with lasting Perfect Insulation power; silent as a desert; stable as due to each cell being coated with paraffin and to over those four separation of cells with a rock. Read waterproof cardboard points that make Eveready B No. Noiseless Operation -due to efficient depolari- 766 the ideal Battery for your zation, thorough connection, and prevention of corrosive puncture and leaks receiving set. High Voltage Maintenance get an -due to right proportion- Then go to your dealer, ing of high grade ingre- dients and to insulation Eveready, hitch it up, and enjoy the marked increase in the effectiveness of your equipment.

AMERICAN EVEREADY WORKS of National Carbon Company, Inc. 226 Thompson Avenue, Long Island City, New York Chicago Atlanta San Francisco

VACUUM TUBE BATTERIES Every Wireless Operator Has Use for an Eveready Flashlight FLASHLIGHTS AND BATTERIES

A-21-TE

www.americanradiohistory.com CONTENTS

VOL. 2 FOR JUNE

PAGE

Money from Radio.... By H. Gernsback 853 The Radio Compass, Vacation Time Radio, By Lt. Com. Frank Luckel 866 By Arthur H. Lynch Who's Who in Radio. Professor Edouard Branly Awards of $loo Portable Radio Prize 867 Contest 855 Atmosferic Conditions in the Tropics, By Charles A. Reberger 867 A New Use for Radio 856 The Arc and Radiotelefone Transmis- The California Theatre Radio Station 857 sion By John F. Bront 868 Give Yourself a Radio Vacation, The Efficient Design of Vacuum Tube BY Armstrong Perry 858 Telegraf and Telefone Sets, The Radio Compass on Airplanes, By Jesse Marsten 87o By S. R. Winters An Efficient Loading Coil and No Dead End Switch By Allen E. Latham 872 The Washington Air Mail Radio Station, By S. R. Winters 86o The Construction of Intervalve and Tele- f one Transformers.. By Joseph G. Reed 872 Church Uses Radiofone 86o A Universal Receiving Cabinet, A Portable 200 to 90o Meter Regenerative. By Hilbert R. Moore 873 Receiver By F. J. Fox 861 Results Accomplisht with One Bulb, Construction of Ball and Cup Variome- By Albert R. Champlin 873 ters By Edmund S. Smith 862 Radio Digest 874 Audio Frequency Transformer Built from $10o Radio Accessory Prize Contest 875 Auto Spark Coil Secondary, Newspaper Uses Amateur Radio Reporters 875 By G. H. Stackpole, Jr. 862 The Thirteenth Tap, A. C. for Heating V. -T. Filament, By Bernard S. Greensfelder 876 By Professor M. Moye 863 Married via Radio..By Erald A. Schivo 8i7 A Tube Transmitter Using A. C. on the With the Amateurs 878 Plate By D. S. Basim 863 Junior Section 88o

A Mental Telegraf, Junior Constructor 881 plllil IUfl11111iUilUIIIIIU By Maurice Buchbinder 864 Correspondence from Readers 882 Washington's Birthday Relay Results, Club Gossip 883 By H. W. Kirwan 864 I- Want -To -Know 884 The Vacuum Tube in Radiotelefony, A "Scoop" for RADIO NEWS 886 By John Scott -Taggart 865 Judge Mayer Sustains Armstrong Patent 886

- 9./U/.!l/

RADIO NEW S is publisht on the 25th of each month at included. ALL accepted contributions are paid for on publication. A 233 Street. New York. There 12 Aton are numbers per year. Subscrip- special rate is paid for novel expe¢im,ihts ; good photographs accompanying tion price is $2.00 a year in U. S. and possessions. Canada and foreign them are highly desirable. countries, $2.50 a year. U. S. coin as well as U. S. Stamps accepted (no foreign coins or stamps). Single copies, 20 cents each. A sample copy will RADIO NEW S. Monthly. Entered as second -class matter June be sent gratis on request. Checks and money orders should be drawn to Sth, 1919, at the Post Office at New York, N. Y., under the Act of order of ELYPERIMENTEIì PUBLISHING CO., INC. If you should March 3. 1897, Title registered U. S. Patent Office. Copyright, 1921, by change your address notify us promptly, in order that copies be not mis- E. P. Co., Inc.. New York The Experimenter Publishing Co., 233 Fulton carried or lost. No copies sent after expiration. Street, N. Y., N. Y. The Contents of this magazine are copyrighted and All communications and contributions to this journal should be ad- must not be reproduced without giving full credit to the publication. drest to : Editor, RADIO NEWS, 233 Fulton Street, New York. RADIO NEWS is for Unaccepted contributions been sale at all newsstands in the United States cannot be returned unless full postage has and Canada; also at Brentano's, 37 Avenue de l'Opera, Paris. Publisht by EXPERIMENTER PUBLISHING CO., INC. 233 Fulton Street, New York City H. GERNSBACB, President S. GERNSBACX, Treasurer L R. W. DE MOTT, Secretary

www.americanradiohistory.com Radio News for June, 1921 851 JUNE ATLANTIC RADIO" ULL TIN

Have YOU Received A new idea in Radio Tele- phone Transmitting and Re- particulars of the ceiving Apparatus. Panels new are all g inches high, varying widths. Designed for placing side by side with binding posts in line for con- DE FOREST venience in wiring. Adapt- able to any operating re- "INTERPANEL" quirement, - short or long wave reception, - telephone EQUIPMENT? transmission, - one or two stage amplification, -etc., etc. Panels supplied with Special bulletin on request. or without cabinets.

A New Amplifying Transformer -G. R. 231A

Are you getting the most out of your tube A complete amplifier is m o r e than a mere assembly of parts. It consists first of the selection of units of correct electrical characteristics. An amplifying transformer must be more than a coil of wire and a core. It must have incorporated in it the results De Forest of engineering skill. Type 231A amplifying transformer is Hand designed specifically for the new Radiotron tubes. The design is right, the appearance Microphone is right and the price is right. Price completely mounted, $5.00 Furnished with cord Shipping weight 1 lb. and terminals for connection to binding posts. Transmitting Tube Rheostat Westinghouse Radio Price $6.00 Equipment The new five watt Radio- Ship. wt. 5 lbs. tron tubes require a. filament current of 2.35 am- Westinghouse Radio Equipment embodies peres. Type 214A is a the latest ideas in receiving equipment, 2 -ohm transmitting tube providing a most efficient set for telegraphs rheostat which will carry and telephone reception over the amateur This 2.5 amperes. re- and normal ship wave - length ranges. Dubilier Universal sistance is sufficient to The regulate the new tubes on Type R. A. Short Wave tuner, Stylo as high as a 12 volt sup- 307159, responds to a. wave-length of 180 Condenser ply source. This rheostat to 700 meters and is especially selective. May be used in audio and Radio fre- does not run hot scot may accordingly be mounted Type D. A. detector -amplifier, stylo quency circuits, for receiving equipment, a vacuum tube detector self- rectifying circuits, direct current inside of enclosed trans- 307190, combines transmiters and other tube transmitters mitting cabinets where with a two -stage amplifier. Both units up to 100 watts. space is often very limit- are mounted on JIicarta. panels attached ed. Like the G. R. re- mahogany cabinet. Simple mfd. to a polished No. 301 1000 Volts 0005 ceiving tube rheostats in design -easy to operate -single- tuning No. 303 1000 Volts 001 mfd. and grid biasing potentiometers, it is made in two styles. 214A No. 305 1000 Volts 002 mfd. for back of panel mounting and 2141.1 for surface mounting. circuit. Highly efficient. mfd. No. 307 1000 Volts 005 Type R. A. Tuner $65.00 Price $2.50 Typo D. A. Detector Amplifier 65.00 $2.00 Shipping weight 1 lb. Type R. C. (Combination of above in single cabinet) 125.00 Shipping wt. 1 lb. mounted

Radio Corporation Intervalve Transformer Model U. V. 712 Designed especially for use with the Radiotron U. V. 200 New Universal and U. V. 201 Vacuum Tubes. Pacent Price $7.00 Shipping Wt. 2 lbs. Plug General Radio "A" Battery Potentiometer Similar itr appearance to Type 214A, but wound to a re- New Patient Universal Plug consists of three parts; two moulded Bakelite Pieces, each with $4.00. (Stripping weight 1 lb.) sistance of 400 ohms. Price a recessed finger grip, and the plug with it connecting spring clip. The two Bakelite pieces are held together with a screw that fits into. a threaded brass insert. This screw is "dead" SPECIAL high potentials or extreme Just a few Roller -Smith Type T -A -W Rot Wire Ammeters, electrically, a necessary precaution when the plug is used with (0 -1, 0.2.5. and 0 -5 amps) still offered at the remarkable highs amplification. The plug may be used to "plug" in a telephone headset, a Microphone price of $5.00 each. transmitter, a manipulating key, a loading inductance, a plate battery, etc. In fact its VACUUM TUBES adaptability renders its name synonymous with its uses. Radiotron UV 200, Receiving Tube $5.00 Radiotron UV 201 Amplifying Tube 6.50 Price $2.00 Radlotron UV 202 5 watt Transmitter 8.00 Radiotron 1/V 203 50 watt Transmitter 30.00 Shipping Wt. 1 lb. ATLANTIC RADIO COMPANY, Inc. 88 Broad Street Branch: 15 Temple St. Boston 9, Mass. REQUEST "BULLETIN 14" Portland, Me.

www.americanradiohistory.com S52 Radio News for June, 1921

A COLOSSAL EVENT The new RASCO catalog just off the press is one of the greatest events in amateur radio. There are many radio catalogs, but the RASCO catalog is an event by itself or the simple reason that it Contains 50 Vacuum Tube Hook -Ups-UCs This is the one and only radio catalog containing such wonderful free information. Complete hook ups of all important vacuum tube circuits are given in clear diagrams with complete explanation. Just to name a fewerThe V.T. as a detector; detector and one -step ampline regenerative circuit; De Forest id- traudion ; V.T. to receive undamped and spark signals; Armstrong; circuits; one step radio frequency amplifier and detector; three stage audio- frequency amplifier; short wa.:., regenerative circuits; V.T. radio telephone; 4 -stage radio frequency amplifiers; radio and audio frequency amplifier, inductively coupled amplifier; Armstrong superautodyne; radio frequency amplifier and crystal deter` ,r; C. W. transmitters; self - rectifying l tube C.W. transmitter; V.T. transmitter with 6 volt battery; '...el''nhone using plate and grid modulation; one tube radio transmitter and receiver; experimental radiophone; r.. hipbone using Colpit oscillator circuit. This list is only a partial one. You most positively see this wonderful boc:, 'o appreciate it. It is made to fit the pocket -has heavy covers to withstand the wear c is tear which it is sure to have at your hands because it will be your constant companion. And Oh yes! Before we, forget it. If you are in need of the following, reinu"ber "RaPvo has it." These are only a few things contained in this catalog: Lugs, Nuts, Dials, Knobs, Washers, Clrystads, Lita Wire, Selenium, Cord Tips, Cap Nuts, Tin Foils, Name Plates, Spring Posts, Szitch Parts, Metal Ribbon, Carbon Balls, BID ding Posts, Switch Points, Switch Levers, Carbon Grains, Metal Pointers, Contact Points, Low Melting Metal, Carbon Diaphragms, Screws, Copper Strip, "Spaghetti," Name Plates, Sliders, Mica, Switches, Resistance Wire, Variocoupler Rotors, Test Clips, Condenser Plates, Condensers, Antenna Connectors, Threaded Brass Rod, Ground Clamps, Etc., Rte. The catalog contains lb° illustrations. On account of its great cost, this catalog cannot be distributed free of charge. It will only be mailed upon receipt of' 15c in stamps. 185 Illus- THE RASCO "BABY" simply unscrew the knurled cap and insert your trations GALENA PATENT SLIDING HARD crystal into the stand, screw home the cap which NICKEL DETECTOR RUBBER KNOB leaves a goodly portion of the galena exposed. The Rasco "Baby" The contact is perfect, while the crystal can be CUP AND BINDING exchanged quickly _-Hero it is boys! The smallest and most POST in less than three seconds. By efficient detector in the world-as well as slightly unscrewing the cap, the crystal can be the cheapest. Our illustration is full size, changed in position, in order to explore other and while the various details can be seen sensitive spots. The cstwhisker is of phosphor at a glance, we feel so enthusiastic about bronze and is attached to the horizontal bar by it that we must tell you all of its good points. means of a Mister head :crew. Can be readily First, there is a solid hard rubber composition exchanged in less than two seconds. Wires can base, size 11" x 13b ". We have not forgotten be connected to the bindinc Tort in a jiffy All two holes to screw down the detector. NICKEL HOLDER metal parts are nickte plated, and you will be Then we have the pickle holder and binding AND BINDING proud of this little masterpiece. post combined which holds the sliding, knurled, POST hard rubber composition knob. As you see, this p. , _ No. 1898 Rasco Baby Detector complete knob not only revolves in its holder, but can also QPS with galena crystal, prepaid ...... 50c be moved back and forward in order to explore c" each point of the detector crystal. No. 1899, The same but furnished with an Next we see the patent sickle detector cup and - SOLID additional piece of tested radioclte crys- binding post combined. This is a little marvel all R COMPOSITION tal, prepaid 75c by itself and will not fail to avoke your admira- .SASE tion. No clamps, no soft metal to fuss with. You Ready for distribution June Illustration Full Size 30th.

pe-30,2tl o 000

Cgl1PLIN)

803 804 802 801 RASCO DIALS Again Rasco is setting the pece. Here are our new Re co Dials. A revelation in every respect. These dials measure 21" diameter and are made in heavy brass. They have two extra holes to fit our No. 139A. B Knobs (see last month's advertisement.) The finish is silver white. Lettering in black enamel, inlaid. There is nothing on the market like it for finish. Consider the very low price of these dials. Note particularly that we make six different types with following denomin- ations: "Plate Variometer ", "Primary Condenser ", "Secondary Condenser ", "Filament Rheostat", "Coupling", "Grid Variometer." No longer do you have to guess what each dial on yotu set stands for, as each one is now plainly marked. Order by number. The large dial is shown in its full size. The smaller illustrations are only given to show style. 800 Designs Copyright 1921 by It. S. Co. Prices all styles ... , . prepaid ea. 30c SPECIAL Did you see 'our DEALERS' G A series of 6 dials complete prepaid, $1.70 full page ad in the May issue? We PPROPOSITION expected a good deal of business but we were actually Do not compare these dials with some other snowed under! It shows that Rasco- goods are wanted. In makes as there is positively no comparison between one week we filled over 600 orders and each and every them. Must be seen to be appreciated. Money order was shipped within 24 hours! Surely a record. back if not satisfied. We even filled orders for articles not listed. Our prices are low -our service the quickest -and your small order is never side -tracked as all our orders are small. One trial order will make you a life customer. Try us with a 50e order. We can only "stick" you once! ! Trade Mark

WE GUARANTEE EVERY ORDER SHIPPED WITHIN Factories: 96-98 PARK PLACE, NEW YORK CITY Brooklyn, N. Y. Elkridge, Md. 24 HOURS. sa..::a _-

www.americanradiohistory.com RADIO NEA s.. H. GERNSBACK- Editor ROBERT E. LACAULT- Associate Editor

,,,1,1,11111111,,,111, No. iz Vol. 2 JUNE, 192I

MONEY FROM RADIO is up -to- heard it said that radio is used by talk with the jeweler, because not every jeweler WE have often to the the amateur only as a sort of diversion or date and will see the advantages. An invitation sale in most sport. Unfortunately in most cases this is amateurs' radio station will perhaps clinch the is to work The amateur buys an outfit and being a cases. If once the jeweler sees how simple it true. soon become en- selfish sort of person, immediately begins to a time receiving radio outfit, he will as of his tribe have done, will even go it for his own personal benefit and instruction, and as a thusiastic, and many use outfit in a show window in order to is all that the country at large ever gets out of this so far as to put the rule that a jeweler in the South who uses a outfit. It is true that once in a while the amateur attract trade. We know particular of his window where everyone for half condescends to do a little relay work and to give out weather loud talker outside can hear when NAA sends out the time or market reports for someone who might happen to ask a block around for them. But how many amateurs are using 'radio as a at noon. directly or indirectly? Then we have the country factory and the manager's or money -maker either for quite a distance. There Perhaps few realize that there is money in radio at all owner's home usually separated a wire connection between them. It should and for that reason they hardly ever bother their heads is not always to connect the two by radiofone, because as a rule about it. For those unenlightened ones, this article has be simple is not very great, and the innovation would be been written. There is indeed quite a good bit of money the distance by the up -to -date business official. to be made out of radio. Particularly is this true during welcomed man or college man Here is another wrinkle that may prove a steady income vacation time when the average young reports hands to commercialize his art. to the amateur. We refer to giving regular weather has plenty of time on his idea are thousands of islands located in by mail or by fone to a number of subscribers. 'This In this country there in the southwest, as well as in our oceans, and these islands was recently tried by a young amateur various lakes, quite a little money out direct communication with the mainland, and we understand that he makes have not always to whom he furnishes or telegraf. It should be simple for an of it. He has about 40 subscribers either by telefone either by mail or by telefone. Not amateur to visit such islands and try to find out daily weather reports intelligent he give weather reports, but he gives them mar- the commercial possibilities are to connect such islands only does what news as well, and also press news, if it is of sufficient with the mainland, either by radio telegraf, or better, by ket lay particular stress on the latter be- importance. It works as follows : radio telefone. We has a subscription card or camps can afford to pay a regular tele- The young man in question cause few hotels for mail service and a higher rate for It is, then, up to the amateur to sell not charging a low rate graf operator. The fone service takes more time, is his temporary services, but to sell the outfit and the telefone service. only more expensive and as it is prompter for the subscriber, installation as well. as in doing so. We it is worth more money. The mail service is simple: As a rule he can make good money amateur, he amateurs have made a tidy soon as the weather report is received by the know of a few cases where hectograf copies, which he such installations. Radio telefone outfits typewrites it and makes little sum from a one cent postage stamp. It takes simplified now and the amateur who knows sends out at once under are becoming few minutes to do this. To those subscribers firms manufacturing either complete outfits or the him but a all the telefone service, he must of course call up each one to make an outfit, should have no trouble in dispos- wishing supplies separately which necessitates more time and expense. The ing of several installations this summer. and excursion beauty of the scheme is that it provides a steady income to Then we have the large excursion autos him and lake boats, the amateur and his expenses are very low. It costs boats, such as yachts, motor- boats, river the stationery of such can be made to nothing to receive the radio messages and only houseboats, etc. If the proprietor Usually a yearly a radiofone outfit that does and postage is an item to be considered. see the advantage of carrying payable monthly. The amateur can sum, an order will often follow. The contract is made -bills not cost a huge rates to suit himself and of course the subscrip- the average layman is that he does not realize make the trouble with should be low enough, otherwise he will not have a low range radiofone outfit can be bought. tions how cheaply As is the case with any kind of subscription, it is them have an idea that such an outfit in order to many. Most of the quantity that counts. If an amateur can get anywhere over a mile would cost a thousand dollars, or perhaps talk from 5o to Ioo subscribers, he can make a pretty little Consequently they never take the trouble to investi- More. be penny, besides rendering valuable services to the com- gate and find out that a two- station radiofone outfit can many munity. The thing of vital necessity is, however, that the for a fraction of that sum. It will save its cost bought service be prompt, because only then will it be beneficial over, because it usually makes a hit with the public. times has to the subscribers. It need not be mentioned that it is a Then we have our friend the jeweler. Perhaps he time by simple matter these days to obtain such a subscription from not a complete radio outfit to give him the exact there the bright ama- farmers or others interested in weather reports where radio. It should be a simple matter for advance weather outfit at a very are no daily papers within reach and where teur to sell his local jeweler a complete importance. solicitation and a little and crop reports are often of vital good profit. Of course it means H. GERNSBACK.

www.americanradiohistory.com 854 Radio News for June, 1921 Vacation Time Radio By ARTHUR H. LYNCH

seen portable transmitters, of which but very few are really practical. Do you remember ever having seen a portable combination transmitter and receiver, which you felt was really suitable for obtaining anything like the results to which you have been accus- tomed? Even tho you may be in that fortunate class of radio enthusiasts whose purse limitations have no bear- Here is the Shore Station Which is of the Same Type as the ing on the amount One on the Canoe. Note the Size of the Complete Station. of equipment, you have decided that the outlay for struction of this portable set. It is complete, This is a Real, Complete Portable Set, With a Range of such a set, simply for summer in every detail, as shown in the accompany- Wave -Lengths from 150 to 3,000 Meters. Everything is In- time operation, -and not the ing fotografs. With cluded in the Carrying Case. the single exception of best of operation at that -was not the antenna, EVERYTHING fits in the to be given very serious consid- small carrying case, RADIO manufacurers and the coil of wire and dealers eration. Procuring the parts and the may be strapped to the outside of it with have come to look upon the summer time necessitated in assembling them would very little trouble. time a EVERYTHING in- as period of little business encroach materially upon the capital which cludes the complete receiver, two receiving in which they may devote their at- would be needed for the purchase tubes, tention of the "A" battery, two 20 -volt "B" bat- to the formulation of plans your canoe, the refitting of your house- teries, telefone receivers with headband, for the campaign of new business, which boat or the time needed for getting spark coil, spark gap, the fall always brings. key and the "send - With the rapid ex- your motor boat or automobile ready receive" switch, as well as the antenna in- pansion and development which the art has for the summer's campaign. You, like so sulators, undergone and there is enough space left for within the past few years and many others, decided that the game was not a few tools, a pad and pencil. There are especially the last year, it is very doubtful worth the candle. but that two terminals on the outside of the such a condition will be found to exist case and they are for the "ANT" and either this summer or the summers which "GND" follow. 0 connections. One method for avoiding The complete outfit with everything neces- this slump is sary for receiving well under way, as may be seen from the and sending including the accompanying antenna wire, and the power supply for fotos. A very potent, in fact, lighting we may safely say, the most important rea- the filament and supplying the son for this transmitter, weighs about twenty -four seasonal decline is that many pounds; of the amateurs spend much of their va- then, it is vastly different from any cation time in places some other portable set previously described, in distance from that it does their homes. If they do not leave their city not require such a great dup- residences for the entire lication of parts or the procuring of new summer, or even ones. for part of it, they almost invariably find There is a section, in the upper half some sort of the carrying case, as indicated in the of outdoor occupation for their Complete Hook-up of the Portable Set Shown in fotograf, leisure hours at Fig. 1. which is just the proper size to the seashore or in the accommodate woods, on the golf links, tennis court one of the popular receiving or sets. For those who already what not. A TRULY PORTABLE SET have a receiver of this type, it is but necessary to Even present -day radio stations, in most A combination transmitting and receiving procure the remainder instances, may hardly of the equipment be termed portable, set, embodying everything that is necessary and for those who are not supplied with even tho there is a marked tendency to for good operation, which is economical and such a receiving set cast aside the "pillar" inductance the purchase of the and glass - which enables you to use most of your pres- entire outfit does not mean that it may be plate condenser and rack of yesteryear for ent equipment, has been designed for this used only portable the more compact for purposes. At the and efficient concentrated very purpose. It combines a receiving set end of its career as a portable outfit, the inductances and moulded condensers of to- which has a wave -length range of 15o to receiving set, which is day. Many a complete unit, may portable receiving sets have 3,000 meters and a very simple transmitter, be withdrawn from the carrying case and been described from time to time, but one with a distance range of several miles or mounted in the usual does not manner, in the sta- find the ultimate of satisfaction in more, depending upon the type of antenna tion. The outlay, in any case, above that listening to others operate without being used, as well as the sensitivity of the sta- necessary for the receiving able to have set, is corn - a word or two himself with tion at the other end. (Continued the rest of the world. Then, again, we have It has taken a long time to on Page 9i6) develop a receiver which would work well on the range of waves mentioned, and tho the demand for it has always been great, caused, no doubt, by the desire to work on amateur waves and still be able to receive the time and news from NAA, there are but few such receivers on the market. There is little need be which said The Op and His Set Aboard the Liner. Erecting Aerial. No in If You Own Such the Poles are Necessary, Just a Kite connection with a Boat You Should Install a Set on Board and Keep in and Up Goes the Wire Used as an Antenna. the design and con- Touch With the Camp During the Trip. Photos by courtesy of A. H. Grebe & Co., Inc.

www.americanradiohistory.com Radio News for June, 1921 855 Awards of $100 Portable Radio Prize Contest THIRD HONORABLE MENTION

1131, ,,,, ,,,11111,,,1111,,,1111

The fotograf on the right shows the inside of the portable set, The coupling is varied by opening the box more or less. On the left is Mr. Dick, designer and builder of this small pocket receiver.

spective positions in the case by the tubing TELEFONE CONDENSER. which was left sticking beyond the coil The telefone condenser was made of two Smallest Portable Radio itself. The primary was wound with 5 sheets of heavy tinfoil separated by sheets layers and the secondary with 7 layers with of waxed paper. The tinfoil was 4" x 5" Outfit taps taken off at each layer. The plan used and the waxed paper was cut a little larger in the coils is similar to that de- By H. B. DICK winding to avoid any possible chance of a short scribed in the December, 1919, issue of circuit. RADIO NEWS, being 24 nails in each The general enthusiasm for an efficient there WIRING radio outfit that can be taken on hikes, row. About / of a pound of number 24 camping, on visits to friends, etc., is pretty D. C. C. was all the wire required for both The wiring diagram is very simple, and well establisht. Certainly every one of coils. I believe it will need no explanation. All us has at some time or other wisht that The switch points used were /" x %" the wiring was done with rubber insulated, he (or she) had a small radio set which head with /" shank set in a piece of wood silk covered, stranded wire. All possible could be slipt into a pocket or hand bag cut to fit the inside of the coil tubing. The connections were soldered; a very impor- and taken with him. For this reason I taps were soldered to these because the tant part of a crystal set. have designed and built the outfit described points were too close together to allow the below. One which anyone should be able to use of nuts. The knobs used were the BATTERY These bot from make and be mighty proud to own. smallest procurable. were The battery to supply current to the buz- & Co. for seven cents GENERAL DESCRIPTION the J. H. Bunnell zer can be of any make two cell flashlight As stated in the title of this article, the each. DETECTOR battery. The size should not be any larger outfit is of the smallest size and yet good than 2%" x I/" x ". results are obtained. As may be seen in Amrad / The detector was the familiar AERIAL AND GROUND Figure i, the fones occupy quite as much type C -1. It was bot some time ago for space as the set. The dimensions are as $2.50 and can now be bot for $2.2 with- The aerial, found to be sufficient, was wide, follows : 3/ inches long, 21/4 inches out the base. The size is very convenient number 18 annunciator wire 95 feet long. and 2/ inches deep, thus occupying but for the set, being only /" in diameter and To prevent grounding of the aerial, two little more space than 23 cubic inches. 1/" high. The two binding posts which small porcelain insulators were used, one on The case was made cf Spanish cedar came with the detector were used for the each end of the wire and held away from (cigar box wood) put together carefully so aerial and ground and two others were bot the tree by short lengths of wire or cord. A as to avoid cracks and thereby keep out all from Amrad at $.17 for the telefones. very efficient ground connection was obtained then sanded with fine sand- dust. It was BUZZER by driving spike into the base of a live tree paper and stained mahogany. After being and wrapping the ground lead around it. allowed to dry, two thin ccats of damar var- The buzzer was of the common watch- During recent tests away from the city, nish were put on and these allowed to dry case type which can be bot most any- QSA. was taken out of several amateurs were heard At one about 36 hours. Then the whole sanded where for about $.75. It was time, when I lived in New York State, I and waxed. The results obtained were its case and mounted directly to the wood outside. heard NAH (600 meters), a remarkable wonderful. case with two small screws from the record considering the size of the outfit. The tuning is accomplisht by opening and Just above the buzzer is the push button closing the box on its hinges. which was made from a piece of phosphor The author would be glad to hear from INDUCTANCES. bronze 1/" long and !/" wide. The buzzer anyone who should happen to construct a little testing various tone regulating screw was screwed into the set similar to the one described here or After some with from any one who might be in doubt to types of inductances, it was decided to use side of the case directly opposite the buzzer as arm so that adjustments could be some of the constructional details of the coils of the honeycomb type. These coils vibrator set. inch wide and wound made from the outside. The push button, were made / were H. B. Dicx, 4o Westernview St., on cardboard tubing I% inches outside di- too, could be placed on the outside so as ameter. The coils were held in their re- to make the testing easier. Springfield, Mass.

.1.11,,,,,,,111111111111,1,,,.

On the left is a view of Mr. Dick's complete portable set, including the aerial, insulators and telefone; while on the right is the complete hook -up of the receiver.

11111 Inteluzmetvarremia Fig. 3

www.americanradiohistory.com 856 Radio News for June, 1921 A New Use For Radio

vacuum tube in use, for amateur work. Union's Radio Club has been heard by more than 2,000 amateurs to date. The sending is done on a 35o meter wave -length, interesting information for those amateurs within a radius of 1,200 miles of Schenectady ,1111, who have not yet listened in on the concerts or sermons. This is a view Some of the well of the letters received in reference known Union to these concerts are interesting. One from College Radio Beloit, Wis., from Glen Franz, said: Club station. "Heard you fine tonight. On the left Using only one is the six tube. Keep up the good work." 50 -watt tubes Another from a little town in North set, while on Carolina, the right, signed by Taylor M. Simpson, re- just above the ported that the concert was very loud in head of the that place. C. W. Carter of Shawinigan smiling fel- Falls, Quebec, said: low, are two 250 -watt "I've just been listening to your Radio tubes mount- concert, and it was very good indeed. Wish ed on a board. you could give one every night." A little rivalry is evident from another 11111111111111111101111111.111111.,,, communication sent by R. J. McKnight of Springfield, Ohio. He said he heard the concert and that it carne in a good deal louder than either "NSF" or "KDKA". The former is a Government station at Wash- ington and the other is a station in Pitts- burgh. A correspondent from Fort Wayne, Ind., NCUSE me a minute, Officer, College Radio Club" and then the music reported hearing the radiofone concert very till I switch on the wireless music. would start. eistinctly, and a similar report was received "FJ Then we can leave the baby The baby- carriage stunt is not all that the from Keyser, West Va. Another report alone while we go for a stroll." Union College Radio Club has done in Ra- received from Francis Duffey of Cabery, Such a statement, coming from a nurse dio. For months it has been giving weekly Ill., said: maid, may sound rather far -fetched or the concerts every Thursday night; and for the "Very loud here; heard your concert last prediction of a scientist of what we may last few weeks, sermons, prepared by Dr. C. night. I could hear you all the time about have 25 years hence, but such is not the A. Richmond, president of Union College, to feet from fones and at times 3o feet case in Schenectady, N. Y. It is a reality have been sent out at 8 o'clock Sunday from fones." there; the Union College Radio Club has nights. These are preceded by a hymn played Another message from Ontario congratu- made such a feat possible. The wireless on the fonograf and followed by another, lated the Club, saying : baby -carriage has already been demon- and then the doxology is read -a real church "Your concert was heard here frightfully strated, wheeled thru the principal streets of service at home heard by amateur operators loud. This fone is the finest I have heard that city and thru the parks, with lullabys in no less than 24 states of the Union, in to date. It beats 2QR and NSF." pealing forth from the radio receiving horn four provinces of Canada and by ships 700 An interesting message came from the attached to the carriage just as plainly as miles from New York, at sea. This fact steamship Peeksville, 700 miles out of Am- tho coming from a fonograf a few feet is attested by the hundreds of letters and brose Channel. It follows : away. cards received by the Radio Club from "Thanks for your concerts. I never knew The music is sent from the Union Col- amateurs telling of having listened in and that `Annie Laurie' could sound so well." lege radio station, the sounding tube of a complimenting the Club on the clear tone small victrola being attached to the mouth in which the music or sermon are received. Editor's Note: piece of an ordinary telefone, which carries Radio is not a regular study at Union The little' stunt of going around the town the music to the aerials, where the sound - College, but rather a side issue with the waves with a baby carriage equipt with a Radzo- are sent out thru the ether. It can boys, most of whom became interested in fone attracts the be picked up in attention of the public. Chicago, in fact in any the science during the war. Equippt with It is hoped that some clubs city within a radius of 1,200 miles, as will find some just the most modern of apparatus, including six other use for Radio, so as to gain new mem- easily as by the baby- carriage in Schen- of the new type 5o -watt and two 250-watt bers and ectady. attract more boys in the game. Radiotrons, the most powerful sending Let us hear some more about it. This wireless baby carriage, devised by the college boys, has an antenna of three wires, stretched across the top from two pieces of a bamboo fish pole. Underneath the carriage -body is the storage battery, and hidden under the canopy in such a way that it in no way interferes with the baby the amplifier, which multiplies or adds to the volume of the music as it is sent to ,u1111,11111113111t11111111111111111, the horn. an ordinary megafone secured by wires to the front antenna pole. The Here is the tuning baby truck box is attached to the rods leading to the equipt with handle of the carriage. radiofone. After thoroly testing the carriage in the The nurse does not need electrical laboratory at the college, the tour to sing to of the city was started early in the even- stop the kid's ing. The music was turned on as the boys crying, she has only to with the carriage left the college grounds switch the re- and it is doubtful if a circus parade ever ceiver on, and created more attention and curiosity than music sent by radio comes this musical baby -carriage as it was pushed to keep him thru the streets. After an hour's tour it quiet. was stopped in the park. Some at first thot there was a fonograf hidden somewhere in the carriage, but such ideas were dispelled when, without anyone going near the carriage a voice from the horn would immediately announce upon conclusion of one selection the name of the next, with the information "by the Union

www.americanradiohistory.com Radio News for June, 1921 857 The California Theatre Radio Station The DeForest radiofone station operated at the California Theatre, in San Francisco, by the Moorhead Laboratories, Inc., of that city, which is the exclusive distributor of the DeForest Company on the Pacific Coast, has been in operation for over a year and it is thot that 'a description of same will be found of interest to the readers of RADIO NEWS. The California Theatre is the largest motion picture house in San Francisco, and is one of three controlled by the Famous Players -Lasky Corporation, the other two being the Imperial and Portola Theatres. A fourth, the Granada, is now under pro- ,111,,,,,,,1,,,,,,,,111111,,,,.,,,,111 cess of construction. early in 1920, Here is Big The station was installed Jack, better thru the courtesy of Directors Roth and known under Pardington, of the "Big 3" Theatres, and the name of room in the fly Dempsey, is located in a concrete listening in to galleries of the theatre. The antenna is fixt the radiofone on the tower of the Humboldt Bank Build- music, He the theatre. was stung by ing, directly adjoining the bug and The transmitting set consists of the is taking les- standard DeForest i kw. radiofone set with sons in radio additional loading inductance so as to ob- now. tain the working wave -length of 1,26o meters. The call letter of this station is 6XC. The antenna current varies from four to five amperes, according to the amount of input energy. Ordinarily, less than a half kilowatt is used for transmission. As the set is essentially an experimental one, various transmitting circuits of the DeForest Company have been tried out. The circuit in use at present is one developt by the engineers of the Moorhead Laboratories, for which patents have been. applied. The receiving set is of the standard DeForest type. For best results in receiving from the California Theatre, the following ultra Photo Underwood & (.'nderwocd. honeycomb coils should be used Primary- microfone trans- bear directly on the microfone diafram in on moderate end of the horn, a Kellogg DL 200, with series condenser mitter is mounted in a vertical position. place of the usual fonograf diafram. antenna ; secondary-DL 200 ; tickler -DL From here the usual wires are led to the For special concerts, which are frequently I50. trans- given, a sound proof room in the basement of radio modulating circuit. For the In connection with the transmission mission of fonograf records, several de- of the theatre is utilized. For small music, several interesting methods have vices have been used. One is a standard chamber or instrumental music, a Magnavox been developt thru experimentation. For horn similar to the one suspended in the from Magnavox fonograf microfone, consisting collecting and transmitting the music of the fly galleries is utilized, but for vocal selec- Orchestra of 5o of a microfone mounted at the end the Theatre's Symphony -arm. Another method tions Kellogg desk transmitters are used a large Magnavox horn is suspended usual fonograf tone pieces, Moorhead Laboratories is by each singer. By placing the singers with in the fly galleries in such a position as to developt by the piano used for needle holder so as to their backs to the grand be clear of the side "drops." At the small to utilize the steel accompaniment, enough of the sound intensity from the piano is obtained thru the singers' microfones so as to obtain a proper blending of the voices and piano. Harp solos by Miss Jay Clark, piano solos by Mr. Hans Hanke and vocal solos by Miss Mary White, Miss Ruth Williams, and Mr. Ford Rush, of the California Thea- tre, and Madam Frieda Hempel and For- 111111111111111,1,1,111111111111 rest Lamont, stars of the Chicago Grand Opera Company, have been the big features This fotograf shows Miss of the special concerts. Mary White The regular concerts, consisting of the singing at the Herman Heller Orchestra music and fono- radiofone sta- at 4:00, 7:15, and tion of the graf records, are sent out California 9:0o P. M. on week days, lasting for at Theatre, with least one -half hour. Special vocal and in- Dr. DeForest, sent out at 9:0o whose com- strumental concerts are pany installed P. M. on Wednesdays, and a special Sun- the set. Note day concert given by the Herman Heller the extra in- A. M. until ductance fixt Orchestra is sent out from sr :oo behind the noon. panel to tune The transmission of music from the De- pp to 1,260 Theatre meters. Forest station at the California has developt from an experimental stand- point to a worthwhile contribution to the musical progress of the city, and receiving sets for the reception of this music alone have been installed at clubs, hospitals, hotels, and many private homes since the inauguration of this service. The accompanying fotograf shows Dr. Lee DeForest, inventor of the audion, at the radio set, and Miss Mary White singing (Continued on page goy)

www.americanradiohistory.com 8 ;8 Radio News for June, 1921 Give Yourself a Radio Vacation By ARMSTRONG PERRY

111111111111111111111111111.

Among the people in the hotel are several who will be interested by radio and take it seriously, A practical demonstration may be made by playing chess with a friend by radio. There will be some players among the spectators who will become interested in radio thru their hobby. Instruction in radio for boys and girls and adults. AM MI11111111111111111111111111111, Radio chess and chec'rer matches. Photo, Radio press dispatches. Underwood Information about ships. & Underwood. Weather forecasts. RADIO DANCE. TIMES are getting better, but some trade. The better the place the more likely The radio dance is already an establisht radio amateurs are still trying to de- the management would b° to take an inter - institution. When a man is dancing it cide whether to take a real vacation est in radio service as a feature of its house. makes little difference where the music and go without that new apparatus The papers are full of hotel ads and post- comes from so long as it is the right kind they want, or to get the apparatus age stamps are cheap. Why not outline a of music and he has his arm around the and go without the vacation. Why not get practical proposition to ;,a few houses and right girl. But the fact that the music the apparatus and take the vacation' see what happens? Here are a few items comes by radio will be a topic of conversa- It is a wise man who capital- tion at the time and in hun- izes his hobbies, for he who dreds of homes and clubs later, 6@ does, can ride them farther and IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIU more and the hotel that introduces comfortably than he who the novelty will be prominently does not. W e expect our daily mentioned where others are for- work to pay for all its acces- ERE is another article from the pen of Mr. Armstrong Perry that will not fail to enthuse gotten. No successful hotel sories and provide a living for thousands of amateurs man ourselves all over the country. Not only does Mr. Perry show how is ignorant of the value of and our families be- such mouth -to -mouth advertis- sides. The hobby should at the amateur can have a free vacation, but if his suggestions are followed, there is no reason why he cannot ing. least pay its own way and pro- make very good EMERGENCY vide for a vacation. money besides. SERVICE. If only a thousand amateurs were follow Free emergency radio service It is a recognized fact among to Mr. Perry's plan could psychologists and pedagogues this summer, this alone would do more for the radio fraternity be furnisht by an amateur connected a that we do best that work in and would tend to popularize radio more than all the radio maga- with Radio which zines combined could ever hope to accomplish. Relay League or any other or- we are most interested. ganization maintaining Is there an amateur who goes Let us hear from those amateurs who have taken a free vaca- relay tion, suggested by this article. stations. Even an amateur could to his dry goods counter or his The Editor will be glad to pay at least bookkeeping desk, good rates for such articles, and those with equal some of the wire or whatever fotografs will be service provided at summer his regular job leads him to in especially welcome. -Editor. and the winter resorts, both in speed morning, with as much zest and accuracy. as he takes up his fones Telefone service at at many isolated resorts is more night? Or switches on the of juice and starts a joke than a reality and the talking serious situations arise machine? By all the laws of mind some- and mat- that might be included : times which a radio ter the radio amateur station would relieve. ought to be able to Radio dances. DEMONSTRATIONS AND EXPERIMENTS. get a rich man's vacation as easily as a poor Free emergency radio man's wages. service. We who have stations come to feel that Demonstrations and experiments. (Continued The vacation business of seashore. moun- on page 924) tain, lake and river resorts depends upon features to a e-reat extent. These resorts multiply annually and competition is keen. A few places maintain their leadership and get the best trade by keeping up to the times. The rest catch the overflow and the cheap

y1111111111111111111111111111111111111 An hotel that introduces the novelty will be prominently mentioned where others are forgotten, During vacation at camp a radio set is also very useful to keep in touch with the town. and receive all the news sent by radio.

1111111111111 11111111111111111111111111

www.americanradiohistory.com 859 Radio News for June, 1921 The Radio Compass on Airplanes BY S. R. WINTERS

THE establishment and equipment of the 78th Naval aircraft station with radio apparatus emphasizes the swift progress of this form of communication, as applied to operations of 4m1114mmmm,ummmmmmm the Navy Department. The developments A very com- are brot into review by detailed infor- plete radio mation supplied to the writer by the Radio station is in- Division of the Bureau of Engineering. The stalled in all the big value of a system of shore radio compass planes. stations as an ally to navigation is sub- This foto- scribed to by hundreds of letters received graf shows masters of merchant vessels. on the left the from the receiver and The desirability of reducing the extra in the center weight of an airplane to a minimum has the amplifier. necessitated the use of extremely light radii sets for aircraft communication. "Surpris- 4mmlmm,mm,mmm,,,,,,,,m ingly good results, however, have been obtained with the sets now in service," says an official of the Navy Department. An example of the communication range is suggested by the efficiency of one of the sets employed during the Trans -Atlantic view. Here is an illustration cited by the ings taken at long distances should be flight of the NC -4, this particular equipment Radio Division of the Bureau of Engineer- treated as great circles to avoid errors. Th.- received being heard a distance of 1,430 miles from ing in support of this conclusion : A plane American steamship Eastern Breeze a shore radio station. The lessening of the has flown out to sea. picked upon the radio a set of bearings from the New York Har- noise of the motor and electrical disturb- signals of a battleship under way at an un bor entrance stations which fixt the vessel's ances present in the radio receiver while re- known position, which was afterwards position at 83o miles southeast of New ceiving on board an airplane have been found to be loo miles from the plane, flown York. Subsequent determinations verified objectionable factors inviting constant re- directly to the ship, turned around and flown the accuracy of this finding to within one search. Aircraft receiving equipment, how- back to its original station, navigating by and one -half miles of its actual location. ever, has been developt, which renders it means of the wireless signals from that sta- Harbor entrance stations are negotiated in feasible to receive wireless signals on board tion. Shore radio compasses, or occasion- groups of three or more and centrally con- an airplane at a distance almost as far as ally denominated radio goniometers, consist trolled from a plotting station connected from a ship or shore station. of a special type of radio receiving equip- with each compass station by land wire tele- Naval aircraft wireless transmitting sets ment coupled with a revolving coil, the out- graf. To illustrate: A ship approaching derive their power in two varying ways. fit being capable of determining the direc- New York and desiring her position, would one from a wind- driven propeller with gen- tion of signals emanating from a ship's call "NAH," the central control station lo- erator connected and the other from a stor- raio transmitter. Stations have been erect- cated in New York City. The latter would age battery. The latter method involves the ed at choice locations along the coast and in notify by land line the compass stations at of "excess " the vicinity of principal harbor entrances, Montauk, Fire Island, Sandy Hook and transportation baggage -greater call let- weight than is practicable. This determin- maintaining a continuous watch 24 hours a Mantoloking. that a vessel (giving ing factor operates toward the discard of day for 365 days. ters) was requesting bearing. When all storage batteries for all kinds of aircraft A ship at sea, seeking its bearing from stations have acknowledged, the control sta- radio transmitting apparatus. The Navy one or more of these radio compass station by distant control using the New York in regular way and makes a Navy Yard transmitter directs the ship to Department employs both telefone and tele- tions, calls the her graf sets, the latter being abandoned for prearranged radio signal for one minute: test, whereupon the shin then transmits long distance communication, owing to the the operator at the compass station takes the call letters repeatedly for one minute, dur- ship's bearings while it is transmitting, for- ing which time the compass stations are tak- fact that for the same weight of equipment The a telefone set will only transmit half the warding the bearing by wireless to the ship. ing observations to obtain the bearing. distance covered by a telegraf set. A hearing may be obtained simultaneously bearings thus recognized are given the con- from any number of these stations within trol station by land line, the control op- The aircraft radio compass is a recent (Continued on page gob) contribution of helpfulness to the naval range and by use of two or more bearings the Master can accurately determine his aviator, when Columbus -like land is beyon I position. Instances are numerous, however, where an ideal location of a radio comnas station cannot be made with respect to navigation and military operations. Environ- ments may retard the proper functioning of the compass ; for example, the site must be free from surrounding metallic structures. Preferably the location should be on a low. sandy beach, far removed from hills and elevations. Rocky ground, elevations and metallic structures influence the refraction or bending of the wave front, thereby producing objectionable deviation in the observations. A significant feature in the estab lishment of a radio compass station is the selection of a site permitting the use of an existing radio transmitting station. Other wise, it is imperative to construct a radi , telegraf transmitter, which involves extra expense and also creates interference. According to the Navy Department, the range of shore radio compass stations is in- fluenced by the following factors : Sensitiv- ity of the radio compass receiving apparatus, power of shore and ship transmitters and accuracy of calibration. Navigational requirements limit the range to to miles, since the majority of ship transmitters are ineffectual for compass activities at a greater range. High -powered transmitting out- This Fotograf Shows the Radio Compass In- In This View May Be Seen the Air -Propelled fits, designed for military uses, however . stalled Aboard a Big N.C. Plane. Note the Loop Generator Supplying the Power to the Radio Set. have ranges of boot) miles or more. Bear- Aerial and Scale on the Left.

www.americanradiohistory.com 86o Radio News for June, 1921 The Washington Air .Mail Radio Station By S. R. WINTERS

the absence of spreaders, its installation involving the use of four wires spaced by the means of a metallic bridle. The roof of the Post Office Department building serves as a counterpoise. The situation of the sta- This fotograf tion shows the 2 permits a direct lead -in with the an- K.W. arc tenna. Favorable location likewise facili- station in- tates the use of ground leads not exceeding stalled in the 15' in Post Office length. Building at By way of functioning in a twofold pub- Washington, lic capacity -the application of wireless D, C., which communication is used to as a vehicle of immediate send informa- service to a large group of people -this tion and radio station lends itself to convenient op market re- eration. In the selection room ports to farm- of the and ers, and com- the installation of equipment, special atten- municates tion was given the desired objective of re- with the other ducing the moves of the operator to a mini- stations of the air mail mum in the performance of his manifold service. duties. This - end has been achieved, an ' the change from receiving to transmitting 1,,11111111111111,1111111,11111,,,, is effected without undue delay. The rate of communication is approximately 400 words an hour for each of the 15 stations. The quarters containing the radio operator WHEN in Washington, D. C., if the coast -to -coast air -mail service and in and apparatus likewise lends itself to use as opportunity should permit, visit the the dissemination of market reports of the a modern government office. J. C. Edger United States Post Office Depart- United States Department of Agriculture to ton, the capable director of the Transconti ment building, at Eleventh street farmers. The transportation of 200,00') nental Government Wireless Service, an as- and Pennsylvania Avenue, and first -class letters daily, involving the use of sistant and a stenographer, comprise the once within the ancient- looking structure, 65 airplanes, covering a distance of 2,710 office force necessary to the execution of ride the dual-purpose elevator, a passenger miles, suggests the purpose of 15 Radio the duties which intimately relate to the De- and cargo -carrying vehicle, for eight sto- Stations for sprea'ing information as tp partment of Agriculture and Post Office ries. Alight and turn sharply to the right, inter- station traffic, the distribution of me- Department. moving straight ahead until you anproac'i teorological data, and as an agency for Ten of the 15 Radio Stations of the a room with the modest identification, Transcontinental relays from Washington. Transcontinental Service were establisht "8to E." Having gained admittance, you Such was the specific purpose for which the outright, interlocking with an equal num- will be introduced to a Radio Station that service was originally establisht, the broad- ber of flying fields maintained for shiftin assuredly can lay claim to being a novelty, casting of news as to market conditions be- the postal bureaus from railway trains ti if not one without a duplicate in the United ing an additional burden only recently as- mid -air. Army and Navy Radio Stations States both in arrangement and in the char- smned. are employed where practicable, thus avoid- acter of service it renders. Reverting to the wireless equipment and ing duplication of construction and the dim Government owned and operated, the wire- quarters in which it is housed : A 2- kilowatt ination of working interference. Govern- less equipment installed in this room, 25' Federal arc set was so modified as to be ment stations al -eady e>tabl +sht that share long, 25' wide and 14' high, is employed in the equivalent of 4- kilowatt in strength. The this additional duty are: Cleveland, Chi- the two -fold function of imparting infor- antenna and ground arrangement are of cago, San Francisco, and C ncinnati. The mation in conjunction with the operation of novel design. The former is maintained in (Continued ois page g 4 Church Uses Radiofone

OR the first time, so is far as known, congregation followed the Episcopal pastor the great flexibility of wireless telefony. radio telefony has been used to trans- thruout. During the sermon of the Calvary There may mit be in the future a central pastor F services from one church to an rector, intense interest was maintained at who will talk to thousands other, in order that a congregation without the Herron Avenue of congrega- church, so clearly and tions situated in all parts of the world, but a regular pastor could have the benefit of distinctly was the message received. this may take Sunday evening time. The idea is not far- worship. The churches in It is hard to say just what demonstra- fetched by any means, as the transmitting which this was done successfully were the tions like this will do, but certainly it proves of the Calvary services proves. Calvary Episcopal and the Herron Avenue Presbyterian, both of Pittsburgh, Pennsyl- vania. During the last few months the Sunday evening services of the Calvary Episcopal ,I1111111111111111111,11111111111111 Church have been broadcasted from a radio test station in The invisible East Pittsburgh, Pa. These minister at services have been eagerly awaited by radio the pulpit of amateurs all over the United States. a Presbyterian Church of The Herron Avenue congregation has Pittsburgh, been without the services of a regular pas- Pa., giving tor for some time. One or two of the con- the Episcopal gregation being wirless enthusiasts, got in service to touch with the Westinghouse the congrega- Company, re- tion, On the questing the installation of a small receiving table ma-y be outfit in the church, in order that the mem- seen the re- bers could hear the Calvary services. ceiver and This amplifier used was done and a compact set consisting of in conjunc- a loop antenna, amplifier and condenser was tion with a placed upon the rostrum in front of loop aerial the and a tele- pulpit; the loud- speaking horn rested di- megafone. rectly on the pulpit. An expectant throng filled the, church and 1111 was - not disappointed, . for the voices and music of the Calvary choir, the sermon an 1 the organ were received clearly and distinct (Photo courtesy of the ly.- In spite of the difference between Epis- Westing- copal and Presbyterian services, the latter house Co.)

www.americanradiohistory.com Radio News for June, 1921 86i A Portable 200 to 900 Meter Regenerative Receiver i By F. J. FOX

Lá ,1i i i i i i 1i1111111iiii1iiiiiii1ii15i 1 Rheas L / On the right is a fotograf of the port- ' able set. é On the right of the cabinet may be seen 1 the B battery 1 % Ph made of flash- Ant e.._e Gnd. light cells. OO #-OO B'Baf/. If desired ! ^r A" this battery . - t _ o( may be fist inside the set Fig 2 as there is enough room Front View of the Set Showing the General Lay- for it. out of the Switches and the Dimensions of the 1101111111111111111111111111 Panel and Cabinet. The Features of this Set Are 1 11111101 Its Compactness and Good Design,

IHAVE always been in the habit of going away to the shore or woods for my summer vacation, and, being a "ham," I have always found it necessary to insure peace and happiness by teurs tuned by use of the secondary taps inside, it would be very convenient to put taking along some form of a portable radio and the tickler coil. When I constructed in the correct amount of "B" Battery. I set. Until this year, because of its con- the set I had on hand an unmounted De will, however, describe it as I made it and veniences, I have always used some form of Forest CV -soo variable condenser, which Í leave such changes to the individual con- galena set. These served very well for corn - used. Altho the condenser is very rugged structor. mercial stations, but as a The set has been very rule I had to get along with- thoroly tested. It works al- out hearing my "favorite" I. most as well as any of the relay stations, to my great . high -priced regenerative sets regret. One year I took a now on the market. (( With two -inch coil with me but Íillll1ll11I Iii I it, in March, I have copied because of bad amateur re- i i mm n s 11,1111IIII.II. numberless I's, 2's, 3's and ceiving facilities it proved 8's (district stations) and to be useless. quite a few var Loading 4's, 5's, and With this in mind, I have tond coi/ many g's. I used a tubular designed the following set. audiotron mounted in an old I am sure it is the solution V. T. socket, and no am- of the portable regenerative _`°` plifiers. I consider this very receiver. Its range is from I 4í+ good for such a compact 200 meters to goo meters. It f/g fy. 4 5 set. regenerates well, is very DESCRIPTION simple to operate, is ex- Details of the Inside of the Set, Showing Arrangement of Coils and Condensers. Procure a piece of for- tremely selective and is very mica, bakelite, or fibre to compact. For portable purposes the short I think a smaller condenser of a different fit snugly into a box 63/q" x 73" x 6" wave condenser in series with the antenna or make could be used to good advantage. (see Figs. I and 2), or as nearly this ground is not required, but if the set is With a small condenser such as a "Con- size as possible. Do not get a smaller box used in a station it is desirable to use it necticut" and a little rearrangement of the than this, and be sure to fit the panel to for amateur wave -lengths. A condenser panel, the vacuum tube could be mounted the box you are going to use, first. The is used across the secondary for commercial inside the panel very nicely. However, I box may now be prepared or rather fin- waves : it may also be used for amateur prefer to have the vacuum tube easily ac- ished to suit the individual taste. In my work, but usually louder signals are ob- cessible for the purpose of removing it (Continued on page 92o) tained if it is cut out of circuit and the ama- while en route. Instead of putting the tube

Pho/7es

The view on the left shows the inside of the set removed from the cabinet. On the right is the diagram of connections of this unique set.

¿. fad mnd.

Ca > Deforèsf var C3. Shari ware rar Li-Laadmg ü7472/ciaoce T cae 5 =Shnrf ware sw.

C/ased for 4ao io sae met

www.americanradiohistory.com 862 Radio News for June, 1921 Construction of Bali- and -Cup Variometers By EDMUND S. SMITH --. .Tape eighths inch thick. Equi- distant from the ` I . II edges a hole is drilled in two of the sides cf the frame. These should be drilled to- I gether in order that they may be exactly Q i Ñ the same. One hole is threaded for the Complete con- pointed screw. Two wooden plates are structional made of dimensions shown in Fig. 2, with III0 details of the holes 3" in diameter in the centers. Two Ro i1I well known ll type of blocks measuring about 5" square (C and D) are temporarily tacked to these plates. fiy. f k variometer Wooden plate used in the C and D are screwed on each side of the regenerative rotor as shown in Fig. 3. fg 2 sets. Follow- .Pane/ The primary is .Spxei ing the in- then wound upon the iYOodenp/ate structions tape on the rotor. When about one -half given in this IppiNalpI interesting way across, a space of /" should be left article, for the bearings, otherwise the rotation of Poi» /ed .s?,-en' any amateur the shaft will wear away the insulation on may build his the primary winding, thereby short- circuit- own. ing the two coils. The leads of the pri-

1.111111111111,,,, mary coil are brought out thru small holes in the wooden plates, one on each side. The inductance of this coil should exactly IIIIItimimm0 equal that of the secondary, and this may be Fg 5 P/exibte leads - fiis.6 brought about by using the same size wire and the same length, 24 feet. After I1 is an admitted fact that this type of Fume other insulating compound to hold completion, one side of the frame is re- variometer is more efficient than any the wire securely in place. When set, a moved and the rotor with its two windings other, due to the close proximity of few yards of three -eighths inch cotton tape is inserted, making sure that the shaft pro- the two coils, allowing maximum energy (do not use friction tape) is wound at jects thru the hole meant for it. C and D to be transferred from one coil to the right angles to the length of the rotor, so are tacked to the frame thru their re- other and therefore the maximum ratio that each turn overlaps its predecessor. spective plates. Any small cracks that may of inductance is obtained. But owing to This tape is only temporary and will be be left on any of the edges should be filled the difficulty of constructing this type, ama- removed later. paraffine length with to make them liquid -tight. teurs prefer to make their variometers of A 3" of three -sixteenths inch The variometer is now ready to be filled two cylindrical tubes, in which case, in brass rod is shellacked into a hole drilled with melted paraffine or in other insulating order to rotate freely, the tubes must be exactly diametrically the rotor, extend- compound. Be sure the compound is very of such different diameters that the effi- ing partly thru the center hole, as shown well melted so that it will run in between ciency of the variometer is greatly reduced. in Fig. 5. It should be threaded for '/" the primary wires and hold them securely exterior end accommodate a knob Where the usual procedure of construct- at the to in place. When. hard, C and D are re- ing ball-and-cup variometers is followed, it and dial. Exactly opposite this shaft a moved and the wooden plates permanently is next to impossible for the average ex- small countersunk hole is drilled. See A, hole fastened to the frame. (See Fig. 4.) C perimenter to wind the outside coil, which, Fig. 5. Drill the same size thru a and D were only on the frame temporarily for convenience we will call the primary, 10-32, or 10 -24 machine screw, and sharp- in order to prevent the melted compound successfully, as the wire must be wound en the end opposite the head to a point, from leaking out between the éoils. on the inside of a concave surface. How- which will act as a pivot for the rotor. A ever, if made in the following manner it fairly heavy copper wire is inserted thru The tape is now cut at places shown in will be found to be a comparatively sim- the screw and rotor, to the inner end of Fig. 4, and by pulling each remaining strip ple task. which is soldered one connection from the out separately, it will be found an easy A rotor, for the secondary, is first pro- secondary. The other secondary connec- matter to remove all the tape. Be sure to cured. It can be turned on a lathe to the tion is soldered to the shaft. Flexible wait until the compound has thoroly hard- ened, as shape shown in Fig. 1, or bought directly leads are then soldered to the external otherwise the wire will be pulled from a supply house. It should have a ends of the copper wire and the shaft, as out of place when removing the tape. You will now diameter of 31/2" and a thickness of 2 ". illustrated in the cross -sectional view of have a variometer whose coils The size of large inner hole should be the variometer, Fig. 5. Due to the prox- have a separation of only about twenty-five the inch. at least 1/" in diameter. It is wound full imity of the coils, connections must be thousandths of an of No. 24 D. C. C. magnet wire (about 24 taken off in this manner. It can be mounted on a panel as shown feet), and the ends of the wire passed A frame of maple or other hard wood in Fig. 5, using a spacer, which can be thru small holes drilled near the faces. is made with outer dimensions of 43/4." made of several washers, to separate it The whole is then dipped in paraffine or square by 2" wide, wood about three- (Continued on page 892) AUDIO FREQUENCY TRANSFORMER BUILT FROM AUTO SPARK COIL SECONDARY By G. H. STACKPOLE, JR.

Here's your chance, amateurs, haul out wire there are 33333.33' of wire. No. 39 your antiquated Ford spark coil and make it wire has 26315.79' to the pound. work for you. In 2 oz. or % of a lb. of No. 4o wire, Here's the "how." Cut from stove pipe there is 8 _ 33333.33 = 4166.66' per 2 oz. iron, enough laminations, %" wide by 3" Now to determine the ratios : A good ra- long, to make a closed core transformer. tio is :: 4. Dividing 4166.66' by four will About 15 plates or laminations are enough give the number of turns in feet to be for each leg of the core. Assemble two legs wound on the primary. of the core and tape loosely. To determine the number of feet of wire Take a fibre tube, /" in diameter by 1 ;4" in a single layer on the primary tube, may long, insert a dowel and mount for wind- be done in this way. ing. The formula is: We will take up the secondary next, since (D x W xLxn) = 12 =No. ft. in a we determine the primary from this coil. single layer. Weigh the secondary coil ; perhaps it Where: W = 3.1416 weighs 3 oz., subtract 1 oz. from the total D = (Diameter tube) .5" L winding in inch- weight and call the remainder the weight = (Length of Here Boys is a Cheap Amplifying Transformer of the wire, since the paper on such a tube es) = 1.5" That You May Easily Build Yourself. weighs about an ounce. In a lb. of No. 4o (Continued on page 896)

www.americanradiohistory.com Radio News for June, 1921 863 A. C. for Heating V. T. Filament By Prof. M. MOVE*

4megohms

.00006mí --> .

50 carbonc /amp- Step down - A.C. - +aov.oC //OK A.0 transformer

Here is Something New to Experiment With. The Hook -up on the Left Shows a Receiver Using Six Volts A.C. as a Supply for the Filament of the Y.T. Without Potentiometer or Other Instrument Than a Crystal Detector. In the Center is a Diagram of a Detector and Resistance Coupled Amplifier Using the 110 V. D.C. On the Right is a V.T. Detector Entirely Supplied With A.C., Which is Rectified for the Plate Only.

WORKING with the hook -up defor any case of H. F. magnification where steps resistance amplification. On the posi- scribed in RADIO NEWS for January a tuned circuit can be provided in the plate tive lead to the filaments, a carbon filament (p. 447 ), I found I could even dis- side of the last V. T. of the receiving set. lamp provides the right voltage for the pense with the potentiometer, provided re- . When using a tuned circuit on the plate correct heating. A small rheostat will be ceivers are put, with a galena detector, on side of a V. T. working in H. F. amplifi- useful. shunt to a tuned circuit on the plate side cation, the signals being detected with a For A. C. work, a rectifying device is of the valve. crystal in shunt with the tuned circuit, you needed for the high voltage, but not for Not the slightest humming is to be heard, can dispense not only with the four volts heating the filaments of V. T. A very good rectifying device was given in RADIO 'while signals come loud and clear, the accumulator but even with the "B" battery, as a further magnifi- drawing any voltage, high or low, from NEWS, February, 1921, issue, p. 540. A tuned circuit acting -up is cation. The explanation is that this cir- the mains. As explained in a previous very simple hook given there which responds to the high frequency of note, the tuned circuit effectively drowns is also self -explanatory. cuit see that no cell nor wireless signals but remains deaf and any perturbing noise and wireless signals Experimenters can the low frequency of A. C. come quite loud and clear. battery is needed and dispensing with them dumb to very will in cases. (5o periods per second). For D. C., the hook -up is very simple, be welcome many The method seems general and useful the scheme being self -explanatory, two- * University of Montpellier, France. A Tube Transmitter Using A. C. on the Plate By D. S. BASIM THERE is no doubt but that tube few, if any, have given real constructional age transformer thru the plate coil. transmitters are the coming thing, and data for building a simple and efficient out- The high voltage transformer is not dif- the winter is over there will fit for 200 to 35o meters ; also they fail to ficult to construct, and as several good ar- before have a number in use. Straight C. W. give any hints on operation or to tell the ticles on their construction appeared be large in a number magazines the writer does fine for the fellow who can afford it, but reader what to do in case the set refuses to of is little article not think it necessary to give details on a few of us still belong to the "Limited work the first thing. In this and to this small I will endeavor to supply these details. this. Pocketbook Fraternity," be article is directed. The exact efficiency of the following out- The filament of the tube may lighted group this by a separate or an is no question but that modulated fit has not been accurately determined, but battery, transformer There a single extra winding on the power transformer. C. W. has it all over pure C. W., for the five -tenths amps. were put out on the most efficient way wire 5o -foot antenna using a Western Elec- However, if the same transformer is used present at least, and relay it is to use A. C. on the plate. tric VT -2 tube; no doubt this radiation to supply the high and low voltage, a to modulate to be used to make and break the only A. C. that the average amateur could be increased by employing a larger ought The high circuit while if a separate has access to is the 6o -cycle lighting cur- antenna. voltage a low note, but one CONZTRUCTIONAL DATA. transformer is used the key may be placed rent ; true this gives turns in side of the step -up transformer. is clear and musical and carries thru The grid -plate coil consists of 70 the Ito which on a tube To accomplish anything at all some form static very well. Considering the simplicity of No. 20 S. C. C. wire wound construction and operation 4" in diameter and 5" long. A well shel- of a hot wire ammeter is necessary; how- and low cost of ever, you none small bat- of this set it should prove quite popular. lacked "Hominy Grits" box will answer if possess put a of articles written on this the purpose very well. tery lamp in your antenna lead. This Of the number makes first-class little indicator. When subject that have come to my attention, A tap is taken from the center of this a winding and on the side of this center tap you purchase the bulb, look on the carton taps are taken every five turns (grid coil) and find what the ampere consumption is, while on the other side of the center a tap in this way a fairly accurate idea of your every ten turns (plate coil). These taps radiated amperage may be attained. It will should be made by leading a loop of the be best to start with a 2 or 3 tenths amp. wire thru a small hole in the tube and lamp. You may short this lamp when full brot to binding posts on the end of the adjustments have been made. tube as the antenna coil is to slide over ADJUSTMENTS. this coupling coil. The antenna coil consists of 3o turns of Slip the antenna coil over the coupling No. 20 S. C. C. wire wound on a 2" sec- coil a little toward the plate coil side of the tion of a "Quaker Oats" box. 'Paps are to center, and place a few turns of wire in be taken every three turns by scraping the the circuit if your antenna is large or near- wire bare for %" and twisting a small ly all if it is small. Light the filament, loop. After these coils have been wound press the key and with the insulated grid they should be shellacked well and put wire touch the various taps on the grid away to dry. coil, changing, if necessary, the plate con- The condenser consists of two sheets of nection to its various binding posts. Next, thin brass 2" x 3 ", separated by a sheet of slip the antenna coil toward the plate coil 300 fo mica. The whole can then be clampt be- until best radiation is secured. 400 V. tween two pieces of bakelite. The capacity If you have no wave -meter the best way Here is a Simple C.W. Set That Operates on A.C. as it mere- to arrive at your wave -length is to have The Transformer Supplying the H.T. May Easily of this condenser is not critical Be Built. ly prevents the shorting of the high volt- (Continued on page 892)

www.americanradiohistory.com 864 Radio News for June, 1921 A Mental Telegraf. By MAURICE BUCHBINDER

length (5o' or so) would have to be used before the effect of true radiation could be noticed. Stable transmission of speech by means of an oscillating vacuum tube in a simple circuit is unthink- able at a frequency of twelve million F/g. / cycles. Fig 2 The next idea Diagram of the Receiver Unit and Description of Instruments Description of Items in the Transmitter Unit. that strikes us, of Used. course, is high fre- A -10 turns coil same as transmitter coil. B- Tuning capacity A -10 turns flexible cotton covered wire, No. 18 about, 10 "x12" adjusted to 400 meters with coil A. C -R. F. transformer; honey- sewed in the plane of back of vest, wires spaced about % ". B- quency induction. comb coils with turns taken off until tuned to 400 meters. D- 10 turns coupling inductance with same dimensions as above and Why not build a B battery unit 30 flashlight cells. E -4 -volt storage battery. F- coupled thereto. 0-Tuning condenser for 400 M. capacity of high frequency Stopping condenser, 0.0005 mf. mica dielectric. G-A. F. trans which is 0.0005 mf. Can be thin mica with tinfoil plates at 3 former; Federal, Acme or Century. The vacuum tubes used are sq. inches in area. D- Stuffing condenser to keep B battery from transformer of ex- of Moorhead make It is seen that the circuits used are as sim- short circuiting; capacity 0.01 mf. The high frequency choke is ceedingly loose ple as possible, this being necessary of course to save in weight, a DeForest L -100 coil. The audio frequency choke can be a coupling (150' be- space and reliability. No rheostats were found to be necessary single 1000 M. telefone (No. 66A Western Electric Co.). The tween primary and and the storage batteries have sufficient capacity to serve thru a voice transformer is a 201 -C Western Electric. The B bat- reasonable time. A cut out switch for the batteries, which is tery unit consists of 60 flashlight units. The modulator grid bias- secondary), im- the single control for the operator is brut out for easy and ing battery is made of five flashlight units. The filament bat- press the speech on concealed use Thus only when bulbs are actually used are they tery is a 4V storage battery. the primary, and lighted. pick it up on the NEARLY everybody is familiar with secondary? The beauty of this method, if it body in the plane of the coil did not appear the theatrical act wherein somebody works, is that the two circuits, that is, the to alter either the tuning or the current in the audience whispers the name two people carrying them, can move about in that circuit. With this much found out. of a song to one of the performers freely and yet carry on their intercourse with the rest was comparatively easy and merely and then is greatly surprised and ease. It was found that with a single vac a question of design. imprest to hear the resounding notes of the uum tube receiving and a single tube sending, Of course speech transmission is some- called -for melody, from the stage. Or may- with the primary a square coil of io turns and thing far more complicated than mere tap- be it is the name of a person or of a thing ping of dots and dashes. It was decided which is thus tranferred in utter disregard _:/75/72, Cc%s that to receive the signal with suitable A and of space and time. d audibility, a separate oscillator tube and The superstitious ones in the crowd will, modulator tube would have to be used in on being confronted with such a phenome- a conventional Hussing circuit. For receiv- non, be inclined to lay it to mental telepathy, ing one -step of radio frequency tuned am- a transference of non -physical thot thru plification and one of audio frequency after physical space, in spite of the incongruity rectification was used. of the explanation. The skeptical man will The next problem was that of picking up say it is all a "put up" job between some whispers by means of a transmitter con- pseudo spectators and the performers, but cealed on the chest. The ordinary carbon your scientific minded fellow will think hard back transmitter, as any amateur knows, and try to devise a means of doing the is far too sensitive for that purpose. We work. nearly fell over this stumbling block when It is the object of this article to describe working out the problem. Fortunately, we in a not too detailed way an apparatus ran across the dictagraf transmitter with which the author will call the "mental tele- its polished spherical carbon balls, and it graf," which is capable of transferring worked beautifully. whispers over a range of i5o', capable of The next and last problem was that of absolute concealment as to both receiving concealment. It was the easiest of all. The and transmitting ends, -which has been /4' coils are sewed into the back of a canvas constructed and operated for the purpose Batteries /»,00ckets vest. In the pockets of this vest are placed mentioned in the first paragraf. Of par- like cartridge belt little "B" batteries (flashlight units) fixt is it to Radio amateurs be- mica tuning condensers, the necessary ticular interest This Sketch Shows How the Various Parts of trans- cause it reveals the manifold applications of the Set Are Fixt in Pockets on a Canvas Coat formers and chokes, the vacuum tubes, and their hobby. The idea is original, so far as That is Worn Under the Dress of the Operator. in the lining, special two -ampere hour lead who was largely in- Specially Built Storage Batteries Are Used in batteries. The entire known by the writer, Two Large Pockets. apparatus, when ar- strumental in perfecting it. ranged in the vest, weighs not more than The first thing that comes to mind when 15 pounds for either sending or receiving we think of the transmission of intelligence 12" side, and the secondary identical, signals units and is so economical in space that it is, -radio waves. Yet second thought will could be transmitted from one circuit to the can be worn under a full dress or business show that for the purposes we have in next, by tapping the grid, thru a distance coat with suitable padding. For receiving, view, radio waves are not suitable. For a of over 150" at a wavelength of 40o meters. head telefones are, of course, necessary. But distance of 15o' waves of extremely short Furthermore, the immediate presence of the (Continued on page 929) WASHINGTON'S BIRTHDAY RELAY RESULTS By H. W. KIRWAN, 9XE ON the night of February 21 -the big- better shape, and the other two words were Pacific Coast, and the remaining two from gest free for all relay was run thru- easily copied from the middle west. the Mississippi Valley. Some perfectly out the United States and Canada. An COMPLETE CORRECT MESSAGE. wonderful receiving was done and some real May the spirit of Washington be our guide actual count of the answers received showed in all our national aspirations and may the records made and as a whole it was a very that over 7,240 amateurs sent in reports. current year mark the return of tranquility, creditable performance of the real amateur Harding, stability, confidence and progress thruout entire body. The message was one from Mr. world. If this magazine were large enough now President Harding of the United Fourteen of these words representing the it would publish each and every name of States. It consisted of 3D words and i4 of first, third, fifth, etc., were sent from the those who participated, but we don't be- from the Atlantic Coast in lieve that it them came thru Atlantic Coast ; fourteen representing the. would be interesting. As far great shape, 14 from the Pacific Coast in second, fourth, sixth, etc., came from the (Continued on page 929)

www.americanradiohistory.com Radio News for June, 1921 865 The Vacuum Tube In Radiotelefone By JOHN SCOTT -TAGGART

7 nate. This necessitates a source of e.m.f. B to give G a neg- C, ative potential. A battery may be the radio used, but since T frequency e.m.f.'s are probably o high, it is possible to utilize CZ the potential drop across the grid leak of the master oscil- iiii- ,000099 ill 1111111111111111111 H lator to give G the requisite potential. The gird leak is preferably a wire coil from which a tapping may be taken. Fig? , to It will usually be preferable In This Circuit the Variations of Potential of the Microfone -way along Are Impresst Upon the Grid of the Power Amplifier. operate V not half its curve, but at the foot of THE essence of valve radio telefony it. No anode current will now flow In This System of Modulation the Tube Shunts lies in the system of modulation. The thru V, except when the modulated the Inductance and the Leakage Thru it is Controlled by the Grid Variations. production of oscillations is an easy oscillations from the master oscillator potential of G. Preferably, this matter; the three -electrode valve, the arc vary the (c) High frequency energy is and the high- frequency coupling is effected by inducing the absorbed alternator have latter from the input grid circuit by the microfone all been used for the production of the modulated oscillations into an aperiodic coil arrangement. carrier wave which is to be modulated by G and F. The coupling between this across A form of 2 (a) system is in the microfonic currents. The purity the the oscillator is adjusted to pro- the shown of coil and Fig. 2. A source V, of pure continuous os- waves produced and its adaptability to duce the maximum output from V without cillations small work The above amplifier induces into the grid circuit L, of power make the valve an ideal producing distortion. V,. The grid is given a negative potential generator. The other of -fre- has disadvantage that the aerial sources high system the by a source .B having an e.m.f. quency energy cannot be controlled in the comparable to the e.m.f. of in L,. A large number of ways that it is possible to the oscillations modulate microfone M arid microfone transformer T the output of a valve, but on the will vary the gride base -line potential dur- other hand practically any valve modula- ing speech. Conditions are roughly illus- tion system which can be used an arc with trated in Fig. 3. When not speaking, the or high- frequency alternator can also be grid potential used with A is such that the oscillations a valve generator. D do not cause the grid potential to pass THE AMPLIFICATION OF MODULATED beyond the bend in the curve. Consequent- ENERGY. ly, the power developt in the output circuit It is not essential to proceed further, once of V, (shown this time loosely couplied to a suitable method of modulating oscilla- the antenna circuit) is very small. When tions has been devised. Even if the power M is spoken into, the positive half -cycles of thus modulated is very small, yet long the microfone potentials cause the grid range telefony many be obtained by ampli- base -line to move towards the bend. The fying the weak modulated energy. This oscillating potentials of the grid pass up method is very old, and is an obvious one. Grid vo/is the steep portion of the curve to an extent The fundamental circuit is shown in Fig. depending on the movement of the grid I. Across the grid G and filament F are base -line produced by the microfone. The applied the weak modulated oscillations output of V, increases greatly, and will be which will be usually produced by an oscil- Fig. 3 directly proportional to the microfone po- lating valve. The valve V will amplify tentials. This system gives very good these weak oscillations, and the power out- This Curve Shows the Variations of Grid Poten- speech. tial When the Microfone is Spoken Into. put will be developt in the antenna, or in a The 2 (b) arrangement differs in that the circuit coupled to the antenna. Several circuit has to be in tune with the frequency microfone M and transformer T are re- valves may be connected in cascade if the of the local oscillator. This disadvantage moved from their position in the Fig. 2 final power is insufficient, the coupling con- does not arise if a fixt wavelength is used. circuit, and connected in place of H. The sisting of impedances, or air core (or iron MODULATION SYSTEMS. power developt by V, is directly proportion- core) high -frequency transformers. to now come to the important problem ate the anode voltage. This anode volt- The amplifier arrangement of Fig. i We age is supplied by M and of providing a modulation system which T, and the output which lends itself to all systems of modula- is consequently proportional to - will give perfect articulation. The follow- the micro tion has a high efficiency. The "master fone potentials, which is what is desired for oscillator" valve may operate off the same ing are some of the more important methods of the high -frequency out- good articulation. Obviously the power source of filament and anode current as the modulating developt by M and T is too small for gen- power valve V. The normal potential of put of a valve: - use, in eral and valve amplifying arrangements the grid G may be such that the operating l. Grid potential control consists vary- are used to provide a suitable source of e. m. a the normal point is half -way along the grid-potential- ing by means of microfone f. for the anode circuit of V,. It will be anode -current curve of the amplifier valve operating point on the anode current curve noted that this arrangement, like the pre- V. This curve will usually, and should, lie of an oscillating valve. The output of the vious one, is a "quiescent aerial" system. completely to the left of the grid zero ordi- valve depends largely on the normal grid No is radiated, in its energy except when speak- potential. This system is critical ing. Sometimes, however, a source of e.m.f. action and is not to be recommended, tho the principle has been utilized in very many (Continued on page 8g8) circuits. 2. An amplifying- power valve is used in conjunction with a separate source of pure oscillations which excites the grid circuit of the amplifying L O M.F. valve whose output may be modulated by any of the fol- B F lowing methods :- (a) The grid "base- line" -111111111111- 111 potential (or operating volt- Fig. age) is varied by a microfone Fig 6 arrangement. This Diagram Shows the Typical Circuit of a is This is the Choke Control or Constant Current Power Amplifier Tube as Used. in Radlofone (b) The anode voltage Modulation System in Which One Tube is Used Hook -ups. varied microfonically. as Oscillator and One as Modulator.

www.americanradiohistory.com 866 Radio News for June, 1921 The Radio Compass By LIEUT. COMMANDER FRANK LUCKEL, U. S. NAVY

station and they will be a maximum again States shore radio compass stations pro- when the coil has been revolved 180 deg. vides for furnishing bearings from a sin- and the other side is pointed toward the gle independent compass station to vessels station. There will be two minima at from so to loo miles at sea. It also right angles to these two maxima. This is provides for accurately determining the known as the bi- lateral effect. Unless position of ships near shore or at har- there are practical considerations that limit bor entrances by bearings from two or the working arc to less than 18o deg., or more stations using group control. The F9 I f79 unless several stations are taking bearings group stations are controlled by a control 2 at the same time, it is impossible to be station. Radio, landwire, and submarine Fig. 1 Shows the Current in a Coil or Loop certain which of the two bearings is the cable may be used for communication be- Aerial, While Fig. 2 Shows Same in a Vertical correct one. This difficulty can be over- tween the control station and the other sta- Aerial. come by superimposing the signals of a tions of the group. vertical antenna upon the signals from the At present the radio compass is used in THE development of the shore radio coil. This gives what is known as the uni- two ways, insofar as navigation is con- compass station has been so rapid lateral effect. Without going deeply into cerned: In one system, the compass coil that comparatively few people have the theory, we will plot the signal intensity is mounted on shore and the ship's bearing been able to keep themselves in- of a single coil, assuming a maximum is furnisht after it is determined by an formed of the working principle and value of one. This current value will observation taken on the ship's signals. In ii application. Many who are otherwise reach a positive maximum when one end the second method, the coil is mounted on well informed do not know what a radio of the coil points toward the sending sta- board ship and bearings are taken on a compass station is and some do not know tion and after passing thru the zero shore station or another ship. A similar what it is used for. While these stations position it will reverse and reach a maxi- method is utilized by air craft to take bear- have only recently reached a practical de- mum in the opposite direction, when the ings on a shore station, a vessel, or other velopment, the compass coil is by no means other end points toward the transmitting air craft. Both systems are used in the a new invention. Early in the present cen- station. Both these maxima give a maxi- United States, but our shore radio com- tury investigators discovered that a coil mum intensity of signal even tho the pass stations are being developt to use of a number of wires wound upon a frame current flows in one direction in one semi- the first system. The advantages of each picked up a maximum of current when par- system are as follows : allel to direction of propagation of a trans- ADVANTAGES OF COMPASS COIL ON SHORE. mitting station which was radiating on a Station can be calibrated and errors care- wave- length corresponding to the period of fully plotted. the coil. Conversely, the signal was a min- N of so much metal to distort waves and imum when the turns of the coil were at introduce errors. right angles to the bearing of the trans- Not much electric current in vicinity to mitting station. cause distortion. No practical application of this principle Not necessary to transmit continuously to determine the direction of a distant and transmission is only necessary when transmitting station was at first possible bearings are being taken. on account of the extremely small currents Power used for transmission can be va- set up in the coil, even with the largest ried to suit conditions and distances. size loop that it was possible to use. With Personnel should be more efficient, owing the advent of the vacuum tube amplifier it to constant practice and specialization. was possible to amplify up these faint sig- Station can usually be located at water's nals so as to make them readily audible. edge and at low elevation. Rapid strides were made under the stress No extra equipment necessary on board of the recent war, in the development and ship, and the ship's radio equipment is all amplification of the radio compass on land, that is needed. at sea and in the air. No practical suc- Not so much interference. cess has yet been attained in the develop- Permits present existing shore radio fa- ment of a coil for submarine or subter- Experimental Type of Radio Compass Station cilities and landwires being used in many ranean use. What was perhaps the most Used to Determine the Best Point to Locate the instances. surprising step in the development of the Station Along the Coast. The Hut in Which ADVANTAGES OF SYSTEM HAVING COILS Are the Instruments, is Screened With Wire radio compass was the use of a coil on Cloth. ON BOARD SHIP. the German Zeppelins to determine their Operation of coil is entirely within the bearing from a German shore station trans- control of the ship's personnel, who can mitting intermittently on a cerfain wave- circle and in the opposite direction in the take as many bearings as they desire. length. The Allies used the compass to other. Results of bearing will be available good advantage in determining the position The curve, Fig. 1, shows the current in sooner than is the case when using the first of German submarines. a coil. In the case of a vertical antenna system. All radio compass coils in practical op- the signal is positive thruout. If we as- Not the uncertainty and difficulty which eration in the United States operate on the sume a maximum strength of antenna cur- is experienced when it is necessary to call principle that where lines of force cut the rent of one, we would have the curve of (Continued on page 894) coil, currents are induced. These currents Fig. 2 which always has a positive effect. are maximum when the greatest number If we couple the antenna, which is non - of lines of force cut the coil. When the directional, to the coil, we have an effect turns of the coil are parallel with the di- which may be grafically shown by super- rection of the propagated waves emitting imposing one of the above curves upon the from the transmitting station, the greatest other. The two components are shown in number of lines collapse upon the coil and dotted lines and the resultant in full line, the maximum current is induced. As the Fig. 3. coil is revolved about a vertical axis the It will be noted that this new curve gives current becomes at first slightly diminisht a minimum when the coil is pointed at and later the decrease is more rapid as the right angles to the direction of the trans- coil approaches a position at right angles mitting station, and that this minimum is to the transmitting station. This gives a not very sharp. It does, however, give only broad maximum and a sharp minimum. In one minimum instead of two. In the prac- order to understand this, it is necessary to tical operation of this coil the approximate remember that the actual line of a strain minimum is first determined using the uni- in an advancing wave front are at right lateral system. Then the antenna is dis- angles to the direction of propagation. For connected and the bi- lateral system used to this reason the maximum number of lines determine the exact minimum. Two mini- are embraced when the coil lies in the di- mum positions may be found, but the pre- fity rection of Propagation. liminary observation will indicate which The signals will be a maximum when the of these is the correct one. This Diagram Shows the Result When the Two coil is pointed towards the transmitting The practical development of the United Components Shown in Figs, 1 and 2 Are Added.

www.americanradiohistory.com Radio News for June, 1921 867 Who's Who in Radio No. 5 PROFESSOR EDOUARD BRANLY

DOUARD BRANLY, son of a pro- conductibility under certain influences, such ceiving sets was co', and they were sepa- fessor of the Paris University, was as the oscillations radiated from an oscillat- rated by several walls, as the experiment ,born in Amiens, France, Oct. 23, ing circuit. was made inside a building. I In his hooks, publisht in 1890 and 1891, Professor Branly did not only show the He made a serious study of litera- are described several types of the "Radio - powerful inductive effects caused by an oscil- ture at the St. Quentin College, until his conductors, some of which have single con- latory discharge at a certain distance, but 57th year, when he turned his attention to tacts and others have multiple contacts. demonstrated the rôle of what was later science, which attracted him. He entered Among the latter, the tubes containing pow- called an antenna, and which consisted, in the Scientific Section of the Ecole Normale dered iron, nickel, gold, etc., were consid- his sets, of long, metallic rods fixt to the Superieure of Paris in 1863, where he spent ered particularly remarkable, owing to the electrodes of the spark gap and to the ends three years, leaving in 1863 with a Licen- simplicity of the construction. of his coherer. tiate's Degree in mathematics and physics. Full details about this were given in sev- He was appointed professor at the Bour- FIRST WIRELESS SET. eral bulletins publisht in 1891, and the fol- ges College, but was soon called back to Nov. 24, 18go, Professor Branly made a lowing experiments were described. Paris as Chief of the Science Faculty's demonstration of the phenomenon before the If the receiver, composed of a coherer, a physics laboratory, but his first experimen- battery and a bell, was enclosed in a metal tal researches were interrupted by the war box, it was not effected by powerful dis- between France and Germany in 1870 -1871. charges near the receiver, while the circuit Professor Branly, in 5873, was made Doc- was closed and the bell made to ring if a Physic Sciences, and was appointed small external wire, insulated from the tor in and sub -director of the laboratory. metal box was connected to the coherer In the old, shabby building of the Sor- the transmitter placed a distance away. his working facilities were In Marconi's first experiments, the same bonne Institute, were poor, and no help was given to those who circuit and apparatus were used that to the work which was designed by Professor Branly, but the dis- devoted their time was for the benefit of all. For tance between the sets he was glad to greatly increased and the this reason on out accept a position as profes- experiments carried at the newly of doors. sor of physics remembered formed Catholic Scientific It must be in that Mr. Marconi recognized University of Paris, 1875, inven- hoping to be helped mate- Professor Branly's management of tion, when he sent the fol- rially. The telegram March 28, the new Institution prom- lowing furnish him with an 189g, across the Channel: ised to "Mr. Marconi sends across up - to - date, specially - built this promise the Channel by wireless laboratory, but compliments to was not kept, and a provis- telegrafy, his which he Mr. Branly, as this wonder- ory installation is partly still uses today, was all he ful achievement due to Mr. Branly's work." obtained. This message was sent by Fearing that the new Uni- the re- have to close, wire to Paris from versity would station erected at owing to lack of funds, Pro- ceiving Wimereux and the telegraf fessor Branly began the Professor E. Branly, Who Invented the First Wireless Telegraf System, Using success in order office recognized the study of medicine Hertzian Waves. new system of to make a living, in case of the dur- Paris Academy of Science, whereby a small telegraf y. that misfortune befell him. He studied held in and consequently could quantity of metallic powder was made con- When, at the Universal Exhibition ing his spare time, Branly was award- do very little in the way of experimental ductive, when a spark caused by the dis Paris in 1900, Professor charge of a leyden jar occurred a certain ed a first prize for his instruments, the researches. made the prominent In 1882 he received his Medical Doctor's distance away. French Government again able to carry The receiving circuit was composed mere- professor Knight of the Legion of Honor. degree, and in 5887 was discovered the prin- out his experiments. ly of a dry cell and a galvanometer hooked with the mention, "Has the modification of elec- up to the Radioconductor or coherer, which ciple of wireless telegrafy." He first observed made possible not only tric losses in darkness, determined by the closed the local circuit each time a spark Professor Branly conductor, but Pro- occurred at the sending set. The resistance wireless telegrafy, but also carried out some nature of the electrified and designed fessor Branly's researches. that have been of the coherer was restored by a light tap researches in Radio control world, are on the glass tube containing the metallic some apparatus that can be operated at a called to the attention of the and later him to the discovery of the powder. distance. He used tuning systems those that led page 929) imperfect contacts that have an intermittent The distance between the sending and re- (Continued on ATMOSFERIC CONDITIONS IN THE TROPICS By CHARLES A. REBERGER* read our sig- ISUPPOSE all amateurs have heard static is very noticeable. Ask any operator miles north of us could not let me say com- who has had cause to work down in this nals altho we were then getting twelve am- of static, but -the musical mercial operator who is forced to portion of the earth during the summer peres radiation and had a fine clear especially during and he will put, up his hand and swear spark. Radio engineers claim a musical work in the tropics, - static interfer- the long hot summer months, is the "never again." For the fellow who has spark is easily read thru realizes what static is, never been to these parts, it is very diffi- ence. only one who really I had the pleasure of and believe me, he knows. How we dread cult to realize how bad conditions are. All A few nights later en- day it is a continuous roaring, grind- listening to Swan Island working a United it! Fame and fortune await the radio long had to the wireless ing and crashing in the receivers. During fruit liner. After this station sent gineer who can present the vessel in- world, a real true static eliminator which the hours of the night it is worse -far each letter twenty times. for usage aboard ships. worse. Nine times out of ten the crashes formed him that it could not distinguish will prove efficient Only an hour before he We all know that at the present time, a will entirely blot out all signals. his characters. It is very difficult to work thru heavy had forwarded his "TR" to Swan Island number of our coast stations :ire using south of static eliminators to great advantage, but static. Let me give you an idea. One and was no more than Zoo miles they still confess that static is not elimi- evening we attempted to establish commu- this land station. nication with a station in the Canal Zone, Operators I know personally- strong and nated entirely. trop- Many of the readers have no idea how which was about zoo miles away from us, healthy -after a year's service in the are during these and failed. It was absolutely impossible ics, were forced to abandon the wireless bad working conditions breakdown. There is months. Even during the winter months to even hear his signals, due to the heave game due to nervous A only go (Continued on page 907) * Chief Operator, S. S. Atlantic Sun. atmosferic conditions. vessel

www.americanradiohistory.com erg Radio News for June, 1921 The Arc and Radiotelefone Transmission By JOHN F. SRONT

Author's Note: producer gas, free hydrogen and (The entire object of this paper others have been used in this re- is to run over the important points spect. Steam, however, has failed of the arc converter and attempt to to give more than negligible results accelerate the interest of the ama- Producer gas has the ill effect of teur in the use of the arc for tele- sooting the arc chamber walls and fonic and telegrafie work, and show the electrodes and holders. Being a the possibilities of the adaption of poor conductor of heat, the soot re- the converter to amateur work. As tards the proper conduction and dis- Mr. Gernsback stated at one time, sipation of heat from both the cham- the apparent interest of the average ioaaiiior ber walls and the inner chamber amateur in the development of radio J{_ space. telefonic work has not been quite up ._\1/. / In some smaller types of convert- to the expectations of many. In the ers, the magnetic blast is omitted personal opinion of the writer the \=e and with fairly satisfactory results. amateur interest in the radio tele- There is the matter of expense to lone has been negligible. It is in- be considered by the average ama- tended that this article may tend to teur, but it is an assured fact that show the real simplicity of the ap- all the pains spent upon the making plication of the arc to telefonic work of a well functioning blast will be and in the main give a few sug- amply repaid in the excellence of the gestions for construction.) obtained results. THE furore caused by the ad- It must be kept strictly in mind vent of the audion has ap- that in the construction of a con- parently caused a lapse in the verter of any kind whatever, a mans development of other appa- of protection must be employed for ratus in the non -professional the exusion of undue gas pressures radio field. The truth of the mat- from the interior of the chamber. ter is that the professional field has In the ease of hydrogen especially, turned its chief attention to the the envelope is explosive to a high vacuum tube. The practical appli- degree. With the hydrocarbons, ex- cation of the amateur to the radio plosions have nearly the same effect telefone will be looked upon with as those of the internal combustion favor by all those in the non -pro- engine and may be the cause of the fessional as well as the commercial bursting of the arc chamber. radio business. Relief for the high gas pressures At the time of the late war the may be readily provided for by the trained amateur was of inestimable introduction of pop valves into the value to the nation at large, and at y. sides of the chamber walls, and the the same time a great asset to the adjustment of the former for open- commercial world. The value of ing at pressures not to exceed zo trained amateur to the radio field Inside View of a Low -Power Arc Converter. Note the Cooling pounds per square inch as shown by of the future in a commercial way Flanges of the Copper Electrode. gauge. Pressures depend upon the will be of incalculable value, espe- construction of the converter but in cially when, as the present trend the small converter, the pressure shows, the radio telefone will be brot up to regulating resistance and iron core choke should not be allowed to raise above that an efficient stage of perfection and of daily coils, thence to the arc points thru the mentioned. use in the affairs of the day. blast coils. The functioning of the regu- Carbons of medium size will serve in the A combination of the arc as an emitter of lating resistance aids in the power ranges small converter. Some copper form of elec- continuous waves and the audion as a de- of the arc and at the same time guards trode should be employed for the anode. tector and amplifier, is an ideal basis for the against the overloading of the generator In this regard for the cathode, soft carbons perfection of the most desirable communica- at the time the arc points are struck. or unknown compositions should be dis- tion system. The arc converter far exceeds Damage to the generator by excessive carded. Considerable effect upon the opera- the audion tube as a transmitter of un- loads is prevented, The current at the tion of the arc is due to the burning down dampt waves from the standopint of econ- arc points is increased as the arc gap is or the building up of the electrodes. Proper omy and power. The outstanding feature of gradually widened for the maximum of cooling must be provided for. High tem- the arc is the propogation of radio frequen- power emission while the hot wire ammeter peratures will result in the comparatively cies directly from a source of direct current, is scrutinized for the maximum of radiation swift disintegration of the electrodes and and the stability of the apparatus if con- in the antenna system. the general poor functioning of the- con- structed, attended and operated with all due In the larger types of converters (and in verter. At the same time high tempera- regard to mechanical and electrical conven- the smaller, well constructed) solenoids tures cause the highly accelerated vaporiza- tions. When certain rules are followed sym- throw a magnetic flux across the gap at the tion of hydrocarbon bases pathetically with regard to requirements and the resultant the time the latter is functioning. The blast superheated gas soon comes to the explo- of such apparatus, the converter will func- stretches the flame and assists in raising the sive stage. tion with full efficiency and the desired ex- arc potential. Of further assistance in the Producer gas has cellence of results. the quality of building raising of the arc potential is the envelop- up the negative electrode. The use of al- Arcs have been successfully operated at ment of the gap in a gaseous surrounding. ranging cohol is recommended by the writer as the potentials from rio volts up to hun- Steam, and volatilized kerosene, alcohol, and hase employed for dreds and the production of a gas thousands. envelope. Mixtures of High power stations favor kerosene current drawn from 500 - and alcohol are volt machines which are used with satisfaction. designed for the produc- Producer gas is of unde- tion of large current val- finable mixtures and ad- ues. The series or paral- mission of these mixtures to the arc chamber will lel operation of these ma- cause chines gives a flexibility irregularities of op- of operation rendering eration, and the refusal sufficient current supply of many small arcs to for the individual re- function may be traced to quirements of that par- this very cause. ticular station. Efficient vaporization of In almost all types of the hydrocarbon bases is Figs. 5 and 6 Show Various Systems converters, is led of Cooling by Water mm a hard matter to realize. current Circulation Inside the Copper Electrode, While on the Right The from the generator thru is a Detailed Sketch of the writer advises that Carbon Holder. in the small transmitter,

www.americanradiohistory.com Radio News for June, 1921 869 a porous material be placed poration of the cores, as about or adjacent to the eir5 the frame of the apparatus, negative electrode whereby may well serve to further the heat from the carbon the compactness and the iLÍi volatilizes the base uni- ,u rigidity of the apparatus as formly and the envelope is a unit. The strength of the formed with little or no blast depends upon the ap- difficulty. Effiçient cooling plied current and upon the of the copper electrode is extend of the windings. requisite, else irregular op- Specifications for the proper eration and wavering arc construction of the blasts potentials will result. Dis- may be found in most text integration f o I I o w s high books from the furnisht electrode temperatures. formulae relative to flux Revolution of the carbon and current relations to tends toward the even burn- cores and windings. Proper ing of the latter which is calculations may make it important in radio telefonic s/o /e' possible for the formation work where a steady, sharp, of the blasts in such form even emission is desired so as to serve both as chokes efficient modulation and blast coils at the same that IResisionce Rodio may be accomplisht. Reactance Amps. time. Thrusting of the core Water circulation seems ends thru the walls of the the premier means for the Fí9.3 jacket brings the blast in anode cooling. Careful Here is An Arc Converter of the Magnetic Blast Type With All the Necessary immediate adjacency to the planning will result in the Controls Fixt on the Base. arc gap. In the construc- possibility of the admis- tion of converters using sion of a large stream of circulating to a small value of temperature, the dis- the magnetic blast, it is important that water to the copper electrode. A requisite charge of the condenser occurs again. the chamber be made of other than in this method is proper circulation. There is a lag of the fluctuations of the magnetic material to prevent magnetic This may be effected by the thermo- temperature and the electrical fluctuations shunts from the gap and the inevitable syphon system or by input from the house in the circuit. eddies. Copper, aluminum or brass may be water supply and outlet to waste drainage. In converters of comparatively low power employed in almost any kind of converter A steady dissipation of heat from the elec- the water cooling system may be well dis- for the jacket construction. High thermal trodes, as well as that from the jacket, is pensed with and somewhat satisfactorily. conductivity is important. thereby accomplisht. Wide hollowing of Radiating flanges attached to an extension For amateur work on short waves, the the copper electrode will allow the admis- of the copper electrode thru the base of the insertion of the arc in direct series with sion of comparatively large quantities of converter into the outer air, will dissipate the antenna and ground leads is recom- water and the important factor of stabiliz- heat with considerable consistency. mended. The employment of the shunt ing the copper anode at low temperature Cooling of the arc chamber is mandatory condenser around the arc may serve in the values will be accomplisht. when the heat dissipation from the elec- easy adjustment of the apparatus. The In this respect the following may be ex- trodes is of negligible quantity. By the condenser referred to previously, regarding planatory : attachment of radiating flanges to the outer the wavering of the arc current is the shunt With the primary flow from the gener- side of the jacket, a fair means of radiation condenser mentioned here, but in the ab- ator, current will flow into the condenser of heat is accomplisht, but this means is sence of this latter, the charging and dis- until such a time as the gap breaks down. not readily recommended. The cooling of charging of the antenna, functions almost This occurs at a time when the condenser the chamber and the electrodes cannot be in exactly the same manner. The shunt is not at a full state of charge with certain impresst too strongly for the correct and condenser with the arc in series with the adjustments of the arc gap. There is a efficient operation of the converter. Many ground and antenna proper, serves for the division of current between the condenser low power transmitters after a few scratchy easy adjustment of the correct capacity val- and the arc circuits. The current across emissions lay down and give up the figura- ues for the wave length used which is done the gap is reduced. This raises the poten- tive ghost and refuse to function on this by the change in the aerial tuning induct - tial and the condenser charging rate is ac- account alone. The matter of heat dissi- (Continued on page t92) celerated. At a point near the complete pation effects the vaporization of the gas charge of the condenser, a discharge of the envelope base, and at the sane time the latter starts across the arc gap. The ex- latter and the undue rise in temperature cessive current, that of the condenser com- of the anode and cathode directly effect the bined with that of the arc gap, brings the arc potential, the radiated energy and the arc points to a state of high temperature. working distance of the transmitter. SIARTIHG Before the arc points have the opportunity In this regard, at the period of the dis- AESIS. to cool to normal or reduce their hot state charge of the condenser across the arc, the excessive heat brings the electrodes to a state of high temperature. Necessarily the .41114 surrounding gas medium is highly ionized. Pe* :20) ft The conductivity of the arc gap is greatly 4eA increased. Oscillations occurring at a high . REACTANCE STARTING 0515. ® ® ® frequency, the electrodes are not allowed ioari 'ìr. ,r I S/afe- Top lrien. IIIIIIIR1111n1111111 sufficient time to cool, as mentioned before, and the potential of the arc at that state is fiQ 4 !hÌIIGÌI 1 I II IIEIIIIIIIIIIIIIIIuIiIIIIIIIIIIIIIII1g likewise. LldlliulllllllllOMIIIImRi I I nlmmllsliulomtmrllilrm 19PIfiI less and resistance of the gap

1111 1 0.0 » 11111 111 Il llll age When the current increases the electrodes 04Iroho/ Pop Valve have not sufficient time to reheat and con- Brass. Iron 1111111 11111111111111111111111111 sequently the gap resistance at that time is 1111111111 I I IIIIIIIIIIIIU IIIIIIIIIIIIII high. There is a lag of the temperature behind that of the oscillations, and the well functioning arc, therefore, must have a 0 steep characteristic curve and consequently a high negative resistance. 111111111111111 The smooth operation of the arc not only 1N I, depends upon the good functioning of the Ya apparatus beneath the chamber shell, but . Irmmullurm n Iln mrmmllllllllll J14114114 I!IiIIIIIIIIYIM Sv upon the steady supply of DC to the circuits of the arc and that of the condenser. Good insulation must be maintained in both the DC circuits and the radio frequency, as well as in the base of the converter itself. The blast bears directly upon certain po- Front hair arc length of the flame tential limits of the Fig 4 Fig. s and the resultant amount of radiated or small Arc Converter of the Amateur Type. The The of transferred energy. employment This Arc Set is Designed for Lower Power, But Body is Made of Brass and the Base of Slate; in making of cores is on the Top are Fixt a Pop Valve and an Oil soft Swedish iron the is Also Fitted With a Magnetic Circuit to Blow Cup Filled With Alcohol. recommended by the writer. The incor- the Arc,

www.americanradiohistory.com 870 Radio News for June, 1921 The Efficient Design of Vacuum Tube Telegraf and Telefone Sets By JESSE MARSTEN

REVIOUS to the recent complete Similarly the decreases in plate current development and understanding of must be effected by the oscillating circuit. the action and theory of the vacuum The oscillating current io increases and de- tube, it is probably true that trans- creases the plate current. mitters were largely designed by the The action of the modulator may be "cut and try method." That is, the cir- briefly described as follows : The relation- cuits associated with the vacuum tube, ship between modulator tube and oscillator and their constants were varied until the tube is identical with the relationship be- operation was considered satisfactory. tween oscillator tube and R. F. oscillating Those constants, circuits and designs were circuit described in the preceding para- then chosen which were most suitable and graf. The two tubes are connected in gave the best output and efficiency. It is shunt with reference to audio frequency probably also true that the "cut and try" currents. The supply current, I, as before, method of design is still much in use in is maintained constant by means of the spite of our increased knowledge of the choke coils. The modulation tube resist- subject, and perhaps justly so. For after ance varies between two extremes due to all, this is the ages -long method of learn- variations of the speech voltage applied to ing everything, it is the method of expe- the grid. Thus the current in the plate rience characterized by the phrase "see- circuit of the modulator tube will vary in ing is believing." accordance with the changes in grid volt- Taken by itself, the "cut and try" method age due to the speech. But since the audio is long, laborious and expensive. But choke coil A, prevents the supply current when used in conjunction with an under- In This Radiofone Circuit for Short Waves, the from varying considerably in audio fre- standing of the tube and its circuits, it be- Constant Current System of Modulation is Used. quency manner, it follows that the plate comes a very powerful method. For the F. oscillator may be briefly described as current variations in the modulator must knowledge of the theory and action of the R. be supplied by the shunt connected oscil- circuits, and of the functions of the ele- follows : The oscillating circuit and the lator tube, the only other source. Thus ments comprising the circuits, enables the tube (considered as a variable resistance) are connected in shunt the condenser the oscillator tube will lose or gain current predetermination of the less difficult parts thru (which is added to or subtracted from of the design. This leaves the more diffi- C . The characteristic of this circuit is modulator plate current), in accordance cult and new parts of the design to the that the current supplied by the generator with the speech as the resistance of the "cut and try" method, which is given more is kept constant no matter how the tube modulator tube decreases or increases. resistance varies, or how the plate current A R thru the tube varies. This is accomplisht by means of the choke coils A and R. The supply current delivered by the generator may vary either in radio or audio frequency manner. Choke coils A and R are properly designed to be of such high values that there can be no variation of the supply current (efficient choking action), the A coil preventing any audio variation in supply current in front of the Fig. 5 Fig. 1 -a modulator tube, the R coil preventing any Here is the Correct Way to Connect the Choke radio variation in supply current in front Coils and Capacity to Smooth Out the Current The Dotted Lines Show How the Condenser Cp From a D. C. Generator. Forms With Audio Frequency Choke Coil a Low of the oscillator tube. Any audio vari- Frequency Circuit. ation is permitted between modulator and Thus the R. F. output of the oscillator will oscillator tube for modulating purposes. be modulated by speech, by a variation of intelligent direction by the knowledge of The choke coil R at the same time serves amplitude. the theory. to prevent the modulator tube acting as a The design of these circuits will now be Straight electrical engineering has short circuit (shunt connection) to the taken up element by element, and the con- reached the position where it has sufficient radio, frequency thru the oscillator ditions and factors determining the choice data and verified theory to enable in a valve. Thus, since the supply current, I, of design constants, etc., fully considered. large measure the complete predetermina- to the oscillator valve is held constant, It is assumed that the plate voltage is ob- tion of constants and performances. Ra- then any variation in the tube resistance, tained from a D. C. generator of ordinary dio engineering is fast approaching this due to a variation of grid voltage, results commercial design, giving the required stage. It is the object of this paper to in- in a plate current variation which cannot voltage. The discussion will apply also appli- dicate in an elementary manner the be supplied by the generator. This varia- when the source is rectified A. C., but then cation of these ideas to the design of tele- tion is taken care of by the oscillating cur- we start from the condenser terminals .de- graf and telefone transmitters of the rent. Thus assume that the grid oscillat- livering the D. C. vacuum tube type. ing voltage at any given instant is such as SMOOTHING OUT CIRCUIT. To make the problem more concrete the to decrease the tube resistance, the plate discussion will revolve about a definite current must then increase, but since I is Starting at the generator, the first ele- oscillation circuit and telefone system. The held constant by the chokes, the increase in ment to be considered is the generator con- circuit chosen takes in practically any prob- plate current must be supplied by the oscil- denser Cg. D. C. generators do not give lem which might arise in practice, and the lating current io thru the condenser CO. an absolutely straight line voltage. There discussion which applies to this circuit will is always superimposed a small A. C. volt- also apply to other circuits with little mod- age called "commutator ripple," and the ification. magnitude and frequency of this ripple The oscillating and telefone modulating varies with the design of the generator. circuits to be considered in detail are This ripple produces a tone modulation of shown completely in Fig. 1. Modifica- the R. F. oscillations depending on the fre- tions of this are shown in Figs. 2, 3 and quency of the ripple. This tone modula- 4. Consideration will show that these are tion may be quite strong in the receiver all practically identical. The oscillating (commutator hum) and it is necessary to circuit goes by various names, but is best eliminate it. This is effected most simply described by "Shunt Circuit" or "Con- by the generator condenser Cg. stant Supply Current Circuit." The modu- The action of this condenser may be lating system is popularly known as the considered as follows : it is placed across "Heising System," but is better described Fig 3 the generator terminals, practically parallel by the name "Plate Injection System." This Circuit is Merely a Modification of the with the oscillator tube. (We are con- Assuming the modulator tube not to be Hook -up Fig. 1. Two Separate Inductances Are sidering the R. F. oscillating circuit, and working for the moment, the action of the Used for the Grid and Plate Circuits. therefore disregard the presence of the

www.americanradiohistory.com Radio News for Jude, 1921 871

relatively simple and allows the use of smaller capacity. ,, RADIO CHOKE. c We pass now to a consideration of the choke coils. As stated in the general discussion of the action of this circuit the function of these coils is to maintain the supply current from the generator prac- 11111111 111111111 tically constant. Later on, another point of view will be given, but at present the one given will suffice, namely the preven- Illlltlllllllllllll frequency or radio frequency tion of audio fig. 2 fig. 4 fluctuations of any considerable magnitude. action of the coils is based In This Oscillating Circuit the Plate and Grid This choking Inductances Are Shunted by Condensers and the In This Diagram the Oscillating Circuit is In- on the fact that they present a high re- Plate Inductance is Inserted in the Aerial ductively Coupled to the Aerial Inductance. actance to these currents, thus reducing Circuit. the A. C. to a negligible minimum. audio choke A.) Hence, if the reactance On first consideration it might be thot amount depending on the coil design. This of the condenser is made very low com- that if the inductance of these chokes were capacity may be sufficient to by -pass the pared with the oscillating tube resistance, made large enough, the reactance would radio currents thus destroying the choking most of the A. C. due to the commutator then be great enough to prevent any kind effect of the coil. It is necessary, there- ripple will pass thru the condenser and of fluctuations. Thus, just one choke coil, fore, to design the radio choke either not the tube, thus having no modulating A, would be sufficient, for if its reactance without any appreciable distributed capac- effect on the R. F. oscillations. Another were large enough to prevent audio fluc- ity, if this is possible, or so that the dis- way of considering the action is to consider tuations, it surely could prevent radio tributed capacity may be used to effectively the generator and condenser as an alternat- fluctuations. Consequently the other choke assist the choking action. This problem ing current circuit comprised of inductance coil, R, could be dispensed with, in this is capable of simple mathematical analysis, and capacity, the inductance being internal way simplifying the design problem. This but will not be given here separately as in the generator. If the reactance of the is not so for two reasons. In the first it is taken up and considered under the generator inductance is high and that of place assume that only coil A were used. sub -heading below : "Design of Oscillating the condenser very small, most of the A. C. This is necessarily an iron core inductance Circuit for Maximum Output and Effi- commutator ripple voltage will be con- for good audio choking, which means in- ciency." The conclusions to be drawn sumed in the internal inductance of the evitably a high distributed capacity in the from that analysis which are pertinent to generator and none, or very little, will be winding and between winding and core. our present subject, will be here given. available across the condenser, and hence This distributed capacity would by -pass In the analysis mentioned above, the not available for producing the undesirable the radio currents, and thus render the impedance of an inductance shunted by hum. Both these ways of considering the coil ineffectual as a radio choke. In the a condenser is derived in terms of the action mean that the condenser practically second place if only one coil A were used inductance and resistance of the coil, ca- short circuits the A. C. voltage (due to its there would be no safeguard against the pacity and frequency. In the case of the very low reactance to audio frequency cur- radio frequency from the oscillator tube choke coil the capacity is the distributed rents) and hence renders the ripple in- kicking back into the modulator tube capacity of the coil which behaves as tho effective. To produce a low reactance at which is shunted across it. Thus two it were shunted across the coil. The an- audio frequency requires the use of rela- choke coils are absolutely essential as in- anlysis shows that if the resistance in the tively large condensers of the order of / dicated in Fig. 1. circuit is negligible the impedance is in- to I microfarad. It might also be thot that the higher finite at the natural frequency of the coil, Thus consider a tube whose resistance the value of inductance in both chokes and becomes smaller the more the depar- is say lo,000 ohms. Let us assume the the more efficient they will be as choke ture from this frequency. But the resist- frequency of the ripple to average 800 coils. This is not so. There are definite ance of the coil is generally not zero, but cycles. If we use a I microfarad con- limits to the most efficient values of the by good design may be made very small, denser the reactance is choke coil .constants, and no advantage is and in this case the impedance is shown gained by exceeding these limits. It may to be very great to currents of the same I I in fact be disadvantageous to do so. Fur- period as the coil period. This gives the Xe = = an- X thermore, as will be shown, there is important conclusion that a coil behaves 2irfC 27r 800 X Io.s other factor in the radio choke besides in- most efficiently as a choke at its own nat- = 200 ohms (approx.). ductance which must be considered in the ural frequency. The more the current -to- This is only 2 per cent of the valve re- choking action. We will consider the he- suppressed departs from this natural sistance, thus practically all of the A. C. radio choke first. frequency the less efficient will be the current would flow thru the condenser and just as in the audio choke coil. the radio choking action. none thru the valve, thus producing no choke may possess distributed capacity, the This does not mean that it is essential hum. In such a case lower capacity con- to have a separate choke coil for each op- densers could be safely used as / or even erating wave -length. If a plot is made of microfarads. The generator inductance Impedance A the impedance of the choke against fre- is easily of the order of several henrys in quency a graph similar to Fig. 6 will be the high voltage type of generators used obtained. This shows that at wo the im- on these sets, let us say 2 to 4 henrys. The pedance is a maximum, being the natural inductive reactance is therefore frequency of the coil. On either side of wo there will be a range of frequencies at Xi 27rfL 27r X Soo X 2 (or 4) = = which the impedance, altho not a max- = 10,000 tO 20,000 ohms. imum, is very high and the choking action The capacity reactance is thus only 1 to 2 good as between w, and w,. Thus a choke the inductive reactance and Na/ura /,ceriodie./y per cent. of of coil maximum coil designed to have a natural period cor- therefore only r or 2 per cent. of the rip- impedance responding to we, would act efficiently as ple voltage will be available at the con- a choke between frequencies corresponding denser terminals, which produces no harm- WZ to w, and w,. ful effect. The answer then, is a coil having ap- equal to Some generators have a very bad ripple frequency proximately the natural period and may require as much as 1 or 2 micro - that of the current to be choked. The farads to eliminate the hum. In case of question of the design of a choke coil to very severe ripple the following arrange- have any given period, without using a ments (an expansion of the principle un- concentrated capacity, is not capable of derlying the second explanation advanced) absolute predetermination, due to the dif- will prove effective and sometimes neces- ficulty in calculating the distributed ca- sary. Heavy choke coils L, and L, (Fig. pacity of the coil. Thus, for practical en- 5) are placed in the generator leads gineering purposes a semi -empirical method and the condenser across them. The choke such as the following would be employed. coils consume still more of the A. C. volt- Having chosen the hest type of coil to be age leavin¢ almost pure D. C. across the used, designs of coils with given dimen- condenser. This filter arrangement is Fig 6 sions and with a varying number of turns sometimes an engineering necessity when are made, giving different values of in- of the Choke the D. C. voltages used are very high. For, This Graph Shows the Impedance ductance. These coils are measured for Against the Frequency. On Either Side of Wo natural and a plot or table is made building a high capacity condenser for use There is a Range of Frequencies at Which the period on high D. C. voltages is by no means an Impedance is Very High and the Choking Action for this type of coil, showing the relation easy job, whereas building choke coils is Good, as Between WI and W2. (Continued on page 8go)

www.americanradiohistory.com 872 Radio News for June, 1921

An Efficient Loading Coil and no Dead End Switch By ALLEN E. LATHAM which, if extended, would pass thru the center of the torus. These coils may also be made flatter and larger in diameter, as shown in Fia. 1. This is the shape in which our coils will be made. The forms for these coils may be made from wood, 111,1111111111111111111111111111111 but heavy cardboard is just as good and much easier to handle. The material from Here is a sim- which the ks ple dead end di are cut should not be switch, easy thinner than % ". The outside diameter fro/1/ to build and 'should be 8" and the hole 2 ". Eight of '" efficient in the these disks should be receiving sets cut to make an inductance which will load about 2,50o me- fy.1 . for long waves. ters. No. 20 or 22 S. S. C. wire should L_ be used in winding these coils. They will take two pounds of No. 20. It will be necessary to make a bobbin on which to 4 put the wire, in order to pass it thru the i2' hole when winding the wire on the disks. z The bobbin is simply a stick about a foot Pip,. 2 /`,./p.4 long with a notch in each end, see Fig. 2. Each disk will take about 80' of wire. This amount should be put on the bobbin IN the receiving circuit, the greatest ficient coil would be obtained, but this preparatory to winding the coils. As the losses occur in the dead ends of the would be a clumsy and unsatisfactory ar- bobbin is a foot long 4o turns on it will loading coil. These losses are partly rangement. be approximately 8o'. The only difficulty overcome by the use of the various types In the coil and switch, which I am about that will be encountered in winding will of no dead end switches. The most ef- to describe, these disadvantages have been be the spacing of the wire on the outside ficient of these switches are the ones which overcome, and there is added the advan- and pressing it tightly together on the cut out the unused portion of the coil en- tage of being contained in a small space. inside. tirely, but the types of switch which simply as compared with the ordinary tall coil When the eight coils are finished. the short circuit the unusual portion are far and is therefore useful in making Up small next step will be to make the no dead end worse than the ordinary switch, for the portable sets. These coils have no stray switch. This switch was designed for use short circuited sections of the coil form magnetic fields so it is not necessary to with these coils and like the coils, is very closed oscillatory circuit which uses waste- keep coils in different parts of the circuit efficient and neat looking. Where the fully a large part of the received current. separate to prevent their feeding back and switch is to be placed must be decided upon The only way to overcome the mutual in- causing the circuit to howl. by the builder. It may be put on a panel duction between the sections in the ordi- The coil itself is composed of a number with other instruments, or it may be on nary loading coil is to make each section of coils wou id in the form of a torus. A a panel by itself. Bakelite is the best ma- separate and place them at right angles to throidal coil is usually the shape of a aerial to use for this purpose, but a piece each other or else place them some dis- doughnut with the wire wound radially, of hard wood. such as oak, thoroly im- tance apart. With these sections connected that is, the wire is wound from the inside pregnated by an insulating paint is just as by a good no dead end switch, a fairly ef- to the outside. Each turn forms a line (Continued on page 905) The Construction }tof Intervalve and Telefone Transformers By JOSEPH G. REED UCH has been written in connec- be assumed and a transformer designed to tion with audion amplifiers, both have an impedance of this value at the Seeäon afbobb/OO for radio and audio frequency, usual signal frequency will now be con- i y but very little attention has been sidered. The assumed frequency of goo paid to the correct design of cycles is that used by telefone engineers audio frequency transformers for inter- for speech work, and is approximately that valve and telefone purposes. of the beat note produced by heterodyne Before setting out to describe the actual reception of undampt waves. -s' - construction of these transformers, let us The impedance of an inductive winding is 3p 2 - consider what they have to accomplish. It given by the VR02 f2:9, plate in it/hiehj Fiy P formula R, = +(2piFL)2, fraosf /5 ep{/osed is their function to extract the maximum but as the 2piFL component is the only amount of energy from the plate circuit, one which can extract useful energy from and according to one of the fundamental the plate circuit, it alone will be consid- laws Tronsformer of electrical engineering, this will be ered. At Boo cycles 2piF equals 5,000, cose the case when the impedance of the load therefore, 20 henries inductance is required. equals that of the generator. In this case It is just here that the experimenter strikes the plate -filament path is considered to be trouble because there is no reliable formula the generator, and the primary winding of to calculate the winding for this value and the transformer the load. From observa- A. C. bridge measurements are beyond the s° tions I have made with a sensitive milli - scope of most amateurs. Having these Fig. 3 ammeter in the plate circuit of a Marconi facilities at my disposal,. I was able to de- Class 1 V. T. I have found that the re- velop the following design for a trans- sistance of the plate to filament path varies former. Constructional Details of the Amplifying Trans- between 50,000 and 150.000 ohms. there Figure 1 gives the size of the bobbin, former Which May be Built by the Amateur fore, an average value of ioo,000 ohms will (Continued on page 906) Who Has a Few Tools.

www.americanradiohistory.com Radio News for June, 1921 873 A Universal Receiving Cabinet By HILBERT R. MOORE

" ALTHO fully aware of the many eter, c "" wall, and 7/ length advantages of a "universal" re- with No. 24 S. C. C. or S. S. C. o ceiving set, most amateurs are pre- There are 28o turns. Begin- vented from owning such a valu- ning with the first, taps are because of taken every 3o turns until the able piece of apparatus O the prohibitive cost. Being in such a finan- 27oth. As will be seen in the cial predicament myself, I set about to de- drawing, the primary has two ,í. sign an outfit which would suit both my switches with nine points for taste and requirements as well as my each and one in common. The purse. The result was that the instrument 27oth turn is led to this extra described herewith was developt. point. Then nine taps of Despite the fact that it embodies a com- one turn each are taken off in paratively wide range of wavelengths, an the last to turns and the lead audion detector and a two -step amplifier soldered to the switch points. together with the controls necessary, the set Thus both fine and coarse tun - , is very compact and is readily portable. It ing are provided for. is possible with this cabinet to tune from The secondary is wound on about zoo meters to 7,50o meters, and with a tube similar to that of the the addition of a long wave -length loading primary, but of 35/s" outer di- coil or coupler, European stations may be ameter. It consists of 36o readily received. turns of No. 27 S. S. C. wire. 4 "- a point disregarded in the de- Nine taps are ta'.:n off. Be- Flexibility, 24" sign of most outfits, is a pronounced fea- ginning with the :ii*st and end- a is Front View o f the Cabinet Type Receiver for Short and Long ture. By means of a four -pole double - ing with the last tap This Receiving Set In- 45 Waves Descr ibed in This Article. throw switch of the anti -capacity key type, taken off every turns and elude s a Detector and Two -Step Amplifier. may be made from crystal led to the switchpoint. The instant change in half so detector to audion or to amplifier. An secondary has two switches as shown. switch and the primary cut audion- ultra -audion switch is also pro- The corresponding points on the upper and that when tuning short waves half the coil of two crystal detectors may the lower switches are interconnected, in may be cut out. vided. Either the be used by means of a two -point selective this way providing for the reversal of Two variable and two fixt condensers secondary connections. As is well known, are needed. An .0005 M.F. is shunted. across switch. in As the cabinet is to hold the weight of some signals come in louder in one direc- the secondary and an .00r M.F. is placed a complete receiving apparatus, it must be tion than another. the ground circuit in series with the pri- made rather strongly. The woodwork is The loading coil consists of four layers mary. They may be purchased unmounted No. 28 enameled wire on a 4" tube 8" and mounted on the panel or may be con- of 1 " oak and the case measures 24" x 20 ". of The panel is a sheet of ?e " formica 18" long. The winding itself extends for 7". structed. Instructions for the latter are x 24". As this is a stock size it is cheaper A tap is taken off at the first and one at to be found in back issues of RADIO NEWS. than one cut to another dimension. the middle and end of each layer, thus The writer purchased his, knocked down Altho bank windings might have been giving nine taps. The end of the coil is and assembled them. much economy in space, the old soldered to both point No. q and one of A small fixt condenser is shunted across used with the type of coupler was adhered to because of the primary switch levers. Thus when the receivers to give increased efficiency. A its superiority in the matter of close tun- loaded switch is placed on this point, the grid condenser is also needed. This may ing. whole coil is cut out. be either fixt or variable. Its capacity The primary is wound on a non- shrink- A two -point switch may be located as should be about .000i to .00025 M.F. The able cardboard tube of 4/ " outside diam- shown in the drawing for a dead end construction of a simple grid condenser is as follows: Roll a small wire tightly into one corner of a leadfoil gum wrapper, fold the wrap- Z 3 per double and cut to the size of a I/" P .5 P .5 square. Make two of these. Then cut four pieces of ah " mica I / " square. Place two pieces of mica between the foil and one on each side. This small package should then be wrapt tightly and impregnated with insulating compound. P The grid leak is merely a series of pen- T0005MF _11011- i + cil lines drawn between two binding posts 6Y.60Amp 1.- 45 -60Y.. -5' Boll a Ä" Ball mounted on strip of cardboard about two inches long. May Complete Hook -up of the Receiver. Note the Switches Whereby Crystal or Audion Alone be Used Without the Use of Plugs and sacks. (Continued on page 898) Results Accomplisht With One Bulb By ALBERT R. CHAMPLIN*

For over a year I have been assigned to ragged and the filament stands much abuse. S.S. Heredia and have been using no more As a sensitive detector I found the elec- than one bulb or an amplifier for recep- tron relay to be the best, but the filament tion of both arc and spark stations. My life is short and an expensive upkeep for runs have been in the Gulf and Caribbean the radio station. Fine results have been waters. accomplisht with this bulb and signals, long anyone running in these waters as over 1,50o miles away have been copied io time knows what as i have in the summer to 15 feet from the fones. real STATIC is and the conditions an op- my ex- For the last six months I have employed erator has to put up with. During only one bulb and get everything required. periments with bulbs I have used most and spark stations. -I and V -T -2 This includes both arc every type including the V -T I can obtain better results from a detector the Western Electric Company; Navy of than any other circuit with amplification. Plitrons, Electron Relay, Marconi V -T -1 DeForest and French during the static months, as the intensity- and V -T -2, some is Shown and static is amplified about fine In This Diagram the Secondary Alone of both signal bulbs. These last two are detectors. With the Connection From the Aerial for Long - in an amplifier and makes re- confined to the Pri- the same My experiments were mostly Wave Reception. For Short Waves, ceiving difficult. ,so I have confined my cir- Electric bulbs which are the mary Circuit is Used and the Aerial Switched the Western it. cuit to one bulb. best for all round work. They are built to * Chief Radio Operator S.S. Heredia.

www.americanradiohistory.com 874 Radio News for June, 1921 Radio Digest WIRELESS L T E E F O N E OUTFIT and gas -emitting devices which would en- invention of MM. Abraham and Planiol for PROVES A SUCCESS ABOARD danger whole armies without risking the life utilizing ordinary telegrafic apparatus for of a single pilot. But as one enthusiast sug- sending, receiving, I A LIGHTSHIP. and printing wireless _ gests, "perhaps it will By Charles A. Reberger. be better to wait until messages. Prof. Lippmann said that ex- we are sure we are not dreaming before we periments made before telefone has a number of official A wireless set been installed claim too much progress." experts between Paris and Nogent le Rotrou aboard the Bar lightship "Liverpool" for the had given brilliant results, purpose and that as many of being in direct communication PROVISIONAL WIRELESS TIME as 7.000 words had been automatically reg- with the Mersey Dock board offices at istered in one hour. Liverpool Pierhead. Weather reports off SERVICE. that port, together with any information It is announced for general information pertaining to navigation, which may have that arrangements have been made for a SOUTH AFRICA WIRELESS been received, will be forwarded hourly by provisional wireless time - service from the TELEFONY. standard mean -time clock of the Hector Ob- The British Government wireless telefone from this light vessel to servatory is experimenting the above named offices. (latitude 41° 17' 03" .8 south, with wireless telefony with the view of link- At the first demonstration of the system longitude 174° 46' 04" east of Greenwich), ing the chief centers. Communication has a few days ago, the to Wellington. This service was begun on Oc- been successfully establisht installation proved tober between Jo- be a great success. Officials "listening in" I, 5920. hannesburg and Bloemfontein. It is hoped at the offices reported that the speaker's The time -signals are transmitted by the to extend the system gradually, thus lessen- was Wellington Radio -station (latitude 41° 16' ing the cost of ordinary telegrafie voice heard very loudly and distinctly. south, and tele- The lightship is located only io miles from longitude 174° 46' east of Greenwich) fonic working, which is unusually high, on a wave-length of 600 meters. The send- owing to maintenance charges over the City but the builders of the apparatus ing -key immense claim it has a normal at the radio- station is automatically distances.- (Electrical Review.) working range of operated by the from 4o to 5o miles. It is so simply con- Observatory clock. structed that it can easily be manipulated ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,11,,,,,,1,11111111111x1,,,111,1111,,,,,11,,,,,,,,,,,,,1,..,,,,1111111 ERRORS OF DIRECTION FINDERS. by any person without any special training, By Dr. E. Bellini. as simplicity was the keynote in designing the entire set. Radio Articles Appearing in In the early period of the existence of This is the first occasion on which the the June Number of Science the direction-finder it was generally thot wireless telefone has been utilized for regu- that a well- constructed direction-finder ap- lar commercial purposes in the British Em- and Invention paratus, installed upon a homogeneous pire. Officials stated that plans im- S. S. "Aeolus" stretch of land and free from local influ- would Works 3,103 Miles ences, mediately be drawn up for the installation with 2 K. w. Arc Set, by Arthur would give exact bearings. Experi- of similar wireless telefone instruments H. Lynch. ments confirmed this idea. At that time, aboard other light vessels located at vari- Loop Aerials and Their Applications spark transmitter and moderate wave -lengths ous points of the Coast line. -With Particular Reference to the were used, and, since amplifiers had not It has not been made public what wave- "Loop" as Used in Connection With been discovered, the distance at which a length is used in the transmission nor what Special Audion Amplifier Circuits station could be located was limited. system is used. in the French Army Signal Corps, But the discovery of the amplifier, which by Robert E. Lacault. enormously extended the range of the direction- LONG FONE WEATHER REPORTS. A "Funny- Tone" Radio Receiver, by finder, and the adoption of undampt E. Stuart. waves of very great lengths, completely That wireless telefone and W. telegraf A Motor- Driven "Bug" Key, by changed the working conditions of these ap- weather reports sent out from Madison at Norman H. Allen. paratus. The satisfaction of being able to 12 :3o daily are heard in Texas, Kansas, Utilizing Morse Relay as Coil Inter- reach enormous ranges was counterbalanced New Jersey, and on the Canadian border is rupter, by Penuel E. Ballard. by the dissatisfaction at finding a new indicated by letters received at the wireless The Deflecting source of errors, errors which could be at- experimental station of the physics Wave -A Gripping depart- Story of Radio and Zeppelins, by tributed neither to the conditions of the ment of the University of Wisconsin. Re- Herbert Moulton. earth's surface nor to the influence of neigh ports show that the wireless mes- L. telefone Question and Answer Column. boring bodies. The characteristics of these sages are 'clearly heard at these distances. new errors are their magnitude and their The reports of weather changes that are 111111,11,11,11,11,11,,,,,,,,,,,,,,,,,, variability. Minimum in the daytime, they sent out are received from the United States become larger at sunset and reach their weather bureau at the university. CHANGE OF MOON EFFECTS maximum at night, becoming sometimes enormous, as WIRELESS. much as 5o. 69 and even 9-) FRENCH CLAIM PRIORITY IN The changes degrees. Their rate of change may reach of the moon have been found several degrees per minute. WIRELESS PLANE GUIDING. by the radio officers of the small American A very interesting study of this subject French aviation experts are flatly denying fleet in the Adriatic Sea to have a striking and its development effect upon the efficiency was publisht in The the assertion made by bankers last Marca of the atmosfere Electrician, of London, Feb. that the invention of a pilotless airplane, or for transmitting radio communications. The 18, 192T. rather a plane guided entirely by wireless, officers have succeeded in drawing curves is of American origin and are showing that and other diagrams based upon months of NEW DAILY RADIO WEATHER the French have been experimenting suc- observation, which, they assert, reliably REPORT. cessfully along these lines since September, serve to indicate what atmosferic and celes- In co- operation with the Office of Com- 1818, when a plane was launched against a tial conditions affecting radio service will munications of the Navy Department. the strong wind and manoeuvred for more than he met at any particular date in the future. U. S. Weather Bureau will issue a special 5o minutes without accident. Since then The discovery apparently has special ap- bulletin containing surface weather obser- machines adapted to various weather con- plication to the vicinity of the Adriatic, for vations from regular Weather Bureau sta- ditions have been entirely approved by spe- there the changes in the atmosferic con- tions, upper air observations from aerolog- cialists at the Villacoublay aerodrome near ditions caused by the change in the world's ical stations maintained by relation the Navy, Army Paris, and have even circled over the capital to the moon are much more marked and Weather Bureau, and a summary of at a great height when guided by aerial than anywhere else in the world, so far as weather conditions, forecasts and yet discovered. warnings. vibrations from the Eiffel Tower. The bulletin is for the benefit of marine and But the latest development in the argu- The Adriatic fleet under Admiral An- aviation interests, but is designed especially ment will give American inventors a sur- drews depends almost entirely for its com- to meet the needs of the latter. The munications upon bul- prise, as it was announced recently that radio service, and having letin will begin June 1, 192r, and demonstrations only receiving and will be are to be commenced at sending apparatus of broadcast from the Naval radio station at Villacoublay which will show it is moderate efficiency, it has especially that pos- benefit- Arlington, Va., each morning at io :3o sible to send up a pilotless plane equipt with ed from the discoveries. The powerful land o'clock (75th meridian wireless stations, time), Sundays and sensitive instruments which under certain such as the new Lafayette holidays included, on a wavelength of weather conditions, such as station near Bordeaux. manage 5,950 fog banks o- to overcome meters C. W. This service is in addition to impending storms, will flash back a signal . unfavorable conditions by using great power, the distribution now being and so made each night to the guiding station. If the French claims are not concerned about which way from the Naval Radio stations are justified. it will even the moon turns. at Arlington, be possible thru Va., Key West, Fla., Point Isabel, Texas, this to revolutionize all ideas of aerial war- Great Lakes, Ill., and San Juan, fare, as the development of mechanical ap- NEW RECORDER. P. R., as described in Weather Bureau circular of pliances responding only to wireless control Prof. Lippmann, lecturing at the Acad- Oct. 26, 1920. could easily be applicable to bomb -dropping emy of Sciences, on May g, described an (Continued on page 93o)

www.americanradiohistory.com Radio News for June, 1921 875

LuDJJIiAILVJIVd dpl/dunNJJUnmuumdA%oi L/J0.Iu /u A /I0./Jrv1 VJI/JU LVJtuuJJt%1lVdtV Vdtw l/JUJJ6 uJ.4iJ9VdLVmisoVowJ llm

$100.00 RADIO ACCESSORY PRIZE CONTEST

ERE is a new contest of radio messages better and dial, a new switch lever, a new for our budding radio easier. There are a thousand panel switch, .a new socket, a geniuses. This time such ideas waiting to be exploit- new switch point, etc., is the kind the contest is not so ed by the radio fraternity. of idea we desire, always pro- much about big sending Every once in a while we pub- viding that the idea is new and It is or receiving outfits, but it cen- lish a little stunt that means a has not been used before. immaterial from what materials ters on radio accessories . small revolution in radio con- the article is made. This is left When the automobile business struction. For instance, some to the designer. was young, the main thing was years ago a clever "bug" showed the automobile itself. No one us how to put the scale, previ- While it is not absolutely thot of manufacturing, adver- ously always attacht to the necessary that a model be sub- tising and selling accessories. panel, right on a rotating dial. mitted with your entry, we ven- But every city now boasts of one Today, there is practically no in- ture to say that the judges would or more stores where nothing but strument on the market which rather like to see a model, as it is auto accessories are sold, be it a does not include a revolving often much simpler to judge an tire, a spark plug, a crank, a graduated dial and knob attached idea if you have the actual article horn, a tail -lamp, auto gloves, a to it. before you; but as we said be- pressure gauge, a gasoline tank, That is what we are trying to fore, this is not absolutely neces- a washer or a valve -you can get at in this contest. We want sary, but desirable. In all events buy them all readily at a low ideas on little things that can a complete sketch must be fur - price. nisht by the contestant. What holds true in the auto- No manuscripts entered in mobile business is now being re- 1st Prize $50.00 in Gold j this contest can be returned. We peated in the radio field. At reserve . ourselves the right to first there was nothing but the 2nd " 20.00 " " publish all worthy ideas, which or the ap- 3rd " 15.00 " " a by paying actual complete outfits 1 did not win prize paratus. Gradually the radio 4th " 10.00 " " regular space rates. In publish- accessory business came to the 5th " 5.00 " " ing the various ideas, all the con- front and today dozens of RVIANI títiltai1AiillM / í1t/ ít11Y a m rights revert to the publishers. cerns are engaged in selling and Use only one side of the paper manufacturing nothing but little be readily made by the amateur for writing and keep sketches on adjuncts. To mention only a and can also be manufactured a separate sheet. No penciled few, as can be readily appreciat- and standardized by the manu- matter can be considered. More ed by glancing at the advertising facturers. What we want there- than one idea may be entered by columns of this journal: Com- fore, are ideas on little improve - contestants. The contest is open position knobs, switchpoints, ments on radio apparatus and it to everyone, radio clubs included, minerals, all sorts of parts, panel makes no difference whether the except manufacturers of wire- switches, dials, sockets, sliders, improvement is for the transmit- less apparatus. All prizes will connection plugs, bulb safety ting or receiving set, or whether be paid upon publication. fuses and dozens of others. it is a new wrinkle that can be This contest closes at noon, There are always new im- attacht to the aerial or to the August loth, New York, and all provements cropping up as ground. It MUST be a little entries must be in at that time in everyone can see by looking over thing, a true accessory to exist- order to be qualified. Should the advertising pages of our ra- ing radio apparatus. two contestants submit the same dio publications. In other words, no prize will idea, then in that case the same But there is much room for be given to anyone who designs prize will be paid to both. Ad- such as a dress all communications to Ed- improvement ; there are many a complete instrument, little things needed that will detector, condenser or the like. itor Radio Accessory Prize Con- make transmission and reception For instance, a new plug, a new test, care of this publication.

bzlrianr. r.nafilir.araitfilatiNIIr.iIIik+rrtIMMIrrtiItmit .tilr. rr.tiltiornitr.aad tr lr.'d tr. rmd Ir. gr.vltrallr.ariortiolr.rllr. Newspaper Uses Amateur Radio Reporters

NEWS, under town, thus acting as Radio reporters for might be transmitted, the atmosfere was N the last issue of RADIO clear of the usual host of conversations be- the title "Government and Amateurs the Tribune. told how the ama- The first amateur Press service has tween amateurs, and all the operators in I Join," Mr. Winters the bay district turned their ears to the teurs can use their receiving sets to pick proved successful and further tests will be reports and de- made to extend the area from where news test work. up the market and weather few and in their towns who are may be received. Interruptions were the trans- liver them to those mission was effected with little repetition. interested. From the time that R. W. Carroll, secre- Tribune, under the tary of the club, sent out, one evening re- Great interest was shown up and down the The Oakland (Calif.) message coast by the tests being staged by the Bay auspices of the Bay Counties Radio Club, cently, the "QST," or broadcast a test, whereby ama- to the radio amateurs to "cut out the idle Counties Club, for when midnight came and recently conducted (Continued on page 888) teurs sent by Radio the news from their chatter" in order that the Tribune news

www.americanradiohistory.com 876 Radio News for June, 1921 The Thirteenth Tap By BERNARD S. GREENSFELDER

"I attempted to struggle to my feet and retaliate, but the inspector prevented me from ,,.,11111,,,,,,,,,,1,,,11,,,,111 doing so. Duane, perfectly calm, held out the meter to the inspector, and said, Something, a `Sorry we had to have this unpleasantness; mysterious it will be a good force, came lesson for him.' He point- over me. ed to me, adding, `Well, good -day, in- The throbbing spector. Don't be too hard on the poor blood vessels fellow,' and out. in my body strolled seemed to be "I was left alone with the inspector, who on the point was still holding on to my arm. He said, of bursting. `I am also very sorry The rheostat that this has occurred. moved slowly. However, you are a good operator, and we The thirteenth are several men short at present, so I will tap! Death! give you a third Livid flames and last chance.' sprang forth "He would listen to none of my explana- like demons tions. My thoughts of getting revenge on from the over- the return trip charged subdued my pride, and I wires. grudgingly agreed to stay. "That afternoon we left for Seattle. ,,,,,,,.,,,, During the night all I did was to toss and twist in my bunk, thinking of schemes for revenge. "For all my thinking I could not find one JOHN HANSEN walked complacently The stranger continued, "To start at the plan that could be carried out with im- up the Embarcadero. He had punity. little beginning, I was born in Oregon thirty - Then I remembered the $250 I to worry about, with a pay -check in one years ago. had entrusted to him. Another his uniform When I was a boy, in 19o7, strong rea- pocket for six months' I developt the love for radio which has son for punishment! service as radio operator. His ship, not yet left "Pistols, poisoned the me. After I graduated from food, sawed -off shot- WEST CAMBRIDGE, had docked that a local high school I went to guns, daggers, red seas of blood; all passed morning at San Francisco. Seattle. There It had taken I secured a clerking job. On and off I before my eyes. him little time t0 report, and by noon he dabbled in electricty, and the crude "What a fool I had been ! To absolutely was ready to see the wire- sights of the Golden less apparatus of those days. Finally, in lose my head in that embarrassing situa- City. 1912, I took the examination tion! Sauntering along, and secured he was about to enter a berth on the S.S. KODIAK, plying be- "By the time daylight arrived I had a café, when a man with the general ap- tween Seattle cooled off sorhewhat, pearance and Sitka." and determined to wait of a person of forty-five, ap- "All went well for some time. until some opportunity offered proached. Two large I made a me the ful- red scars horribly number of friends and acquaintances at filment of my greatest hope-to show up the marred his left cheek, his hair showed both ports, in particular cur, who, oddly enough, tinges an adventurer, had a good name. of gray, and it could easily be im- James Duane. He was apparently In this state of mind I again agined that he had greatly made the once gone thru some interested in the ship's wireless set, and trip to Sitka. My main object was to square terrible physical and mental test. often came to see things and escape Hansen paused me while we were in port. detection. for a moment. During these visits I explained "I made inquiry tor my enemy "Pardon me, sir," pleaded the a great deal as soon as stranger, pertaining to radio to him, and as a reward I reached shore, but the most specific in- "could you spare an ex- wireless operator for my efforts he gave me various formation I got was to the price a Indian the effect that of square meal ?" With a sor- trinkets he had collected. After a Duane had left with three ry attempt at a while other men to smile he added, "I was once I entrusted him with $25o, -over half my spend the summer in hunting in a position like yours, but and seal - -" meager savings -to be invested in a sure - catching on one of the wooded His voice broke and he off -shore turned his face. thing gold mine. Later, as we grew more islands. No one could state his exact lo- Something unusual in the man's voice intimate, I decided not to further cation, tho some said that struck Hansen as encour- he had passed sounding rather odd and age his friendship, for he seemed to have thru another town before leaving, obtaining tragic. Certainly this man who spoke in certain undesirable petty traits. his supplies there. refined accents, and who was perhaps fif- "One day, while the boat was docked in "My hate for this man soon apparently teen years younger than his disfigurements Sitka, he came on board. died out, but him When my back later developments proved gave the first appearance of being, was turned he attempted to slip a small, that it was only slumbering. merited investigation. After a minute's but very expensive measuring "Several thought instrument months afterward, while midway Hansen replied, "Sure, old man! into his pocket. between Seattle and Sitka, I And what's more I want you to step in heard an un- "As luck would have it, the Marconi in- familiar station, KIF, sign off. I had here and have chow with me." spector was on board, and never heard it before. The stranger in the act of No such call was in hesitated, conscious of his coming to see me, when Duane reached for the Call Book, so I got in communication neat, but worn -out clothing. But he con- the instrument. with the nearest naval radio station and sented, and together they entered the res- "The inspector coughed, sent, `QRA taurant. but this didn't KIF? PSE.' In a minute I re- bother Duane. He calmly put the meter in ceived, `KIF is a new station -island-- Hansen ordered the food, and then re- his pocket and stepped aside. The inspector 2KW controlled by James Duane.' lapsed into a thotful silence, which was had immediately recognized the instrument, "James Duane-radio set -island -these rather embarrassing to his guest, who ven- as there were few Alaskan ships brief words brot back the tured a few questions that had forgotten past, on modern radio them. He inquired of Duane what it and fanned my rage into a fiercer practice. Hansen gathered his heat than wits and meant. before. My OK to the naval station con- took upon himself the task of worming "The reply was, `I beg your pardon, sisted of a miscellaneous jumble the veteran's secret from but of dots and him. this operator just gave it to me as a, per- dashes. Over their coffee Hansen asked, "How is sonal gift.' "And so I located it him. The ship neared that you are no longer an operator ?" "I was staggered, and the look the in- the Alaskan shore until we were The other gave a slight about 75 start. Then, spector gave me must have resulted from miles from our destination, Sitka. We bracing himself as if for a cold shower, the stupefied expression on passed an island he my face. with which I was familiar. launched forth, "Well, you have certain- "I blurted out, `He lies !' and Two radio masts projected then Duane ! ! ly treated me white from its top for a chance acquaint- struck me in the face, knocking me over. This was something new to me, ance. I have had a premonition who had that this He was well known in those parts and had sailed on the same route for over two and will be my last opportunity to relate what somehow been able to keep a good reputa- a half years. no other man living knows. I will feel tation. On the other hand I had once com- `Night fell. I relieved my mate, who better when I have told it. Will you mitted a slight irregularity which was brot went to his dinner. I tuned promise me secrecy ?" around the to the notice of this inspector. That fact, commercial wavelength of 60o meters. With a smile of anticipation Hansen read- coupled with my foolish stare, put me in a Then, weak for its nearness, came, `SOS ily agreed. bad light (Continued on page p10)

www.americanradiohistory.com Radio News for June, 1921 877 Married via Radio By ERALD A SCHIVO

CHARLES KENNISON was disappointed. Neighboring amateurs in- vaded the atmosphere in all directions and with evident success. Dis- tant stations were called: the high - pitched sparks of the powerful San Fran cisco amateurs always received a reply from equally efficient fellow amateurs in other Let's not get States, but try as he might he didn't seem into an argu- to be able to locate the trouble in his re- ment like last night. We are ceiving apparatus, which made him fail to going to get hear the Honolulu station. married by Kennison ground his teeth in disgust and radio and before that's all contemplated the intricate apparatus there is to him. Weeks of experiment and hard work it. Are you had amounted to naught. Altho radio sta ready? tions within a radius of one hundred miles sounded like the roar of cannon, the distant ,11111,111,,,,,,,,111111111111111 stations could not be heard, not because of the intermittent interference, but due to the inefficient "hook -up." Ile would make one more change in his connections and if satisfactory results were not attained, a popular regenerative circuit which was used by the successful mass of amateurs, would be his alternative. now working very satisfactorily. loudly, "the question I asked you is not fool- Midnight was approaching and already The air was quiet. No spars interrupted ish. May I ask to whom I am talking ?" the weary "wireless bugs" were bidding the stillness. Kennison was expecting to "You are fibbing," sobbed the girl in dis- good -nights. Kennison quickly made the hear a remote call at any moment. tress, "you promised-never mind, you intended change in the circuit and readjusted Wishing to know it there was still any- needn't call me again, I will have nothing his instruments. After the receivers were one listening in, he changed his aerial switc-r to do with you-so there." resting securely against his ears, he closed to the sending position and transmitted the "By Jove !" crie I the mystified operator, the circuit which supplied the filaments of general call. No one answered doubtless "you surely have me puzzled; I said noth- two vacuum tubes w'th necessary current. all the enthusiasts had retired for the night, ing impertinent, wtlat in the world do you The dull roar of a near -by amateur sounded altho a few generally listened into the early mean ?" in his headset. The operator was calling a hours of the morning. "Do not say another word," the girl was station in a Southwestern State. Listening Kennison was in no hurry. He antici almost crying, "you promised so-so -good- intently, Kennison waited with keen expec- pated excellent results from the new circuit bye." tation for the Southerner's reply call. and determined to wait for them. The "Say !" ejaculated Kennison in perplexity, A half minute passed- another. Impa- hands on the clock were slowly nearing the "please wait a minute, I meant no o,iense." tiently Kennison lessened the resistance of hour of two when, with cne last sigh, which "Remember, never see me again, unless - the filament rheostat, thus allowing an in- sounded like a dull tick, the clock stopt. unless you change your mind," were the crease of current to Pow. Simultaneous The young operator smiled and half rose girl's last words and the hissing noise which with the brightening of the filaments a from his chair with the intention of re- always accompanies a wireless telefone sub shrill spark vibrated in the receivers. An winding the piece of machinery. Synchro- sided. amateur a thousand miles to the southeast nous with his grasp on the clock a loud "Hello, hello," called Kennison, but re- was answering the call of the San Fran- feminine voice caused him to jerk the tele- ceived no answer. After a few moments cisco station. f ones from his head and stupidly place them the low tone of a near -by station called him. Jubilant with success the local amateur upon the table. He stared around the room "Go ahead," said Kennison over the tele again flasht his signals. Communication dumbfounded. f one. was establisht for a period of five minutes. "Charlie, my dear Charlie," laughed a "Say, old man," transmitted the operator, The signals from afar then began to fade girl's voice, "hello, Charlie, my dear boy, "I just began listening in when you started and could no longer be heard. didn't expect me at this late hour, did you ?" that one -sided conversation of yours and Kennison was not troubled with fading Glaring at the receivers, to all appear- believe me you had better see a doctor. Who signals which are most detrimental to long ance innocent of any duplicity with the in the world were you supposed to be talk- distance transmission. Thruout the conver- mysterious voice. Kennison promptly grasped ing to? I have five amplifiers and I heard sation he was able to copy the messages, them with the full determination of a man no one but yourself." and also after the near -by station could no to investigate the matter. Kennison tried to explain the matter to longer hear them. The new circuit was "Charlie, Charlie," reiterated the voice as his friend, but being so perplext himself, if chagrined at the possibility he said nothing that sounded logical. that she was not heard. "Well, Charlie," replied the spark sta- "Charles, why don't you an- tion, "I'd advise you to see your doctor, swer me? Your wireless tele- I heard no girl's voice; guess you were fone is not out of order ?" dreaming and talking in your sleep." Wireless telefone ? Hennison Head swimming with numerous ideas as had not used the instrument, re- to the girl's identity Kennison decided to cently purchased, for three retire. Only after concluding the whole days ; in efficiency it was very matter as a joke played by some of his much lacking. Only neighbor friends did he relax and sleep. ing stations responded to his re- All day, Sunday, he visited radio friends; peated calls. The voice was everyone affirmed that they knew nothing coming from his receivers, cer- and could give no explanation. L iscour- tainly, but who could be calling aged and considering the situation seriously him? Manipulating a number the wireless man gave up the attempt to of switches, his own wireless solve the problem. He would try to corn- telefone was soon in working municate with the girl that night. order. Several amateurs were aware of his in- "Hello, hello," he cried into tentions and the air was a bedlam of sparks the transmitter, "who is call - until far into the night. He would not give ing, me ?" a call until a quarter to two, the time the "Why, Charlie," said the girl girl's voice had first greeted him. Absolute in surprise, "what do you mean silence prevailed as the time approached. by such foolishness? You know Kennison decided that at least amateurs I don't like fooling." 5) Kennison Heard the Gruff Voice of a Man Reciting the Mar- were listening in ; the news had spread re- riage Sermon. "Do You Take This Woman as Your Lawful "'My dear young lady," Ken- Wife ?" Asked the Man. ri nison was excited and spoke (Continued on page 923)

www.americanradiohistory.com 878 Radio News for June, 1921

Department is open to all readers. efficiency It matters not whether subscribers or not. All photos are judged for best THIS of the apparatus, neatness of connections and general appearance. In order to increase arrangement and make it a rule not to publish photographs of stations unaccompanied by a picture the interest in this department, we We prefer dark photos to light ones. The prize winning pictures of the owner. pictures smaller must be on prints not smaller than 5 x 7". We than 3% x 3%". All pictures must bear name and address written in ink on the back. cannot reproduce giving full description of the station, aerial equipment, etc., must accompany the pictures. A letter of not less than 100 words PRIZES: One first monthly prize of $5.00. All other pictures publlsht will be paid for at the rate of $2.00. m ,,,,,,,,,,,,..... ,,,,,,,ß,M1111 111111 1111;1,...,, III ll,..,1.,1, X11111111111 1111,,, 1111101 /1111111111111111111111111 1111111111,11l,,,,,,,,,, ,,, ,,,,,,,,,,,,,,,, .o..,,,,,,,, ,,,,,,,, , w.,. M Station 96Y

Every Thursday evening between 8 and g o'clock, the amateur station of the Kar- Iowa Radio 1111111111111111111111111111, Corporation, gBY, at Rock Island, Ill., gives a fone concert which is Some station, heard over a 300 -mile radius ; the boys! How voice and would you I. C. W. signals regularly cover up to goo like to own miles. this little This radiofone set station is equipt with a / k.w. D and the well - Forest oscillion transmitter and a t k.w_ designed 1- spark set, makinó- available for instant use by K.W. spark means of the proper control, C. W., I. C. W., set? Quite fone, an idea to fix synchronous rotary spark and i2o your quencht cycle quencht spark. Honeycomb coils gap on a are used exclusively in receiving, for short panel like and long the one in waves, as tickler regeneration has this foto. been found more reliable for their work. 9BY will be glad to receive reports from 1111111,1,1111,111,,,111,,,111111 amateurs who hear the concerts or the D. X. work, and will appreciate a word from distant amateurs who can pick up signals. Paul Oard's Moving Station Paul Oard, of Oard Radio Laboratories, respondent of Stockton, G. E. Reynolds, on the special telefone equipment having been Stockton, Calif., has set up a radio ap- a trip in order to prove beyond a doubt adjusted, from station 6FI. paratus on his automobile, with which he that his apparatus was all he had claimed Many experiments has given some very interesting are to be carried out demonstra- it to be. The first message received was in this way to develop a set that can be tions. The accompanying illustrations one that had been previously filed by Mr. used on an automobile show Mr. Oard and his and render service, unique set. Reynolds at the local station of Calmo especially when help is needed while out This traveling station is capable of re- Wiles. What is believed to be a record in in the country far ceiving signals from stations from a garage, and it is too miles amateur transmission and reception ender expected that in a few years an auto sta- away without any trouble, when the car is like conditions was made when 7BQ at tion in motion, will be as common as a ship station in spite of the magneto breaks. Eugene, Oregon, and 7ZI, located in Wash- is today.

Here is a summer type of station. During his vacation, Paul carries his station with him and he is always ready to pick up a call. Note the aviator cap he wears to avoid the noise from the engine, and to keep the receivers tight to his ears.

The antenna is suspended directly above ington, were also copied the top of the automobile, as shown in the from the automobile, when illustrations, and the receiving set, which not in motion. These were is of the regenerative type, is fixt behind both copied on a single the operator. The battery of the car is tube, the latter station using used as an "Al' battery and the frame of C. W. the car is a counterpoise. As a final test, a musical Mr. Dard recently took a newspaper cor- entertainment was given.

www.americanradiohistory.com Radio News for June, 1921 g79 Edgard A. Green's Station

The accompanying fotografs are of myself and my set which I enter in your amateur station contest. The O. T., "B" battery, long wave cabinet, and detector and two step amplifier are of my own manufacture. My sending set consists of the following: I/2 k.w. Thordarson type R, glass plate condenser, meteor gap, O. T. and meteor key. I am radiating 3.2 amperes. My receiving set consists of long wave cabinet using honeycomb coils for stations sending on 600 to 20,000 meters. I also have a Grebe C. R. 2 with detector and two step amplifier. The amplifier is so arranged that it may be used on either set by means of jack and plug. I am using W. E. V. T. I and Acme transformers for amplifying. My long wave set was made from instructions furnisht by Mr. Groves, and surely is delivering the goods. When using detector alone, most of the long wave stations can be read with the fones held at arm's length, and when using ,,,1111111,,,,1,,,,,.,,,,111111111 two steps of amplification, they can be read We extend fully 75 from the fones. our compli- My set is on the second floor, and on ments to Ed. for his neat good radio nights the music from KDKA, and nice -look- 2XQ and NSF can be heard very plainly ing station, downstairs, when using the Grebe with It seems that kewpie dolls two steps. are extensive- My aerial is a four -wire inverted L 75' ly used in and 28' high, wires being spaced 2' radio stations long these days; apart. For a ground I use a ground plate Ed's is on the an water pipes. "B" battery keeping the The two boxes on the right -hand side of voltage up. the shelf are my 6 v. "A" battery and 4g v. "B" battery. The "B" battery is the one my 11111111111111111111111,1111,1,1 assistant operator is sitting on. I am using W. E. and meteor fones and think the W. E. are best for signals, and meteors best for music. Under the table may be seen the loose coupler of old age and the tungar rectifier used for charging my batteries. EDGAR A. GREEN, 825 Cedar St., Hagerstown, Md.

K. H. S. Radio Club Station

The following is a description of our The sending set consists of an Acme coupler. Since the picture was taken, a station : I K.W. transformer, Thordarson oil con- hot wire ammeter has been added. This The station is located in a corner of the denser, Murdock rotary gap, Murdock os- is mounted to the left of the aerial switch physics laboratory in the high school and cillation transformer, Boston key. and an with an s.p.s.t. switch below it for short the aerial is on the roof. Amrad wavemeter, which is set on the loose circuiting. Proper switches are mounted at the right side of the lower switch hoard. The receiving set consists of audiotron detector and panel, variometer, 200 -1,500 meter loose coupler, 250 -5.000 meter navy type loose coupler, either of which can be used by throwing the switches, and a Brandes headset ; a Murdock variable condenser is also used for tuning. Since the picture was taken a radiotron and panel has been installed and various experiments A nice little have station you been conducted with one -stage radio have boys. frequency amplifier. A long wave set is Compliments being planned. for the wave - meter; that is Beneath the table and to the left is a the first thing battery charging set. a radio club should get. It is impossible to mention all the stations heard, but among them are NSF, ,,,111111,1111,,,,1,1,,,1,1,111,,,,,, NAA, NAJ, NFN, NAT, WCY, WCG, NRS, NSR, NUD, NAH, etc., ships and amateurs galore. We would be glad to hear from anyone hearing 9DFH, our official call. K, H. S. RADIQ CLUB, Kendallville High School, Kendallville," Ind.

www.americanradiohistory.com 88o Radio News for June, 1921

.v .y S r.Mr. a,tc;t' "+`: rt 13i f`'wtiÌi LÍ.. -°'`

Junior Radio Course RADIOTELEFONY

the last lesson was set, relied upon as in explained the an or- principle dinary C. transmitter. of Radiotelefony and W. the absorption Hf F If maximum modulation method is obtained, that is to say, if of modulation. We now come to the constant the emitted oscillations are current completely modulated as in system of modulation which, so far, XI, Fig. 2, the increase of is the best for the intensity read at experimenter to use. the H. W. The 1 ammeter, when the micro - circuit that we shall fone is spoken into, use to explain the is about system, is 22 ner cent. over the normal the Heising circuit, in which MT radiation. two tubes are used, one as an oscillator and one as a QUESTIONS FOR THIS LESSON. modulator; see Fig. 1. If more power is to be obtained I. Explain the difference by the use of several tubes Fig. between the absorption and in parallel, constant current methods of the same num- This is the Typical Circuit for Constant Current Modulation. In This Radiof one ber of tubes should be used Hook-up One Tube is Used as an Oscillator and One as a Modulator. The H.T. modulation. as oscillators and as modu- May be Supplied by a Battery or a D.C. Generator. 2. What is the range limit lators. of a Radiofone set? quency and causes the necessary low fre- What is quency the influence of the modulat- THE CIRCUIT. variations in plate current, and, ing system upon the amplitude of the therefore, of the radiated emit- In the circuit shown C. W. ted wave? in Fig. 1, some in- By comparing Fig. 2 with 3 struments are used Fig. of the that may not be familiar last lesson, the decided advantage of the to the average student. H. F. is the Radio constant current method of modulation golumt frequency choke may coil; stopping at high' f re- easily be understood. \A/hìle with the ab- .quency current and keeping them out of the sorption method, under the best Dictionary of Technical low frequency or conditions modulating circuit, it is the amplitude of the oscillations is decreased Terms Used in Radio merely an inductance having a sufficient to a minimum, with the value. constant current it L. F. is an audio frequency choke is decreased, but also increased to about coif having an iron core and keeping con- double the normal value, as shown stant the at X voltage furnisht by the H. T. Fig. 2. The output is then completely mod- Selectivity- Having the power of selecting source. M. T. is the modulation trans- ulated in much former, a more efficient way, and any particular wavelength from a number as described in the previous lesson, the range increased for the same normal to the exclusion of the others. and L is a grid leak that must be adjusted output. In fact, it must be remembered that Selenium -Se. An element closely allied in order to impress the proper negative volt- certain sounds, to such as "e," produce very sulfur. Found in three forms, one a age upon the grid of the oscillator tube. little variation in the amplitude of The constant current the os- brick -red powder soluble in carbon bi- system of .modula- cillation, while "o" prcdrces maximum va- sulfide; tion depends upon the fact that if a steady another as a crystaline dark- riations. grey solid which is not in plate voltage is applied on a C. W. trans- soluble carbon Since it is necessary to understand the bisulfide. and a metallic selenium which mitter, continuous waves of constant ampli speech, in order to receive all the tude variations is also not soluble in carbon bisulfide will be emitted; see Fig. 2A. Any of amplitude, the range of Radiofone set is change that occurs in this plate The crystaline selenium has S.G. 4.8 and voltage is limited to the distance where the smallest melts at 217° F, immediately reflected in the change of am- and its resistance is ma- variations act efficiently on the receiver; terially decreased by light rays. plitude of the emitted oscillations and if the this is the reason one often hears a "broken voltage is caused to vary in accordance with voice" in which only certain Self- Excited Dynamo - Machines whose syllables are field magnetism is the speech, the amplitude of the oscillation understandable in spite of very fine tuning produced by their own will fluctuate in the same manner as in generated current. Fig. 2B. Self-Induction -When a current is chang- The circuit and the tube on the left side ing in a coil of wire a back E.M.F. is of Fig. 1 form an ordinary C. W. transmit- 1I111I1I11111111iI1 i II produced tending to stop flow of current ting set, sending continuously, when in Iiillllll_LI_Ilili,.;1"'1!1-l'1 being changed. Also known as Electro- working order, a wave of the shape of A magnetic Inertia. See Lenz Law. in Fig. 2. Separate Touch- Divided Touch. Method The action of the microfone and the mod- of magnetizing a a bar of steel by placing ulation transformer, as well as the rôle f,.2 opposite poles of two magnets of equal played by the grid in a vacuum tube, having The Section A of the Curve Shows the Normal force in centre and drawing each magnet been described in previous lessons, we will Output of the Set, Section B Shows the Varia- simultaneously towards opposite ends of not explain them again, but merely the rôle tions of Amplitude Produced When the Micro- the bar. of the modulator tube, which is as fol- fone is Spoken Into. If the Set is Properly Ad- justed the Maximum Amplitude Obtained May Separators -Materials which are used to lows: be Double That Obtained When the Microfone is separate the positive Not Used, and negative plates When the microfone is spoken into, the in an accumulator. Take the form grid voltage is made to vary, thus of varying For the reason explained above, the con grooved wooden boards, crinkled and the plate current. These fluctuations are, stant perforated celluloid sheets glass however, opposed current method of modulation is more rods, etc. by the large inductance of efficient, as greater variations of amplitude Series -A number of instruments or cells the choke coil, and set up across the choke are obtained than with connected up in a circuit having no a varying difference of potential. This the other system, dif- thus increasing the range of a set for a shunts, that is, current must pases thru ference of potential is consequently added given power. each conductor successively. to or subtracted from the normal H. T. In a Radiofone using this Series Dynamo- Machines have field so voltage already active in circuit, the in- the circuit. tensity in the aerial is not an indication of wound that all of the generated current As a result. the difference of potentia' the range and should not be, except as an must pass -thru field coils. Voltage varies across the condenser C varies at vocal f re- indication of the proper functioning of the (Continued on Page 91-z0

www.americanradiohistory.com Radio Ne vs for June, 1921 '88r Junior Constructor

A NEW SYSTEM OF CONTACT FOR A CHEAP "B" BATTERY. A GALENA DETECTOR. Amateurs can build a very economical As shown in the diagram the sharp edge high- tension battery using waxed-paper used instead of the tubes with a cork at the bottom. Inside. of a Gillette blade is positive -out pocket common cat -whisker to secure a contact on put sacks from worn when set up, dry cells, and ' a little strip of zinc with the crystal. This detector, soluticn, get out of adjustment. It is simply suitable connections. As exciting cannot dissolve two parts (in weight) of "agar - made of a copper wire along which a bind- plate can move. agar" (a well -known sea -weed) in lao ing post supporting the water, add 20 parts of screw is fixt on parts of boiling An old spark coil vibrator chloride of ammonium stir 'up well and the base, and allows a close adjustment of the galena, fill, when still hot, the paper tubes. The the pressure of the blade against solution quickly becomes a soft jelly and by means of a cotton thread fixt at the which you have a cell unbreakable, unspilling in upper end of the copper wire, and any way, quite clean and very constant. can be wound or unwound around the screw Here are the Honeycomb Coil Coupling Scales detector, You Have Been Looking For. With 36 cells in a cardboard box, you of the vibrator. To adjust this easily get 4o volts and loo milliamperes, is 1 /3o the blade is first fixt so that it about invaluable for portable radio sets. by turn- A VARIABLE CONDENSER FROM of an inch from the crystal, then Contributed by PROF. M. MOYE. ing the screw of the vibrator, the thread TWO CONES. fixt to the wire, which acts as a spring First make two cones of heavy wrap- loose and allows the contact to he ping paper 12" in diameter at the base, SIMPLE POLARITY becomes and high. Fig. INDICATORS made -on the crystal with the proper pres- tapering to s" at the top 6" By B. G. Silberstein fit inside one sure. This detector when adjusted is very I. Make a wooden base to of these and wooden tops for both. Now YOU are constructing a three step am- steady in operation and may be easily built plifier, perhaps desribed in this maga- constructor. make a wooden base 14" square and mount by the average junior the of this. Now,' zine. Everything is going fine. You have Contributed by M. DESFORGES. the cone hase in center in the center of this base, mount 8" of % " all the connections made and the tubes in brass rod. place, and you are just about ready to con- Shellac the cones and mount one on the nect your "B" and "A" batteries. You ..Razor blade M prepared base. Take the top of this cone and bore a /" hole in it, now slide it down the brass rod and fasten it to the cone top. Brass - /Ba / Mere Make the top of the other cone fit the rod snugly. :Mount this on the outside p ,mod cone, \ar 's Now shellac both cones and apply alternate tinfoil sectors I " x 7" long, tapered Cone J to nothing. Fig. 2. Have these I " apart ba s rim' at least; use about 18. When dry, connect kse riOeC as shown' to two conveniently located switches ; see 2 Rep Idig. 3. Now place the outer cone upon ^,{ the rod. - fig. 3 P92 revolving the By raising, lowering and Here is a Merry -Go -Round Type of Variable otter cone, the capacity is changed. Condenser Made of Cones That Turn, to form a Here is a Use for Dad's Old Razor Blades, They The roc] should be notched Don't Need to be Stropped for This Use. dial. To make a grid condenser the measure- connect them, put the fones on your head, ments must be made to conform to the ca- light up the filament, and tune up for some SCALES FOR HONEYCOMB COILS. pacity desired. station. -No sound in the fones -you wonder what is the matter? You know If the average experimenter was asked By covering the inside cone with empire without scales or cloth a fair transmitting condenser can b your connections are right -hut-those "B" to use his variometers and "A" batteries You don't- know if up his hands in made. This is for small powers on'y dials, he would throw explan:.- their poles are connected right. You work And yet we use honeycombs with- (spark coils). The sketch is self- horror. tory. around with the batteries and don't know recording device ; the result is. of out any by EDWARD GREENLEE. tvhich pole is which and how to find out. course, that when we want to hear someone Contributed the It is because of this and because polarity whose wave is a little sharper than indicators are used in many other ways in a lot of "feeling around" Potato...., average, there is your "Lab." that T am going to describe and much time is wasted before we can several types which are easily constructed, tune the station in. All this is at once which will help "Bugs" out of just such obviated by the use of scales. and many other. kinds of trouble. The materials needed are a few square Green Sermon spat Referring first to Fig. i, we have the inches of sheet brass, a pair of binding si/ver wire simplest one of all, the potato polarity in- posts and some celluloid or paper. Since dicator. A fair sized potato is secured and the real value of honeycomb coils lies .in peeled. Cut two pieces two inches long which may be great range of wavelengths Phena/phtha/eine of No. 28 German -silver wire and stick attained, it is essential that any device used so/utibn them into opposite ends of the potato. on them does not affect the changing of dif- Binding posts are fastened to the end of ferent coils. Thus the indicating arrows the wires and we are ready to test it. are bolted to the hinged elements. These Connect. the binding posts to the opposite arrows are made of brass strip about /" poles of the batteries; a green spot will he wide and 4" to 5" long. One end is pointed, seen in a few minutes around the positive and a / " hole is bored in the other end. wire. The strip is now bent into a right angle. In Fig. 2 we have another type of po- the side containing the hole being about s" larity indicator. Dissolve in a little water long. Two of these strips are made and a small crystal of sodium sulphate. This bolted to hinged member by the screw which is a common medicine in most households holds the lead wire ; the upper screw is under the name of "Glauber's Salts," When preferable. The strips may now be twisted dissolved add a drop or two of phenolph- so that the broad side faces the operator. thaleine. This is easily obtained from some The scale support may be made in a Bubb /es dispensing chemist as he uses it very fre- variety of ways. It is "T" shaped with quently. and if the "Bug" is a customer, the So /1 water he would most likely make no charge for the upright about half the length of /edro cross -piece. It is secured to the panel Vass f /yhie - such a minute quantity. Now get an incl- Glass tube about or inch by two binding posts to insure rigidity. The fig J or twc of glass / / itself may be made of celluloid or in diameter; fit it with a couple of good scale preferably) and pass thru paper and numbered as the operator desires. Polarity Indicators. corks (rubber Some Clever Ideas to Make a length of No. 28 German - Contributed by Beat the H. C. L. by Using a Potato as Gal each short JAMES F. ZWEIGHAFT. vano .eter! (Continued on page 904)

www.americanradiohistory.com 882 Radio News for June, 1921 Correspondence From Readers MORE ABOUT THE PRICE OF VT'S. I was attracted by one of the covers of MORE ABOUT THE COVERS. Editor RADIO NEWS : RADIO NEws and will say it seems queer Editor RADIO NEws : In the April issue of RADIO NEWS, Mr. the way they (the amateurs) kick about the Stone, of the Pacific Radio Supply Co., covers of this fine paper, and, With the exception of one, all the issues Mr. Editor, of RADIO contradicted the article previously publisht I am well pleased with the whole paper and NEWS, since November last, have in your magazine. have not kick, I contained comments on J. F. Maher's criti- say, "Keep it up." cism I wish to make a come-back to Mr. Stone. Yours for doubling the and I wonder why someone has not subscriptions. come to his aid. Not so many years ago -. ROLLA the electric (vac M. GARDNER, In these uum) lamp was brot into ordinary use. It Eugene, Oregon. days of enlightenment ( ?) it is was cheap seldom that you can pick up a magazine very and as it became more pop- without ular, became still cheaper owing to high THE "SHIMMY" seeing on the front cover a picture production. GAP! of a young lady and gent seeking to dis- The Igth Assistant Editor, cover Now the Audion Bulb had just the oppo- some new method of kissing; a girl, Spark Gap Design Dept., RADIO NEWS, not clad in winter clothing, trying to turn site sort of a life. When it came out, it was New York, very high in cost, but since has become somersaults or some equally shocking, non- 'slightly reasonable. U. S. A. sensical picture, and a fellow has some Salesmen were not Honored and Esteemed Mister respect needed for the bulbs. Are they needed for :- for a magazine that shows none of A copy off yer RADIO NEWS for Febru- this. the V. T.? No ! Because use has made ary, 1921, blew up here on de iceboat It is a relief them almost a necessity, and then too, is ex- to be able to read a publica- press a month ago and I looked at page tion from cover to cover without having there any firm here in America that has a 527 at the bottom line of salesmen and seed a new kind of sex news glaring at you from every second just for audion tubes ? squeak box panel transmitter built page. I will admit. and I think Mr. Boddington by Mr. Marion W. Taylor. He got the rite idea But RADIO NEWS, with the exception will also admit, that he forgot about the about of royalty, the dat shimmying spark gap, but why the much discust September issue, has given labor and the patent expenses, not do it de way dot I did us sensible, but even so, should the audion when I was a appropriate cover designs, in be as high keeping with its policy in cost as it is? Now I, leave the answer of being the best Aerial ¡Os/randa 'x85 /sc wire Radio magazine publisht. to the Radio. amateur ! Think it out your- selves, amateurs, and Perhaps Mr. Maher was a wee bit hasty let's hear your answer with his criticism, in the Best Radio Magazine on earth. but we notice that, since the publication of the notorious ( ?) letter, CHARLES TIDD, JR., no more osculatory Camden, N. J. designs have appeared on RADIO NEws covers. Well ! here's hoping that RADIO DOESN'T LIKE THE STORIES. I NEws 5OO.t'N' will continue to give "clean" news and no Dynamo Editor RADIO NEWS : more wif600HP. of the so- called "human interest" Allow me to congratulate you on your steamerF» pictures. wonderful magazine, especially on your last Wash A well satisfied reader, . -9 d 5000 furo *Ooo wire month's number. You have a real maga- J NO. BERRIGA N. zine and have the rest of 'em backed off Dunedin, P. E. I., Canada. the board. But, "for the luvva Mike," Coi/ Yo series with don't, give us any more fony fiction stories DC /ire to obtain like that "Martian Madness" and "The the same break SEMI- OR BI- MONTHLY. Phantom and the Circuit." You have some as coi/ vibrator Editor RADIO NEWS : real serious articles in your magazine, but Why all the talk about a bi- monthly? I those "futuristic" stories make it look fool- guess one month is long enough to wait, ish. Let's have some real radio stories that without waiting two months for RADIO deal with real stuff. Don't think that I'm NEws. Do you realize, all you fellows who an `old fogey," but I do hate to see a "roo have been advocating a bi- monthly paper, per cent. Radio" magazine filled with that that you have been asking for one every kind of bunk. I have talked with several two months? I guess maybe it is a semi- radio men, and they think the same as I monthly you want, or one every two weeks. do. What do the rest of the gang think That's better than a bi- monthly, eh? I sec- about it? ond the motion to have a semi -monthly, if Yours for snappy radio stories, it is possible. EDWARD GRIMM, JR., R. GERALD WILLIAMS, 5215 Figueroa St., 56 Academy St., Here Are Some Ideas, A Synchronous Gap May Los Angeles, Calif. Be Used With a Spark Coil as Shown in These Presque Isle, Maine. (Correct. We too like `snappy radio Diagrams, A Movable Electrode May Be Fixt stories," to be sure. But, sorry to say, we on the Vibrator and the Other One Made Ad- haven't got the justable, so That the Discharge of the Condenser ABOUT TRANSFORMERS. time to write 'em. We Occurs When it is Fully Charged, or an Electro- RADIO don't always get good ones-roo per cent. Magnet May be Used for the Same Purpose, Pro- Editor NEWS : ones-so what can the harassed Editor vided it is Connected in Series in the Primary I wish to object most emphatically do? Circuit. to an Suppose, Mr. Grimm, you sit down and article in the April issue of the RADIO slam out a good one. We'll print it- NEws, entitled "Construction of Trans- Editor.) honored ham in 1845? I built one jist like formers," by Ben H. Woodruff. His article Mister Taylor's but I put a synkernous shows a woeful misconception of the mean- ut. ing of the Underwriters' HERE IS A SATISFIED ONE. gap on The attached skiagram shows table of carrying how I done it and also how Mister Taylor capacity and its scope; also, he fails to Editor RADIO NEWS : could fix her transmitter so as to work the realize the most conservative possibilities I have been a reader of RADIO NEWS for saim way. The synkernous in flux densities in transformer a long time gap is more steels. He and I take pleasure in saying effishent then the nun -synkernous type that may have in mind the use of "stove pipe that I believe it is the best Radio paper he rises as shown iron," the grade available publisht. by the marvelous activi- at hardware stores, ties of the Hon. 2RK who burned out 19 for which his idea of flux density is per- It seems to me that the readers of this sets of Baldwin fones haps correct. However, magazine are making up hear this past the kind of iron too many complaints four months, which none of the non -syn- and also the use of varnisht laminations and about it ; I also believe that Mr. Gernsback kernous gap stations, a lot of other essentials has far more even the notoriable are left to the experience in the publishing 8NH- 8ER-8ZL, or 3DH with the 325 imagination. work than we have ; T believe that he knows long and 988654 broad (meaters) wave However, it is in his method more about makino- can of figuring the cover designs. He hoap to do. the sizes of wire for his windings that he is trying to make his paper attractive to the I am shure that if Miss commits the most unpardonable eye Taylor will try errors. The and I believe he is making a success out my stunt that I will hear her most appropriate usage for a of it. with an transformer andibiluty of about 3500, if he isn't any built on a basis of about 30o circular mils I agree with Mr. S. M. Boddington, farther north than Mexico. per ampere would be as an electric radiator whose article appeared in the April issue, 73 OM. or foot warmer. Both No. r8 at 5 amperes concerning a monthly issue; it takes me and No. 8 at 5o amperes more TES EVITARENEGER. afford about 300 than a month to grasp the printed Operatuh, circular mils per ampere at his rating, matter inside its covers. at Station ORM. and I say let's have it (WR IT no transformer with less than 60o monthly as it is coming now. CMS PM) circular Niki, Greenland. (Continued on Page 89o)

www.americanradiohistory.com Radio News for June, 1921 883

as every ama- N. Y., INC. Rivoli Dance Palace, the club staged the first radio ment of the "CW" transmitter, RADIO CLUB OF BROOKLYN, sending set. That its progress in this di- The members of the club at the last meeting, dance to be held in the city. Various C.W. sta- teur's along the Atlantic seaboard contributed with rection has been great is evidenced by the fact held on April 27, were honored with the presence tions meeting it is enrolling new mem- George Eltz, past president of the Radio music. Mr. Ogborn, of the Westinghouse Electric that at every of Mr. the club; bers in the "CW" chapter, and it is now reach- Club of America, who gave a lecture on the uses Si Manufacturing Co., is president of in the Fleetwood, vice -president, and Benjamin ing the point where a spark transmitter of the Armstrong Super Autodyne System. Mr. Harry a rarity, partly because of of the British signal Fleetwood, secretary- treasurer. The club is for- vicinity is becoming Eltz covered the problems radio its unpopularity, but chiefly because the members corps, which were encountered during the World tunate in having as honorary president and efficiency of executive, Mr. George Bliziotis, radio engineer recognize the extremely high relative War, which finally led to the designing of the the continuous wave transmitter. Armstrong Super Auto-dyne receiver by the Amer- and director of the Newark Radio School, at which who meetings of the club are held. Those in and around the Second District, icans. Mr. Eltz also covered the subject from place the are hearing 2XK, 2BNL, 2ACT, 2QK and others the amateurs' point of view, when he pointed out A radiofone and several measuring instruments the are nearing completion and will soon be ready regularly, do not have to be apprised of good to the members present, some of the tricky parts work the members have already done. of the circuit which he believed would be en- for use by the club members. Meetings are temporarily being held at the home countered by the average amateur, who contem- The club desires to secure as members, ama- the suburbs of New- of L. M. Cockaday (2XK), 2674 Bailey Ave., plated building one of the above sets. teurs and operators living in Monday 8 P. M. As yet, ark. At present we have members from Newark, Bronx, every evening at and Elizabeth. attempts have been unsuccessful in locating a de- LONG BRANCH AMATEUR RADIO CLUB Belleville, Jersey City, Arlington sirable meeting room where a radio station can The Long Branch Amateur Radio Club held Persons interested are cordially invited to pay word would be appreciated night at 284 Market be installed and a its first regular meeting on April 29, at the us a visit any Wednesday from any one knowing of any such available home of Eldon Presly. Officers were elected St., Newark, N. J. space. as follows: Kenneth Adams, president: Ells- The club is, of course, open for membership, worth West, secretary, and Eldon Presley, THE OSHKOSH RADIO CLUB a cordial Radio Club held and this opportunity is taken to extend radio instructor and inspector. Since then eight At a meeting of the Oshkosh invitation to all interested in radio, to attend honorary members have joined. The purpose of recently in the physics laboratory of the Oshkosh the meetings held at the above address. Com- this radio club is to create an interest in wire- Normal School, the following officers were elected: munications are invited, and should be addrest less telefony and telegrafy. All of the mem- President, J. N. Becker; vice-president, Charles to Mr. Richard Leitner, 1113 Forest Ave., or bers have good size receiving sets and small port- Clemans; secretary and treasurer, Percey Stephen- the secretary, Mr. William Weller, 2156 Webster able sets. At every meeting the members have sen; corresponding secretary, Vernon Wood. Ave., Bronx, New York. buzzer contests and this increases their alert- At present there are seven government licensed ness in code work. They are now planning to stations in this city, two of which operate radio THE QUEENS RADIO CLUB build a small headquarters so that they can con- telefone sending stations. An up -to -date radio The Queens Radio Club was organized on April struct a club set. Correspondence from other telefone station is in the process of construction 11, 1921, at Long Island City with 20 charter mem- clubs will be greatly appreciated and should be at the Normal School, where experiments con- bers. The object of this club is to advance all addressed to Kenneth Adams, 111 Atlantic Ave., ducted have thus far proved promising. E. A. members in radio science. Meetings are held Long Branch, N. J. Clemans, of the Normal School faculty, Vernon weekly at the industrial branch of the Y. M. C. A., Woods, Charles Clemans and John Becker, are 426 Jackson Ave. (Bridge Plaza), Long Island PLAINFIELD RADIO ASSOCIATION conducting the experiments. City. Lectures are given and merits of apparatus Other local stations are contemplating installing discust. Membership fee is $1, A radio club, incorporated under the New Jer- between and hook -ups sey State law, as the Plainfield Radio Association, similar outfits soon and communication and dues are 25 cents a month. Any one may Plainfield, N. J. members by the use of radiofone entirely, will become a member regardless of age or education. has been organized in then become a simple matter. It is composed of wireless enthusiasts ranging New members are welcome and may obtain any from first-class "hams" to naval operators, and information from the secretary, Mr. Theodore in the very near future a first -class telefone trans- LA CROSSE (WIS.) RADIO CLUB Holzinger, 481 Grand Ave., Astoria, L. I., New mitting and receiving station will be installed at The following program was given at the meet- York. the headquarters. ing of the La Crosse Radio Club April 4: CLARK RADIO CLUB We would like very much to have reports from "What Other Clubs are Doing," R. Hammers - The annual meeing of the Clark Radio Plainfield telefone sets, as burg. Club, Clark University, Worcester, Mass., was any stations hearing R. there is a great variety of testing and experi- "Long Distance Stations and Their Records," held in the Physics Laboratory on May 4. The menting going on. Address reports to Plainfield White. meeting was called to order by President Parkes. Radio Association, P. O. Box 204, Plainfield, "Kinds and Makes of Receiving Instruments," The chief business conducted was that of electing N. J. W. Herbert. officers for the ensuing year. A. W. Parkes was HADDONFIELD RADIO LEAGUE Mr. Prottsman also gave one of his invaluable re- elected president; R. R. Smith, secretary. and The Haddonfield Radio League was founded two instruction series, and the committee on consti- W. R. Francis, treasurer. A committee of five was years ago and boasts of an increasing member- tutional amendments' report was presented. appointed to take charge of the sub -freshman day ship every month. Our meetings occur every It is the desire of all the members that visitors celebration. This committee has arranged for an- two weeks at an appointed member's house for come to the meetings. other concert to be given by radiofone, and also two meetings. At these meetings business is for numerous other experiments in order to give transacted first, followed by lectures on theory THE CHICOPEE RADIO ASSOCIATION the men of meager information a more complete and operation of new and complicated apparatus The Chicopee Radio Association has been or- knowledge of the operation of the apparatus. Be- and book -ups. ganized at the Falls with the following officers: sides this committee, several others were appointed Dues are $2.50 for the term of 10 months; meet- Instructor, George Smiley; president, James Duffy; for maintenance of equipment, operatin shifts, ings are not held during July and August. With secretary, Edward Benoit; treasurer, Stanley Pady- etc. these dues the expenses of the club are paid and kula; house committee, the president, secretary, After the business session, the members talked apparatus bought for the use of the members. A treasurer; entertainment committee: Stanley Pady- over the problems which are to be undertaken dur- wave meter is our most recent "buy." kola; press committee, Euclide Beaudry; finance ing the coming year, especially the erection of an THE RADIO NEWS is our official organ. committee, Claude Smith, Arthur Fay, Eugene umbrella -type of antenna, 150' high. It was pro- The officers are: President, Edward Braddock, Baker; committee of affiliation with the Amateur posed that the individual wires be controlled by a 3BAY; vice -president, Jesse McNeal, 3BBH; sec- Radio Relay League, George Smiley, Arthur Fay switch so that it could be employed as a gonio- retary, John L. Barnes, 3ABW; treasurer, Jared and President Duffy. meter. Barnes; and inspector, Jesse J. Haydock, 3AQF. The club has 15 members and is arousing the in- ELBERON RADIO CLUB Anyone wishing to communicate with this club terest in wireless thruout Chicopee Falls. It pro- The Elberon Amateur Radio Club held its first should correspond with the secretary, John L. poses to apply for admission in the Western regular meeting on April 27th. Officers were elect- Barnes, 113 Mansion Ave., Haddonfield, N. J. Massachusetts Traffic League. It is planning to ed as follows: William Bryan, president; J. give a radiofone concert for the members and a Calder Scobey, secretary; Henry Hacker, treasurer. THE PENN RADIO CLUB few invited guests, including Mayor Higgins. At The purpose of the club is to bring the amateurs The first meeting of the Penn Radio Club was that time music will be heard from various clubs of Elberon together and instruct them in radio held at the residence of Mr. Orion G. Albert, 667 as far south as Washington, D. C., and as far telegraphy and radio telefony. All owners of N. Preston St., West Philadelphia, Pa., on Thurs- west as Buffalo, N. Y. The members are very radio sets in Elberon or vicinity are invited to day, April 21, at 7.30 P. M. The main objecta of much interested and feel that with Mr. Smiley join; also correspondence from other clubs is in- the club are code practice and theory. as instructor, they can advance rapidly. He has vited. Address all communications to William The following officers were elected: President, been studying wireless since Marconi first came Bryan, Elberon, N. J. Robert Little. treasurer, Orion G. Albert; and into notice. He is a member of the Connecticut Leroy Valley Radio Club of Springfield. The club mem- HURON RADIO CLUB secretary, Ritter. Fav recent- At the first official meeting The dues are 15 cents weekly, the proceeds to bers gathered at the home of Arthur of the Huron Radio apparatus and ly and listened to a concert given in Hartford. Club, of Huron, S. D., the following officers were be used for the purchase of new meeting elected: President, Lewis for better headquarters. We expect, in the near Mr. Smiley will give a talk at the next Terpening, and secre- -stage am- of the club on the "Principles of Radiation." tary- treasurer, Arnold Anderson Prof. Ralph D. future, to install a radiofone, also a two Doner, author of the article plifier and a Magnavox, provided we get enough on "The Hall Air -Jet are inter- RADIO CLUB Radio Relay," which appeared in the February members to enroll. Fellows, if you FORDHAM issue of Science and Invention, ested and have a set, it's up to you to become a The Fordham Radio Club was organized Nov. is our instructor - to Bronx, New York City. At that member, as is also Mr. Knapp, formerly an oper- member. Kindly address all communications 6, 1920, in the ator in the Navy. The Leroy Ritter, secretary, 2415 S. Sartain St., Phila- time conditions in that section of the city were following are the present where constant communication members: Lewis Terpening, Arnold Anderson, delphia, Pa., or call any night at the president's reaching the point Chester Bailey, William Whorton, home, 5856 Windsor Place, West Philadelphia, between stations only a mile apart could very sel- Jack Foasburg, of the incessant roar Bernold Kyes, Prof. Doner and Mr. Knapp. and at the treasurer's home, 667 N. Preston St., dom be maintained because We plan West Philadelphia. of local interference, a large part of which was to install a complete receiving set as The pressing need of immediate soon as wo can find a room Anyone desiring to unintentional. join the club will have to NEWARK WIRELESS CLUB organization to correct a condition that was de- pass a test before do- May, stroying amateur radio in the district was recog- ing so. The Newark Wireless Club, organized in We desire to correspond with is holding meetings every Wednesday night nized by a few of the more advanced men, and other clubs. 1920, the result is the present Fordham Radio Club. Please address all letters to the secretary, Arnold at 8 P. M. Anderson, 1250 Ninth St., Huron. S. On Wednesday, March 30, in Newark, at the This club's primary object is now the establish- D.

www.americanradiohistory.com 884 Radio News for June, 1921

filft

THIS Department is conducted for the benefit of our Radio Experimenter. We shall be glad to answer here only publish such matter of sufficient interest to all. questions for the benefit of all, but we can 1. This Department cannot answer more than three questions for each. correspondent. 2. Only one side of the sheet should be written upon; all matter 3. should be typewritten or else written in ink. No attention paid Sketches, diagrams, etc., must be on separate sheets. This Department does not to penciled matter. 4. Our Editors will be glad answer questions by mail free of charge. to answer any letter. at the rate of 25c for each question. If, however, questions cate calculations, patent research, etc., a special charge will be made. entail considerable research work, intri- You will Before we answer such questions, correspondents will be informed do the Editor a personal favor if you make your letter as brief as possible. as to the price charge.

A. C. FOR POWER TUBE RADIO FREQUENCY AMPLIFIER. A. 1. A ground FILAMENT. (215) is not necessary for the George W. Jackson, of Alexan- reception of Radio signals or fone mes- (213) Jack Knebel, of Larchmont, N.Y., dria, Va., requests the following informa- sages. A tion: loop or a counterpoise may be asks: used. A loop is a closed circuit which Q. 1. is Q. I. Could A. C. be used for the fila- Can one step of radio frequency connected in the same way as the secondary ment or grid of a 5o watt power tube? amplification be attached to any type of of a loose coupler valve receiving or other tuning coil. A A. 1. A. C. may be used to light the set. Please publish a "dia - counterpoise is merely another aerial used filament of a power tube, but a D. C. volt- gram of a one -step radio frequency ampli- as ground; on the fier. airplanes, the counter- age is needed for the grid bias voltage. poise consists of the motor, guys and other Q. 2. Could I lawfully use a Radiofone A. 1. A one -step frequency amplifier may metallic parts connected together. on over 200 meters and how? be used with most receiving circuits. For long A. 2. No, you must not use a Radio - waves, resistance coupling may be SPARK COIL DATA fone over 200 used as shown on page 596 meters, unless a special li- of the March (219) J. G. issue of RADIO NEWS, Schroeder asks: cense for the use of a longer wave is and for short waves, Q. 1. a tuned Can I use 32 -volt D. C. from bat- granted to the station. circuit, such as the one shown on teries for supplying Q. 3. Give a page 441, of the January the plate voltage to a Radiofone hook -up to use issue. Radiotron U. V. 200 with a tube? 5o watt Cunningham tube? A. i. Yes, this A. 3. This hook -up was publisht on page TICKLER H. T. supply is quite COIL. suitable, but a potentiometer 796 of the May issue of RADIO NEWS. (216) E. O. Lund, of Minn., should be Vining, used, for a U. V. 200 tube requires wants to know : only Q. 4. What would be the range of this 2O/ v. on the plate. set if the plate voltage is 400 volts? Q. 1. When a tickler coil is used, is it Q. 2. What is the proper sparking dis- A. 4. It is difficult to say, for the range necessary to have it near the receiving coils tance for depends greatly upon or loose coupler, i k.w. rotary spark gap? the surroundings of or can it be placed any - A. 2. There is no the station. the adjustment of the set and where on the panel? fixt sparking distance for a spark set; the proper length of spark especially upon the type of receiver used at A. i. The tickler coil should be mounted should the receiving so that be found by experimenting, and de- stations. Under good con- the coupling between this coil and pends upon ditions, it may be about loo miles. the secondary is adjustable. the capacity used in the oscillating circuit, and upon the speed of Q. 5. What should be the height of an Q. 2. Is paraffin wax a good dielectric motor. the aerial 125' in length, to work with this for soaking coils? set? Q. 3. Please A. ç. About 6o' would A. 2. Yes, paraffin give me instructions for he suitable. wax is suitable as in- building a three -inch sulating material for coils. spark coil to operate on a 32 -volt D. C.; size of wire, amount HOOK -UP FOR THREE HONEY- wire required of SPARK COIL SET. and size in square inches of COMB COILS. (217) condenser. Grahame H. Hardy, of Ashland, A. 3. (214) Raymond Drake, of Indianapolis, N. H., asks: A three -inch spark coil to be used on 32 v. may be built Ind., asks for the following: Q. 1. Can I use a step down transformer as follows: Length of core, I2 % "; diameter of core, Q. 1. Please show a hook -up for three that has steps from three volts to 24 volts 13/"; the primary is wound with No. 14 wire honeycomb coils, a variable and a fixt con- for current to operate a spark coil that has layers; in six denser, using the secondary is wound in 16 a crystal detector. a spark length of % ", and what voltage with pies A. 1. The hook -up for these instruments shall No. 32 wire. Weight of secondary I use? wire, eight pounds; appears on this page. You will note that a A. 1. Yes, the condenser consists a step down transformer may of 18o tinfoil sheets, variable condenser is necessary in the sèc- be used with a spark coil, but the 9" x 7"; wall of in- ondary circuit. vibrator sulating tube between primary needs a careful adjustment; on a %" coil, ondary, and sec- Q. 2. Using this hook -up, would it be about six volts should be used. / possible to catch A. N. A., using a 60' Q. 2. Please give hook -up for the fol- VARIABLE aèrial, 30' high, and what honeycomb coils lowing sending set: One %" spark CONDENSER should coil; one be used? spark gap; one Helix with two clips; one CAPACITY. A. 2. We are afraid not, the distance be- key; and five dry batteries. I have no (220) Erwin W. Schmidt, of Medina. ing too great and the aerial too small. condenser; if I need one, how can I make Ohio, inquires: Some L 400 coils should be used to tune in a cheap sending condenser that Q. 1. What is the capacity N. A. A. will do for of a variable the above mentioned sending set? condenser which has 22 stationary plates A. 2. A hook -tip for your instruments 4" in diameter, No. 24 gauge aluminum, appears on this page. You should use an (Continued on page 904) H. T. condenser in your circuit and also a hot wire ammeter in the ground lead to see your radiation, and if your set is properly tuned. An H. T. condenser may be made of 41 fotografic glass plates 4" x 5 ", with some 3" x 4" tinfoil armatures; 20 tinfoil sheets are required for each armature, which should be fitted with lugs for connection to the circuit. COUNTERPOISE. (218) Francisco Pineda -López, of New York City, would like to know : Q. r. Is it absolutely necessary to use a ground for the reception of wireless signals? If so, how do airplanes manage to This is the Hook -up for a Spark Coil Using an get them when in flight, Auto Transformer with no ground Hook -up for with a Quenched Gap. available ? Three Honeycomb Coils with a Crystal Detector,

www.americanradiohistory.com Radio Rows for June, 1921 885 / URDOCK ARIOMETER No. 345 THE LATEST V ARIOCOUPLER No. 346 No. 345 -P Variometer, complete as illustrated with panel, knob and dial and panel mounting brackets $7.50 No. 345-G Variometer, complete as illustrated with panel, knob and dial and panel mounting brackets $7.50 No. 345-P or 345 -G Variometers without knob and dial $6.75 No. 346 Variocoupler, as illustrated with panel, knob, dial, and panel mounting brackets and back cornccted tap off switch $8.50 No. 346 Variocoupler without knob or dial $7.75 WINDING FORMS ARE "MURDOCK MOULDED" "THE PRICE IS UNUSUALLY LOW, THE QUALITY IS No. 346 Variocoupler No. 345 Variometer REMARKABLY HIGH" $7.50 SEE THEM AT YOUR DEALERS $8.50 MURDOCK No. 55 MURDOCK RADIO RECEIVERS Variable Condensers No. 366 -43 plate .00r mfd. with oil containing case $4.75 No. 367 -43 plate .00r mfd. 4.50 No. 368 -23 plate .0005 mfd. 4.00 PANEL MOUNT TYPES No. 3660 -43 plate .00i mfd. $4.00 No. 3661 -43 plate .00r mfd. 4.25 No. 3662 -43 elate .00r mfd. 5.00 No. 3680 -23 plate .0005 mfd. 3.25 3000 No. 3681 -23 plate .0005 mfd. 3.50 'OHM No. 3682 -23 plate .0005 mfd. 4.25 DOUBLE SET $5.50 MURDOCK Variable Condensers

OR YOUR MONEY BACK" G, PERFECT SATISFACTION GUARANTEED BUY THEM FROM YOUR DEALER SEND FOR BULLETIN No. 20 STREET WM. J. MURDOCK CO* CHELSEA, MASS. 509 MISSION STREET, SAN FRANCISCO, CALIF.

www.americanradiohistory.com 886 Radio News for June, 1921 Crosley Ca . nets A "SCOOP", FOR RADIO NEWS WE do not often boast about our II Frequently our Washington representative achievements, but we think the at- finds it necessary to telegraf tention of the us and this 111111 radio fraternity should happened with bill H. 4132. be called to the fact R. As a matter that we scored a clean of fact we were about to go to press and "scoop" in our May issue, as they say in the issue was newspaper parlance. closed, but bÿ lifting several i(IilllíllllllllllIllllilllll pages including the Ildlll . Editorial, it was pos- Our smaller friendly contemporaries are sible always to include this important information. ready to honk their own horns as It should be noted The tendency in the radio fie d today is to put to the service which that this is not the apparatus in cabinets not only for appearance sake they render to the only radio bill that has been brot but as a protection from dust, dirt, atmospheric radio fraternity, but to our conditions. etc: Realizing we notice that RADIO attention of late. As a matter the demand for attractive NEws is always there of fact there stock cabinets of various sizes, we are building them first. Radio Bill H. has been a regular avalanche, but most of in quantities in our large wood working plant. These R. 4332 was printed in full in our May is- the bills cabinets are all uniform in style. The panels are sue. No did not concern the amateur di- rabbeted in to the front. As the outside dimensions other notice of this important bill rectly, so we did not print them. and inside dimensions are either larger or smaller appeared in any of the. than the panel itself, we show panel size and also other May issues of This notice has not been inside dimensions. Prices our contemporaries, written in a vain- quoted do not include the altho one or two of glorious spirit -it simply calls the panels. them came out after us, and attention All cabinets are waxed antique mahogany finish. therefore had of the radio fraternity to the fact that Wood used is either gum, genuine solid mahogany more time to get the information. RADIO or quartered oak. Lids or tops are hinged. Sizes NEWS is on the job at all times. Not and prices are shown below: We believe that RADIO NEWS is the only only this, radio publication but if at any time certain radio CABINETS Quartered that maintains a repre- legislation should threaten For Panel Oak or Ma- sentative in the amateur, Size Inside Washington for the express even after RADI) Dimensions Gum hogany purpose of safeguarding NEWS has come out, we Height Width Depth the interests of would immediately transmit the informa- 6 x 7 5% 63¢ 7 $2.50 $3.85 the amateurs. There no 6 x 103¢ is radio bill that tion by mail to our 534 10 7 2.75 4.40 does list of over 50,000 radio 6 x 21 . not come to 5% 20% 7 3.95 - 7.3.1 our immediate attention. amateurs located all over the 6 x 14 531a 13% 7 3.30 5.55 United States. 9 x 14 832 13;4 10 3.70 6.80 12 x 14 11% 13% 10 4.40 8.50 12 x 21 11% 2034 10 5.25 10.60 JUDGE MAYER Cash must accompany order. No C. O.D.'s. We pay SUSTAI NS ARMSTRONG PATENT transportation charges. We can furnish genuine formica panels 3/16" thick, AS a result of litigation extending ove was appreciated cut to the at an early date and li- following dimensions. 6 x 7; 6 x 10% a period of years, the Armstrong radi o censes were 7 x 9; 6 x 14; 7 x 12; 6 x 21; 7 x 18; 9 x 14; taken out by the Atlantic Com- 12 14 feedback" patent, x 14; x 1s; 18 x 21. Price of panels -2%c. controlled by th e munication Company, the Goldschmidt Corn- per square inch. For odd sizes order the next Westinghouse Electric & Manufacturin g largest size; we will trim. We pay the postage. pany and the Marconi Company during the has been held valid by Judge Mayer. years 1914 and 1916. This patent covers what is CROSLEY probably the All radio amateurs are familiar with the Host important circuit arrangement in use circuit. It permits n modern them to receive on a MAGFON radio. It made possible trans- simple small antenna the radio oceanic radio communication and has signals No radio station com- con- transmitted from great distances. Thus it 1 plete without it. tributed much to the art of radio telefone is possible for Built in horn: am- communication. an amateur in and about plifies signals, voice, New Yoric with feedback his antenna located on his or music, making The circuit magnifies the signals apartment house and using head phones un- 'eceived by wireless instruments the Armstrong necessary except on thousands feedback circuit to hear messages from weak signals. Uses of times, so that signals previously 'in- Nauen, Honolulu, one watch case re- udible are now Darien, Norway, Philip- ceiver, any make: easily readable, and it f ur - pine Islands, Lyons, and the great Lafayette simply insert it in her permits of very great selectivity, mati- Station installed hack of cabinet. ng possible by the Americans during Beautiful antic' u, reliable communication between the war at Bordeaux, France. mahogany finish, wo stations regardless of atmosferic It is also Price, $10.00 con - depended upon in the delicate work of di- litions and of the transmission of messages rection finding, which Dealers wanted. MANUFACTURERS OF )y other stations. requires receiving in- RADIO APPARATUS -send us samples or struments of the utmost delicacy. drawings Mayer, in his opinion, It was of your cabinets for quantities prices. Judge says: used on the NC Navy planes which crossed Get your name on our mailing list to receive latest This case is another contribution to the the Atlantic. bulletins of our latest radio specialties. -omance which has so often characterized Prof. M. I. Pupin, of Columbia Univer- CROSLEY MANUFACTURING CO. the history of forward inventions. As .a sity, says: Dept. R. Cincinnati, Ohio boy of 35, Armstrong became interested in "Edwin H. Armstrong's contribution to radio and erected a radio station at his the radio home. art is epoch making. No one who In the spring of 1912 he began a has employed his close study of feedback can fail to ap- the fundamental action of preciate its eminent value and inexhaustible the audion and read all the literature on the possibilities. Armstrong subject. Some time made his invention during this period, he when he was about 21 years connected a condenser across the telefone of age and be- of fore he graduated from the Department of a single audion receiving system, and no- Electrical ticed Engineering at Columbia Uni- that on some bulbs an increase in sig- versity in 3913. The nal strength would result. regenerative receiver It is important, and the regenerative oscillator will always at this point, to realize that Armstrong is figure among the classical inventions and a remarkably clear thinker. His achieve- will occupy a foremost Build Model Planes ment was not position in the re- the result of an accident, but search laboratory, as well Wading River models are exact scale re- the consummation of a thotful and -imagina as in the com- productions of real planes, that's why they mercial wireless service. It entitles fly. tive mind. Step by step he proceeded Arm- You can't go wrong with Wading River with strong to a very high place among elec- plans and parts. Send 10 cents for new the study and experiment. He was obtain- trical inventors." 56 page catalogue, showing 25 different ing what seemed to him remarkable models that you results, The principal defences urged can easily build. and in December, 3932, he had by the De succeeded in Forest Company and the American Tele- Rrill WADING RIVER MFG. CO. improving the sensitiveness of the audion fone Dept' H, 672 Broadway, Brooklyn, N. Y. & Telegraf Co. were prior invention by means of a new connection. The merit by Dr. DeForest and that of the invention was soon Armstrong's in- recognized, and vention was of a very limited character. the very apparatus of which A rmstron- Judge Mayer held that Armstrong made the invention was subsequently utilized was the first inventor and that the invention was of commercially at Sayville, Long Island, a very Electricity shortly broad character, covering any feed- A practical training in this great profession will after the outbreak of the war in back arrangement. make your successful future a certainty. We 1914, to overcome difficulties in the recep- teach all branches of Electrical Science and En- gineering. tion of signals from Nauen, Germany." SOME When the LETTER! HUH? ELECTRICAL ENGINEERING United States entered the war, First Am.: Say, did you know With Armstrong, who was then working that "Q" B. S. Degree in 3 Years with is the most dangerous letter in the continen- Electrotechnics-12 to 36 mos. Electrical & Professor Pupin in the Hartley Mechanical Drafting -6 to 12 mos. Automotive Research tal code? Electricity 3 mos. Laboratory, Columbia Armature Winding & Motor - University, was com- Second Am.: No. How so? Generator Repair, thorough 3 to 6 months' course. missioned as Captain in the Practical Electricity -6 months. Army and First Am.: Why, because it contains A place for every student. Up- served in the Signal Corps, A. E. F., where T. N. T. . Q. to -date laboratories-faculty of he rose to the rank of Major. The inven- (- - -) = 90 experts; Individual instruc- ROBT. E. tion. Write for latest catalog; tion, which by that time had become widely S'NYDER. mention age and education. New term soon starting. known, was used by the Signal Corps or FORGOT THE all the armies in the field for receiving DETECTOR. SCHOOL of ENGINEERING radio finks: My wireless set must be worth Dept. RN -6 messages under the difficult conditions of a lot. 373 Broadway, Milwaukee, Wis. warfare. l3inks: Why? The commercial value of the invention finks: They say "silence is golden."

www.americanradiohistory.com Radio News for June, 1921 887

RADIO DI STnIB UTIfIG .COM PANY. This Mark gRADISCO2 Your Guarantee RADISCO APPARATUS - BETTER "B" BATTERIES are an investment in satisfaction! To pay less is to sacrifice essential elements of quality. To pay more is unnecessary -a needless use of money which might better 111111111111111111111 111111111111111 lll be put into other apparatus, Operating life, - 600 to 1000 hours 15 cells, - - - 22* volts No batteries at the price are as good.

No. I (3j x 2 x 2z in.) - $1.50 Shipping weight 2 pounds _ No batteries at any price are better. No. 2 (6} x 4 x 3 in.) - $2.65 Shipping weight 5 pounds. - Larger size has variable voltage feature Tapped in groups of three cells. Ask your dealer to explain it For radio phone ,cork, Radisra Better `B" Bat- teries provide a reliable source of power, without the disagreeable hum of a motor generator or the rectified 6o cycle tone Radio Distributing Co. Newark New Jersey

PAT. APPLIED rota

15 DAD40 DISTQ IBU TINCTCGhANV

._ 111111IIII CELLS

Ii l iiiÌ IIIIIIIIIII IIIIIIIIIIIIIIII I i¡IIIIIII111111I111 2.5 RADISCO VOLTS ,., APPARATUS

BETTER "B" BATTERY \ ADE ACCORCIN4 TO V, t, GOVERNMENT 5PECIPCATIOMI RADIO DISTRIBUTING CO. `rt11111 ._ NEWARK, N. J

11 Lw- AVI l IIIimIIIÌÌÌÌÌÌÌÌIIII'WIII , BOSTON, MASS. NEW. BRUNSWICK, N. J. SCRANTON, PENN. T HE RADIO DEAL Shotton Radio Mfg. Co. ERS listed below are Atlantic Radio Co. Geo. N. DeLaplaine P. O. Box 3 306 George St. and progressive merchants. 88 Broad Street. Branch 8, Kingsbury St. 8th and Magnolia Sts. Jamestown, N. Y. They are equipped to give BROOKLYN, N. Y. OMAHA, NEBRASKA. SEATTLE, WASH. you helpful advice and real Kelly & Phillips Northwest Radio Service Co. service in selecting your 312 Flatbush Ave. O. B. Radio Supply 6og Fourth Ave. equipment. As an in- 406 Brown Building. radio CHICAGO, ILL. WASHINGTON, D. C. dication of their up -to -date PHILADELPHIA, PENN. Eastern Radio and Elec. Chicago Radio Labs. Co., 1405 Florida Ave., methods, they carry a corn - 1316 Carmen Ave. Philadelphia School of ap- Wireless Telegraphy N. W. plete line of Radisco Branch, Peoria, Ill. WICHITA, KAN. the new Broad and Cherry Sts. paratus, including ILL. The Cosradio Co. Coils, EUREKA, variocoupler, Radisco Klaus Radio Co. PITTSBURGH, PENN. 1725 Fairmont Ave. Better "B" Batteries, Cor- Radio Electric Co. Canadian win Dials, etc. Buy from KANSAS CITY, MO. 3807 Fifth Ave. BEINVTLLE, QUEBEC. Radio Mfg. Co. the nearest Radisco agency, McCreary Radio Supply Canadian 4th and Delaware Sts. PORTLAND, ME. and be sure of satisfaction. MONTREAL, QUEBEC. N. J. Atlantic Radio Co. J. B. Miller NEWARK, 15 Temple St. 136 Vendome Ave., ALBANY, N. Y. A. H. Corwin & Co. Shotton Radio Mfg. Co. N. D. G. 4 West Park St. R. I. 8 Market St. PROVIDENCE, TORONTO, ONTARIO. Island Electrical ASHEVILLE, N. C. NEW ORLEANS. LA. Rhode The Vimy Supply Co. In- Rose Radio Supply Equipment Co. 567 College Street. Hi -Grade Wireless St. strument Co. 604 Gravier St. 45 Washington To Responsible Dealers ATLANTIC CITY, N. J. If you are in a town where there is Paramour.t Radio Supply no Radisco Agency, you will benefit Radio Distributing Co. Newark, N. J. by writing for the Radisco plan. Arkansas &ADISCO Pacific Aves. Your Assurance Satisfàctory Perfirmance"

www.americanradiohistory.com 8 Radio News for June, 1921

Newspaper Uses Amateur Radio Reporters (Continued from page 875)

Wfl:Y? 1..1111111,,,,,111113,1,,,,,1 ...... the transmission of the news was complete, officials of the radio club received messages from stations as far south as Los Angeles and as far north as Portland. These stations said that they had listened in on the Tribune news, many of them up and down the coast copying off the notes of the day's doings in Hayward, Vallejo and the other towns of the district. Sev- eral volunteered their services in a test of wider scope, which would embody the entire Pacific Coast. which is now being discussed by the Club as a result of the success of that night's test. Results of the test were discussed at the meeting of local radio amateurs at the Bay Counties Radio Club the following Friday evening in the Alden branch library and various plans for future tcsts of wider scope were presented. Following are some of the Tribune de- 5980 6000 6020 6040 spatches received in the press service test, with the names of the operators who sent N'flliELENGTH- METEP5 and received them, and their call letters : FIRES NOW COME TO RICHMOND FIREMEN Sent by A. E. Poage, 6HP. Received by W. D. Wood, 6KL. did Richmond, April 19. -A garbage truck while we start building condensers? loading waste excelsior at a store at Sixth and should you investigate Cotoco condensers? McDonald Avenue caught fire today. People were should startled by the approach of the truck at full speed WHY you use a Cotoco condenser? and ablaze. The truck was brot to a quick stop in front of the fire station and the fire extinguished. It was later called for by the crew. The blaze ii as extinguished before serious damage was done The curves to the truck. above were made to compare the sharpness of It is related that in the early days of Rich- mond when the fire department was a volunteer resonance of our condenser with organization, and there was some complaint that the usual type assembled be- the department was slow in getting on the job, a city commissicn made a motion that whenever tween bakelite there heads. It gives the essential reason Y was to be a fire the fire department was to WH be notified and then the fire brot to the fire partment. de- this condenser will produce results you want. If this is not RANCHERS PROTEST GORDON VALLEY PLAN sufficient reason, let us send you our descriptive Sent by R. J. Eeler, 6IM. bulletin, which Received by R. W. Carroll, 6BG. will give you all Vallejo, April 19. -The formal protest of the the details. Suisun Valley ranchers in regard to the construction of the proposed Gordon Valley reservoir in Napa County was received by the city council Made in three Tuesday afternoon and filed. sizes .0005 M.F., .0007 M.F. and 001 M.F. The city of Vallejo has already filed a request with the State Water Commission to impound in case as shown, or unmounted. scme of the waters cf Gordon Valley creek in the reservoir to be erected on the Scally ranch Napa in County, and it is expected that the coin - miss-on will act on the matter during the month of May. Get on our mailing list NOW Four men are now at work in Suisun Valley taking water measurements in the Suisun Creek and reports are being forwarded each week to the water commission. The city of Vallejo bonded 87 itself last fall for the sum of $1,260,000 for the Willard Avenue Gordon Valley reservoir project, and today some- C TO-COIL s PROVIDENCE, R. I. thing like $30,000 has been spent in survey and CO investigaticn details. MT. DIABLO STUDENTS WILL RALLY TONIGHT Sent by C. S. Mundt, 6AJ. Received by R. B. Lohry, 6AN. Concord, April 19. -The results of the high school baseball game at Antioch last Saturday THE ROTARY MODULATOR were: Mt. Diablo 11; River View, 4. A New CW Unit For Tone Transmission Mt. Diablo students meet Wednesday night. With Power Tubes Yell Leader Ed Drew, Superior of the University of Cali- to buzzer modulation as all forma, will be the speaker and a University quar- tubes can be used as power oscillators tet will furnish the music. Invitations have been with 100°ó modulation. Designed for extended to Contra Costa County High School operation in any CW circuit now in students to attend. use. A pure, clear, audio note at any fre- LARGE CROWDS SEE OPENING quency desired is obtained by regu- Sent OF CASINO lating the motor by O. F. Willey, GPR. speed. The rotor is Relayed by C. C. Whysall, 6TV. perfectly balanced and can be driven Received by the smallest motor. by S. C. Houston, 6AVF. Complete instructions Santa Cruz, April 19.- Informal opening of the are furnished Casino and plunge was held Friday, 15th. with each modulator including blue large crowds Very print and data attended. for a self -rectifying Fine work has been done on the Watsonville transmitter using the . new 5 and watt Santa Cruz highway. The highway will be tubes. completed in a few Price of modu'ator weeks. Mountain highways complete, not in- are hoped for completion by middle cf chiding motor $10.00 July. We prepay postage. State size of This new motor shaft. Order from your dealer and useful activity of the or direct from Radio amateurs is certainly to be encour- aged by other newspapers, which will real- Northern Electric Company ize the utility of SCHENECTADy, the amateurs CS reporters NEW YORK in each town, especially those deprived of P. O. Box 371 op quick means of communication..

www.americanradiohistory.com Radio News for June, 1921

"JUST LISTEN THE OMNIGRAPH WILL DO THE TEACHING Learn The Code With The OMNIGRAPH AT HOME-in half usual time-Wireless or Morse Transmitter will teach you either Wireless or Morse Telegraphy-at home-in the The Omnigraph Automatic Phone, or with Sounder, shortest possible time and at the least possible expense. Connected with Buzzer or Buzzer and messages, by the hour, at any speed you desire. It will bring an Expert Operator the Omnigraph will send you unlimited license. into your home -and will quickly qualify you to pass the examination for a first grade -right will send, you would need If you should undertake to record on paper tape, all the new messages the OMNIGRAPH a strip long enough to reach around the globe.

Radio Convention, March 16 -Ig, Examina- I92I. tions for Hotel licenses Pennsylvania were given Roof, by the .New York Dept., every City. afternoon and evening with the Exhibit of OMNI- Dept. of GRAPH. Commerce, Bureau of Navigation.

THE OMNIGRAPH is always used to test all applicants applying for a Radio License G and by a large number of the leading Universities, Colleges, The OMNIGRAPH is used by several departments of the U. S. overnment Schools throughout the U. S. and Canada. Technical and Telegraph The Radio Institute of leading and reliable Home -Study Radio School furnishes their students with an Omnigraph. Practically every Extension Division, 375 Lexington Ave New York, and the New York America, 326 Broadway, New York; The United Y. M. C. A, Schools; York, all endorse and use it. Wireless Institute, 258 Broadway, New models the Morse and Wireless Codes with the OMNIGRAPH. Send for free Catalog describing three - Thousands have learned both IT TODAY, The OMNIGRAPH is sold under the strongest of guaran- $14 to $30, or order direct through any of the following dealers. DO tees -if not as represented, your money back for the asking. Bunnell & Co., J. H New York City Richardson Ave., Bamberger & Co., L Newark, N. J. 4341 Continental Radio & Elec. Carp New York City New York City, Honolulu, T. H. 21, 1920. Cton, Neill & Co., Ltd Jan. California Electric Supply Co San Francisco, Calif. THE OMNIGRAPH MFG. CO., Duck Co., Wm. B . Toledo. Ohio Street, New York. Electric Co Pittsburgh, Pa. Cortlandt Automat'. c Trans- Doubleday -Hill Gentlemen: I wish briefly to commend your very excellent Killech Co.. David New York City I was successful in obtaining a first -class Commercial Radio New York City mitter. Recently aid. Manhattan Electrical Supply Co' license and I believe that the Omnigraph was my principal Manhattan Electrical Supply Co Chicago, Ills. weeks course at a Resident Radio School in Theory only. I San Francisco, Calif. I took a four Omni :rapt, Manhattan Electrical Supply Cr relied on the Omnigraph to get my Code tO the proper speed, and the Manhattan Electrical Supply Cr St. Louis, Mo. chid it. M eyberg Co., Leo 1 San Francisco. Calif. a first -class License. The I of two in a class of eighteen to obtain Cleveland. Ohio was one a short Newman -Stern Co for the others was CODE . . And I know that Boston, Mass. stumbling block them to pass the Pitts Co., F. D time, receiving Onmigraph messages daily, would have enabled Radio Institute of America Now York City as easily as I did. New Orleans, La. examination and cheapest method to Rose Radio Supply Ce I believe the Omntgraph to be the easiest, quickest Stewart Elec. Co., Frank H Philadelphia. Pa. learn the International Morse Code. S-hmidt & Co., Rudolph Rochest,r. N. Y. Cordially yours. San Dhge Calif. E. SELLERS. Southern Elec. Supply Co (signed) GEO. Southern Calif. ,Elec. Co Los Angeles, Calif. Williamson Elec. Co.. H. E Seattle, Wash. Wolfe Electric Ca Omaha. Nebr. Zamoiski Co.. Jos. M Baltimore, Md. 97 Thorne St. Jersey City. N. J. May 6, 1921. The Omnigraph Mfg. Co. OMNIGRAPH MFG. CO., 26 Cortlandt St., 26 A Cortlandt Street New York City New York City. my First Grade Gentlemen :-I am glad to intone you that I secured on April 25th and as far as passing the code test, I owe Commercial License to go to a most all my success to the Onmigraph. I see no reason for any one Mfg. Co. learn the code, when they can have such a wonderful teacher The Omnigraph resident school to me you so desire. as the Omnigraph right In their own hone. Refer any one to if 26 A Cortlandt St., Yours truly. (Signed) CIrESTcTt RACKET., New York City Gentlemen :- As per your ad its R.spto NEWS please natif me your free catalog Port Aransas. Texas. of Omnigraphs. May 1, 1921. THE OMNIGRAPH 3ÍFG. CO. and I Name Gentlemen.-A few months ago I bought one of your Omnicraphs for it. as it increased my receiving from about five to have nothing but praise time. Address six words per minute to twenty words. in two or three months' Always a Booster for the Omnigraph. (Signed) CHAS. F. O'DELL. City State

www.americanradiohistory.com 890 Radio News for June, 1921

It is up to you amateurs to "beat the wire" whenever there is something worth while to send to the local paper, and if ACME C. W. you get the big papers interested in ama- APPARATUS teur Radio, you may be assured of having some big Allies to help you fight any bill that may be put against amateur Radio in the future. C. W. Power Transformer Let's hear more similar ventures. For use with rectifying devices or for A. C. directly on the plates of power tubes. Correspondence From SPECIFICATIONS no volts 6o cycles Readers Out- Filament Filament Plate Plate (Continued from page 882) put voltage current voltage current 50 Io 2.5 35o I00 Two filament windings mils. per ampere would stand up long. In- 200 deed, for the type 12 5 25o -55o 200 of service he has in mind, Two filament windings generally cooled by plain radiation into the air, Boo or 1000 circular 500 o o I000 mils per ampere -1500 400 would be far safer and more logical. No Filament windings At C.W. Power Transformer the outset he speaks of "efficient transformers." At the copper densities he proposed, the I2R losses alone would be PA Henry Choke Coils nearly to per cent. of the input. Horrors! A density of 4,000 amperes per square inch! For use in ironing out pulsations and for Underwriters as transformer designers. moduating single and double iso MA and Soo I trust this may find a hearing on the MA capacity. page "Correspondence from Readers," for I think Mr. Woodruff may lead a good many astray, as C. W. is much in vogue and involves transformers very often. Filament (Heating Very much relieved and unburdened. R. C. KANE. Transformers Warren, Ill. allow the use of A. C. for power tube filament heating. The Efficient Design of V. T. Telegraf SPECIFICATIONS ID) volts 6o cycles and Telefone Sets (Continued from Filament Heating Transformer Output Secondary voltage Secondary current page 871) 75 8 -ro 7 iiiiiiii..iiiiiiiiiiiiii ,,.,. 111.11,.,,..11,,,,1111,,,,,,,1,,,_ 550 10 -12 13 between inductance, natural period and number of turns. This would enable easy design of coils for future possible re- Modulation Transformers quirements. Just as engineers have graphs of inductance against turns which enable give maximum modulation without distortion. the ready design of inductances, so there "The Apparatus is no reason why graphs cannot be made to enable the ready design of radio with a chokes. The question of which type coil is the best Guarantee" Your Dealer will be glad to arises. On the low wave lengths up to 400 or 50o say, the optimum inductance of the show these choke is not very high, making the coil dimensions small with relatively few turns. Ask for Bulletins This means a very low distributed capacity and thus the coil is best made a single layer solenoid of small diameter. The single layer coil would really be the best type of coil for ACME APPARATUS COMPANY 188 MASSACHUSETTS AVE., any wave length, except that when the high- CAMBRIDGE 39, MASS. er wave lengths are reached, the coil be- Transformer comes too large and unwieldy. Consequent- and Radio Engineers and Manufacturers ly, for purposes of space economy, it becomes necessary to use multiple layer coils. The multiple layer solenoid will be found to be very inefficient, as far are operation and space economy are concerned. A su- New "MIRACO" Vacuum Tube perior type of coil is the circular coil of Detector rectangular cross section. This type of coil COMPLETE, READY TO USE, (Postpaid) only can be designed for any wave length range, gives most efficient choking action, and oc- The new "MIRACO" Detector contains fea- cupies tures not found in others at double the price. e.ven for very high inductances, a ri- There is ample space in the hinged covered diculously small space. As a final word, cabinet for "B" batteries and additional too much binding posts emphasis cannot be laid on the on the back of panel enable the $7.85 point, that if the choke operator to connect them inside. coil is designed regardless of its distributed capacity, and its CATALOG FREE WRITE TODAY inductance is entirely depended upon for choking, multiple layer coils must not be used. They will pass radio frequency cur- MIDWEST RADIO COMPANY rents as easily as any condenser. (To be continued in July 3423 DURY AVENUE, Dept. A. CINCINNATI, OHIO issue.) WATCH YOUR STEP! READ First Ham, (listening in to Radiofone the CLASSIFIED ADVERTISEMENTS on PAGES concert) -"The `Blue Danube' doesn't come 932 -934 YOU'LL FIND MANY in very well." GOOD THING =S THERE. Second Ham -"No wonder, we are using a two -step amplifier. " -P. S. Poindexter.

www.americanradiohistory.com 891 Radio News for June, 1921

IIIIIIIIIIII lllllll lulw

JUNE, 1921

Illillllllll

PUBLISHED EVERY MONTH IN RADIO NEWS BY THE CONTINENTAL RADIO AND ELECTRIC CORPORATION

C. W. NEW YORK RADIO In the words of Dr. Alfred N. Do You Own a SERVICE BY MAIL Goldsmith, at the Second Dis- New York City is the center trict Radio Convention, "Here's of radio development. A ma- to the amateur, continuously jority of the big manufactur- he wave!" If there is ers are located in or near may Quarter? New York. The latest ideas, anything you want for C. W. the most advanced apparatus work not listed here, write us If you do, -and you're interested in radio, usually appears in New York for information. We have it, thing you can do with it is to first. The Continental Store, -the best in the Heart of Downtown or can get it for you quickly. exchange it for the Creco catalogue. New York, is in the best position to secure advance news C. W. Inductances The Creco catalogue brings you 112 pages, and apparatus. The Conti- No. 181 Tuska C. W. Induc- full to the brim with descriptions, illustra- nental Mail Order Service tance $7.50 tions, prices, on radio apparatus for every puts all these advantages, plus No. 181 Tuska; C. W. Induc- the most complete stock in tance, unassembled 5.00 need. It includes codes, abbreviations, the world's biggest city, as No. 182 Tuska C. W. Induc- tables for quick calculations, and other near to you as the quickest tance 10.00 valuable material that you will use every mail express. No matter No. 182 Tuska C. W. Induc- where you live, Continental tance, unassembled 7.50 day. can, -and will,-fill all your No. 183 Tuska C. W. Induc- And anyway, your quarter is refunded on radio needs with tance 12.50 be a No. 183 Tuska C. W. Induc- your first $5.00 order. Come on, Courtesy : Speed : tance, unassembled 10.00 sport, risk a quarter. You'll never regret Accuracy. Choke Coils it after you see the Creco catalogue. And To avoid delay, please make M.A you'll be mighty glad you saw this ad after all remittances by bank draft Acme 1% Henry, 500, Mail or P. 0. Money Order. Single Coil 6.00 25 cents you once experience Continental Acme VA Henry, 500, M. A. Order Service. Double Coil 8.00 stamps Acme 1% Henry, 150, M. A. Just your name and address and 25 cents. Single Coil 4.00 or coin. edition is limited Acme 14 Henry, 150, M. A. But do it now, -the Double Coil 6.00 Do You Spend C. E. Co., ZRX .8 Henry, 150 M. A. Single Coil 3.75 12.00 No. 127 Gen. Radio flush 0 -5 Acme, 50 Watt, unmounted Over $50.00 a Telephone Transmitters Amp. 7.75 Motor Generators I No. 127 Gen. Radio flush 0 -10 V. 100 Watt Sterling Microphone 2.50 7.75 International 500 Year for Radio? Leonard) Amp. A.C. Drive Resistances (Ward Rheostats 500 V. 100 Watt Resistance, International 110.00 THEN YOU can afford a Ward Leonard 214 Gen. Radio front or back D.C. Drive 5000 ohm 1.70 mounted 2.50 Electric Specialty Co., 350 V Paragon R.A. Ten Receiv- Ward Leonard Resistance, Paragon Rheo. front or back 50 Watt A.C. or D.0 97.00 the original price 10000 ohm 2.95 mounted 1.75 Condensers er. Although Ward Leonard Resistance, Mesco Porcelain base 1.20 tested 1500 ohm 1.50 WE 21 A AIMED is Eighty -Five Dollars, the Buzzers for Buzzer Modulation at 1000 volt, each 2.55 Ward Leonard Resistance, 2.50 F D Mica guarantee protects 12000 ohm 3.50 Century 168 Buzzer Dubilier .25 M iron -clad Mesco No. 55 Buzzer 2.50 Condenser, tested at 1800 Lavite Resistance 48000 ohm 6.00 you from any up -keep expense for Radio frequency am- Mesco 251 Buzzer .95 Volts plifiers 3.00 HIGH FREQUENCY Dubilier .0005 Grid Condenser for two full years! CHOKE COILS 1.504 for transmitting sets 2.00 Air invest- Modulation Transformers Electrodyne Rectifier consists High Voltage Variable Combine your radio 7.00 of 500 V. Transformer and Condenser will stand 1000 V Acme A -3 mounted tubes .001 M F D. Just ment for the next two years Acme A -3 semi -mounted 5.00 2 rectifying vacuum Capacity 4.50 all mounted ready for use. the condenser for your An- and invest in a Paragon. Acme A -3 unmounted less 29.00 now, C. E. CO. ZRM MODULA- No. 25 R. T. Rectifier, tenna circuit In no other way can you get TION TRANSFORMER 4.50 tubes 35.00 Telephones No. 25 V. T. Vacuum tube 4.50 pleasure, such re- Leaks No. 55 Murdocks, 2000 ohms such genuine Grid each 7.00 No. 55 Murdocks 3000 ohms 5.50 results from any Marconi 1, 2, 3 or 5 meg- TRANSMITTING TUBES 7.50 2000 ohms 8.00 markable 1.25 6.50 Brandes "Superior" of money. For, ohms Gen. Radio Drum Switch Brandes "Trans- Atlantic" 2800 equal amount Chelsea Variable % to 5 meg- G. R. TRANSMITTING ohms 12.00 you pay for a Para- ohms, 10 values 3.00 TUBE SOCKET 1.75 "Navy" Type 3200 every cent 3.00 Brandes gon represents high quality Chelsea Oscillator Jewell Meters ohms 14.00 Meters (Weston Model 301) Model 33 0 -1 flush 6.00 Baldwin Type C Navy Stand- materials and workmanship. 0 -3 flush 6.00 16.50 Model 301 0 -3 amperes flush 8.50 " ard ` 0 -5 6.00 Type E Super - The unequalled design, -the 301 0 -5 amperes flush 8.50 flush Baldwin's Model " 0 -50 Volts flush 6.00 20.00 Model 301 0 -50 volts flush 8.50 Sensitive secret of Paragon's marvellous " 0 -500 Volts flush 15.00 Century 2200 ohms (Govt Model 301 0 -100 Milliam- 6.00 12.50 selectivity and amplification, - flush 8.50 " 0 -50 Mil Amp Standard) peres " 0 -100 Mil Amp 6.00 Century 3,200 ohms (Govt doesn't add a cent to the cost Model 301 0 -300 Milliam- 6.00 14.00 peres flush 8.50 " 0 -300 Mil Amp Standard) you would pay for " 0 -500 Mil Amp 6.00 Brown 4000 ohms imported over what Model 301 0 -500 Milli-am- double arma- flush 8.50 Jewell Thermo Ammeters super-sensitive inferior engineering principles. peres 0 -1 Amp. 15.00 ture 20.00 Model 301 0 -800 Milli-am- 15.00 In last month's advertisement, peres flush 8.50 0 -3 Amp. Transformers (Acme new type) unsolicited letters 0 -5 Amp. 15.00 Acme 250 watt, mounted 16.00 we printed Meters (Hot Wire) 0 -10 Amp. 15.00 Acme 250 watt, unmounted 13.00 (includ- (For C. W. Work) from three operators, No. 127 Gen. Radio flush 0 -1 Transformers Acme 500 watt, - mounted 22.00 200 Watt, mounted 20.00 a Y.M.C.A. radio school), Amp. 7.75 Acme, Acme 500 watt, unmounted 18.00 ing No. 127 Gen. Radio flush 0 -3 Acme, 200 Watt, unmounted 16.00 Acme 1000 watt, mounted 33.00 all of whom had made actual Amp. 7.75 Acme, 50 Watt, mounted 15.00 Acme 1000 watt, unmounted 28.00 tests and comparisons. In each Vacuum Tube Sockets "fulfilled No. R -300 DeForest 1.50 case, the Paragon No. M -300 Marconi 1.50 every advertised superiority." No. 55 Murdock 1.00 man said, "Nothing like it No. 156 Gen. Radio 1.75 One No. R -400 Inverted Type 2.40 ever heard before, especially Vacuum Tubes de- CONTINENTAL U. V. 200 Detector for strength of signals on Radiotron tube, just out 5.00 tector alone." RADIO AND ELECTRIC CORP. Radio U. V. 201 Amplifying the tube, just out 6.50 Certainly, it pays to buy Treas. Electron relay 6.00 J. DiBlasi, Sec. r J. Stantley, best. Order your Paragon Moorhead Amplifier 7.00 hard Trans 7.50 R.A. Ten, or send for FREE Moorhead extra St. New York. -- A-udiotron 6.00 descriptive booklet today! Dept. C35 6 Warren

www.americanradiohistory.com 892 Radio News for. June, 1921

, ,:,,1,1111111111,111,,,,1,,,,,,,,,,,,1,,,,1,1,111111.1111,111,1111111,11111111,,,,,,,,,,,,,,,,,,,,,,,,,,,,,1,,:,,,,,1,,,,1 BUST THRU THE QRN WITH A Tube Transmitter Using The Benwood "Utility" Spark A. C. on the Plate Gap (Continued from page 863) Designed for the experimenter Equipped with the Benwood Remov- a nearby friend "listen in," cautioning him able Point Disc. to adjust carefully, for tuning is sharp, and let him Disc is six inches estimate your wavelength, which, in diameter and both if above 200 should be decreased by reduc- sparking electrodes are One Inch in ing the number of turns in antenna coil, width. Is of more than ample size for then readjust both plate and grid connec- any I KW. installation. tions until maximum radiation is noted. There is plenty of room between 18o and Can be driven by any motor either by 200 meters. belt or direct coupling. In case the set refuses to function try the following; go over wiring carefully Any Speed Any Note Any Frequency and compare with diagrams, test the con- The denser to see whether it is shorted, seethat best open type rotary spark gap that the filament is can be produced. burning at its required bril- liancy; if the tube is "blueing" badly re- Price as shown $19.50 duce the plate voltage, see that the transformer is delivering the juice. Be sure that the antenna is insulated and the The Benwood Removable ground O. K. and last of all -is your tube all right? Don't be discouraged if the set Sparking Point Disc won't work the points are variable from 2 to 16. first five minutes after it Teeth are Renewable as well as Removable. has been assembled. Success is largely a Disc is Six Inches in matter of adjustments, so take your diameter and sparking points are One Inch and time Complete disc weighs less than half in width. you will be amply repaid for your pa- balanced. pound absolutely accurate and finely tience. This disc enables the operator Practically as many tubes may be put in to vary the frequency of the spark at parallel as will re- . gardless of the speed of the motor used. It the builder cares to use, bring - the maximum radiation enables the operator to obtain ing up the output; however, if more than from any spark transmitter by being able to change two Western the spark discharge frequency to conform Electric VT -2 tubes, or their Any Wave to Any Condenser Capacity and equivalent, are to be used, the Length that is in use at the present time. This should inductance increase the transmitting disc will absolutely be wound with No. 14 hare wire range of Any spark transmitter because it is at once spaced with heavy applicable to any make transformer on the market string. This winding is the regardless of the voltage. It should be shellacked, dried, the string re- ultimate in rotary disc moved design and fills the long felt and the winding shellacked again. need The antenna and coupling coils of every radio man. consolidated may be A Clear note can now be had but no gain in efficiency is at all noted, while if they are separated times. As soon as the ted the emit- sparking points of this wave -length may be readily changed disc over quite a range become worn and uneven a without having to dis- complete turb all the connections and adjustments. new set can at once This be put into service thus assur- is quite an item when one particular ing the wave -length is badly crowded operator of maximum jump and you can results at all times. either above or below it by a few The center meters and have clear sailing. of the disc is Once adjustments Moulded Bakelite the best in- have been made all sulation connections should be soldered. obtainable. Disc is may The set fitted with carefully machined be mounted in panel or cabinet form brass or on the table, either of which bushing and set screw easily can be for fastening to the motor done as there are no moving parts. shaft. It is also furnished with shaft for use with any of the enclosed Benwood The Arc and Radio Tele- gaps that are. now in use. . fone Transmission Price complete with 16 sparking points, $10.00 Specify size of motor shaft when ordering. (Continued front page 869) Extra sparking points 20 cents each or $2.50 per set of 16. COMPANY, ance. The 1300 ói;ET>BENWOOD Inc. producing and radiating circuits ST. LOUIS, MO. are thus reduced to a state of homely sim- DEALERS : -WRITE FOR plicity. The tuning INFORMATION of the circuits should l e left to the hot wire ammeter after the necessary constants for the required wave are ascertained. With attention to the D.C. supply, proper attendance to the converter along with the proper tuning of the WIRE MARKET frequency radio R T S circuits, the transmitter may be brot up to the state of maximum NOW IS YOUR OPPORTUNITY TO BUILD radia- We can YOUR NEW SET tion and transmission range. furnish you with the following size s of magnet wire, ne..tly highest grade wire obtainable. spooled. This is the

Size 11i Weight Double Cotton ll mil111.1111,11111.11:11111111nii. No. 20 / lb. 49c AERIAL WIRE. No. 22 / lb. 52c JUST THIN%- NEARLY 2 ft. of pure solid No. 24 / lb. 58c copper No. 14 Aerial wire for lc. (Order Construction of Ball and No. ° 26 y lb. 72c YOURS Now,) No, 28 lb. 92e No. 14 Solid Copper Aerial Cu P Variometers We charge / Wire Per 100 ft. nothing for Spools. When Order- $0.58. No. 14 Solid Copper Aerial Wire per (Continued from page 862) ing include postage. 1,000 ft. $5.50. DID YOU SEND 10c FOR THE R.T.S. CATALOGUE? RADIO TESTING STATION BINGHAMTON, N. Y. from the instrument. This is necessary in order that the flexible lead from the may shaft Add rotate freely. Due to the extremely MONEY to your Salary-Make extra Pin Money. -srp for You Start a lucrative ch tuning made possible Spend an hour each day taking business of your own. with this vario- subscriptions for the "Radio News." We'll pay meter. the large Navy celluloid enjoy the work. Write for full particulars. Circulation you well and you'll dials lend ]few York City. Dept., RADIO NEWS, 236A Fulton St., themselves remarkably well for use with it, they being divided into zoo divisions, as well as having a blank smooth surface

www.americanradiohistory.com Radio News for June, 1!)21 893

Announcing the YÄJou

4111110te At last Vocaloud - Laboratory Type (Shown above) An ideal loud-speaker for $25.00 Complete with 0 ft. cord. $23.00. Hook a Firco Vcca'cud rigLt cn to your receiving apparatus, in place Sound chamber alone, of your phones, and get your signals QSA -all over your house! No $12.00. adjustmer.ts, no extra equipment needed whatever! Just Sound chamber, with batteries,-no base, $15.00.. hook your Vocaloud in and listen! Vocaloud reproducer Vocaloud reproduces wireless telephone perfectly, as well as code. Mr. with 0 ft. cord, the $9.00. P. E. Fansler of Stamford, Conn., received wireless telephone from Station Type, $25.00. S.S. "Gloucester" (ras miles distant) with just one tube! He writes, (Complete as slit wn in "The conversation was entirely intelligible and perfectly modulated. large photo.) The reproduction of the human voice was fully equal to that in a phonograph reproducer." Vocaloud reproduces voice and music just like a high priced phonograph, because the reproducing elements are the same. The reproducer itself employs the famous Baldwin amplifying mechan- ism, with genuine mica diaphragm. The sound chamber is de signe 1 and shaped like a human ear, -the most perfect sound amp:ifier known These exclusive features are not duplicated in any other loud speaker at any price. Yet the price of a complete "station type" Vocaloud, (shown above) in an exquisite solid mahogany cabinet is only $25.00. Examine a Vocaloud at your radio dealer's. If he FIRCO Audion Detectors should lack a supply, write for leaflet direct to and Amplifiers Radio Frequency Amplifiers John Firth 86 Company, Inc., 18 Broadway, New York High Voltage Units (:caf, any Primary xohajic) Baldwin Phones Firco Vocaloud Saco -Clad Transformer Firco Accessories Kolster Decremeter /O United States Bureau of Standards Wavemeter //ECO SAD Eldredge Meters (indirldually calibrated) EQU/PMENT Brownlie Phones ',odiusmbk) Pioneers -since isoi"

www.americanradiohistory.com 894 Radio News for June, 1921

upon which the calls of stations received may be conveniently written. If these dials are used, a special type of fixed pointer fbH11tiMNMNkhtihtihV\ must be employed, as the or- 4`A.e dinary short scratch in the panel filled with white lead will not be accurate, or have a good appearance. As it was not possible to obtain a suitable pointer, the author constructed two in the following manner: A strip of one -sixteenth inch brass sheet was cut into two pieces, one was one and seven -eighths inches long by one -half inch wide, and the other was the same width but one and five- eighths inches long. An inch and one -half length of glass of the same width and thickness as the brass was ground to a point at an angle of about 43 deg. to its length, as illustrated in Fig. 6, A. Two holes were drilled in the two brass strips three- eighths of an inch from the ends of the longer piece, by placing them together so that one pair of ends met. Thru these, two brass screws were inserted upon each of which a nut or other spacer was threaded. All the brass parts should be nickel -plated, and the glass clamped lightly between the top brass strip and its nut. A scratch made with a glass- cutter or piece of carborundum, equi- distant from the sides, was filled with India ink, and this formed a "hair- line" behind which the values upon the dial could be easily read. COMPLETE Set of Four Units in Cabinet, Fig. $189.25. Tubes and Batteries not include d 6, B shows how the parts were assembled. The pointer was then mounted upon the panel, and two more nuts threaded on the screws held it in place. The author has made two of these variometers and has noticed that greater se- ADIOPHONI: lectivity and sharper tuning, as well as 1 REG.U.S.PAT.OFF. greater audibility can be obtained with them than is possible with factory -made variometers where the separation of the coils is "INTERPANEL" SET much greater. The superiority of the re- Provides a complete RADIOPHONE Transmitting and Receiving Set of hand- sults obtained with this type of variometer some design and unequalled efficiency. Will transmit speech 30 miles on the over those possible with the usual type average amateur antenna ; boo -mile range possible under faborable conditions. constructed by experimenters, amply re- Reception possibilities unlimited. One 6 -volt battery required for filaments and pays the little extra difficulty encountered microphone; power supply may be motor- generator unit, rectifier unit or `B" in its construction. batteries.

"INTERPANEL" Sets give expansion without discarding previously purchased 11111111111111111111111111111111111111111111111111,,,,1,111111111111111111,,,,11111111111111,.111, apparatus. They consist of a series of panels, each panel comprising a complete piece of apparatus in itself. Any desired combination of panels may be had. The Radio Compass The equipment is sold completely mounted in cabinets ; with legs for horizontal table mounting; or with legs for upright table mounting without cabinet. This (Continued from page 866) is the most advanced idea in Radio apparatus ; find out more about it. ,11111,111.11111111111111111111111111111111111111111111,11111111111.1111111111311111111.111.111111 11111111111.1111111, Send now for Catalogue "E" giving full Complete Details Mailed Free information and costs on all combinations. up the shore station and request a bear- De Forest ing. Radio Telegraph & Telephone Co. Capable of being used by vessels having Inventors and Manufacturers of High Grade Radio Apparatus only a coil receiving set and amplifiers and no expensive transmitter is necessary on 1415 Sedgwick Avenue - New York City board ship. Sole Distributors for Pacific Coast. Would be more satisfactory to PACIFIC RADIO SUPPLIES naviga- CO., Henry M. Shaw 638 Mission Street, SAN FRANCISCO. tors who could find it analogous to the \44,,N\11\\V1bSMt hN?hkNjÑwNyH4iyNbf- present system of taking visual bearings on lighthouses. Would limit responsibility definitely and exclusively to ship's personnel and obviate fiN/lvitt4\kirk \111 hhbK hlh Ate. s anv future claim that erroneous bearings were furnisht from shore. Has a considerable strategical value in HIGH GRADE scouting. MOTOR GENERATORS The Designed for Radiophone and C. W. of various capacities and voltages following interesting features have been noted in radio compass coil opera- Type "C" Motor Generator 300 volts, 15 watts. Only $40.00. This type is excellent tion: for 5 watt U. V. 202 power tube Send for bulletin describing Short waves are sometimes more effective different types. for radio compass operation than long THE KEHLER RADIO LABORATORIES, Dept. R, ABILENE, Kansas ones. Bearings over very long distances are objectionable owing to the correction for the curvature of the earth that must be VACUUM TUBES REPAIRED applied. This will be eliminated when Cash Must gnomonic charts are used. Relay I RELIABLE I Electron wave (lvoo h ad I Accompp any Order Audiotron SERVICE A traveling along more or less parallel to high bluffs will be subject to con- EASTERN VACUUM TUBE LABORATORIES tinuous reflection and the apparent direction as indicated 178 Washington St. Boston, 9, Mass. by the compass coil will lie to landward of the true direction. A wave passing over a mineral bearing A welcome addition to your library: Send 52.00 today, plus postage for 7 lbs., and your country will of bound volume 1 copy become distorted. No. of Radio Amateur News will come forward by return mail. Experiments indicate Experimenter Publishing Company, Inc. 236a Fulton Street, New York City that the most e- ratic results are experienced when it is

www.americanradiohistory.com Radio News for June, 1921 895

I ' IIIIIIIII(

lL' HR)1111111 N 1111111 I

t. . . , a1I Hill 11111110 écognized Si/oz6ol fJuPerior Pet/bi-/name

Amrad VT Detector $15.00

VT 1 Stage Amplifier EFFICIENCY is the key- B. Bat, Box $21.00 $9.85 note of all Amrad vacuum tube apparatus. Designed by radio engineers of established reputation, it is to be expected that the name AMRAD is recognized as the symbol of efficient operation and rugged construction.

Send for bulletin V. Amrad VT 2 Stage Amplifier Detector -Amplifier Interior $39.50 $34.50 SURPLUS GOVT. MATERIAL have a small supply of aeroplane antenna wire -a residue of WEwar contracts. Constructed of 16 strands of No. 28 wire - braided, it makes a wonderfully flexible, highly conductive antenna wire. We will sell this wire at a price way below its actual value. The supply is limited.

Postage extra. 200 f$ -' $1 00 Shipping weight 3 pounds. Send 10c. for complete catalog. AMERICA/4 RADIO AND RESEARCH CORPORATION 203 College Avenue Medford Hillside, Massachusetts

www.americanradiohistory.com 896 Radio News for June, 1921

daylight at one station and night -at the other. No Time Like the Present Abnormalities increase with increase of to Commence Building That Up-to- Date - -- distances. A high speed alternator is more efficient Receiving Set or Phone and Transmitter for compass work than is either an arc or CW a spark: ,r o` -` " . rt mss.+.+ Federal 1435W jack $1.20 á+' Federal 1438W jack 1.50 When a compass coil indicates a very (New fie. control type.)) broad minimum it will usually be found 1 - Western Electric Special polished nickel plu that the wave front has become inclined e our price I.35 JIMIg from the _I - Federal open jack .70 perpendicular. Federal closed kt. jack .85 Radio compasses are not efficient for - a no 1 Federal double clot. jack 1.00 getting the W. E. 4,A brass ping 1.10 bearings of air craft when Federal 4 -pole, 2 -throw Anticapacity switch 2.80 these are more or less overhead, probably General Radio 231A amplifying transformer, owing to the wave not having become prop- .,R0,a for UV 201 5.00 UV 201 Rad.otron, 45v. plate 6.53 erly lined up. Sorala S10 VT socket 1.10 The higher the frequency the better are LO V Radio Service double socket 2.50 Itl I _! I. p' I , the results within practical rheostat, 6 ohm 1.75 limits...... nu L... e. +. mroaDTO,, ..., ..... Paragon Gen. Radio rheostat, 7 obni 2,50 A loosely coupled COMA., DETECTOR- Anvun[R- MTN'MED BACK -SNOW. OSC Or rI ArcsT ((10P01. .HEKa sharp wave is better on which to take bearings than a close The Most Satisfactory "B" Battery on the Market! The Eveready e coupled broad wave. 44 v. adjustable, $3.75; 22 v. adjustable, $2.00 A synchronous gap is better for compass PLEASE NOTE:-That these prices Include Postage! work than is a non -synchronous one. WE WILL BUILD DETECTOR OR AMPLIFIER. p VOLT-3 PANELS TO YOUR SPECIFICATIONS, BUS WIRED, 3 A modulated wave is not as suitable for or merely ASSEMBLED. t . ins,a -- TYPE 1X compass work as is a non- modulated one. UV200 Radiotron, 22v. plate, $5.00, unequalled as a !09 s A. C. 0.15 detector. For best results use exactly 1 amp. in Radio VOLTMETER The deviations differ for different waves filament. You'll KNOW if you use a TYPE J meter. 5omerwlle Laboratory $8.30 Postpaid and consequently a radio compass is not 1$ -3 meg. 6 step grid leak, variable, 75e.; .0005 and dia. .00025 grid condensers, 25e. < 3s/4" dependable for wave -lengths that are much Bakelite Panels V4" thick, 3c per sq. inch, dozen 12e. different from the one for which it is Snsulated binding posts, $1.25. Black or yellow empire cloth tubing, per in. Ir. calibrated. Anticapacity Contacts, threaded shank and tiny 3/16" The simplest form of compass station nut, 4c or 45c per doz. Gen. Radio switch lever, -_-_ is 1%" radius, 95c. Small switch lever, '/s" radius, that in which an existing radio station 40e. General Radio switch stop, each 5e. is used for control purposes, for the charg- CHELSEA VARIABLE CONDENSERS ing of batteries, and for the accommoda- Panel type, with bakelite dials which run true and Jewelled bearings, magnetic vane movement, quick won't warp. Counter -balanced. No shd .0011 mfd., clamping. The same value as our TYPE J. 1). C. tion of the personnel. The policy is to $4 -75; No. 4bd .0006 mfd., $4.25. meter and bears the same guarantee. Defective build compass stations upon modest lines Chelsea Dial Indicator, 3,4" d'a., $1.00 meters replaced and damaged meters repaired at cost. THOUSANDS BUT NOT ONE at first, with the intention of adding build- SENT FOR BULLETIN NOW IN PnEPARATION FIECSTOM7R! DISSATIS- covering the new $2 SO \MERVILLE DIAL INDICA- ings later, when the station has proved its . TOR, and the new 21/x" BAKELITE &'OB INDI- A TYPE J, JX, or JT meter provides the best pro - worth. CATOR, to match. Our new line of cOT'O T ABORA- tection for your VT and assures maximum operating TORY CONDENSERS ALSO DESCRIBED. efficiency. Present indications point to a very rapid W e s e r n t Electric _ TYPE J D. C. .11illiammeters, 31/4" d. flush, $6; Microphone Trans- development of these stations. It is prob- r°`ÿ' y +, 0 -50, 0 -100, 0 -300, 0 -500, 0 -1500 m. a. ranges mitter No. 323W, Type J D. C. Voltmeters, 3,4" d. flush. 0 -500 v., able that after mariners get more confi- $4.00. With special . $16.00; 0 -1000 v., $24.00; 0 -1500 v., $30 00. dence in nickeled bracket, 50c the system, the entire art of navi- (Above have external resistance boxes. ) extra. Federal Desk gating in thick weather, will become par- type M i e r o p hone Typa J D. C. 0 -13f and 0 -3 Ammeters, $6 tially dependent upon radio Transmitter, w i t h ;' Gen. Radio II. W. Animaters, 774" flush. $7.75 our compass cord, $6.50. Western e -1/, 0 -1/2, o -1, 0 -21/2, 0-5, 0-10 amp. ranges system. Like any other new development, Electric No. 326W ALL RADIOTRON POWER TUBES Is STOCB! the compass be ' heavy current airplane er" Descriptive bulletins free. will subjected to cons'der- type transmitter, with able prejudice from those who always op- trtea B a k e lita BUILT FOR THE RADIOTRON UV202! front and nickeled General Radio No. 231 modulation transformer. pose innovations. It has already proved shell, 5.50. fully moan c,I, the best yet, $5.00. its worth, however. So far as is known No. 323W Variable Air Condenser, specially built to (Descriptive bulletin 907 on request.) no vessels have been lost altho" some withstand 1000 volts continuously, Bakelite insulatisa and heavy aluminum plates, cot out of round, to Ward Leonard 5000 ohm grid leak $2.25 have been saved thru the agency of the give an even calibration. 1/4" shaft, panel type, compass. . .0005 mfd. INTRODUCTORY PRICE, $7.50. Sorala CW Inductance Form. 3%" d $3.00 Any carelessness in operation (Additional capacity may be had by shunting with (6" long, of bakelite, 10 threads to inch ) that results in a vessel being hazarded will the following fixed condensers.) Radio Service CW Inductance $8.50 do much to the is 1800 v. .0005 mfd., mica condenser 5,50 Wound on slotted bakelite form, of No. 9 copp^r destroy confidence that 2000 v. -001 mfd., mica. condenser .90 wire, 3 insulated clips provided. at present being built up. For this reason COMPLETE SET OF NEW BULLETINS SENT FOR 20c. VALUABLE AND TIMELY! it is necessary for all concerned to keep GREATER BOSTON AMATEURS! -If you are in good standing at your radio club, you may abreast of the development of the radio take advantage of our discount to radio organizations. compass, and thus insure its success. Amateurs in the first, second, third, fourth and fifth zones will receive their shipments postpaid. Other zones take a 50 percent allowance on postage charges. A BOOST FOR BETTER RADIO Most everyone now admits that our purchasing manager is gifted at selecting nothing but the best in Audio quality and value in radio apparatus-and just as important, getting it in stock first! You'll say so too Frequency Trans- when you receive your initial order, well packed, with - helpful - bulletins and blueprints exclused, covering the latest developments. ' formers Built from Auto 102 HEATH STREET, Spark Coil Secondary I Somerville Radio Laboratory, WINTER HILL, 45, MASS. (Continued front page 862)

n = (No. turns wire per inch) WIRELESS MANUAL M12 use a table. You should have it even if only super- Containing as it does a fund or valu- wire ficially interested. Around about you every able information not generally contained (.5 x I.5 x 3.1416 x *205) = 12 day you read of some marvelous occur- in a catalogue, it approaches nearer rence in which wireless played a distin- text book in the fascinating field of wire- Note. -The above winding formula is guished It may not be entirely clear less telegraphy. part No expense has been merely given to show the method. Second - to you. The Manual will explain it. To spared to make it accurate and reliable. the student of Wireless Telegraphy, the aries vary so widely that no definite infor Manual contains much that is indispens- No Wireless Experimenter Should able to a proper understanding of the art. be Without the Mecca Wireless mation for procedure of determining the It contains 200 pages, fully illustrating Manual, We ask 25 cents (25e) number of feet required is necessary (205 and describing the many instruments used for it-give you a coupon receipt turns enameled wire No. 4o to the inch). in Radio. 45 pages cover general instruc- which can be applied on any fu- tions, diagrams, station calls, .tables, ture order. Therefore, use this formula: codee and other information. in The book is printed on highly finished Send your name and address now, and Number of feet required primary - paper with a two -color cover and meas- get one of the most complete, comprehen- (4166.66 - - by number of feet in one sive and reliable 4) ures 9 z 5% inches. wireless books published. layer gives the number of layers needed. MANHATTAN ELECTRICAL SUPPLY CO. INC. Wind the primary and mount primary and 17 Park Place 114 S. Wells St. 7106 Pine St. 604 Mission St. secondary upon the core already made, then New York Chicago St. Louis San Francisco lay up the rest of the core. From one of Woolworth's many empo- riums, or from a hardware store, secure Insure your copy reaching you each month. Subscribe to Radio News-$a,00 two shelf brackets as per fotograf, and a year. Experimenter Publishing Co., 236 -A Fulton St., N. Y. C. mount the whole business; not forgetting something to mount.

www.americanradiohistory.com Radio News for June, 1921 not RADIO APPARATUS Distributors of Reliable Radio Apparatus to Schools, Colleges and Experimenters All Over the World !

"PITTSCO" "Remember" The sign of service and When You Say prompt delivery. "Pittsco" You Think

All we ask is a trial ! of Everything in Radio!

CONDENSERS CONDENSERS (Variable) RECEIVING APPARATUS No. 3 Chelsea, .0011 Mfd. unmounted 4.75 No. D -100 250 Watts 10,000 V. .007 31.F 19.00 4.25 AMPLIFYING TRANSFORMERS 14,000 V. .007 ALF 30.00 No. 4 Chelsea, .0000 3Ifd. unmounted Radio new type. just No. D- 101 500 Watts 182 -G Radio .001 Mfd. surmounted 9.75 No. UV -712 Corporation, No. D -102 1000 Watts 21,000 V. .007 3I.F 45.00 No. General ' $7.00 .001 Mfd. unmounted 4.25 out, very efficient No. 1000 21,000 V. .007.3LF 50.00 No. 366 -Int. Murdock No. 231 -A General Rad:o, new type 5.00 D -103 Watts 1000 Watts 21,000 V. .01 3I.F 50.00 ' Na 226 -43, Federal, mounted 7.50 No. D -112 FILAMENT HEATING TRANSFORMERS No. D -113 1000 Watts 25,000 V. .01 3I.F 55.00 Acme 75 Watt, latest type, mounted 12.00 AMPLIFIERS No. T -1 Thordarson oil type, 0013 to .009 automatic fila- Acme 75 Watt, latest type, unmounted 9.00 No. RORK Grebe two step with 31F. capacity 25.00 Acme 150 Watt, latest type. mounted 16.00 ment control 55.00 No. 433 Murdock .0017 51f 3.25 step with auto- Acme 150 Watt, latest type, unmounted 13.00 No. RORD Grebe Det. anil two LINE, PROTECTORS matic filament control 75.00 FILTERS No. Y-2 Acme in cabinet 13.00 No. AM -88S Dubilier 2000 V 4.00 No. 170 Tuska type 16.00 AUDION CONTROL PANELS No. CD -S88 Dubilier 3000 V 6.00 No. RORH Grebe in cabinet, with tickler con- No. 453 3Eurdock, red type 7.50 HIGH VOLTAGE CONDENSERS No. 452 Murdock, condenser type 9.00 nections - 17.00 No. 21AA Western Elec. 1 ALFD. 1000 V 2.50 No. Y -1 Acme in cabinet 10.00 SPARK GAPS No. 181 Dubilier, 0005 MFD. 1000 V 1,00 No. P -1 Paragon, moulded type, small and No. P -1 Bell gap, very efficient 55.00 No. 1S2 Dubilier, .001 .3135'D. 1000 V 1.00 compact 6.00 No. 443 Murdock with motor 4000 RPM 18.50 No. 1S3 Dubilier, .005 MFD. 1000 V 1.00 "B" BATTERIES No. 444 Murdock with larger motor and rotor No. 193 Dubilier, .01 MFD. 1000 V 2.00 1.50 25.00 No. 7623 Standard, 22.5 V. small splendid with 1 KW INDUCTANCES, C. W. 22.5. V. 2.65 4, S, 10 14 No. 7625 Standard. large No. P -1 Bellwood with or point feed 7.50 No. 7650 Standard. 22.5 V. variable 3.50 rotor, practically noiseless 30.00 No. 181 Tuska, Cap. -back circuit 2.25 1.8.50 Nb. 182 Tuska, split filament 10.00 No. 763 Everready, 22.5 V. small No. P -2 Benwood Utility type, just out 12.50 No. 766 Everready. 22.5 V. large 3.50 No. P -3 Benwood Utility rotors, from 2 to No. 183 Tuska Grid tickler No. 760 Everready, new type 22.5 V. variable 3.00 16 points 10.00 KEYS, (Bunnell) CONDENSERS (Fixed mica type) No, P -4 Benwood extra sparking points .20 No. 8650 Mascot, lacquered brass 3.00 No. ROCC Grebe .0002 ME 1.00 No. G -1 Amrad Quench type 1. K. W 41.50 No. 7939 Standard, dull nickel 4.00 IK. W 24.50 No. ROOD Grebe .0005 3IF 1.20 No. G -2 Amrad Quench type r/a METERS No. G -3 Amrad Quench typo r4 K. W 12.00 No. ROCE Grebe .001 MF 1.60 No. 127 General Radio, Hot wire, flush, 1, No. ROOF Grebe .005 MF 3.80 OSCILLATION TRANSFORMERS 2 5, 5, and 10 Amps 7.75 .5 meg. 1.20 No. ROCA Grebe .0002 MF and leak 10.00 Model 301 Weston, D. C. meters, flush, 0, -100, No. ROCA Grebe .0002 31F and 3 meg. leak 1.20 No. T -1 Thordarson, pancake type No. 424 Murdock 5.00 300, 500 and S00 milli -amps 8.50 DIALS No. TEL -100A International, ideal for '/z K. W. 0 -1, 2, 3, 5 and 10 Amperes 8.50 No. 41 Chelsea bakelite dial, (4 ' or 3/16" shaft 1.00 sets 14 95 MICHROPHONE TRANSMITTERS No. -800 -H Clapp Eastham, new type, just F No. L -052 Clapp- Eastham, large type for 1 No. 323 -W Western Electric 3.95 out, bakeli`e finish, 3/10" .75 K. W. sets 17.50 with bracket 4.50 No. T -1 Tuska. 4" din. Bakelite, new type. Na. 323 -W Western Electric, 1.52 ANTENNA WIRE No. 5176 -A Connecticut, with Adj. arm 4.00 just out No. HM -100 De Forest, hand type 6.00 DETECTORS, (Crystal) "Pittsco" No. 14 Hard drawn copper, per lb .50 No. D -101 Deforest, dustproof 2.61 (30 ft. per lb.) MODULATION TRANSFORMERS No. RPDA Grebe, dustproof 2 75 1000 ft. 5.00 Acme A -3 semi -mounted 5.00 No. 8854 Jove 1.80 "Pittsco" 7 strand No. 92 tinned copper, strand- Acme A -3 fully mounted 7.00 .01 231 Radio, new type 5.00 GRID LEAKS ed (65 ft. per lb.) per it- No. General 1000 ft. 8.50 MOTOR GENERATORS No. MW -1 Radio Corporation, (4, 1 1.5, 2, ft .02 "Pittsco" 7 strand No. 20 phos. bronze, per V. A, C. 3 and 5 megohms, complete 1.25 8.50 International 100 Watts, 500 Drive 99.00 Grid leaks only .75 500 ft. International 100 Watts, 500 V. D. C. Drive-110.00 Bases only .50 GROUND EQUIPMENT RESISTANCES REGENERATIVE RECEIVERS "Pittsco" 100 Amp. 600 V. ground switch 4.50 Type HS Ward Le, onard 5,000 ohms 2.25 No. CR -3 Grebe "Relay Special" 175 -680 "Pittsco" No. 4 ground wire. per ft .08 Type HS Ward Leonard 10.000 ohms 3.50 65.00 for meters "PTttsco" Porcelain cleats with screws RHEOSTATS No. CR -3A Grebe 175 -371 meters with tube ground wire. per pair .12 control, complete set 45.50 "Pittsco" ground clamp .25 National Controller type 6.5 amps., easily take 2 5 5.50 No. CR -5 Grebe "Super - special" 150 -3000 UV -202 watt tubes meters. complete set. ideal for jewelers for RADIOPHONE AND C. W. APPARATUS No. 214 -A General Radio 2.5 Amps., easily take time signals 80 00 1 UV -202 1 Watt tube 2,50 No. CJt -6 Grebe 175 -680 meters, Del. and two C. W. POWER TRANSFORMERS VACUUM TUBE SOCKETS step amp. self contained complete set 200 00 Acme 50 Watt 350 Volts. mounted $15.00 No. MW -1 Radio Commotion 1.50 No CR -7 Grebe 500 -20 000 meters "Lon^, Wave Acme 50 Watt 350 Volts, unmounted 12.00 No. 156 Gen. Radio 1.75 Special" complete set. 210.00 Acme 200 Watt 350 -550 Volts. mount(-1 20.00 No. 550 Murdock 1.00 (New England di.ctribu'nrs of Grebe apparatus. Acme 200 Watt 350 -550 Volts, unmounted 15.00 VACUUM TUBES (Radiotrons) Always in stock.) 1000 -1500 Volts. mounted 25.00 Acme 500 Watt No. UV -200 Radiotron detector 5.00 500 Watt 1000 -1500 Volts. unmounted 20 00 TRANSMITTING APPARATUS (Spark) Acme No. UV -201 Radiotron amplifier 6.50 CHOKE COILS No. UV -202 Radiotron 5 Watt transmitting 8.00 TRANSFORMERS (Transmitting) 4 00 No. FV -201 Radiotron 50 Watt transmitting 30.00 vn. P -1 Thordarson 250 Watt Type R $14.00 Acme single coil 150 M. A. capacity coil 500 31. A. capacity 6 00 No. UV -204 Radiotron 250 Watt transmitting I 10.00 Sr.. P -2 Thordarson 500 Watt Type R 22.00 Acme single in stock. anywhere in Type R 40.00 Acme double coil 150 M. A. capacity 6 00 (Radiotrons always Sent Yo. P -3 Thordarson 1000 Watt 8.00 U. S. A., posture and Ins. prepaid.) No. P-4 Thordarson 1000 Watt Type RS 30.00 Acme double coil 500 3f. A. capacity

"Let `PITTSCO' products, super- service and delivery solve your Radio problems" SEND US YOUR ORDERS TODAY ! Send ten cents in stamps for Catalog No. 22. Over 100 pages, over 150 illustrations, over 600 items "PITTSCO" SERVICE REACHES ALL OVER THE WORLD ! WHY NOT LET IT REACH YOU! F. D. PITTS CO., Inc. 12 Park Square Dept. C Boston, Mass., U. S. A.

www.americanradiohistory.com 898 Radio News for June, 1921

A Universal Receiving Ready -CORWIN'S 1921 CATALOGUE Cabinet Thirty -two pages of up- to -the- you can always rely on Corwin (Continued from page 873) minute radio. All Radisco appa- Mail Order Service to ship every ratus. Instruments for every instrument listed in the cata- part of your station logue, Of course the tubes must be purchased. at moderate or in this advertisement, A 'tron is excellent for prices. Tables of codes, the initial detector, abbrevi- quickly, in perfect condition, and . but Marconi V. T.'s are far superior as ations, etc. Much larger, better with an unconditional guaran- amplifiers. If a tubular bulb is used, either illustrated than last year's. And tee of satisfaction. a variable "B battery or a high resistance potentiometer Send us a is necessary to regulate the dime today. We'll mail the voltage. It is catalogue the instant much easier to get the crit- we hear from you. ical plate voltage with the potentiometer, and the cells wear out more uniformly Universal -Coil Mounting Plugs than when a variable switch is used. Anyone cart easily make smooth -running mountings with Nearly all experimenters have several these plugs. No bending, no filing, -they are made to fit old rheostats which they can readily con- exactly in the first place. Suitable for Radisco and all vert into the back mounted type by the ad- hand -wound coils. A few minutes' work with these plugs dition of a shaft, a knob and a pointer. will save you dollars that can be put into better apparatus. Any crystal detector almost may be mounted Price, 80 cents, postpaid on the panel and most "bugs" already have some type. De Forrests and Crystalois are especially adapted for such New Radisco Vario- Coupler work, however. An extremely efficient instrument -accurate to the .002 part of an inch! Materials are special moulded composition, Formica and Brass thruout. IforníCa 32 thread Price, $7.50 postpaid VARIABLE CONDENSERS VACUUM TUBES A. R. Co., .001 $6.25 Electron Relay 6.00 A. R. Co., .0005 5.00 VT Amplifier, 1 lb 7.00 With No. 67 Dial add $1.00. VT Extra Hard 7.60 Murdock 366 4.75 AMPLIFYING TRANSFORMERS Murdock 367 4.75 A. R. Co., 1 lb. 6.00 Murdock 368 3.75 Federal, 1 lb. 7.50 Clapp-Eastham 800 7.50 JACKS AND PLUGS Clapp -Eastham 800A 9.50 Federal Closed Circuit 85 Clapp -Eastham 800B 11.50 Federal Open Circuit .70 Complete with dial. Federal Double Circuit 1.00 Cam Lever Confadf maker 4`brass Shipping weight One Pound Federal Plug 2.00 q hide GRID Postpaid. CONDENSERS Constructional Details of the Small Telefone Radisco, Postage 3 cents .35 ALL RADISCO COILS Switch Used in the Receiving Cabinet. ANTENNA SWITCHES ROTARY SWITCHES Clapp -Eastham, No. 19 1.00 Murdock, 3 lbs. 4.50 Clapp- Eastham, No. 19A The key Clapp- Eastham, 10 lbs 12.50 .85 switch is readily made from the Our Own, No. 1 .40 dimensions and specifications given OSCILLATION TRANSFORMERS Our Own, No .2 .55 in the Postage .05 drawings. The hole in the panel thru Murdock No. 424, 5 lbs 5.00 CORWIN DIALS which its handle protrudes may be faced RADIO CRAFT PRODUCTS No. 66, 3" .76 by the nickel plate used on telefones where Detector 15.00 No. 67, 3" with knob 1.30 the receiver hook extends thru the case. Two Step Amplifier 50.00 No. 68, 3W' 1.00 Altho the binding posts may be Detector and 1 step 45.00 No. 69, 37" with knob 1.70 mounted Detector and 2 step 70.00 Postpaid. on the main panel, the writer found it more Postage paid. RECEIVERS convenient to place them on small formica Murdock No. 55, 2000 ohm 4.50 blocks 2%" x I" inlaid in the "B" BATTERIES Murdock, No. 65, 8000 ohm 5.50 ends of the Radisco No. 1, 2 lbs 1.50 Brandes Superior 7.00 cabinet. There are two pairs, one for Radisco No. 6, 5 lbs 2.65 Baldwin C 16.50 aerial and ground, the other for the fones. Eveready Storage battery prices on Baldwin E, improved 20.00 A large size 45 -volt "B" battery is mounted application. Brownlie, New 12.60 on a shelf in Shipping 2 the cabinet and posts are pro- TUSIA C. W. APPARATUS weight Pounds CONTACT POINTS vided at the rear for wires from a 6 v. 181 Coil, 2 lbs. 7.50 CP -No. 1 Brass, 6o amp. hr. storage battery. 182 2 dozen .25 Coil, lbs. 10.00 CP -4 Brass, dozen 183 Coil, 3 lbs. .86 12.50 CP -6, Nickel Plated, dozen .45 170 Filt., 8 lbs. 16.00 Postpaid. All orders for apparatus not listed as postpaid The Vacuum Tube in must be accompanied by postage charges. Radio Teletony A. (Continued from page 865) ?.m111111111111nn11u111111 111111n11111111111111111. H. 1111m11 1 1 1 1 1 1 1 1 CORWIN & COMPANY u m 1. 11,3n.11111m111m11111111uunuun11111111111111r. Dept. B2 4 West Park Street, Newark, N. J. f. is connected in series with the trans - formee T. The microfone potentials now increase or decrease this fixt e.m.f., and so vary the output. OUR MAIL ORDER SERVICE IS RIGHT In system 2 (c) a valve as a resistance is used to damp the oscillations in the grid We ship same day order is received from our oscillatory circuit or anode oscillatory circuit Fig. 2 large of a arrangement (with M and stock of reliable manufacturers products. T eliminated). The filament and anode of a three -electrode valve are connected across Get your name on our mailing list. the circuit in question and the energy dissipated in this valve depends on its grid PHILADELPHIA SCHOOL potential which affects the conductivity. OF WIRELESS The microfone transformer is connected TELEGRAPHY across grid and filament of the dissipation valve, and thus the 1002 Parkway microfone controls the Building, Broad and Cherry Sts., Philadelphia, Pa. amount of energy wasted. It is easy to arrange that energy is only absorbed during speech ; sometimes, however, energy is always being absorbed, and the amount is READ the CLASSIFIED ADVERTISEMENTS on PAGES varied by the microfone. Obviously, if the energy is absorbed on the imput side of V2, 932 -934. YOU'LL FIND MANY GOOD THINGS THERE. less unnecessary waste will occur than if the energy dissipating valve is connected

www.americanradiohistory.com Radio News for June, 1921 899

There' are Reasons Speaking of rheostats for the popularity of WILCOX Switches Here are three good ones. Type 122 This rheostat mounts on the back of your panel and only one hole is needed to put it there. Re- sistance is 6 ohms, wound on fibre support, and the carrying capacity is 1% amperes. All off and all on positions are provided. A feature of this rheostat is the long threaded brass bushing which This cross section drawing tells the story. fastens it to the panel and forms the bearing. A smoother running See or more perfect working instru- L The large highly polished lathe turned and knurled ment can not be had at any price. knob of genuine hard rubber. Price 00c postpaid. 2. The polished spring brass lever securely pinned to the knob. 3. The large smooth brass bearing threaded onto the main shaft. 4. The turned brass panel bushing that works on panels Type 121B up to one half inch thick, This type of rheostat has the same 5, The famous WILCOX tension spring that maintains resistance unit as the one above, but an even and adjustable tension, and holds the switch it is mounted in a lathe turned alum- securely in place. inum case which protects it from dust and injury and adds much to its appearance. This instrument i= adaptable to either front or back of panel mounting and is so finely mad that it is a pleasure to possess and use one. Price $1.75 postpaid.

Type 121A Type 101 The same as Type 12].B except for A beautiful and efficient the dial. This is the finest rheostat rotary switch for general made. Price $2.50 postpaid. Type 102 use. Furnished in two sizes. I" radius Brass fin- Exposed metal parts are nickle plated A compound switch consist- ish, 40c; Nickle finish, 50e. on all these ing of two electrically in- Iy" radius Brass finish, rheostats unless other- dependent switches mounted 50e; Nickle finish, 60c. wise ordered. Resistance units with Type 103 with concentric knobs. 11/4" a carrying capacity of 3 am- A rotary panel switch outside radius. Brass finish, peres and a resistance of which is double pole $1.10; Nickle finish, $1.25. 3 ohms may be had and double throw. Will if preferred. change endeble condenser from series to parallel, etc. I Ve" ra- dies, Brass finish 75c; Nickle finish, 85c.

In One It's easy The best and cheapest socket to build your own variometers and regenerative sets with WILCOX parts and you'll save a heap of money too. YOUR LOCAL DEALER probably carries WILCOX products in stock, IF NOT Order by mail from us and your order will be shipped POSTPAID Our new catalog is being mailed to our old customers. Others should send 5c for it. THE WILCOX LABORATORIES Lansing Michigan WILCOX ingenuity has made this possible. Of course we have had to depart from the conventional pattern but by so doing we have designed a socket that combines the advantages of all, the disadvantages of none and a price lower than any. Just think what this means and look over the pointers named below. Type 5A Variometer Parts STANDARD STRONG SAPS- Complete parts for 5AP1-Wooden parts, in- all as illustrated..$4.25 Fits standard four The construction and the ma- variometer SÁludingariomet inding form 2.00 prong bulbs including the used in this socket are new transmitting tubes. terials SAPS- Complete parts less assembled with Glial 6.50 such that a surprisingly rigid dial 3 00 without dial 5.25 PERFECT INSULATION assembly is secured. The insulation used on ALL PRICES POSTPAID, auction sockets is of the PERFECT CONTACT highest importance. We have Plainly marked binding posts lltateuetivtt5 chosen Bakelite -dilecto, which, make connections easy and Type 1C though more expensive is bet- long spring brass blades make ter than the composition or firm connection to bulb. Variocoupler Parts fibre frequently used. HEAT EASILY MOUNTED 1CP1- Contains all parts WILL STAND $5.00 11I a n y bulbs, particularly This socket may be net up- as illustrated transmitters, develop con- right on a base or easily at- siderable heat while in op- tached to a panel. 1CP2- Contains all parts has wound and assembled eration and much trouble NO METAL SHELL been caused by its softening ready to mount on effect on the insulation of The absence of a metal shell your panel '7.00 some sockets. Wilcox sockets eliminates possibility of noises will stand this heat. from this source. 1C1- Wooden variocoupler rotor only 1.00 Price 75e Postpaid

www.americanradiohistory.com 900 Radio News for June, 1921

across the output circuit. Various arrangements for dissipating energy have been suggested, and will now be discust. ABSORPTION METHOD. It was originally suggested that a gas two- electrode valve could be connected across the aerial circuit of a continuous - wave transmitter, and the leakage thru it controlled by a microfone which produced a transverse magnetic field. The advent of the three-electrode valve made it possible to use this device to absorb energy. Fig. 4 shows a fundamental circuit. A generator A produces continuous oscillations in the antenna ; consequently, there will be a high e.m.f. across L1. During those half - cycles which make the anode P positive. energy is diverted thru the valve, and will dissipate itself on the anode. The amount of energy dissipated depends on the conductivity of the valve P, which in turn depends on the potential of the grid G. By connecting a microfone transformer as shown, the aerial output is controlled by the speech. The valve may be arranged '-o that energy is only absorbed when speaking into M, or as is more usual, the valve may be adjusted (by giving G a suitable SOMETHING potential) to absorb about half the output. CONCISE: A resistance is frequently Concentrated essence of efficiency, the new RADIO SHOP type RS 1 -24 receiver. The latest appli- included in the cation of regenerative tuning to a range spanning every wavelength used in radio communication thrcugb- anode circuit. This improves articulation out the World. and dissipates energy. At first the valve Haven't you ever tired of the "QRM" on amateur wave -length= and wished fcr a receiver that woui.l dissipates most of the energy, but as the bring in the commercial ships and long wave damped and undamped stations, without the trouble of changing wires and plugging in and out of numerous coils? valve passes more current the resistance be- This is it! 100 to 24,000 meters, without a "dead spot," all in one cabinet! \" ariometer tuning ap- gins to dissipate most cf the energy. To plied to the entire scale with the resultant ease cf control of regeneration .. and oscillation. Circuits prevent] the anode potentials affecting G so synchronized that troublesome "combinations" of tuning are entirely eliminated, making definite electrostatically, r. variable inductance adjustments and reliable reception an assured thing, and the RS 1 -24 the ideal receiver for all wave- in lengths, with absolutely no sacrifice cf efficiency cn any particular wavelength. A "stand -bi" arrange- series with a condenser may be connected ment is also incorporated that will broaden tuning, when so desired, for general "listening in" work. directly across G and F. The very popular RADIO SHOP short wave receiver construction applied to wavelengths below 1,000 meters assures maximum selectivity and efficiency fcr amateur and short wave commercial spark and Such an arrangement only modulates the C.W. reception. Wavelengths from 1,000 to 24,000 meters are taken care of by on entirely new appli- positive half cycles. The maximum modu- cation of the variometer principle which has already been employed in the RADIO SHOP long wave lation is receiver, described in previous advertisments. The result: -SATISFACTION. effected when the other half cycles A few mechanical features that will appeal to the most exccting:- P.anked windings. Dials that run are also affected. A second valve may be true. Heavy bus -bar wiring. Non-shorting variable condensers. Gr-ined, engraved, Formica panel. arranged across L, so as to conduct. Interior as well as The exterior workmanship of the highest possible order. NO SEALS. We ore as filament may be connected to proud of our interior as of the outward appeararice and want the purchaser to know just as much P and the about the apparatus as we do. anode to F. The secondary of another The ."RS 1 -24" carries the sane "money back if not satisfied" guarantee that applies to. all RADIO microfone transformer is connected across SHOP products. So far we have never had to live up to this guarantee, an enviable record to say grid and filament of the second the least. valve. The "THE SET THAT YOU WILL EVENTUALLY BUY" primaries of the two transformers are op- Licensed under Armstrong's Regenerative Patent and applying this unapproachable circuit to its erated by the same microfone. Whichever maximum effectiveness. valve is operative, the output is modulated. THE RADIO SHOP type RS 1 -24 Receiver is the most efficient and effective radio tuning device ever built. Instead of connecting the valve across the whole of L1, two valves Price, F O. B. San Jose $700.00 may be used with In ordering please specify whether Oak or Mahogany cabinet is desired. filaments connected together and grids con- DEALERS: We have an interesting proposition to offer you. Write us. nected together. One anode is connected to one end of L, and the other anode to the other end. A middle tapping from L, is THE RADIO SHOP San Jose, California taken to the filaments. The potential of the grids is varied by the usual microfone Variometers, $5.75 Vario- couplers, $4.75 trans- A few still are left former. The oscillatory current L, makes the anodes alternatively positive and negative. Thus both half -cycles are absorbed but only half the e.m.f. across L, is utilized. Special double anode valves may be used in place of the two valves (e.g., those described by the author in British Patent 146,708). Frequently the absorbing valve REMLER No. 93 A BATTERY or valves are connected across an oscilla- - tory circuit coupled to L,. The H.F. generator need not be in the position shown, it POTENTIOMETER sufficing that oscillations are produced in Increases detector sen sitivenes I., whatever the means employed. Another absorption arrangement consists and signal audibility. in connecting a three- electrode absorbing plate voltage of any detector tube must be care- valve across the grid oscillating circuit of a fully adjusted for maximum sensitiveness and signal Pat. Applied For. "audibility. Potentiometer control provides close ad- valve generator. The energy absorbed. justment with ease of operation. This new Reuter which is small, produces large alterations in Un(t with metal inserts provides positive definite electrical No. 93- Remler A-Battery Potentiometer contact and eliminates the uncertainty of carbon to the output. A resistance is usually connect- Unit only, with studs for .75c graphite contact. This Homier Unit is not brittle and ed in the anode circuit panel mounting a7 is connected across the A- Battery to control the plate of the modulator potential over a six volt range by half -volt steps. Cir- valve. This improves articulation. No. 94-Remler Rotary Lever Switch cuit diagram furnished with each unit. The for use with No. 93.45c microfone transformer is, as usual, con- Unit J "Apparatus that Radiates Quality." nected across grid and filament of the modulator -tube. It is to be noted that absorp- REMLER RADIO MFG. COMPANY tion schemes cause a loss of,power and also E. T. ClINNINGHAM, Sales Mgr. cause a variation in the wave -length emitted 163 Sutter Street San Francisco since the frequency of an oscillatory circuit is dependent on the resistance, if any, across it. In high -power absorption arrangements, modulating u-olvec are connected in parallel.

www.americanradiohistory.com Radio News for June, 19Z1 901 ', "The Greatest Radio Catalog In the World The Universal Ver dict of Tens of Thousands of Radio Amateurs Mail 12 cents DUCK'S No. 15 BIG 225 PAGE in stamps or coin (not sent otherwise) for the greatest Radio Catalog published. WIRELESS CATALOG. JUST OUT A Veritable Treasure House of Everything Worth While and Dependable in Radio. The largest, most comprehensive, artistic and educational wireless catalog published. The Beacon Light to guide you right in the selection of your radio purchases, and at prices that will command your attention. Every instrument guaranteed with privilege of return if not satisfied. For 12 Years the Name "DUCK" has had a meaning all its own to radio amateurs. Next month we shall reproduce a number of late testimonials out of thousands pouring in upon us, which will tell you why the overwhelming ANYTH I N majority- of radio amateurs buy from "Duck." Ever since the year 5909 Duck's catalog has always occupied the foremost ELECTRICAL rank among radio amateurs; in each succeeding year, with the constant development of radio this catalog blazed the way with most everything new and dependable listed between the covers of all other catalogs. It has truly been Sell only Goods of Recognized Quality' a "BEACON LIGHT" to the novice and the expert in radio. In keeping and Merit and at Prices that: with the size and completeness of this catalog there has always been a stock - will Save You Money of radio instruments in our place many times larger than that of any other radio house; in fact we believe several times larger than the next largest. Our many years in this business and the immensity of our stocks is con- -established and Oir/O,II.S.A. clusive proof that you are dealing with a big, well dependable concern. CCI ..,,B, YYN.B out., . SERVICE Substantial Reductions on many Radio Instru -j Among many other things, has made our business tremendous, and except for a lim- in Catalog No. 15 ited time after the war, when without actively inviting the business we were ments that appear and The prices of DeForest Honeycomb Coils and ail literally snowed under with orders, our service has always been our pride DeForeat instruments as set forth in catalog No. 15 of radio SERVICE most abused word in advertising have since been reduced to the previous DeForrsn the delight amateurs. -the list which appears in the first edition of our catalog and the hardest and most complex thing to give to radio experimenters. We do No. 14. immediately, but No. 1140 Receiving Set $22.50 not tell you that we can always ship every item in our catalog No. R41 Receiving Set 38.50 our records for some time past prove that we are giving our pre -war service and No. R41a Receiving Set 28.50 THORDARSON TRANSFORMERS. shipping 98% of all orders complete within twenty -four hours after receipt. 1 K.W. Type R 40.00 % K.W. Type R 28 00 % K.W. Type R 22.00 Detector 00 New Short Wave Regenerative Set with 1 K.W. Type RS 30 .1 wonderful % K.W. Type RS 20.00 Listen in to the Radio Concerts with this receiver. K.W. Type RS 15 'n h 25.00 For damped and undamped stations from No. A1792 Thordarson Condenser 150 to 600 meters. Variometer and Nos. 50, 51, 52 Switch Contacts. each .03 vario coupler construction. Variometer No. 1023 Mica. Condenser .60 coupling extremely close giving maxi- No. B670 Detector 2.75 mum inductance. Vario- coupler primary No. A862 Detector 2.75 provided with single and multiple tap No. A1915 Detector 1.50 . switches giving extreme selectivity. Wir- No. .9.367 Murdoch Condenser 4.50 No, Along Receiving Set 975 ing bus bar type insulated with oiled No. A1916 Condenser 1.65 cambric tubing. Brushed Bakelite panel. No. R1xORA Tuning Coil 2.9 Beautifully finished mahogany cabinet. No. 61x10 Tuning Coil 4.95 Tested before shipment in Toledo for No. 14 Aluminum Wire, per lb .90 Binding Posts reduced 33 1 -3 %n radio music from Pittsburgh and Wash- All ington. Absolute certainty of getting Only a few of the many New Instruments what you buy. The maximum range ob- in Catalog No. 15 tained from any type of transmitting station, damped or undamped, using up to 600 meters We unqualifiedly guarantee that there is nothing like Type C -300 Cunningham Bulb 5 00 it on the market fore price. Type C -301 Cunningham Bulb 6.50 No. A204 New Short Wave Regenerative Set with Detector and "B" Battery $65.00 UV -200 Radiotron Bulb 5.0n Cunningham or Radiotron Detecor Bulb, extra 5.00 11V -201 Radiotron Bulb 6.50 No. A210 Short Wave Regenerative Receiver only (style, construction and appearance A Complete Line of New Detector, Regenerative same as No. A204, but without detector) 50.00 and Amplifying Sets. Connecticut Variable Condenser 6.50 'Putney Spider -Web Unit 6.00 Audion Control No. 550 Murdock Socket 1.00 An excellent No. 3660 Murdock Condenser 4.00 Panel for use with new four - No. 3661 Murdock Condenser 4.25 prong bulbs. Grid leak and grid No. 0062 Murdock Condenser 5.00 condenser are mounted on rear No. 3000 Murdock Condenser 3.25 of New type panel rheo- No. 0001 Murdock Condenser 5.50 panel. No. 0002 Murdock Condenser 4.25 etat mounted on center of panel. No. 3064 Murdock Dial Assembly 1.25 The formica panel is attached to MC -1 DeForest Set 40.00 a wood base, upon which is MC'-2 DeForest Set 59.00 mounted the tube receptacle. MR -1 DeForest Set 65.50 MR -2 DeForest Set 85.50 "B" Battery control permitting MR -3 DeForest get 105'.00 of four regulations of "B" Bat- MS -2 DeForest Set 209.00 Note: The above DeForest Sets are just out and tery. Voltage from 18 volts to constitute panel detectors. amplifiers. regenerative 22% volts in steps of % volts. receivers and complete radio telephone transmitting A fine adjustment of "B" Bat- above mentioned and reeiving sets. The various sets tery is necessary for the best re- comprise the various units in cabinets. These units may be bought separately and later added to. sults. Midget Radiophone No. MS -2 comprises a complete No. A200 A200 Panel Detector Set, less batteries and bulb..S7.50 with a thirty -five mile speaking range. regenerative re- No. ceiver; also receiver for wave lengths of 25,000 meters, "n. A201 Cabinet Detector Set, with batteries less bulb ..15.00 and a detector and two -stage amplifier each in sepa- No. A202 Cabinet Detector or Amplifier Set, with Bat- rate units but all mounted in a mahogany cabinet. teries less Bulb $22,00 Type OT -3 Midget Radiophone . consisting of antenna circuit panel and power tube, panel.....$95.00 Microphone. extra a of Power Tubes. extra 26.50 Send 12 Cents for copy Magnavox Radiophone Wand Transmitter 22.50 Magnavox Radiophone Transmitter Tone Arm Our Big Catalog Today MagTRVnx Loud Speaker 37.50 THE WILLIAM B. DUCK CO., 231 -233 Superior St., Toledo, Ohio

www.americanradiohistory.com 902 Radio News for June, 1921

not in the usual manner, but in such a way that the valves become progressively con- TEIG. ductive. This is done by BACK BAY grading the negative potentials on the grids. By this ar- Sq 64 rangement the energy dissipated is roughly proportional to the square of the number of valves used. THE TRIODE AS A VARIABLE CONDUCTOR OZ OF CONTINUOUS OSCILLATIONS. 899 BOYLSTON ST. Another form of modulation consists in using a triode as MASS. MAD a conductor of continuous BOSTON, oscillations and varying its conductivity by means of microfonic potentials on its grid. Fig. 5 shows a typical arrangement. The source A of oscillations is connected in series with the inductance L, and the tube V. Oscillations will only be set up in L, when V conducts. If the grid of V is sufficiently negative no current will pass thru V. It RESti ITS will be seen that'the current thru L will be proportional to the microfonic potentials If you are interested in studying Commercial Radio, the RE- applied to the grid. As the single V will SULTS accomplished by The Eastern Radio Institute should merit only pass half -oscillations (unless a your immediate enrollment. steady positive anode potential is applied), two valves are sometimes employed so as to conduct both half - FOR INSTANCE: cycles of oscillating currents. It would appear that the resistance of the conducting The Eastern Radio Institute was founded in 1913 and is valve or valves is too great for effiicent re- now over six years older than any other Radio and Telegraph sults. These circuits may be arranged so School in New England-We are established! as only to radiate when speaking. It has been proposed also to apply high -frequency The Eastern Radio Institute moreover potentials to the grids of two conducting has given instruc- tubes. These tion at this date to over 4,000 different students, en- potentials may be obtained and has from the main source of energy, and are rolled, graduated and placed more Commercial operators than arranged in phase with the anode potentials. all other schools in New England combined ! We have accomplished things ! Graduates of The Eastern Radio Institute have actually secured go per cent, 89.9 per cent, 89.8 per cent etc., out of a possible go per cent in their Commercial operators first grade examination. We know how to give the student proper training! Successful graduates of the Eastern Radio Institute are found in responsible radio positions all over the world. Why not be one ! It costs no more! Fig. In This Circuit the Source of High Frequency Our latest, illustrated prospectus is free. If you cannot Current A May Be a V.T. Oscillator Coupled visit the Institute send for one. Remember our organization to the Grid Circuit. with over eight years of continued Results and Success is behind every student who enrolls. Send in your Thus when the anode of one of the triodes enrollment is positive the grid is likewise positive. The today! circuit which passes on these high -fre- F. D. Pitts, quency potentials contains a microfone Director. which when spoken into, controls their magnitude and so the conductivity of the tri- ods. This arrangement appears to be difficult to regulate in view of the phase adjustment necessary. All circuits employing a valve as a conductor may be arranged on a small scale and the result magnified by a power amplifier tube coupled to the an- BEGINNERS ! tenna. To obtain a good system of modulation is the first desiratum. It is usu- It is sad but true that the average beginner gets ally desirable to give the grid of the am- stuck with a single slide tuner and other junk which plifier tube a negative potential so that the he is told is the best thing to learn anode current is normally zero, and only on. Soon he will increases when the modulator want some real apparatus $20 circuits in- and worth of useless duce modulated oscillation into the grid cir- apparatus is discarded. cuit of the amplifier. The circuit of Fig. 5 may be modified by replacing A by a three - After much research we have developed an ideal electrode set consisting of Variometer, Phones, valve, its anode connected to F. Detector, Con- High- frequency potentials are applied to the denser, Aerial, and Ground all for $15. This set may grid of this valve. be added to according to our expansion plan in easy CHOKE CONTROL. steps until it becomes a short wave regenerative and The commonest modulation system de- a long wave honeycomb set. And NOTHING will pends for its action on the fact that the be discarded. output of an oscillating triode is directly We take personal interest in each cus- proportionate tomer. Catalog and complete information, 5c. to its anode potential. This fact was utilized in several of the earliest THIS MONTH'S SPECIAL. Grid condenser and leak free radio telefone sets, as far back as 1914. with each RADIOTRON UV200, at $5. Postage extra. One arrangement provides for a microfone transformer whose secondary is included in A. K. LAING, RADIO SUPPLIES, Pelham Manor, N. Y. the anode circuit of a tube fitted with the 4111111 usual oscillation circuits. The anode po-

www.americanradiohistory.com Radio News for June, 1921 903 NOW IS THE TIME TO MAKE BIG MONEY LEARN WIRELESS Know a Dignified In Shortest Time Uncrowded Profession AT HOME At Lowest Cost The Demand for Good WirelessOperators Far Exceeds the Supply The New York Wireless Institute- America's foremost fastest growing Wireless Institute gives you the best instruments, theory, text books and diagrams available. We will MAKE YCU AN EXPERT WIRELESS OPERA- TOR AT HOME, qualifying you for first grade license, in your spare time, easily, thoroughly, in shortest possible time and at lowest cost. No previous training is necessary. Our Home Study Course is prepared by Mr. L. R. Krumm, formerly Chief Radio Inspector, Bureau Navigation, New York, now in position of greater responsibility with one of the largest Commercial Radio Corporations in the United States. Our 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 free will make it as easy for you to learn the Code as it was to learn to talk. All you will have to do is to listen. TRAVEL THE WORLD OVER BIG SALARIES A Wireless Operator can visit all parts of the world at the same time. from $125 to $200 and receive fine pay and maintenance Wireless operators receive salaries a position without travel? There a month and it is only a stepping stone to better posi- Do you prefer steady will be many opportunities for you at the numerous tions. There is practically no limit to your earning Commercial Wireless or with power. Men who but yesterday were Wireless Opera- land stations or with the tors are now holding positions as Radio Engineers, the Steamship Companies. Radio Inspectors, Radio Salesmen at salaries up to The New Intercity Wireless Company will need $5,000 a year. hundreds of new operators 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., needed. The wonderful Receiving and Sending Set, Text Books, etc., all become your property upon completing the course.

of the U. S. Government and The transmitter pictured is the celebrated Omnigraph, used by several Departments Colleges, Wireless and Technical Schools throughout the United States and Canada. by the leading Universities, and this remarkable invention have learned telegraphy with the Omnigraph. Place the phone to your ear Thousands as though you were receiving them thru the will send you wireless messages, thousands of different ones, the same hundreds of miles away. air from a wireless station with the Omnigraph -the same model Omnigraph as we furnish When you apply for your license the United States Government will test you to our students. Ask any United States Radio Inspector to verify this. FREE POST GRADUATE COURSE WIRELESS TELEPHONY COURSE FREE A month's Post- Graduate Course, if you so desire, at We have incorporated in our Institute an up to -date and one of the largest Wireless Schools in N. Y. City -the Complete Course in Wireless Telephony, written by our Wonder City -the largest port in the World and Head- Chief Instructor, Mr. L. R. Krumm. quarters of every leading Wireless and Steamship Com- This Course is included FREE pany.

Medina. N. Y., Sea Cliff, 7a L, Endorsed by United States Government November 28, 1920. December 6, 1920. any Wire- Dear Sirs: Dear Sirs: - by allowing our gradutes highest credit given I have found the Theory Course, the Received your letter of Decem- School in first grade license ex- Omnigraph Set and Text Books most ber 1, and was very pleased to less Correspondence satisfactory, I think your Wire- learn of the lessons in Wireless aminations. less Course is the best and easiest to Telephony to be given to the stu- learn for St's interesting from the be- dents of your school. It shows ginning to end, and the way the Ques- you do not overlook any phase in U. S. SHIPPING BOARD will testify tions are written gets you interested at order to furnish the students once. Yours Truly, with "up to date dope in the of our instruction. (Signed) S. B. Radio line". And I am sure it to the value will be as explicit as your Theory I=1 NM course of Wireless Telegraphy. r ME M - I and - course is as thorough - The - -- -- Conn., Milford, explicit as one could ask for and Oct. 25, 1920. I wouldn't hesitate a moment in ' NEW YORK WIRELESS INSTITUTE New York Wireless Institute, recommending it to any of my New York City. York City Dear Sirs: Radio friends. 1 Dept. 204, 258 Broadway New - and am very Respectfully yours, I received your letter (Signed) C. D. 5f Send me, free of charge, your booklet "How to Become glad to tell you that I containing full particu- satisfied with your course. a It sure is an 1 an Expert Wireless Operator," easy way to learn. lars of your Course, including your FREE INSTRU- Thanking you for your kind attention, (Names and address gladly MENT OFFER. I am, Sineerely yours, furnished on application.) t (Signed) J. A. A., Sr. SEND FOR FREE BOOKLET Name booklet "How Without obligating you in any way, send for our ' Address Become an Expert Wireless Operator"-it is free. Mail the to do today. coupon opposite or postal or letter-but it 1 City or Town Dept. 204 258 Broadway NEW YORK WIRELESSINSTITUTE 7 New York City State

www.americanradiohistory.com 904 Radio News for June; 1921

tential is provided by the microfone transformer and is thus zero when not speaking. The system consequently only radiates when ink Every Wo the microfone is affected. The arrangement is made more successful when a small steady anode potential, sufficient to maintain weak oscillations, is employed. A more usual tho not "quiescent" system provides for a high steady e.m.f. in the anode circuit. The microfone potentials vary this potential THAT'S the universal ex- above and below its normal value and thus perience of wireless opera- modulate the H.F. output to the antenna. tors who use the Brandes Head- The microfone potentials are invariably magnified by one or more valves to give in- sets. The two phones are per- creased power. The output circuit of the fectly matched in tone; they microfone potential amplifier trequently consists of an iron -core choke coil, which deliver signals so faint that is included in the anode circuit of the gen- other receivers fail to get them. erating power valve. The modulator tube derives its anode current from the same Stress of weather and other course as the power valve and is of the conditions of interference are same dimensions as the latter. The modulator when operative is capable of varying overcome in a wonderful way the H.F. output between nearly zero and by these supremely sensitive twice the normal output. The modulator thus contributes to the output by producing and mechanically perfect in- potential surges in the impedance. A typical struments. circuit employing this "choke control" is shown in Fig. 6. The tube Vi is the gen- Send 5c for Catalog G. erator and V, the modulator; Z is the DEALERS choke -coil. In this, as in all other circuits, -Write for a buzzer may replace the microfone if Special Proposition "tonic- train" effects are desired. A recent arrangement proposes to use the microfone C. Brandes, Inc. not merely as a modulator, but as a primary Dept. 23 source of current. The alternating currents are rectified by a 32 Union Square, New York City valve, the resultant direct current being fed to the power oscillator. Abstracted from London `Electrician."

1 1, 1 1 1, 1, ,,,,,,,,,,,,,,,,,,, 1,,,, 1,,,,,,,, .,,,,,,,,,,, 1,,, 1 11 1 1,,,,,,,,,,,,,,,,,,,,.,,,,,,,,,,,,,,, c Junior Constructor (Continued fronti page 881) 1,,,,/,,,,,1,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,11111111111,11,,,,,,,,,,,,,,,1,,,,M,, ,,,,,,,,,,,,,,,,,,,,,,,,,,,,, silver wire. Fill the tube with the prepared solution, and push the corks in tightly so that the inner ends of the wire project about ?4 inch into the liquid. It is "ILLINOIS" THE RELIABLE well, if it leaks, to seal it tightly with some sealing wax. The solution is colorless now, MADE RIGHT - but on current being applied to the wires, STAYS RIGHT a pink coloration begins to form around the wire connected to the negative source Three Styles : No. 1, of supply, but on shaking the tube this will Panel ; No. 2, Open Type disappear. as shown ; No. 3, Fully Fill a glass with a salt water solution as Encased. Anti Profiteer. in Fig. 3 and place the two wires from. Less than pre -war prices. the opposite poles in the solution. A dis- Fully assembled and tested. charge of bubbles will rise from the negative wire. Style No. r No. 2 No. 3 If the "Bug" hasn't any of the materials 67 Plates, $7.00 $8.00 $. =o to snake any of the foregoing polarity in- 43 " 3.50 4.50 4.75 dicators, he may empty a little of the elec- 23 " 2.75 3.75 4.00 trolytic from his storage battery into a 2.25 3.25 .3.50 glass, and place the wires in it, taking care Money back if not satis- to keep them well apart. Bubbles will rise fied. Just return condenser from both wires, but a great many more within to days by insured will arise from the negative side than the Parcel Post. positive. This test is always dependable. 1 STYLE 1 No. STYLE No. 2 With Style No. I. we W,,,,,,,,,,,,,,,,,,,,,,,, 1,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 1,,,, 1,,, 1,,,,,,,,,,,,,1 1 1 1 1 1 1. 1,M1 1, 1 1 1, 1 1 1 1 1 1 1 1 1 1 1 11 will. if desired, furnish 3 inch Metal Dial with large Knob, instead of Scale and L Want to Know Pointer. Extra Price 75 cents. Or we will, if desired, (Continued from page 884) supply the Condenser with smooth 3 -r6 inch center staff, without Scale. Knob and Pointer, at 15 cents off the list to those who prefer to supply their own dial. A " apart, 21 movable plates 3" diameter, Vernier with single movable plate applied to 13, 23 A" apart? Also, or 43 plate condenser, $3.0o extra. what is the capacity of an it-plate condenser, of the same size? We allow no discounts except 5 percent on orders A. r. The 43 -plate condenser has a ca- of 6 or more. pacity of about .00r mf., while the it-plate Sent Prepaid on Receipt of Price condenser's capacity is only about .0oot6 mf.

Except : Pacific States. Alaska. Hawaii, Philippines and Canal Zone, add IOC. Canada add 25c. AMPLIFIER WITH CRYSTAL DE- Foreign TECTOR. Orders other than Canada not solicited. (221) VERNIER Robert G. Middleton, of Hay- G. F.JOHNSON, 625 Black Ave.; Springfield,. Illinois. ward, Cal., wants to know: Q. r. How and where may I obtain a license for sending?

www.americanradiohistory.com Radio News for June, 1921 905

A. r. To obtain a license, you should apply to the Radio Inspector of the Sixth District Customs House, San Francisco, Cal. Q. 2. Can an amplifier be used in connection with a crystal detector? Standardized A. 2. Yes. In this case the primary of the amplifying transformer is connected in place of the fones in the receiving circuit. Q. 3. For receiving, is it best to use a single wire or a four -wire aerial, inverted UNIT .Cabinets. L type? A. 3. The same results may be obtained EACH ABC Unit is complete in itself for its particular purpose. Yet the series with both aerials, provided the same length is so designee that any combination of units works as if it were a single set. of wire is used in both. The photograph below shows three of the units -the Receiving set, the VT De- tector, and the Two -step Amplifier-hooked up together into an efficient, smooth - working combination. LOOP AERIAL. (222) A. F. Wendt, of Tripoli, Iowa, requests the following information: Q. r. In making a loop, could I wind more than one laver of wire, separating them by I ", on a 4' loop? A. i. It would be better to wind your loop with one layer only of insulated wire, putting the turns close together. Q. 2. How long should the wire be to receive up to 25,000 meters wave -length? A. 2. To tune up to 25,000 meters, about 200 turns should be wound on the loop and external inductances used, the whole circuit A Receiving Set or Radio Re- VT Detector. Simply hook Two -Step Amplifier. Adds being shunted by a variable condenser. ceiver. Complete in itself. up this detector to your ABC two stages of radio amplifi- dead end switch could be used to advan- Equipped with selected ga- receiving unit, disconnect the cation to any previous com tage to cut out the unused parts of the loop. lena crystal detector, and crystal detector, and the set bination of units, making a three ABC Inductance Coils. is ready for operation. Price smooth- working, long range Price, $24.50. (less tube), $16.5o. set. Price (less tubes). $45. UNDAMPT WAVE CIRCUIT. (223) William Old, of Norfolk, Va., sends the following request: Receive code and wireless telephone Q. i. Please give in the "I- Want -To- Know" Department the best hook -up for both -at a small initial investment! undampt wave reception using three honey- ABC Units solve the problem of starting off with a small investment, and grad- comb coils. ually increasing your range without discarding a nickel's worth of apparatus as A. 1. This hook -up was publisht on page you go along. 462 of January RADIO NEWS. Start with the receiving unit (complete in itself). Then you can gradually build up your station to include a VT Detector and three stages of radio amplification. Yet, every new combination of units, as you go along is guaranteed to give satis- A. C. FOR V. T. FILAMENT. factory, dependable performance. you a commercial (224) L. London, of Philadelphia, Pa., Finally, when you have secured the complete system, have grade station- equipped to receive all classes of signals ; damped or undamped, wants to know: code or radio phone, on all known wave -lengths. Q. r. Can I use a three -way bell trans-

former instead of an "A" battery on a 1 paragon detector unit? A. 1. Yes, a bell transformer could be The combination shown here is the receiving usait used as supply for the filament of a V. T., (described above), and provided the secondary winding delivering the combined VT Detec- six volts is used with the circuit shown on tor and one -step ampli- page 447 of the January, 1921. issue of fier. Further amplification can be secured by adding RADIO NEWS. a one or two -step amplifier at any time. Price of the combined Detector and one -step (less tubes), I An Efficient Loading Coil $37.50. and No Dead End Switch

(Continued front page 872) ABC Units are standardized in design, and 2nd.Every part. even the least important produced by automatic, machine methods, binding post is standardized, sad down to the smallest switch point. made by unvarying, automatic machines. You can always buy replacement parts that are In addition to the progressive, "building up" identical with the original. feature, this standardization offers three dis- good and much easier to work. The di- tinct advantages: 3rd.Standardized quantity production in mensions are not important, but a good the ABC factory, (the only one of 1St.You can invest in a receiving unit, its kind in the world). has brought about size is 33/2" x 3/" x / ". First the center with perfect confidence that the other economies previously impossible in radio ap- be and a half units, in the same standard design, ready to paratus. That's why we can sell -Profes- of the piece should marked hook on, will be ready for you whenever sional Radio Equipment at Amateur Prices", circle drawn, the radius of which should you want them. We took three years of re- and at the same time back up every ABC you search to make ABC Units right, and the de- instrument with our unequalled guarantee, be the length of a switch lever which sign will remain unchanged in all essentials. Your Money's Worth or Your Money Back!" may have on hand. The ordinary style of switch point with the shank turned right on the point should be used, as in "C," Professional 12adio i;quipment at JImateur Prices Fig. 4. Nine of these points will be neces- he around AB Gob, sary. Nine holes should drilled INC. Pres. circle at equal distances. These WIRELESS EQUIPMENT Co the half Sninflodele holes should be just large enough for a 32 AUSTIN ST., NEWARK, N. J. ' ,riding fit, but not large enough to allow the switch point to move sideways. The next step is to make the two small pieces Wireless Equipment Co., Inc., at a and h in Figs. 3 and 4. They should i 32 Austin St., Newark, N. S. or phos- Dealers- Amateurs- he made from thin spring brass I enclose one nickel, Send me by shape line Includes The ABC new folder. describes. i mail your new ABC folder. phor bronze cut and bent to the The ABC in detail, the five ABC unit cabs- ' return in a complete assortment variable conden- shown. They are fastened to the panel apparatus, nets, the ABC screws of radio sers. the ABC small parts. the 1 Name the r,ositions shown by small brass both assembled and ABC "Clarion ", the Vibratone, a or brass nails. e in Fig. 4 is the switch unassembled. It is Tr. Transmitter, etc., eta Slip ' Address the contact end bent fast selling, profitable this coupon and a nickel into an 1 blade and has" of line, that makes good envelope NOW! and your copy down and the corners rounded off so it Write for discounts. will come by return mail. ' City State will pass easily from one tap to the next.

www.americanradiohistory.com 906 Radio News for June, 1921

The blade should be some springy material such as thin brass or phosphor bronze. RADIO SERVICE Regarding the action of the switch, see The Radio Service Type 55o C. W. Inductance is Fig. 4; when the switch lever e is on a Wound on a slotted bakelite form of 31 turns of contact point it presses it down and dis- number g hard drawn copper wire on a 5 inch diam. connects it from piece b which piece a Supplied with three clips making adjustment varia- had been hitherto pressing down and mak- ble to any fraction of a turn. Tunes to 35o meters ing connection to b through the nut. The and suitable for panel or bench mounting. Mate- circuit now is thru a, c and d. When the rials and workmanship the finest obtainable and the switch is moved to the next contact the price is only $8.50 same thing happens there, while a, at the first If you are starting to build a C. W. set the tap, presses it up and makes contact Radio Service Inductance will start you on the again with b. The movement of the switch right track or if you already have a C. W. Set point should be adjusted by tightening or and you are not getting the proper results try loosening the nut until the movement is one of these inductances and you will be sur- about A ". prised at the increased operating efficiency. The connections to the coils are shown in Fig. 3. Eight pairs of wires are ASK YOUR DEALER TO SHOW YOU ONE OF THESE brot INDUCTANCES. IF HE CAN'T SUPPLY YOU. WE out and numbered as to which coils are to WILL SHIP YOU ONE POST PAID. he connected. All the connections should be soldered. Most amateurs neglect to do Type Soo Variable Grid Leak (% to 3 Meghohms) this and then Helps to increase wonder why their sigs don't your signal audibility come in as loud as those of some other Bakelite Mounted, Moisture Proof $.75 fellow who has the same kind of an apparatus, but who solders his connections. In closing I will say that whoever builds Here's the Wonderful Little Radio Set this piece of apparatus will find himself that was described in April's Radio News, page well repaid by its performance and effi- 680. Just the thing for Boy ciency for the little extra work and time Scouts, Campers and spent on for use on bicycles, etc. Complete in every re- it. spect and guaranteed to give complete satisfaction. Just connect your aerial, ground and phones and you are ready to receive messages. Tunes to 800 meters. The Construction of Inter - Mr. Dealer: This little receiving set will help valve your business over the summer months and ob- and Telefone tain new customers for you. Transformers Type S8 (as illustrated) price $7.50 (Continued page Type S8A complete (incl. phone, aerial, insulators frort 872) and instruction book) 12.50 RADIO SERVICE & MFG. CO., Lynbrook, L. I., New York which can be turned out solid from a piece of well- seasoned maple 4" x 2" x 2" or built up from a piece of fiber or bakelite tubing % " internal diameter and ie "" thick, with end pieces of V4 " stock glued on with marine glue. The maple bobbin should be sandpapered smooth and impregnated with wax. Drill the ends of the bobbin with a No. 6o drill in four places so disposed to ESCO accommodate the lead in and out of the primary and secondary windings. Set up the bobbin in the lathe chuck, or if this is not available, a small emery GENERATORS -MOTOR- GENERATORS-DYNAMOTORS grinder with the grinding disc removed can be called into service with a little ingenuity. Cover the core with a layer of 4 to 32 Volts for Filament paraffin paper, and prepare four pieces of 3/32 B. & S., S. S. C. stranded connections 350 to 2000 Volts for Plate about 12" long for connection to the main winding of 4o B. & S. enamel. For the Capacity primary wind on 20,000 turns, and lead out 20 to 2000 Watts at the end of the bobbin. Now prepare a strip of Empire Cloth V2" wide and 3o " Liberal Ratings long, and with this cover the primary winding to insulate it from the secondary. This Write for Bulletin 231 method of using a tape places less strain which on the fine wire underneath, besides mak- lists ing a neater job than the usual method of 200 Combinations covering with a single wide strip. The secondary consists of 6o,000 turns of the some gage wire. When all is found on, it Motors and Generators Developed and Built for is covered with another piece of %" Em- Special Purposes pire Cloth about 48" long. Take the bobbin from the lathe chuck and fill up the core with pieces of thoroly annealed No. 22 iron PIONEERS IN THE MANUFACTURE core wire. of Now procure a small iron -encased tin about 4" long by 2" in diameter, and cut HIGH VOLTAGE DIRECT CURRENT a slot at one side as shown in Fig. 2; then RADIO GENERATORS place the coil inside with a disc of cardboard at the bottom to keep the coil clear from the iron casing. Thread the flexible leads thru pieces of bicycle valve rubber about 4" long, and fill the tin with molten paraffin wax so as to thoroly seal the coil ELECTRIC SPECIALTY CO. from the effects of moisture. STAMFORD, CONN., U. S. A. Mount the outfit as shown in Fig. 3, and an extremely efficient intervalve trans- 211 SOUTH STREET former is complete. Another very useful transformer is one for the telefone circuit, and should be used

www.americanradiohistory.com Radio News for June, 1921 907 by every experimenter who has any respect for his fones. When it is considered that the fones are liable to be de- magnetized or burnt out by their employment in the high voltage plate circuits, its "The Promised Land" use will be apparent. In addition to this it only takes one jolt thru the top of your dome from an earthen headband to con vince you of the "splendid isolation" af- YOUR OPPORTUNITy forded by the use of a telefone trans- Y former. The constructional details with the exception of the secondary winding are similar to the intervalve pattern. This "The Promised Land" is the name professional operators have given to the New winding consists of 2o,000 turns of No. 36 York Central Radio Station of the Radio Corporation of America on Long B. & S. enamel wire, tapt at 5,coo, and Island, which, when completed, will be the largest and most powerful radio 12,50o turns respectively, giving a range station in the world. of secondary impedances to cover all fones from the humble 75 ohm "proletariat" to This immense station which is now in course of erection, is a striking example the Baldwin Mica Diafram "bourgeoisie." of the great opportunity radio offers you for a successful, secure future. The following table will give the reader an It will be equipped to work simultaneously with five other nations in widely idea of the approximate resistances and in- separated and distant parts of the world and will be epoch- making in the field ductances of the windings of both trans- of international communication. formers. A large number of trained men will be required for its operation and maintenance. Trans- Primary. Secondary. it Ind. A position at this station is the height of every operator's ambition, for former. Resis. Ind. Resis. to higher, more responsible 21.3H 18400W 177x means unlimited opportunity to succeed and progress Intervalve 4000W paying positions in the radio industry. So far as opportunity goes Telefone 4000co 20.711 58ow 1.23H and better Actual Bridge Measure- 155o" 7.70H the successful future of these men is assured. ments at 800 cycles 2800W 19.41H When the telefone transformer is used HOW ABOUT YOU? in an audion circuit, it is absolutely essential that it be shunted by a small fixt or Right now, today, radio offers you big opportunities -if you are properly trained. variable condenser, so as to pass the radio Radio companies need trained executives, engineers, draftsmen, operators and frequency component of the plate currrent mechanics. Hundreds of positions in the ever-broadening field -from ship which previously passed thru the small con- operator to general manager -are open to you, if you have the required training. denser formed by the fone cords. The Radio Institute of America will give you this training, as it has to thousands to According to some "near experts" the of others. If you cannot come to the Institute, the instruction will come winding should possess high ohmic resist- you -to your home. ance, thereby combining a resistance for the coupling effect with the transformer action. This new home course of radio training, which has been developed useful in radio fre- benefit of those who cannot attend the Institute personally, is the same course This resistance may be of elecricity quency transformers to prevent the wind- used at the Institute. It includes everything from basic principles at its natural frequency, but and magnetism, to actual operation of commercial radio equipment. It also in- ing oscillating an in the pattern under consideration any un- cludes the same textbooks used in the Institute classes, as well as Omnigraph due ohmic resistance merely gives rise to set of greatly improved design, with a variable automatic transmitter, tor code losses which obey the familiar C R law. It practice. that it is should be particularly understood of ampere turns alone which transfer the The graduates the Radio Institute energy from one circuit to another. What Our Former Students What the Man Who Are Doing cf America enjoy Mr. H. Payne, former student, a great and exclu- Employs the now Assistant Treasurer of the Radio Corporation of America. sive advantage in Operators Says: The California Walter E. Wood, Superintendent the close connec- in charge of the powerful trans- be- Radio Institute of America, Radio Station oceanic radio station at Chatham, tion existing New York. Theatre Marv. tween the institute Irving Elltngham has a greatly Gentlemen -I have known (Continued from tage 857) prized position in his assignment and the Radio Cor- the Radio Institute of Amer- as radio operator on Vincent Astor's yacht " Cristina," poration of Amer- ica so long and so favorably ica, world's largest under its present title and Raymond Blanqui, although its earlier name, Marconi In- one of the only 20 years old, is now a high radio manufactur- over the set on the occasion of salaried operator in trans- oceanic stitute, that it is difficult for ing and commer- me to conceive that anyone special concerts. service. instruction station is operated under the direc- Watson Sidney. Manager of the cial radio company. can think of The "Mee of the Radio Corporation of in radio without instantly rection of Lieut. Ellery W. Stone, general man- America, Savannah. Ga. The Radio Cor- ognizing its leadership. When ager of the Moorhead Laboratories, Mr. B. Harry Sadenwater, assistant in poration employs employing operators, your Mr. J. E. research in the world -famed radio thousands of men, students are given preference F. McNamee, chief engineer, and laboratories of the General Elec- because several thousand of Squires, operator of the station. tric Company. in its executive de- them have proven their abil- E. N. Pickerel]. manager of the partments on ships ity me a long period Radio Corporation's shore station to over for the port of New York. and at shore sta- of years. Lee L. Manly, assistant super- tions and in fac- Sincerely yours, intendent of the Maintenance De- (Signed) J. B. DUFFY, Atmosferic Conditions partment of the Radio Corpora- tories and labora- tion. tories. A large Superintendent, Eastern Di- in The Tropics William S. Fitzpatrick. As- vision, Radio Corporation sistant Marine Superintendent. percentage of these of America (Continued from page 867) men are graduates of the Institute. =

nothing, in my estimation, which will tend The Radio Institute of America has been an established and successful institution for than at- over fifteen years. The year round average attendance in its classrooms is now 298 to make a person more nervous, students per month. It has trained over 6,000 men, 95% of whom have successfully en- tempting to read weak signals thru very gaged in this new branch of science and industry. You, too, can be successful in this heavy static, as it requires great concen- new field if you properly train yourself by means of the Home Study Course of the Insti- tration of the mind, which is very hard tute. Radio offers an unlimited opportunity for future advancement -why not take ad- upon the nervous system. vantage of it. Write for our booklet and further details, -NOW. If one should "listen in," during one of those ugly tropical thunderstorms, I guar- HOME STUDY DIVISION antee you would think you were at the battle of Liège or in a boiler factory. If you are not convinced, let me say, honest- RADIO INSTITUTE OF AMERICA ly, I have heard static four feet from the (formerly Marconi Institute) fones during one of those storms. It is absolutely impossible to read signals 5o miles away. How can one possibly work 324 BROADWAY, NEW YORK with such unbelievable interference ! What a joy it would be to eliminate this.

www.americanradiohistory.com Radio News for lune, 1921

Should you "listen in," any time of the day or night you would be sure to hear some fellow frantically calling for a vessel USE 32 VOLT D. Ce FOR to relay his traffic. Tho within range of a number of shore stations it is impossible YOUR C W PLATE CURRENT for him to read their signals due to static interference. HOW? Engineers of the various radio concerns A Ray -Di -Co "DYNAMOTOR" are laboring day and night, trying to find makes it possible a way to eliminate this static for the sea- A combination motor and generator within one frame- going operator. Great sums of money are No more space required than for a single unit being spent daily in experimenting. Let us - only hope that these faithful servants of Higher e{ncienc't' obtained than from motor generator the wireless game will be rewarded shortly of same capacity - for their labors. Operates on 32 volts, generates Soo volts, compound wound. TYPE "DY -5" 500 volts 5o watts $75.00 TYPE "DY -7" 500 volts 75 watts 82.5o The Radio Compass For greater capacities the Ray -Di -Co "STANDARD" motor generator on Airplanes unit of the following capacities is recommended: (Continued from page 859) TYPE "SP -lo" 500 volts Ioo watts $115.00 TYPE "SP -17" 500 volts 175 watts 141.00 Motor -32 volts D. C. compound wound Generator -shunt wound orator roughly plotting them to ascertain All quotations F. O. B. Chicago. the accuracy of the type of fix that has been obtained. The latter being found satisfac- Ouatations for special machines upon retjitt'st. tory, the bearings are furnisht the ship in messa_ee form by radio. RAY- D.I -CO Pertinent to this review of the progress (Ray- Dee -Ko) of Naval aircraft is the announcement of 2653A N. Clark St. Radio 9AG results of experiments conducted by the En- CHICAGO, ILL. gineering lìivision of the i nited States Air H. H. BUCKWALTER, 713 Lincoln St., DENVER, COLO. Representative Service as to airplane radio d:rection find- Colorado. Wyoming. Utah. Nebraska, Western Kansas, Northern New Mexico, ing. Wireless was used at McCook flying Deadwood and Lead, S. Dak. field in guiding the return of airplanes to "Watch for our next announcement -you'll be surprised" the home airdrome. The outstanding conclusion of these observations is that any air- - plane can be directed with absolute accuracy to anv radio transmitting station, even in the absence of an experienced operator. A New When at an elevation of 2,070' the airplane "CINO" Special for DA Men! could be guided immediately over the transmitting station, the feat being accomplisht while the man operating the switches in the rear cockpit controlled the rudder and steered the airplane in response to wishes. The experiment was negotiated b;t'h with experienced wireless operators in the rear cockpit and with individuals who had no knowledge of radio and who did not know the Morse code. The results were identical - that is, the airplane was piloted directly over the transmitting station in both in stances with wireless as the sole guide. Dave you ever wished that the manufacturers of Now Traffic Men can this arrangement be improved Even when scaring at a height of 2,000', Regenerative Tuners would wake up to the fact that upon? Everything at your right hand. 'long side of you were right- handed? the key! the operator could detect the failure of the Now look at the above illustration and start from And finally, will they bring them in7 well. write airplane to hover over the station directly. left to right: First the detector, with the present us for literature and if you wish we will give you day tubes it is seldom necessary to readjust a de- a list of satisfied users, distance men and boosters. should the lnarg'n be as little as 1có . tector after arriving at the point where your tube PRICE $72.00 works best. Alright. get it out of the road. which is The method employed in making to say. at the extreme left! We also carry a full line of standard apparatus. the ex- Cunningham 300 -301 -302 Tubes; Somerville Meters; periments involved the use of two closed Next is the plate variometer: Inasmuch as the G-R Radiation Ammeters; Chelsea, Murdock, Acme, plate variometer is used solely for regeneration and eta; Paragon and G -R Rheostats Burgess loops mounted on the wings does not require you look Batteries; of an airplane that at it continually keep Radioelectric Shop - Smoothing -out Condensers 2'f_, It also at the left. MFD 1500 Volt; Bell Rotary Quenched Gaps. at right angles to each other, operating upon Next is the coupling, and last but of most Im- "CINO" Variometers- Forms. $3.00; Mounted $8.00. a maximum signal. The part'cular instal- portance. the Grid or wavelength tuning variometer, Postpaid. "CINO" Variocoupler-Parts $2.50; Mounted and alongside of it the series, or Antenna. Condenser! 57.00, Postpaid. lation was mounted on a Curtiss NJ 4 -H airplane. and consisted of two main, or CINO RADIO MANUFACTURING CO. "fore and aft" loops of four turns each, 218 WEST 12th STREET connected in series, one loop being stationed QNO CINCINNATI, OHIO on the outside struts of each wing. The '8 X N' auxiliary loop was of four turns of wire and was mounted at right angles to the main loops, struts numbers four and ten being employed. The fuselage of the air -going machine was enclosed by this loop. The SPECIAL PRICE REDUCTIONS wire was sewed into fabric and the strips Paragon Control Panel with Radiotron Phone Condensers, .00.2 nit $.2S of fabric were doped onto the struts and Tube $10.50 Wireless Practice Sets 2.70 wings of the airplane. Leads \udiotron Tubes, Two Filaments 5.50 Skindervikin Buttons .90 were brot Radio Service V.T. Sockets .98 J. N. Variometer 4.25 from the loops into the rear cockpit of the Cyclone 22.5 volt small B Battery .98 J. N. Variocoupler 4.75 machine and there connections were mad Cyclone 22.5 volt large B Battery 1.75 Murdock 2.000 Ohm Wireless Head Sets 4.00 No. 766 Eveready large 22.5 volt B Bat- Murdock 3,000 Ohm Wireless Head Sets 5.00 to suitable switches, condensers, ampli'ers, tery 2.75 Marko Storage Batteries: etc. The Paragon Rheostats with .0005 mf. Air Service states that these tests Grid 4 volt 40 to 60 amp 10.00 do Condensers 1.75 6 volt 20 to 40 amp 10.95 not embody any departure in radio di- Rubber Cap Binding Posts, per doz 1.00 8 volt 40 to 60 amp 16.00 rection finding in airplanes, the method in Grid Condensers, .0005 mf .25 6 volt 60 to SO amp 20.00 part being introduced in England during the Prompt attention given to mail orders. The above prices are F. O. B. New York war. The results, however, are impressive in revealing the accuracy which is possible HYCRADE ELECTRICAL NOVELTY CO., 41 W. 125th St., New York when wireless is employed for guiding air craft.

www.americanradiohistory.com Radio News for June, 1921 909

MAGNAVOX PRODUCTS

HAND TRANSMITTER $25.50 MUSIC TRANSMITTER Magnavox special transmitte_ will modulate on ampere of $37.50 voice current and enable you to cover maximum distance. Use a Magnavox transmitting tone arm To increase your transmitting for efficient transmission of phonograph use this most efficient music over your Radio phone. Easily range attached to any phonograph without re- moe ro- plwne. - moving the regular tone arm. RADIO MAGNAVOX --). $45.00 This instrument solves the loud speaker problem for all. With a 2 -stage amplifier, stoials voice or music will be reproduced loud enough to be heard over a large room or hall.

Immediate delivery. Order from your dealer or send remittance direct to the MAGNAVOX COMPANY, OAKLAND, CALIFORNIA

For Short- Wave Results This combination makes phenomenal distance work an every -day occurrence in your station.

CR -3 Relay Receiver Detector and 2 -Stage Amplifier (RORD) This is the famous combination that proved its merit in the relay tests some months ago. It makes a wonderful team both for ease and flexibility of operation and what is far more important-real results!

GREBE RADIO apparatus is licensed under the original Armstrong and Marconi patents.

Enterprising radio dealers carry Grebe Radio Apparatus. Ask yours to men- show you this Combination ; if he doesn't carry it in stock write us, tioning his name, for catalogue. Bunnell h Co., J. H., New York City. Kelly and Phillips, Brooklyn, N. Y. City, Mo. Klaus Radio Company, Eureka, Ill. Central Radio Company Inc., Kansas Louis. Continental Radio and Electric Corp., New York. Manhattan Electrical Supply Co., New York, Chicago, St. Detroit Electric Co., Detroit, Mich. Leo. J. Meyberg Co., San Francisco, Cal. Doubleday -Hill Electric Co., Pittsburgh, Pa. Newman -Stern Co., Cleveland, Ohio. Electrical Specialty Co., Columbus, Ohio. F. D. Pitts Co., Inc., Boston, Mass. Holt Electric Utilities Co., Jacksonville, Fla. Philadelphia School of Wireless Telegraphy, Philadelphia, Pa. Hurlburt Still Electrical Co., Houston, Texas. Western Radio Electric Co., Los Angeles, Cal. A. H. GREBE & CO., Inc., 72 Van Wyck Blvd., Richmond Hill, N. Y.

www.americanradiohistory.com 910 Radio News for June, 1921

The Thirteenth Tap (Continued from page 876) Announcement .aaaaa H,MM111/11/011M11111111111111111111111111111111111111111111111M1111,,,,,a,,,a,,.,I,,,,,,,,,,,,,,,,, In addition to furnishing the highest possible grade of instruction SOS SOS DE KIF KIF- attacked by sav- to wireless men in preparation for their First Grade Commercial ages on-island--storage batteries going- License examinations, the MASSACHUSETTS boat destroyed -help quick-de James RADIO and Duane-KIF.' TELEGRAPH SCHOOL, INC., wishes to announce their entry into the field of "The ether at that moment was being racked by the broad wave of the naval C station 5o miles distant. If KIF was al- -W SALES and SERVICE most indistinguishable to me, only five miles We handle a complete line of C -W transmitting and receiving units and off, who else could have heard it thru the accessories. naval station's QRM ? And the next near- Let us estimate on and assist you with your C -W problems. est station was a ship, 40 miles away." Our 14 years' experience in amateur radio activities should be of some Here VALUE the narrator paused and sipped to you. some water. Beads of perspiration dotted Summer Classes his forehead. Hansen, every nerve taut, sat rigid in his chair waiting for the climax Enroll now for our Summer Wireless Course to be given during July of the and August. High School students get gripping tale. can the proper start during these "I grasped the situation. The two months to enable them to finish their course in the regular Fall man who Classes or at home. had abused, defrauded, and insulted me was in peril of his life. Sweet revenge!! The RATES: blood pounded thru my head; my hands Day Classes $10.00 per month shook. Evening Classes . $ 5.00 per month "No station responsded to the SOS ! To Summer Students only. With my fones still on, I reached up and jammed the secondary of the O.T. down Write, 'phone or call for particulars. into the primary, at the same time pressing the generator starter button. As the whirr MASSACHUSETTS RADIO AND TELEGRAPH SCHOOL, Ine. of the M.G. rose in tone, I heard, even 18 Boylston Street, Boston, Mass. Tel. Beach 7168 weaker than before, `SOS SOS -' With R. F. Trap, Treas. G. R. ENTWISTLE, Pres. trembling fingers. I prest and screwed down the key. Five KW radiated into space, with a logarithmic decrement Lord only knows what! With the fierce interference my set would create, there was not the slightest possibility of KIF being heard. "Vengeance!! Murdered by natives, or- 100% FROM YOUR TUBES dinarily docile, but for some queer reason The new Radiotron Vacuum Tubes are accurately de- inflamed against Duane. signed electrical instruments. To get the maximum re- "For an hour I listened to the hiss of sults from them, they should be used with apparatus designed specifically to agree with their electrical character- the quenched gap. This seemed to be long istics. Our new Type 231A Amplifying Transformer is enough for the Indians to do away with the result of careful engineering design to produce a their victims, so I turned off the juice and transformer which will give the maximum amplification listened cf signals using a UV201 tube. The Type 231M Modu- in. lation Transformer was designed to give the maximum "The minute my spark had ceased, the modulation possible without distortion when used with a air was flooded with QRT's and BK's, but UV202 tube. Send for free Bulletin 907N on the opera- not a signal tion of amplifying and modulation transformers and from KIF. I looked at the completely describing the new Type 231 instruments. quenched gap. It showed a dull red. This brot a thot of radio inspectors to me, but I Price, EITHER TRANSFORMER, COMPLETELY MOUNTED, $5.00 dismissed it for the night. "One thing I was certain of : I would be fined and lose my position, as my tone Radiation and Filament Ammeter was peculiar, and every station knew that Results are not obtained by guessing. They 'come it was I who had interrupted traffic. But from the intelligent application of accurate information. what matter? My revenge was complete. If you desire to get the best results from your CW set, it is necessary to make measurements of the various cur- "The next morning when we docked, the rents. Our Type 127 Hot Wire Ammeters are particu- government officials took me in hand. I larly suited for this service. They are suitable also for lost my license, and was fined the limit for measuring the radiation currents of spark stations, and wilful for measuring filament currents, either AC or DC. Sup- disturbance. I returned, third class plied in a variety of ranges and for front or board, as on the first boat I could get, and with what illustrated. or flush mounting. Described, and ranges money I had left, managed to listed in Bulletin 904N. reach Califor- nia. During the trip I picked up a Seattle Price, $7.75 newspaper. A little notice attracted my attention. It read : `James Duane, well known CARRIED IN STOCK BY LEADING RADIO DEALERS at Sitka, was killed by natives, along with GENERAL RADIO COMPANY three companions, on - Island. A radio Massachusetts Avenue and Windsor Street, Cambridge, 39 Massachusetts set was on the island, and it is puzzling to know why it did not summon help.' "As you can imagine, I expected to be highly gratified at such information. How- ever, the looked -for pleasure did not come BURGESS "B" to me. A nervous reaction was setting in. BATTERIES "When I arrived in California I secured a job, thanks to my radio experience, in a ARE THE NOISELESS KIND large high -voltage laboratory near San - Francisco. I was assigned to the 700,000 - made with and without taps volt transformer experimental staff. This work was extremely interesting, tho hazard- ous at times. Send for catalogue giving sizes and prices "Often as I lay in bed I would think of that insane Alaskan night. Three innocent men sent to their death by my hands!! And another because of a personal insult BURGESS BATTERY COMPANY which assumed less real importance every

Harris Trust Building CHICAGO time I reviewed . it. I would frequently wake up in the middle of the night, eyes

www.americanradiohistory.com 911 Radio News for June, 1921 for experimental cw NEW A -P RECTIFIER TUBE MAKES EXPENSIVE HIGH VOLTAGE D -C GENERATOR UNNECESSARY. A wonder-this newest A -P tube -a Rectifier that can be used effectively with any transmitter tube of any voltage up to 75o, and without a high voltage D -C generator. Step up your iio V A -C lighting supply to 350, 500, or 750 volts, using a small transformer, and two of the new A -P tubes do everything else, rectifying both halves of the cycle so the plates of your transmitter tubes get all the high potential direct current necessary - without the use of a high voltage D -C generator. The A -P Rectifier has a 75 milliampere carry- A -P Rectifiers used in Type O A -C De Forest ing capacity, which is sufficient to operate five Radiophones, equipped with the SHAW stand- A -P Transmitting Tubes in parallel. For high ard condensite four -prong base, and licensed power CW transmission, use additional A -P under SHAW patents. Price $9.75. Order from Rectifier Tubes in parallel. your dealer, or direct from either address below. Diagram of Connections Furnished Free With Each Tube

And for the best book on Radio, ask your dealer for "Elements of Radiotelegraphy," by Lieut. Ellery W. Stone, U. S. N., or order direct from - ATLANTIC RADIO SUPPLIES CO. PACIFIC RADIO SUPPLIES CO. 638 MISSION ST., SAN FRANCISCO, CAL. Price $9.75 each. Order from 8 KIRK PLACE, NEWARK, NEW JERSEY your dealer, or write direct Distributors for Moorhead Laboratories, Inc., to either address in this ad.

'MliWE A-P Rectifier Tube ANOTHER íz TRIUMPH

TYPE V. C. O. TYPE R. V. 0. VARI - COUPLER VARIOMETER for Table or Panel for MOUNTING Complete as MOUNTING illustrated Complete as illustrated Price, $6.50

HERE is a true Variable Coupler for the Radio Man who Price, $7.00 desires an instrument to stand the acid tests of Radio work. our TYPE The latest addition to the MAGECO family is Primary consists of 42 turns of 6 turns and single turns R. V. O. Variometer adapted for table or panel mounting. each wound on Formica tubing. Brass bearings support Constructed of Hard Maple, nonshrinkable and with green the Hard Maple Rotor revolving with very close coupling. silk wire. Bushings are of brass. Accuracy of assembly For panel mounting remove the base and mount. prohibits all wabbling. we will C O. VARIOMETER PARTS Send us your panels and TYPE R. V. /A at, per letter, U with Blue -print and Instructions, Complete $4.00 Engrave them for you

? J I DEALERS, HAVE YOU OUR PROPOSITION Send 10 cents for Catalog THE MARSHALL -GERKEN CO. 26 Radio Bldg., Toledo, Ohio

www.americanradiohistory.com 912 Radio News for June, 1921

starting, breath heaving, from some terrible nightmare in which I was being forced CO- OPERATIVE RADIO_PURCHASINO dowñ, down, into some fiery doom." ' Members of this association participate our profits. Order direct from this ad Again the man hesitated, perspiration in the profits which have accrued or send a stamp for full particulars. standing out in great through their own and fellow amateurs' drops on his agonized Remember "We take pride in our serv- brow. With a visible_effort combined purchases. In addition to this ice." The items listed below are he continued: dividend our service is unexcelled. You but a few of the items which are "At the laboratory we rigged up the neces- also can secure this car- service and share in ried in stock. sary apparatus for some important high- potential characteristic tests- corona dis- RADIOTRON TUBES charge and the like. The TELEPHONES AUDION CONTROLS ultimate voltage UV -200 Gas Content Detec- was controlled by a 20 tor $5.00 Brandes Superior with Navy Clapp- Eastham ZED detector -point rheostat near W -201 Pliotron Amplifier 6.50 band $8.00 panel $12.00 the immense oil transformer. UV -202 5 Watt Transmitter 8.00 Brandes Trans- Atlantic with (We supply full directions Navy band 12.00 Acme Y -1 detector 10.00 "One day when I was immersed in my with either detector or am- Brandes Navy type with Navy Adams Morgan No. 70 con- plifier.) band 14.00 trol 6.00 work, which I did all the more energet- AMPLIFYING TRANSFORMERS Western E l e c t r i c type ically to forget my crime, I determined Clapp- Eastham type QO un- 1002A 15.00 C. W. TRANSFORMERS to mounted 4.00 Murdock No. 2000 try out that night a pet hook -up I had long Clapp- Eastham 55, ohms. 4.50 Acme 200 watt mounted...$20.00 type QO Murdock No. 55, 3000 ohms. 5.50 thot of. Five o'clock came, mounted 6.50 Acme 50 watt mounted 15.00 and the Acme AS with binding posts 5.00 SHORT WAVE SET MATERIAL chief gave me permission to stay. Upon Acme core & coil assembled 4.50 MODULATION TRANSFORMERS Acme AS fully Clapp- Eastham ZRV Vario- leaving he said: `If you value your life, mounted 7.00 meter, without dial $5.75 U. V. 712 List Price 7.00 Acme A -3 semi mounted $5.00 don't turn the rheostat beyond Mfg. by Radio Corp. of America. Clapp- Eastham ZRV Variom- the thirteenth eter, with 3 -inch dial 6.50 tap -the voltage will break down anything CONDENSERS Clapp- Eastham ZRC Vario- CHOKE COILS Connecticut -remember, ! ! .001 encased $6.50 coupler. with knob & dial 7.50 150 M.A. Single coil $4.00 the thirteenth tap is death !' Connecticut .001 panel type 6.50 Clapp- Eastham ZRC Vario- 150 M.A. Chelsea No. 1 encased 5.00 coupler, with switch and double coil 6.00 "With this warning ringing in my ears Chelsea No. 2 encased 4.50 points 500 M.A. single coil Chelsea No. 9.00 6.00 he left me to myself. By the time all was 3BD with dial J. J. Nightingale for panel 4.75 Variometer 4.50 500 M.A. double coil 8.00 dark everything was in readiness for opera- Chelsea No. 4BD with dial J. J. Nightingale Vario- for panel 4.25 coupler 5.00 FILAMENT HEATING tion. I snapped off the lights, and stept Murdock No. 366 .001 en- Murdock G or P Variometer TRANSFORMERS within the danger fence to cased 4.75 No. 345 7.00 more closely ob- Murdock No. 367 .0005 en- Murdock Variocoupler No 75 watt mounted $12.00 serve the brush effects. I shoved the large cased 4.50 346 8.50 150 watt mounted 16.00 control handle to the sixth point. A weird phosphorescent glow played over the appa- MUTUAL PURCHASERS ratus. Needle-like violet points flickered ASSOCIATION E2WSTYOONREK ST., from the sharp bends in the connecting wires. The depths of the room were pitch - dark. "Something in this uncanny situation brot back thot of a dismal Alaskan island. I recalled myself to the work in June hand, but KIF -James Duane-stood in my EMPIRE RADIO Bulletin mind, seared with fire, as I advanced the rheostat to the tenth tap. The discharge intensified, and the resonance indicator AUDIOTRONS moved ten more units. (TWO FILAMENTS) "By degrees, away at the back of the room, a white, draped figure imprest itself upon my brain ! Gradually its distinct- iveness increased. Involuntarily my arm $ 6.00 and other muscles stiffened, spasm -like. Suddenly some irresistible force overcame my will. My hand pushed the rheostat from the tenth to the eleventh tap, tim my TYPE 150 EMPIRE brain struggled against the supernatural power. Nickel Plated Switch Series Parallel Switch "Once more, before my staring eyes my Contacts for above own hand obeyed the force. The twelfth Switch, Each 5c 85c tap ! ! "The discharge was now blue. green, violet, scintillating in its cracklings. Long Attractive Discounts To tongues of miniature lightning leapt out on Dealers all sides. I knew that the condensers would hold, and the spark would jump to me, the nearest conductive object. Empire Radio Equipment Co. "The spectral image in the background Manufacturers and Distributors of Radio Apparatus commenced to fade, then reappeared. The 71 West 125th Street New York City words `James Duane' struggled to my throat, but were strangled. Three other figures appeared to my whizzing brain from out of blank space. "Something, a mysterious force, came over me. The throbbing blood vessels in my body New! NEW! New! seemed to be on the point of bursting. The 11111111111111111 1IIf¡¡¡ff rheostat moved slowly, slowly. lll1\Ì\,aállp(f! MULTIPLE "The THIRTEENTH TAP!!! Death ! ! t RHEOSTAT "The contact was made and livid, search- Bunnell 28 OHMS ing flames sprang forth like demons front "Bunnell Quality" the overcharged high- tension wires!! "Blinding flashes flew Sample by Mail, . . $3.00 before me -. "I returned to consciousness 3o hours r// Get descriptive circular later. llHlfllllll Send Stamp for Catalog 42 R.N. It was then I learned that I had We Carry High miraculously ¡¡I(I(1((1111111111111111111>l\\l\ Grade Radio Goods escaped death by pulling back :ti (l(l¡U(f lll\l

www.americanradiohistory.com Radio News for June, 1921 913

Pacent Universal Plug THE ONLY PLUG FOR RADIO - NO Price $2.00 CONNECTIONS TO SOLDER - CON- NECTED IN A JIFFY -ESSENTIAL FOR MODERN RADIO -FOR TRANSMISSION AND RECEPTION -APPROVED BY THE NAVY DEPARTMENT -USED BY COM- MERCIAL COMPANIES -ENDORSED BY FOREMOST AMATEURS- OBTAIN- ABLE FROM YOUR DEALER

DUBILIER UNIVERSAL CON- DENSER SUPPLIED IN MOST USED CAPACITIES FROM .01 TO .00025 -FOR TRANSMISSION AND RECEPTION - ESPECIALLY DESIGNED FOR C. W. -WILL CARRY ONE peiÉli AMPERE AT 1000 VOLTS-RUGGEDLY CONSTRUCTED KORATEpRc -HAS CONSTANT CAPACITY -- APPROVED BY OUR pEWiO GOVERNMENT -EASILY MOUNTED ANYWHERE -OF =Yp No.57i:;`:; UNIVERSAL RADIO USE Price $2.00 We shall be pleased to send you bulletins describing the above and our other products on receipt of five cents in stamps. immediately for our liberal discounts. AMATEURS AND EXPERIMENTERS -Get in touch with your dealer. DEALERS-Write Sole Distributors for Wicony's Complete Line of "Eventual" Apparatus. Duo -Lateral Coils Pacent Plugs Sullivan Apparatus Standard VT Batteries Dubilier Condensers Seibt Condensers Special Distributors for Brandes Phones ELECTRIC COMPANY, Inc. PACENT LOUIS GERARD PACENT, President NEW YORK CITY 150 NASSAU STREET Telephone Beekman 5810

Condenser No. CHELSEA Variable Condensers 3 (Die -Cast Type) No. 1. -.0011 m. f. mounted $5.00 No. 2. -.0006 m. f. mounted 4.50 4.75. No. 3.-.001I m. f. unmounted - - No. 3. -.0011 m. f. unmounted, without dial 4.35 No. 4.-.0009 m. f. unmounted 4.25 No. 4.-.0006 m. f. unmounted, without dial 3 .85 Top, bottom and knob are genuine bakelite, shaft of steel running in bronze bearings, adjustable tension on movable plates, large bakelite dial reading in hundredths, high capacity, amply separated and accurately spaced plates. "CHELSEA" BAKELITE DIAL NO. 41. Unmounted types will fit any panel with counterweight. and are equipped The Chelsea dials are made of genuine Purchase from your dealer; if he does bakelite, beautifully finished, and bear a it, send to us, not carry 100 division semi -circular scale. The dial is 31/41 inches in diameter, inch thick, with a long, sloping, easily VARIABLE GRID LEAK read marking. Chelsea bakelite dials run Permits the selection of the proper leak re- true and will not warp. sistance regardless of the type of tube, or its is to Ten The complete dial and knob made use as detector, am-plifier or oscillator. fit either 3/16, % or 5/16 inch shaft. Spec- steps give a range from % to 5 megohms. ordering, otherwise the knob. ify size when Genuine bakelite base and inch hole will be furnished. de- All our apparatus embodies the highest in appear- electrical Chelsea dials are beautiful gree of mechanical construction, in price, accurate and durable and good ance, low efficiency, appearance. in service, unexcelled by any, at any price. Purchase Chelsea Apparatus from PRICE $3.00 your dealer Dial and knob complete 1.00 NEW MARCH BULLETIN SENT UPON REQUEST Purchase from your dealer. CHELSEA RADIO CO., 11 Fifth Street, Chelsea, Mass. Manufacturers of Radio Apparatus and Moulders of Bakelite

www.americanradiohistory.com 914 Radio News for June, 1921

Hansen noted a change. His guest's muscles were rigid, his eyeballs staring at a dark corner. In a last miserable, smother- ing, choking gasp, the ex- wireless operator REESOFFERr cried, "God!! Confessed!! James Duane!! F FREE The THIRTEENTH TAP ! ! !" A heavy thud and crash marked the end GOOD FOR 60 DAYS ONLY of the unfortunate being who had so terri- bly paid for his crime. We are heavily stocked on all kinds of standard makes of wireless goods. To convert this merchandise into ready cash we will give to everyone placing an order for $15.00 or over, either through out store or through mail order The Washington Air Mail ABSOLUTELY FREE ONE Radio Station D. L. 1000 HONEYCOMB COIL (Continued from Page 86o) REGULAR $2.30 ,,,,,,,,,,,111111111111111111111111111111111111111,111111111111111111,11.,,1,1,1,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,E This offer applies to any goods we sell, which include a full stock of the new postal wireless stations are to in num- following standard wireless equipment: ber, the first one being establisht at Col- lege Clapp Eastham Magnavox Benwood Park, Md. The others are at Belle- Western Electric Federal Tel. & Tel. Westinghouse Pacent Tusca fonte, Pa.; Hasbrouck, N. J. ; St. De Forest Louis, Dubilier General Radio Marko Storage Battery A m rad American Ever Ready Chelsea Radio Mo. ; Omaha and North Platte, Neb.: Murdock Electrose Mfg. Co. Radio Corp. of America Parkin Electric Grebe & Company Cheyenne and Rock Springs, Wyo.; Salt You can save money by ordering from our list of special priced goods. Lake City, Utah ; Elko and Reno, Nevada. The station in the Post Office Department Immediate Shipment Guaranteed building has proven its efficiency for con- Write for Our Free Catalog stant reception of messages during daylight hours, faithfully copying far -away Rock American Electro Technical Appliance Co. Springs, in Wyoming. Good audibility, thru statics, is possib'e for all air -mail 235 R. Fulton Street New York, N. Y. radio stations east of this point. The equipment of postal stations at Minneapolis, St. Paul and Iowa City is being contemplated. The establishment of the original io stations entailed an expenditure of $26,000. The United States Shipping Board contrib uted a major portion of the equipment, and the sites, for the most part, are located on "DX SIGNALS" government property. The inability of telefone and telegraf companies to render an are getting weaker, and, hence more difficult uninterrupted service of E to copy, now that the het summer imparting informa- AC months tion are coming on. "Step 'em up" with an ACE incident to the oneraticn of the coast - Amplifier Unit and your problem of how to -coast air -mail service, inspired the Post to maintain reliable communication is solved. Office Department to resort to a wireless system as an effective vehicle. The enroll- ACE 2 -stage Amplify-er, as illustrated, completely mounted on a For- ment of the latter as an aid in the convey- mica panel and enclosed in a solid mahogany cabinet with hinged top. ance of postal matter by the air -route is Equipped with anti -capacity switch for shifting the phones from claimed to speed delivery by from 21 to 48 detector to one stage or two stages, or vice versa. An instru- hours. Approximately 15 Radio men are ment of sterling quality. Price $40 in the employ of the Post Office Department and it is planned, when a sufficient ACE 1 personne -stage Amplifyer, construction and quality similar to is obtained, to equip the ACE 2 -stage Amplifyer all air -mail planes wit'i direction- finders. If funds are available. AMATEURS! If your dealer cannot DEALERS! We manufacture a line ground and airplane Radio telefones wi "! supply you, forward your order by mail of equipment which is far above aver- likewise he installed. and it will receive our prompt at- age quality but selling At a price within tention. the reach of all. We know you will be interested. Send 3c Stamp for Catalog. Dictionary of Technical THE PRECISION Terms Used in Radio EQUIPMENT CO. (Continued from Page 88o) Mfrs. & Distrs. of Radio Equipment 2437-2439 Gilbert Ave. Cincinnati, Ohio "YOU MAY PAY greatly with variations in load so machine MORE BUT YOU CAN'T BUY BETTER" is MEMBER A. R. R. L. RADIO CALL "SxB" unsuitable for accumulator charging. Series Windings -See Wave -Wound Drum Armatures. Shackle -An open link capable of being closed by the addition of a special screw. Sharp Tuning- Exists where a very slight Canadian Write to our nearest branch for alteration of the tuner produces a marked effect in the strength of received sigs. Price List "B" of Radio Apparatus, S. G.-See specific Gravity. Amateurs Supplies and Publications. Sheath -The metal plate surrounding without contact the Grid and Filament of a Valve. Shell Type of Transformer-One having a Scientific Experimenter Limited large portion of its core outside the coil. Short Circuit-One having a very small Dominion Bldg., Confederation Life Bldg., 93 King St., E., amount of resistance. Vancouver, B. C. Winnipeg, Man. Toronto, Ont. To cut out resistance of instruments of a circuit. Arcade Bldg., Vai ghan Electric Co., Board of Trade, Shunt- Parallel. Halifax, N. S. 94 Germain Street St. John's, N'fl'd An alternate path for the St. John, N. B. current to pass in a circuit. Head Office, MONTREAL, Show Rooms, Shunt -Wound Dynamo in 11 St. Sacrament St. QUEBEC 33 McGill College Avenue -One which only a portion of the generated current is used to excite field magnets. Gives con- Insure your copy stant E. M. F. and is used for charging reaching you each month. Subscribe to Radio News -$2.00 accumulators. a year. Experimenter Publishing Co., 236 -A Fulton St., N. Y. C. Si -See Silicon.

www.americanradiohistory.com Radio News for June, 1921 915

The Dial The Amplifying Coil The Variometer This 3" knob and dial is our own product, heavy brass dial, black oxi- Our amplifying coils are distinctly R. V. Vario- The now famous Z. dized finish, composition knob í/" different in design and their remark- meter has met with a tremendous diameter. Sup2lied for IV shaft able power of amplification with the sale to thousands of discriminating dial can not chip. or warp tubes at present on the market can know the quality of only. This purchasers who and will run. true. Its beauty is in be testified to by several thousand Clapp -Eastham products. keeping with the best products o f satisfied users. You need not ex- Complete with knob and dial $6.50 the instrument maker. periment with untried products un- Complete without knob & dial 5.75 Price, Dial & Knob F800H less you want to. Variocoupler to match, with complete $ 75 Type Q. O. Amplifying coil as $4.00 knob and dial 7.5o No. 1g instrument switch to illustrated match above r o0 Complete Catalogs Sent for 6c Stamps Patronize your local dealer: If he won't supply our material your order will receive immediate factory attention. CLAPP -EASTHAM COMPANY 120 Main Street Cambridge, Massachusetts HEADQUARTERS FOR RADIOTRON TUBES. ALL TYPES IN STOCK

Enjoy the Summer Months $18 Listen to the Radio Phone Stations

glIA By getting our Short Wave Regenerative Tuner enclosed in a quartered oak cabinet iii x 5 S x 5'/4 inches with hard rubber panel for only $18.00 you can hear louder signals, cut out considerable interference and improve the efficiency of your set for amateur, commercial and radio phone work. Albert L. Vanderbilt, Newark, N. Y., says: "I am getting wonderful results from amateur, 600 meter and radio phone stations with your short wave regenerative tuner and one bulb." Mr. R. B. Moulden, Tuscola, Ill., writes: "I got KDKA very good last night with your short wave regenerative tuner and one Tune In Stations Over a Wider Range bulb." Get the European Stations Q S A $34.50 Because of their unique construction, balanced circuits, variable inductances and variable couplings our Short and Long Wave Regen- erative Tuners deliver the goods. They reduce body capacity and other interference to a minimum. They possess many advantages over other tuners. Price in quartered oak cabinet (Long Wave Tuner) $34.50 Price with hard rubber panel, (Long Wave Tuner) 40.00 Matewan, W. Va., says: "Your Long Wave Tuner is a beauty. Mr. Dennis B. Jackson, getting good results with Although I am in a valley between two high mountains, I am one bulb." "A few days ago Mr. T. W. Jackson, Jamestown College, Jamestown, N. D., writes: 2.000 to 20,000 meter tuners. It is a daisy. I hear European I purchased one of your if I got no more." stations QSA especially POZ. I would consider it worth the money

Send a 2 -cent stamp for bulletins COLBY'S TELEGRAPH SCHOOL, Auburn, N. Y.

www.americanradiohistory.com 916 Radio News for June, 1921

Vacation Time Radio 10c CHARGES YOUR BATTERY WITHOAN F -F BATTERY BOOSTER (Continued from page 854) and your station will never be closed because of a dischargid battery. Is it not gratifying to feel that your filament battery will al- paratively small and the results ways be ready when to be ob- you want it and that tained are indeed great. It needs but some- you will never have to thing of this character to stimulate a sum- give up in disgust mer time interest among the amateur radio when working a dis- bugs, which may tant station? compare quite well with F-F Battery Boost- the interest previously shown during the ers are automatic ana winter. operate unattended. THE SUMMER -TIME ANTENNA Screw plug in lamp socket, snap clips on FADA BINDING POST With most vacationists, the erection of battery terminals and the antenna has ever and always been see the gravity come up. This post Is an original FADA design and is The ammeter shows you made of brass with a looked upon just the amount of non- removable knurled top with some misgiving. It has current flowing. The full wave of '/z" in diameter. The 6 -32 screw post has no always current is screw -driver slot in the top. Very highly hand meant the erection of temporary rectified thru adjustable carbon electrodes buffed, nickel plated and polished. No frills, but masts, or the locating of sufficiently strong which maintain a constant efficiency and a sturdy most beautiful appearing binding post last for thousands of hours. that costs only $0.16 each or $1.75 chimneys from which to suspend the out- Everything per dozen. door components complete in one compact, self- contained unit. of the set, and it has not The F -F Battery Booster is a Magnetic Rectifier for AMPLIFYING TRANSFORMERS infrequently resulted in very serious argu- 105 -125 Volt 60 Cycle Alternating Current. Bantam Type 6 Charges 6 Volt Battery 6 Federal unmounted, I lb $6.00 at amperes. $15 ments with neighbors who had the Type 16 charges 6 Intervalve No. 712, the new transformer of "Light- Volt Battery at 8 amperes.... $24 Type 166 charges 6 Volt the Radio Corporation. The very hest one ning Bee" in their bonnets and who felt Battery at 12 amperes.. $32 Shipping Weights 10, made for Radiotron tubes, I lb 7.00 12 and 15 lbs. sure that radio stations were good for noth- Also Boosters for 12 Volt Batteries at same prices. ing other than tempting Order from your dealer or Send Check for prompt GENUINE BAKELITE demon lightning to Express XX play havoc Shipment. If via. Parcel Post have remittance Sold cut right to your particular size. Prices with their domiciles. In large include Postage and Insurance Charges. Will also are per square inch postpaid. ye" thick, $0.02; cities, where the rapid growth in the num- ship C.O.D. Also F -F Battery Boosters for charging 3/16" thick, $0.03; y4" thick, $0.04. batteries from Farm Lighting Plants. Direct Current ber of antennae has been very pronounced, Circuits and Direct Current Generators. CONDENSERS (Fixed Mica Type) this bugaboo is rapidly dying; he is not For GROUP CHARGING use the Full Wave. Automatic dead. I say F -F ROTARY RECTIFIER of 100 Volt, 36 cell capacity. FADA quality -made of Bakelite XX tested mica this with a heart filled with Order now or write today for Free Descriptive and copper foil. 21/2" x 34" x %" sorrow, because he has shown Bulletin 32 No. I13 -A 0.00025 me that he No. or ROTARY Bulletin No. 32A Mfd $0.85 is still alive, ole &works. No. 114 -A 0.0005 Mfd 0.85 thru the person of my next - THE FRANCE MFG. CO. No. 115 -A 0.001 Mfd 100 door neighbor, who Cle vvell and, Ohiof No. I16 -A 0.002 Mfd 1.50 very unceremoniously Can. Rep.: Battery Serv. & Sales Co., Hamilton, Ont. No.. tl7 -A C. W. Phone Work 0.0005 1.00 chopped down one of my masts, without No . 1 18-A C. W. Phone Work 0.001 1.50 warning, for the very G. W. Condensers tested at 1000v. 100 watts, important reason that overall dimensions one of my 3" x I" x 3/4 ". antenna wires crossed the Reynolds Radio Specialty smallest fraction of a corner of his prop- Company CONDENSERS (Variable) erty, but that is another story. However, No. I Chelsea .001 Mfd. mounted $5.00 in The Largest Exclusive Wireless No. 2 Chelsea .0006 Mfd. mounted 4.50 the country the bugaboo is not as dead No. 3 Chelsea .001 Mfd. with dial 4.75 as he is in the city and many unpleasant Supply Store in this section No. 3 Chelsea .001 Mfd. without dial 4.35 No. 4 Chelsea .0006 Mfd with dial 4.25 words have been spoken in an attempt to of the Country. No. 4 Chelsea .0006 Mfd. without dial 3.85 melt the hearts of those who have not seen No. 41 Chelsea Dial and Knob, 31/2 inches We in dia. for 3/16" or 1/4" shaft 1.00 the light and will not listen to reason." carry a large stock of the following radio Shipping weight I pound per condenser "There is always a way, where there is supplies and can make immediate delivery. CRYSTAL DETECTORS a will," said Themistocles, or somebody AUDION BULBS CRYSTAL DETECTORS like that, so SOCKETS MOUNTED & UN. FADA No. 101 -A $3.00 a method has been tried which RHEOSTATS MOUNTED CRYSTALS FADA Mounted Galena Crystals, each .50 has proven entirely satisfactory. In this, PHONES D IALS I feel sure, you find CONDENSERS BUZZERS INDUCTANCE TUBING will interest and in TUNING COILS AMPLIFYING TRANS- order to be certain of holding your atten- COUPLERS & VARIO FORMERS Gondensite- Celeron tubing with yeth inch wall COUPLERS PLUGS & JACKS cut to size. Prices are per inch postpaid. Di- tion to the very end, will mention at the LIGHTNING GROUND SWITCHES, POINTS & mensions are outside diameters. beginning, that signals received by SWITCH ES BINDING POSTS 3 inch .... $0.25 3yz ineh....$0.30 the DEFOREST COILS DE FOREST UNIT 4 inch.... 0.34 41/2 inch.... 0.36 method to be described, using naught but COTO COILS PANELS 5 inch 0.40 a detector, are at least as MOTOR GENERATOR PRACTICE SETS strong as those KEYS WIRELESS BOOKS & LITZENDRAHT WIRE which are heard with the ordinary method METERS MAGAZINES when a single Complete No. 10 -38 per 100 feet $0.60 stage of amplification is Stock of De Forest, Murdock, John Firth No. 20 -38 per 100 feet 0.90 employed. and Clapp Eastham Supplies. No. 3.16.38 per 100 feet 2.00 IN BY -GONE DAYS Send 2 cent stamp for bulletins TELEPHONE HEADSETS One day Jamaica, L. I., the town where REYNOLDS RADIO SPECIALTY CO. The new Murdock with Navy type headband can my boyhood was spent, held a celebration not be beaten at the price. 613 19th Street Denver, Colorado No. 56 2000 ohm $5.00 for the opening of a subway or something No. 56 3000 ohm 6.00 and there were polo matches Brandes `Superior" 2000 ohms 8.00 and wild Brandes "Trans- Atlantic" 2800 ohms 12.00 west shows and hot dogs and lemonade Brandes "Navy Type" 3200 ohms 14.00 and ticklers and Baidwins Type G, Navy Standard.. 16.50 confetti, but most of all Baidwins Super- Sensitive Type E 20.00 there was a kite -flying contest. Off on a RADIO Shipping Weight each set I pound. high hill, behind the town, they held it, VACUUM TUBES and the winner of one of the events was a TELEPHONE & TELEGRAPH Radiotron UV -200 Detector $5.00 man named Poulsen, who lived in Jamaica. Radiotron UV -201 Amplifier 6.50 From that time on my dad was perpetually APPARATUS OF MERIT Radiotron UV -202 5 watt Power Tube 8.00 No. 119 -A FADA Tube Socket 1.75 dunned for the wherewithall for the pur- Shipping weight I pound each item chase of kites, mattress twine and reels and R20A Rotary Enclosed Gap $25.00 R20B Same without motor DETECTOR & AMPLIFIER PANELS picture wire and percaline.. Before the 20.00 glamor of Rl Open Rotary Gap 16.00 Four FADA instruments that are better than the hobby had worn off our cel- you over hoped to use. Full automatic control lar was bedecked with all manner of kites ÚV200 Radiotron Detectors 5.00 of all filament circuits. Postpaid. and - UV201 Radiotron Amplifiers Detector Control $17.50 kite equipment. 6.50 Detector & 1 stage Amplifier 45.00 Then in walked radio. The kites were ÚV202 5 -Watt Transmitter 8.00 Detector & 2 stage Amplifier 65.00 abandoned and Two stage Amplifier 50.00 all the neighbors were Send 4c for 55 called in our -page Catalog. All orders for apparatus not listed to help in the erection of a pole Full of illustrations, information as postpaid must be accompanied by in the back yard. At that time radio was and prices that will prove attractive postage charges. not such a general hobby for youths as OUR SERVICE TO EACH OTHER WILL it is today, and my station came to be KARLOWA IMPROVE ON ACQUAINTANCE. looked upon with awe by the folk there- RADIO CO. ORDER YOUR SUPPLIES about. It was frequently 611 Best Bldg., Rock Island, Ill. FROM FADA out of order and the services of one more experienced in the art than myself always had to be sought. You can be quickly cured, Frank A. D. Andrea In those days it was a very rare thing to if you hear signals all the way from MCC, the 1882A. Jerome Ave. New York old Marconi station at Cape Cod, Mass. STAMMER In Mr. Gernsback's Modern Electrics, Send 10 cents for 288 -page book on Stammering and which circulated about that time Stuttering, 'Its Cause and Cure." It tells how and which cured myself after stammering 20 yrs. B. N. Bagua dealt more or less with radio as it was 871 Bague 61dg., 1147 N. Ill. St.. Indianapolis.

www.americanradiohistory.com Radio News for June, 1921 917 TESTED RADIO CRYSTALS Mounted in Fusible Metal Buttons and inserted in Nickle Plated, Rotary, Detector FERRO -PYRITES Cups, Ready for use, with Screw Washers and Nuts NAVY -YARD TESTED GALENA CRYSTAL 75c TESTED ULTRA -SENSITIVE FERRO -PYRITES 75c TESTED HIGHGRADE ZINCITE CRYSTAL 75c TESTED FUSED SILICON PIECE 75c Each Mounted Crystal, with its Detector Cup as described above is packed in individual wooden box, stamped with date of testing. MONEY BACK IF NOT SATISFIED - All Shipments Prepaid THE SYDNEY SPECIALTY CO., 43 Murray St., NEW YORK If Your Dealer Cannot Supply You, Send Your Orders Today to: z THE SYDNEY SPECIALTY CO., 43 Murray St., New York ENCLOSED FIND HEREWITH $ FOR WHICH SEND ME GALENA ZINCITE FERRO -PYRITES SILICON a NAME ZINCITE ADDRESS TOWN STATE

STOP ! LOOK ! and ACT!

A Photon V,T. Amplifier, U.V. 201, $630, or an A.P Navy FREE/ Type V.T Amplifier, $7.00, will be given FREE with each Radio Magnavox purchased from us, not later than June 30th. ME RADIO MAGNAVOX The latest development of the Magnavox Company THE RADIO MAGNAVOX THE RADIO MAGNAVOX when used with a suitable amplifier will is manufactured under the same patents give forth signals of far greater volume and on the same electrodynamic prin- than any other receiver. ciple as the MAGNAVOX Radio Tele- megaf one. THE RADIO MAGNAVOX will allow you to have your friends THE RADIO MAGNAVOX listen to all incoming signals without will reproduce signals with the same the necessity for additional apparatus. volume as the Radio Telemegafone. THE RADIO MAGNAVOX THE RADIO MAGNAVOX will reproduce radiophone speech, or can be operated on 2, 3, or 4 dry cells music to such a degree that it may be with wonderful results. A six volt stor- used for dancing if sufficient amplifica- age battery with rheostat is recom- tion is available. mended for continuous operation. QST THE RADIO MAGNAVOX WDNT U LIKE TO HR SIGS does away with a continuous watch, al- QSA lowing the operator to hear what is go- ALL OVER YR HOUSE? ing on at his station while in another The Price is within reach of all part of the house. You need it in your station. $45.00 THE KEHLER RADIO LABORATORIES Dept. R, ABILENE, KANSAS

www.americanradiohistory.com 918 Radio News for June, 1921

then known, stories began to appear of spectacular feats in reception, which in- The Newest de cluded the use of a leader -pipe for an an- Forrest Radio tenna, and the like, So, one day, in keeping up with the age of experimentation, Apparatus Now in Stock the long -forgotten kites were summoned from the cellar and the mattress twine was FOR IMMEDIATE DELIVERY substituted by a roll of single cotton covered wire. The kite was flown and the We also carry a full line of all other standard signals which followed were exceptional. radio and telephone equipment and parts. Our The kite was left flying until late at night wireless specialists and before it had been hauled down, old will gladly give you any advice MCC or assistance you had been heard by all the formerly need. When in Philadelphia come incredulous neighbors, altho none of them in to our showrooms and have us demonstrate the knew what was being transmitted. The newest inventions. No obligation to buy. Our increase in the signal intensity over the Radio Department ordinary antenna was very marked. Vertical Panel -style has grown to its present size A few years afterward, mounting, without cabi- through the two very good net. Two legs hold each same fair and helpful service, for friends of mine spent their vacations in the panel upright. Any num- which upper part of ber of panels may be our general electrical department has been New York State and car- joined and mounted this ried portable sets way. known since 1852. with them, which they used in conjunction with antennae suspended Sole Distributors in Philadelphia from kites. One had a station on for de Forrest Apparatus shore and the other put his in a canoe and let the kite pull him out into the lake. They communicated back and forth, much to the CENTRAL ELECTRIC astonishment and amusement of the other guests, as well as to their own satisfaction AND LOCK COMPANY and pleasure. In those days a galena de- EST. 1852 tector was about the best available and 1309 ARCH Horizontal Table -style mounting. Legs attached therefore the results obtained ST., PHILADELPHIA, PA. to corners of each panel. Any number of panels in the more can be mounted in this style. Ample space under recent tests, owing to the use of regenera- Radio panels for batteries. A very and Electrical Supplies convenient and in- tive receivers have proven to be a revela- expensive method of mounting. tion. That is the form of antenna, which is very easy to get into the air and which produces results beyond the most optimistic expectations. No need for masts, wrang- TRESCO ling with the neighbors or anything of the TEN $ TUNERS sort and just about the best of working with little or no trouble. SOME RECENT TESTS When you think of tuners say TRESCO. Two portable sets, such as here shown One for every need and wave length. were recently used with kite antennae and CIRCULAR FREE. the results were in every way satisfactory. This is the tuner. One station was rigged up on shore and the other in a canoe. In the case of the AS- Arlington tuner -600M to 5000M. shore station, a kite BS Never was flown from the -Long Wave tuner-5000M to 25000M. Silent. dock at the Bayside Yacht Club and was CS- Amateur tuner-200M to 600M. maintained at a height of approximately Coils for either $6.00 and P. P. Used During three hundred feet. DS the The wire kite string -Short Wave tuner $6.00 and P. P. was brot to a small strip of bakelite All three tuners, AS, BS, CS, same general Summer which was used as an insulator shape except and from that the BS tuner has no tickler Static Season it to the terminal of the portable set. coil. In the canoe, arrangements were made whereby the occupant who acted as opera- I received one of your NAA tuners and tor sat in the bow, facing aerial. find them very good. Using a forty -foot the stern and NAA comes in like a ton of bricks. I can get NAA on having the set strapped come in good, too. a bed spring Arcs to the seat before Boys that come to see my net say what good is that little box, him. The kite antenna, but when they hear it working they take their hats off. in this instance, was raised on the dock and then the JOHN LEHTINEN, of the end 1054 River St., Fitchburg, Mass. string (wire) was fastened to in- 10c for Regular Catalog sulator which in turn were fastened to the struts of the canoe. This method of se- curing the antenna served to prevent the TRESCO DAVENPORT occupants from receiving any jolts from - IOWA the transmitter. The ground, in both cases was provided by simply attaching a piece of wire to a brass rod and throwing it into Quality the water. Radio Equipment By having both antennae of approximate- RADIO MAGNAVOX TYPE R -3 ly Latest development in sound amplifiers; the same length the communicating dis- on a protected ele tance of the naturally limited power of the tro- dynamic principle. Emits same transmitters was considerably volume of sound as higher priced augmented. Magnavox Telemegafone. $45.00 THE RITE It may be said, from observations made RADIOTRON VACUUM by Recognized TUBES the writer and those with whom he has as the amateur's and experimenter's stand- conferred on ard for Radio detection, amplification and power work. this subject, that there are but Radiotron U. V. 200 de- Radiotron two types of kites suitable for use in tector U. V. 203 con- $5.00 power tube, 50 watt 30.00 nection with radio work, where Radiotron T.T. V. 201 Special sockets for U. V the best amplifier 6.50 results are desired, giving Radiotron 203, now to stock, the least bother: U. V. 202 each 5.00 they are the "Eddy" and power tube. 5 watt 8.00 (Postage extra on all prices.) the "Aeroplane" or combination kite. The latter is suitable RADIO SUPPLIES FOR CAMPERS for a strong wind and is very steady in its Receive N. A A. Time, U. S. Weather flight, which is Reports, Baseball Scores, Press News, an important factor when Stock Reports, eta, while in camp by C.W. is being received, due to the change using the new GREBE TYPE GR-5 in capacity caused REGENERATIVE RECEIVER, 150- by the raising and low- 3000 Meter wave length range. In op- $80.00 ering of the wire to and eration the last ward in simplicity. from the ground. These kites are harder to make than the former ones mentioned, Dealer's Special Proposition -Mail orders promptly filled and will not fly so readily in a light breeze; therefore, for DOUBLEDAY- all around working it has been found that HILL ELECTRIC a 5 -foot 715 Twelfth St., N. W., CO. "Eddy" kite using an S. C. Washington, D. C. Radio Dept. Desk B 719 -21 Liberty C. cop- Ave., Pittsburgh, Pa. per wire 20 B. & S. is quite superior every respect. in

www.americanradiohistory.com 919 Radio News for June, 1921 PARAGON MEANS "A PERFECT MODEL OF EXCELLENCE" AND IT IS FOUND ONLY ON CONDENSERS DETECTORS SWITCHES RHEOSTATS KNOBS AND OTHER RECEIVERS VARIOMETERS SPECIALTIES V. T. CONTROLS DIALS SOCKETS Manufactured by ADAMS- MORGAN CO. No. 70 Paragon V. T. Control control panel consisting of a standard socket, rheostat, grid A compact a moulded con - condenser, grid leak and nine binding posts mounted on nickel metal parts. A high -grade inexpensive in- densite panel. Polished cabinet. strument that will do as good work as the highest priced Price - - - $6.00 No. 25 Paragon Rheostat mounting. Moulded condensite base. Resistance six For either panel or table grade rheostat ohms. Smooth operation. Capacity 1% amperes. The highest on the market. Price - - - $1.75 MOST ENTERPRISING DEALERS CARRY PARAGON PRODUCTS AS REGULAR STOCK. Illustrated Bulletins will be mailed upon receipt of a two cent stamp. Send us your dealers name. ADAMS -MORGAN CO. UPPER MONTCLAIR NEW JERSEY

MN, A Better Rheostat for less money. Quality at a reasonable cost. That's what you get when you buy FADA rheostats. And here's the quality- of made with a base of Thermoplax (2 /g in. dia.) into which is forced a strip hard fibre wound with Advance resistance wire. Thermoplax is an asbestos - bakelite sheet that resists heat better than genuine bakelite XX. The resistor heat strip is exposed as much as possible and consequently allows the necessary radiation. Can be used for panel mounting on panels up to I/O' in thickness. as Furnished with a polished nickel -plated pointer and a classy bakelite knob well as two nickel -plated machine screws and nuts for fastening to panel. The that can be smoothest adjusting 6 ohm rheostat to safely carry I/ amperes produced. EACH BY MAIL POSTPAID OR AT YOUR DEALERS

FADA instruments MR. SUPPLY STORE MAN. -Here is the plain truth. with and parts are fast gaining a universal reputation for selling quickly cut -price radio no comebacks. They are not a collection of bargain store at a price the supplies. If you desire to sell the highest quality instruments most liberal -you buyer gladly pays, write me your plans. My discounts are profit accordingly.

Frank A. D. Andrea 1882 A Jerome Ave. New York City

www.americanradiohistory.com 920 Radio News for June, 1921

,,,,,1,,,,,,,,11,t,,,,,IIIII,I,,,1111,,,,,,,1,,,,,,,,,,,,,,,,,,,,,,,,,,1,,,,1,,,,,1,11,,,,,,1, On the Job A Portable200 to 900 Meter - QUALITY Regenerative Receiver SERVICE PRICE (Continued from page 861) FOR THIS MONTH ONLY 22% Volt B- Battery small size $1.25 22% Volt 33-Battery large size 2.40 45 Volt Variable B- Batteries 4.00 CONDENSERS Chelsea No. 1 Mounted 5.00 Chelsea No. 2 Mounted 4.50 Chelsea No. 3 Unmounted with dial .0012 Mfd. 4,75 Chelsea No, 4 Unmounted with dial .0006 Mfd. 4.25 VACUUM TUBES Genuine 2 Filament Audiotron 6.00 13V200 Radiotron Detector Tube 5.00 ÚV201 Radiotron Amplifier Tube 6.50 UV202 Radiotron 5 Watt Power Tube 8.00 Electron Relay Detector Tube 6.00 /i////%/iii/ii/o Moorhead Amplifier Tubes 7,00 i/ TELEPHONES ÿN% Á/L/ Western Electric Telephones 14,75 /üii///////////////Í Baldwin Type C 16,50 d Baldwin Type E 20.00 Murdock 2000 Ohm 4,50 The/ distinction Corwin Dials Murdock 3000 Ohm 5.50 impart to a radio station is 73 AMPLIFYING TRANSFORMERS only exceeded by their accuracy No. 226 Federal Mounted 7,50 /5 .1 A -2 Acme Mounted 7,00 and ease of operation. Prices A -2 Acme Semi -mounted Top View of 5.00 are as low as economical pro- the Cabinet Showing its Size. A -2 Acme Unmounted 4,50 duction and efficient marketing We have a limited supply of the new will permit, with Radio Magnavox 45.00 due regard Radisco Variable Couplers 7.50 for quality. Outside of that, Murdock Variable Coupler 8.50 Murdock there isn't any - particular rea- case it is a chestnut box with a natural Moulded Variometer 7.50 son for specifying Corwin varnish finish. A strip of wood is fastened Chelsea Moulded Dials 1.00 Dials. A. H, Corwin Dials 3" 1.25 3" Dial, 75c -with knob, $1.30 to the inside of the box along the top, so 3W' Dial, $1.00 -with knob, $1.70 that the panel may be secured to it by KELLY & PHILLIPS Radises Al all Radisco the wood screws. The arrangement should Agency agencies, 312 and other reliable dealers, he followed out as in Fig. 2. If a slightly Flatbush Ave. BROOKLYN, N. Y. or sent postpaid anywhere different arrangement be substituted be sure the parts will fit into the box and will not A. H. CORWIN & CO. hit 4 West Park St., Newark, when being worked. The exact kinds of IMMEDIATE DELIVERY N. J. contacts, switches and knobs to use, I leave to the builder, as he on any standard make of Radio Apparatus. knows best what he Chicago and Middle has laying around the workshop. In the West distributors for: next Acme ClappEastham Federal step, great care must be used, espe- Redio Corp. Brandes. General Radio cially in duplicating the secondary and tick- DeForest Grebe - ler Burgess John Firth Murdock - R windings. Chelsea T herd arson = KL AUS Take a bakelite tube 3%" in diameter and 'Complete stock-every order shipped same - D 4%" long (good stiff cardboard will do day it is received. New, big catalog ready also) and drill holes as follows along the soon; send now for free bulletins. Blue = I Print of Radio Telephone and C.W. Trans- length of the tube. (No. I.) /" from top, mitter for 10e. = O (No. 2.) from top and one (No. /" 3.) Chicago Amateurs -Come and see our new diagonally opposite this one on the other Radiophone in actual operation. side. (No. 4.) 4/" from top. The upper CHICAGO and lower ones will serve to fasten RADIO APPARATUS CO., Inc. the 50 8So. KLAUS RADIO CO. tube to the panel, and the other two will Dearborn St. (Room210) Chicago, Ill, Manufacturers and Designers allow the rod on which the tickler is mounted to pass thru. Holes must be drilled in Eureka, the panel to CHALLENGE "A" BATTERY Illinois match these. See Fig. 2 and (JOHNSON PROCESS) Fig. 3. The latter shows very plainly the Radio Type 2-Volt Cell method This battery is de- :5111I11111111I111111111111111111111111111II1111111I111L of assembly, the coil and also the signed for filament JIIIIIIIIIIIIIIIIII111111IIIIIIIIIIIIIIIIIIIIIIIIIIII lighting purposes. tickler. Winding "B" (Fig. 3) is the Assembled and sealed primary and consists of about 6o turns, and in glass Tars, enabling LIIIIIII11111111111111111111111111111111111111111111111fi llllllllliilllllllllllllllllllllllllllllllllllllllllllll you to watch the con- is tapped off evenly to 15 points. This may dition of the plates. Authorized be reduced to to points if so desired but Lead connecting 15 give better results. straps furnished Distributors for The winding starts Each cell 35 A. H. i34" up from the bottom and goes down. 2 v. with rubber nut Grebe terminals. Simple to De Forest connect with as many Size of each cell 8% high cells as may be re- Murdock x 6% wide x 2%4 long quired for proper over all. voltage. The beet Moorhead BATTERY for your Clapp -Eastham s NONE BETTER work Boys. Radio Corporation fibre Price in sets of three cells (6 VOLTS) $11.48 Acme Challenge Battery 16 IlliAGnois SLt., Amrad Co., CICO,HW- IL. Brandes IYdxedp Baldwin pr Send for our Bulletins fiy. 7 AMATEURS -- Sea/lag wax Our stock of CW and Spark Radio appa- iIIIIIIl1111NIII111111111111111II111111II111111IIIII1111111111HI111UIIliIIIIIl11111NIIN111111INlllllllllllllllllllllllllll ratus is complete. Send us your order and llllllllm-- it will be filled same day it is received.

N. P., 110 volts, ---6Yood- T & . H RADIO CO. s7`ri,p A C 60 cycle ANTHONY, KANSAS 4 single phase, 1150 R. P. M. 0 oRS LARGE QUANT TIES NEW WASHING MACHINE MOTOR$ rhe. o( derd m ,d y fuf 1 só .5a/der G r Cee ñdr . Cream Sep n tos . Bottle e Washers.a Mir Cem Small rwr,. e.. leads TELEGRAPHY . (Both Morse and Wireless) and RAILWAY ACCOUNTING WeesillxndCOD mill 6 Bter 7 5 -Brads taught thoroughly and quickly. Big salaries now paid. to lull Great oppoxttuUmues for advancement. Oldest New Parks Each ochOol; and largest 1 rmeratW - 1, rr' Vet PIMP established 46 years. Endorsed by Telegraph, Rail - MA NON1CTLIP[A'S way, Radio, and Government officials. Expenses low - CHAS. opportunities H.1OHNSTON - Box' ti e W. E,PlIbburgli,e Pa. Constructional Details of the Condenser and to earn large portion. Catalog free. DODGE'S Coupling of the Tickler Coil. INSTITUTE D Street, VadpareleoIna.

www.americanradiohistory.com Radio News for June, 1921 921

REMLER TYPE 330 VACUUM TUBE CONTROL PANEL FOR THE NEW TYPE C -300 DETECTOR TUBE

REMLER Maximum Value and Quality Through CONTROL PANE, TYPV. 33V Quantity Production THESE SPECIFICATIONS SPEAK FOR THEMSELVES Genuine bakelite, highly polished, 5" x 71/4". White filled en- graving. Special smooth running rheostat back mounted. All bakelite VT socket. The new Remler positive metal contact potentiometer for controlling plate voltage. Variable grid leak. Fixed grid condenser. Busbar wiring. Hard- wood base. All metal parts polished nickel Price $8.00 DEALERS: Send for our trade proposition on Remler Apparatus. "Apparatus that Radiates Quality" REMLER RADIO MFG. COMPANY 163 Sutter Street, San Francisco, Cal.

Federal Standard Radio Accessories ANNOUNCING A Material Price Reduction on the Famous Federal Amplifying Transformer Price, Effective June 1st, $7.00

Federal 226 -W Transformer will give Maximum Amplifi- cation with all types of Standard Tubes on the market.

Write for Bulletin 102 -WB and C Circular describing New C -W Accessories

No. 226-W- Type A Ask Your Dealer for Federal Products. If he does not have them, tell us his name. Audio Frequency Transformer 5i1:ictat & ttcçrapj Co. i3uff ato, Pali pork, &. '. t. MANUFACTURERS OF STANDARD RADIO ACCESSORIES

www.americanradiohistory.com 922 Radio News for June, 1921 Number 28 wire or finer should be used; :! the kind of insulation used does not mat- _ ter, single cotton covered is satisfactory. CFSS The secondary winding consists of 50 turns Wirefor every Wireless Purpose of the same size wire as the primary, with Úfi -AItKS= one tap taken out. The winding starts "`TTICAIACADEMY G about 2" away from the primary winding and a space is left for the rod supporting VAÇHO®L_ the tickler coil, to pass between. Figs. 3 MAGNET WIRE and 4 illustrate the windings very clearly. NEW YORK BOSTON The tickler coil has 4o Offers a thorough course in We are prepared to furnish best turns of the same all branches wire and a space is of wireless teleg- grade magnet wire on % and 1A lb. left in the middle of raphy. Radio Operators earn spools at the winding, also, for the brass rod. The st the start $125.00 the following revised ) per month, prices: tickler is 21/2" in diameter, and about i %" and first class board, etc., free. long. Our school PRICE PER LB. prepares you for I SPOOL Trouble is your license in three to four Single Double Single often experienced with flexi- months. Positions guaranteed B &SGa. Cotton Cotton Silk Enameled ble leads breaking off. Here is a good -, to first grade licensed opera- No. 22 $0,56 $0,68 $0.62 $0.45 wrinkle. Find some old telefone receiver tors. Also MORSE TELEG- No. 24 .60 RAPHY. .77 .67 .47 cord and cut off two pieces, each about a No. 26 .65 .88 .71 .49 Day and evening classes. No. 28 .75 1.10 .85 .52 foot long. Pull back the insulation and No, 30 .85 1.24 .97 .53 wind bare wire around the tinsel on all The leading Nautical School in No. 32 1,15 .55 four ends. Now make U. S. A. 1804. No, 34 a wooden piece as Established 1,52 .59 in Fig. 8. No. 36 1.77 .69 This, when drilled, is placed in- CAPTAIN F. E. UTTMARK, Principal Price on lb. spools side the coil and fastened with a couple of / double above list. Write, call or phone for illustrated All prices are net and include cost of brads and sealing wax ; the hole in the spool and delivery charges via Parcel center is to allow the brass rod to pass thru. booklet. Post to any Post 'Office address in the The ends of the are 'United States; safe delivery guaranteed. wire brot to two brass machine screws, and the prepared tinsel 8 STATE ST., NEW YORK, N. Y. Send for Circular 21 -A giving prices on other sizes, insulations and quantities cords are now soldered to the screws, or Facing Battery Park, N. P. of Magnet Wire, This circular lists else fastened with nuts. "WIRE FOR EVERY WIRELESS Telephone, Bowling Green 8079 POSE." PUR- A good, efficient and compact fixt con- E denser may be made by cutting two strips UTTMARK'S for Nautical Educatie of tinfoil 4" x I%" and two strips of waxed KEYSTONE WIRE COMPANY paper 4%" x 1% ", also a piece of fibre 3" long drilled as follows. 5I111IIIIlIIIIIIIIIlI11II1111111f1I11I1111111111111I1F P.O. BOX 120 InIF SCRANTON,PA. (Hole No. 1) %" from end, (No. 2) /" from end, (No. 3) 2%" from end, (No. 4) 2/" from end. The IIfIimÌi1Il1111111 sheets are assembled as in Fig. 7, and the Canadian Amateurs whole wrapped around the fibre and bound with string of tape. The tinfoil is pushed ATTENTION thru the two inner holes and a brass screw It will save you $$$$ to keep in Canadian Radio Experimenters and nut or a binding post placed there. The SPECIAL two outside holes are touch with us. Radio.' used for fastening Storage Batteries the condenser to the base- board. The whole We give you QUALITY, SER- 40 Ampere hour, 6 volts $22.00 condenser may, if desired, be dipped into VICE, and a 60 Ampere hour, 6 volts 25.00 melted SQUARE DEAL. Baldwin Telephones, Type C 24.75 paraffin. Brandes Telephone, Superior 12.00 The secondary loading coil is wound on a Brown's Famous THI ' 18.00 tube 3" in diameter and wide. Receivers NHI 21,00 I/" There used by, The Admiralty, Murdock Telephones, 2,000 ohm 6,00 are 5o turns with a tap taken out at the Air Force, 3,000 25th turn; Foreign and Colonial Armies and Navies. ohm 7.20 this tap should be about 7" long. Tests lately Lateral Coils to order. In my set the coil is mounted behind my made show an efficiency of Inductances for Wireless Telephone. variable condenser three times that of any other telephonic Milliammeter and Hot Wire Meters. to which it is fastened head gear. Vario- Couplers and Variometers 4.25 by three copper wires. If the expermenter Transmitters for Radio Purposes. 3.50 uses a different 4000 Ohm LOOK condenser he can perhaps $19.25 LOOK LOOK mount his coil on the 8000 Ohm 20.50 HP 110 volt 25 cycle Menomi- base-board by using a Shipping nee Motors 30,00 ube of smaller diameter and greater length weight 2 lbs 1/5 HP 110 volt 25 cycle Menomi- and of course more turns of wire. Now, Send .05c for our list nee Motors 25,00 a word or two about assembly. 1 /10 HP 110 volt 25 cycle Menomi- The taps THE VIMY nee of the large tube should be SUPPLY CO. Motors 20.00 soldered first 567 College Street TORONTO, Send 5c for 30 page catalogue and then the tube mounted. (All switches, ONT. etc., should be on panel). Now the tickler J M. PAQUIN coil is mounted The Electrical Shop and connections soldered. The first condenser is screwed on next, 787 Queen St., West, Toronto, Ont. and PUGET TRANSFORMERS then the variable is put in. The loading inductance is put in last. It is advisable to The last word solder up the connections in transformers 3000 on the short - that are really designed POST- wave switch before screwing to put Ohms PAID on the varia- energy into your condenser. ble condenser. Fig. g shows the way the different parts are to be connected. You 25,000 Volts and Resonant cannot be too careful in putting in the connections. Gives a clear note with an Amrad gap and excells all makes for long The socket is mounted on top of the box. distance. Wherever a connection goes from the panel to the box, use a flexible lead about a foot 500 Watts- $26.75 long so that the panel can he pulled out at any time for inspection. Northwest Radio Service Co. The top of the panel is screwed 99 to the 609 Fourth Ave. Seattle, Wash. "RED HEADS strip in the box and the bottom to a board 6% ". The Accepted Standard in Radio Receivers. x A hole is bored in the center At the new price of $5.00 (formerly $12.50) of the under -side of the box and counter- "Red Beads" are unquestionably the best wireless sunk. A wood screw thru this hole and 'phone value in the world. Increased production, into For Various Reasons decreased costs and a sincere desire to promote the base-board of the panel prevents - lower prices prompt this remarkable saving. the bottom of the panel from moving. P articular SPICIFICAI`IONS: Aluminum back type with I have genuine bakelita ear caps, government type head no handle or strap on my set, as R adio band, extra fine 6 ft. cord with strain loops. it will go in my suitcase Mach receiver 1500 ohms (3000 ohms per pair). or on my motor- ;AC,,,, A mateur Sold on a money back guarantee basis and cycle. The experimenter can easily screw shipped prepaid anywhere on receipt of price. Dealers: Write for complete information. a leather strap to the sides of the case, C ustomers much in the manner that is used in at- O rder from us. THE NEWMAN -STERN CO. taching a strap to a storage battery. PENN Newman -Stern Bldg., Cleveland, Ohio With these directions RADIO APPARATUS CO., Inc. and by careful Box 110 study of the illustrations, I believe any Reading, Pa,

www.americanradiohistory.com 923 Radio News for i une, 1921 experimenter can build for himself this set and I am sure he will be more than pleased with the results. I shall be pleased to answer any questions which may arise about the set, its construction, or operation. HRAMCO

Married Via Radio REO (Continued from trage 877)

garding Kennison and the mysterious girl. Lighting the transmitting bulbs to a bright incandescence, the excited young man prepared to make the call. 'l he girl was the first to call; she had started fifteen minutes earlier than the night before. "Hello, Charlie," she greeted, "are you listening ?" The wireless operator won- dered how he had become a first -class friend again. Likely the dispute of the night before had been settled. "She's calling me, fellows," Kennison called into the transmitter, then with less emphasis : "Yes, I'm listening, won't you please tell me who you are ?" Let it be known here that Kennison was twenty -three years of age. "Cut the comedy, Charlie," roared an amateur spark, "we don't hear anybody." "I have three steps working," shrilled another spark. "Please stand by, fellows," cried Kenni- for your power tube- son, "she's talking again, 23o meters is the wave." New type Shramco Reo, No. 90P. 1.5 ohm "You know, Charlie, I love you," the Nichrome resistance. Current capacity sweet voice was saying. "Please don't ask $2.00, 1 lb. postage. that question so many times." 6 amperes. Price question," said "I. didn't ask any such brass. Spring phosphor bronze blade. Charles in consternation. "I said nothing A BACK MOUNTED panel rheostat, spe- Base 3 ". Overall height 2/ ". Hand- about love." Numerous ha, ha, hi, hi's, cially designed for the Radiotron flashed thru the air. The amateurs were somely finished and accompanied by transmitting tubes. making sport of the "loony 'op.'" U.V. 202 and other an unconditional guarantee of com- "Let's not get into an argument like last Resistance element (i.5 ohm) is most out girl, "we are about to get plete satisfaction. Get the night," said the mounted on a solid married by radio and that's all there is to "Nichrome" wire, of your expensive power tube by it. Are you ready? The justice of the block of asbestos. Allows unusually using a good rheostat. Order a peace is with me." and delicate variation of the Shramco Reo today ! Now ready for Kenniston, "stop, accurate "My Lord!" yelled shipment. please stop, I don't even know you. How filament current. All metal parts immediate can I marry if I don't know you ?" "Ha, ha, hi, hi, hi," roared thru the air. "It is all settled and you know it," said for your VT detector the determined young woman, "are you and amplifier, use the original Shramco Reo type 90. Similar to ready ?" the power tube type, but with a "Nichrome" resistance of 6 ohms. Kennison said he was and added for the Price $2.00, plus postage for two lbs. Also available -"Midget" benefit of the amateurs : "I'm about to get type 90A, same construction, but a 5 ohm resistance and 2%" base. married by radio, fellows; stand by, please, and God help me." Again came the ready laugh of the amateurs. RADIO MFG. COMPANY Kennison heard the gruff voice of a man SHOTTON reciting the marriage sermon. "Do you take P. 0. Box 3, Scranton, Pennsylvania lawful wife ?" asked the this woman as your prices, man. Catalogue "K', listing a complete ine o high grade parts at reasonable "Yes," groaned Kennison. The girl an- sent to any reader of Radio News for five cents in stamps. swered a like question in a most sweet and delightful voice. The ceremony was soon terminated. "Charlie, my husband," laughed the girl happily, "two -." The voice broke off abruptly. Doubtless the girl's transmitter was out of order. Again and again the excited man called but received no answer. The amateurs were now making a huge joke of the affair and BARELITE PANELS the air was loud with their clamor. Kennison passed a restless night. Who 4 =Z" x x 3/16" married? 6/" Best Grade .35 ea, was the girl he had unwittingly Weight 5 oz. each $ hear He awoke from a troubled dream to READY MAY 15 the ringing of the telef one. WRITE FOR CATALOGUE - "Hello, that you, Cl- ariie? Byrne speak- Get a move on and ing; aren't you up yet? YORK buy the latest edition of the Call. Page DAVID KILLOCH COMPANY, 57 NEW five may interest you. So long, hope you enjoy reading it." The speaker laughed and rang off. "No doubt pertaining to my marriage," Have you something to sell or exchange ? A classified ad in Radio News thot the young man hurriedly putting on his will reach 40,500 for only 6 cents a word. clothes. "Oh what a fool I am. She must

www.americanradiohistory.com 924 Radio News for June, 1921

be some long distance from me if no one BACK TO OLD PRICES else heard her. Some `hook -up' I discov Special ered, that's one consolation." Introductory Offer of PARKIN RHEOSTAT Fifteen minutes later Kennison was read the Bronx Radio Equipment Co. ing page five of the Call. His face was 6 volt -60 ampere Storage Battery same as U. S. Gov't specifications 5000 flushed to a dark red as he concluded the sold last year article. for radio airplane work $10,00 at $1.00 40 Ampere Storage Battery 8.50 "Have you read the article in the Call ?" B Batteries, large type 1,75 his sister B Batteries, small type ,95 NOW REDUCED TO asked entering the room, then see- "Special" Electrose ing the paper in Insulators, his hand, "I see you have. 7 / "x /" column, navy type, each .50 Something new, isn't it, getting married by Navy Type Receiving Sets, original 75c wireless? I hope I'll never be as romantic price $245; our price $50.00 up Bakelite cut the size you want it, One - as that girl in Honolulu. Think of her de- quarter inch manding thick, 3c per square inch. such a foolish marriage from her Mail Orders Promptly Filled Due to the general fiancé. I suppose drop in the prices of she and the Lieutenant BRONX RADIO EQUIPMENT CO. raw material and to our large production, on the 687 we have battleship thot it was great fun get- Courtlandt Ave. NEW;YORK CITY been able to reduce all our prices ting married that Agents for Murdock, Federal, Acme to their pre -war level, and in some way, but I don't think so, and even lower. eases do you, Charlie ?" Others. New Catalog No. 5, listing our complete line, sent free. -..11W41.,,..w..,,,.",,.,,,,. Here are a few of the items: No. Postpaid Give Yourself 31 Audion panel with rheostat and B a Radio battery switch $8.00 Vacation 43 45 volt large B battery 5,00 50 PARKIN .001 mf. variable conden- (Continued from page 858) ser, unit only 1,60 ;84.4*ll'Itft-wi 51 PARKIN .001 mf. P.C. with knob and pointer 2.00 APPARATUS 52 PARKIN .001 mf. V.C. with knob all the world knows radio, at least by name. and 3" dial 2.50 It is not so. Not one in a hundred 53 PARKIN molded bakelite fixed of even and SUPPLIES condenser our educated people know anything more .70 about it than ITV 200 New Radiotron vacuum tube 5.00 that a ship in distress can use ROSE RADIO SUPPLY DEALERS it in calling for help. -If you are not on our mailing 604 Gravier St., New Orleans, La. list, write for new catalog and discounts. This season I have entertained at my station hundreds of people Send 10c for Latest Catalog PARKIN MFG. CO., San Rafael, who are far above Calif. the average in knowledge of world affairs - travelers, authors, representatives of big The business and learned professions. Not one original of them had ever listened to a radio mes- Now 25c sage. To put on the fones, turn a knob PLATE BATTERIES and bring in a station was a tested GALENA or delightful new Always something doing with Ersco Batteries crystals SILICON experience. on your plate. iIIIIIVUIId One of these guests, Ersco No, 503 22/ volts 2,00 a man who has been Ersco ' in every nook and corner of the globe No. 803 36 volts $ 3.20 and Black Fibre Panels, /x20x7 3.00 has used radio service many times, was Or cut to size .02% per square astounded at inch. what he heard. The first call ECONOMY RADIO SUPPLIES CO., he brot in was from a ship on which he 232 Sanford Street East Orange, N. J. had sailed. I read the call letters and showed him how easy it was to identify the ship by looking in the Be Sure of Results !- Insist Upon Getting call book. A few moments later he looked up with C. W. EQUIPMENT N. A. A. TESTED CRYSTALS astonishment and exclaimed: "f hear some- We stock a complete line of General Electric Power Tubes, Tuska Inductances, Acme Transformers, etc. one speaking P' And afterwards : These exquisitely sensitive minerals are the "Now they Get our literature and prices. best that money can buy for radio detector and are talking French!" wave meter work. Each crystal is individually I introduced Independent tested, wrapped in foil and packed in a con- this gentleman to a younger Radio Supply Co. venient lithographed tin container. N. amateur who has 3716 W. Douglas Blvd. (Arlington) Tested A. A. a genus for construction Chicago, Ill. Minerals are the original "BETTER RESULTS WITH LESS tested crystals. To avoid their many imitations, He immediately o J Bred the young man a EFFORT" look for the signature of J. S. NEWMAN on position in a summer camp. each box. Galena or Silicon, 25c. Also he ordered a receiving set and offered to pay cash At good Radio Dealers everywhere, or shipped in Brass Binding direct postpaid on receipt of price. advance. He now has his set and is op- Posts - 5c each erating it successfully and other sets are Switch Points, nickle - 4c each THE NEWMAN -STERN CO. being purchased from various concerns as a Battery Rheostats - - - $1.00 Newman -Stern Bldg. result of his interest. In the meantime No order Cleveland, Ohio the for less than 6 Binding Posts or 6 Switeb young operator is looking forward to an in Points accepted. teresting radio vacation. All kinds of Wireless Supplies. At summer and winter resorts there are DREYFUSS SALES CORP. 4th Floor. 150.152 many men of affairs who want to keep up Chambers St. New York, N. Y. WINO to the times but who cannot do all the read- BATTERIES ing and investigating that they would like to For Use With Radio Apparatus do. To them an hour spent in a radio room with an agreeable operator to show them NECTIGUT BUY DIRECT FROM MANUFACTURER how to work a set would be far more agree RADIO EQUIPMENT 6 Volt -4o ampere hour $13.40 able recreation than lolling in a wheel chair. Variable Condseners, Transmit- 6 Volt-6o ampere hour From such men flow streams of influence ters, Head Bands, Panel 15.58 which Switches, Etc. 6 Volt-8o ampere hour 19.85 would be of incalculable value to the science Connecticut dg War Tax included -Express prepaid. and business of radio and to the Tel. Elec. Co,, Meriden, Conn. hotels which are wise enough to put the Fully Guaranteed. demonstrations in their way. WIRELESS STORAGE BATTERIES Send Postoffice or Express Money As for the amateur operator he might Get a Good Storage Battery for Your Wireless Order. receive a good -sized tip if he looked like 4 Volt 40 Ampere hour capacity....$9.00 that kind of a guy: and if he showed a 6 Volt 40 Ampere hour capacity.... 12,00 The Wino Manufacturing Co. character which won the respect and con- 6 Volt 60 Ampere hour capaeity....15.00 717 Sycamore St. fidence of his pupil he might 6 Volt 80 Ampere hour capacity.... 18.00 Cincinnati, Ohio discover that Cash with order. We make Storage he had unconsciously taken his Batteries only first step to- MULTIPLE STORAGE BATTERY CO. ward those larger fields of effort which big P. 0. Box 183 JAMAICA, LONG ISLAND men seldom discuss for 1ec'z .ate of a listener whose intake will carry the juice without blowing a fuse. FOR ONE MONTH ONLY In order to introduce the INSTRUCTION, Radeq Control IfSTAM you stammer Panel to the Amateur, we offer attend no stammering schoolME these panels till you get my large book entitled `STAMMERING. Its Origin and complete with tube and B battery for 115. vanced Natural Method The Ad- Even the idle rich whose indolence of Cure," bound in cloth and stamped in and Add parcel post charges for four pounds, pure gold. Ask for special tuition rate and a vanity are pampered of "The Natural Speech FREE cope by hotels of a certain Radio Equipment designed to use apparatus Magazine." Largest. best equipped ano class are most successful echool in the world for the cure of stammering, ambitious that their children should you have on hand. Send specifications for stuttering, etc. No sing -song or time beat. The North- Write today. he clever and intelligent. Radio estimate. Weaten, School, Grand Ave., Milwaukee, Win might take 2166 the place of many a senseless fad if man- A. C. PENFIELD Conneautville, Pa.

www.americanradiohistory.com Radio News for June, 1921 925 aged by an amateur who could grasp tie situation. All the Little Willie Billionbucks must have real brains somewhere in their PROTECT YOUR VACU u=M TUBES ancestry or there would not .be money in the family and herewith, althó the characteristics which it transm_ts may skip a gen - INDEFINITELY! eration, is governed by fixt laws which pro - duce a genius once in so often if there is any real stuff in the blood. Also, playing opposite the Little Willie3 Multiplies the Life of Your Set are sometimes chorus girls who are not alto- gether the fluffy, brainless things they seem Destructive excessive amperage cannot Now, if some Little Willie, escaped from reach the delicate filaments of any vacuum parental guardianship for an hour, should tube if protected by a happen to be tête -a -tête with some Berenice Carrying in a not too brilliantly lighted corridor, and Capacity the zit sit from a radio room should catch 1 154, 14, 2, Radeco their ears and they should go to investigate: S/ and 3 amp. waves which carry Size % inch and if in the invisible over all. messages between persons on opposite sides SAFETY FUSE they should happen to see a of the earth 3 For parallel with those other waves which carry Slips directly on filament terminals of any from eye to eye and heart to heart standard socket without distorting springs messages or lowering efficiency. RADECO Safety $ 00 of men and women who are with each other Fuses positively protect your tubes indefi- then there might stir within them some long - nitely. dormant force which in a remote forebear RADECO Safety Fuses are equally valuable was developt by the struggle for existence. in all C.W. work preventing injury to meters as a serious resulting from shorts. Send today cash, They might begin to see life money order or certified check. 35c Each opportunity. They might study radio and it might lead them out into paths of useful endeavor. There might be averted a ship ORDER BY MAIL wreck of a family's proud hopes. It might go down in the annals of a nation that He 44 V. VARIABLE met Her at the Glenaether Hotel, or wher- ROTARY QUENCHED "B" ever it was, which always was noted for its SPARK GAP, $20.00 pad BATTERY $3.60 Include postage on 4 lba. unusual features. Complete in handy wooden case and aduatable phosphor Imaginative and improbable tho such bronze "jiffy' connectera Better than block batteries ever amount -if one 4.4 V. unit weakens prematurely, It can be a forecast seems, any man who removed and replaced-thereby not impairing total volt- ed to anything can look back to events which age, which makes this the best battery value is be had at any price. Set of 10 Renewal Units, 44 Volt, $3.10 were far more improbable before they hap- postpaid. Just the thing for C.W. work. pened but which shaped his life. Teaching spoiled children is not a joyous occupation as a rule. but an amateur who Ground Wire 8c Per Foot succeeded in really interesting a class of $7.00 Per 100 Feet No. 4 solid copper- rubber covered-triple braid-in- teen -age boys or girls of this kind at a hotel clude postage on 20 lbs. per 1000 ft. would not have to wonder where his next 100 amp. 600 volt lighting switches, $4. from. The advantages of a noiseless super - vacation was coming efficient rotary gap are now within the CHESS AND CHECKER MATCHES. reach of all. The casing is of cast Aerial Wire is Per Foot aluminum with the cover machined to make an enclosure for ex- 7 strands Na . 22 copper-Un plated to prevent oxidation. . ends airtight the There are enough chess and checker tremely light weight aluminum rotor Maximum radiation and strength. Include postage on in the world to support several magaz nes with hakelite insulation. Stationary 15 lbs. per 1,000 ft. hotel electrodes are of copper with Bakelite and keep the lights burning in many a insulation. The smallest gap motor may long after even the dancers have gone de he used, but is not supplied with gap. CHELSEA GET YOURS SET UP AT ONCE, and DIAL cently to bed. A hotel which would adver- INCREASE YOUR RADIATION AND and tise facilities for radio chess and checker RANGE!! KNOB of experts R matches would attract a group FILAMENT Front of Panel Made of best they might exhibit grade bake - who, whatever faults RHEOSTAT hms, ampss i I'/ lite runs ab- would at least be quiet. And moves I%" dia. solutely true matches are not made with sufficient rapid - and will net $1.75 p,d warp. D l a ity to tax the ability of even a ham. 3%4" in dl- Immediate ameter, 1/4" RADIO PRESS. Shipment. thick. Gen- Standard VT uine dial at Many of the best resort hotels are so far Socket a genuine cities that the morning papers are not Improved Price. from Contact received until afternoon. A hotel that would Dial $ 75 Type Dial and give its guests the morning paper's news the Knob.. 1.00 night before the paper came out would be $1.00 patio Copper foil Send popular. This service alone would be wort, condenser 35c p.p. Today an operator's room and board in any first - class house. A hotel today cann t justly claim to he first -class if it keeps its patrons waiting half a day for news when it is in the air all the time ready to be pickt up Besides the regular press dispatches an ama teur could pick up items about s-.ips at sea which would be of interest to the guests. RADIO EQUIPMENT CO. Very often it would be of vital importance to a business man on vacation to know that 630 Washington Street (4th Floor) Boston a liner was meeting head winds and would be a day late in getting into port. The weather is always a standard topic of conversation at vacation points as elsewhere and the fact that a certain hotel received PROUDFOOT SPECIALS the forecasts the very hour they were made PRE-EMINENT QUALITY -PRICES up by the United States Weather Bureau CANNOT BE DUPLICATED Vacuum Detector Cabinet, 7 "x5 4" $12.50 in itself. / would put it a class by Amplifier Cabinet, 7 / "x5 /" 18.00 It is not to be expected of course that Detector and One -Stage Amplifier, 74"x6 /" 25.00 hotel managers. ignorant like the general Detector and Two -Stage Amplifier, 74"x9" 35.00 is reliable a Regenerative Set, 7/ "x14" 35.00 public of the fact that radio as Regenerative Set with Detector and One -Stage Amplifier, 7/ "x18" 45.00 means of communication as a wire line and Regenerative Set with Detector and Two -Stage Amplifier, 7/ "x20" 55.00 much broader in its reach, are going to fall ALL INSTRUMENTS ABSOLUTELY GUARANTEED at once for the arguments of an amateur who wants a varati'm. Those who are not G. M. PROUDFOOT, 361 E. Ohio St., Chicago, III. from Missouri have entertained guests from

www.americanradiohistory.com 926 Radio News for June, 1921 MIEN= =MINIM that State of Doubt. Every hotel room - even the cubby hole under the eaves whicn ANNOUNCING would please the radio amateur best of all - EMPYREAN RETAIL SALES has cash value in the season. The hotel man does not know that by merely sending some- S - E - R -V- I - E one to ask the amateur a simple question -C about QRM or something he can draw him Embracing a into a discussion which will make him forget AJAX LEARNERS KEY & Downtown Sales Room his meals and thus eliminate that item of expense. He needs to be shown that the BUZZER SETS for the convenience of local fans; thing is practical and valuable and worth "built for service" with code $1.75 and a the money. The best way is to get him into "HYTONE" BUZZERS 60c your station and let him play with the con- Mail Order Department trols himself. external tone adjustments The next best way is to set "as good as the best" where quality and service are un- up a portable outfit in his office and snake Postpaid excelled. Orders are filled and something happen. In either case a brand new impression will be made and it AJAX ELECTRIC CO. shipments made every hour during will Palmer St. Cambridge, 38, Mass. the day, thus assuring you that stick. your order will be on its way COMPENSATION. within an hour or two after it is A good operator is worth a salary and INDICATING DIALS received. expenses, especially it he uses his own set. But if he is obliged Lacquered to accept a proposition brass, EMPYREAN RADIO COMPANY covering expenses only, tnere are ways to 2/' secure an income. in diameter, MASONIC TEMPLE, CHICAGO Dealers in radio apparatus are-, glad to _ genuine have reliable representatives and are willing bakelite MIIMMNIn= MIM IIM. to pay commissions on sa es. It is easy to knob I/" interest well -to -do vacationers in purchas- in diameter. ing sets ranging in price from $50.o, to Offset shoul- $500.co if an amateur has salesmanship qual- ders act as BAKELITE PANELS ities. stops. Same (Black or Brown) Radio magazines welcome subscription dial used by U. S. Signal Corps. Your Cut the size you want them agents and, altho much of their material money refunded if not satisfied. Price, is three for one dollar, postpaid. %" .02 per sq. inch too technical for the average man there 3/16" 03 per sq. inch is always enough of general interest to jus- The Factory Distributing Co. %" 04 per sq. inch tify an amateur in selling a subscription to 130 N. Wells Street Chicago, Ill. Include Postage a man who becomes interested in radio in a general Example : way. 6" x 10" x 3 -16" = 60" x .03 = $1.80 Many wealthy women, wives of men high CARDBOARD TUBING in big business In any length up to 25 ". 3" and 814" Dia., Mc per Send for latest price list. and in government, study inch, 25e per foot. 4" and 4%. Dia., 3c per snob, 30e stenografy and typing in order to handle per Poch,. 3 ", 3% and 4" Tubing has ÿ¢' wall. Michigan's Largest Dealers in 4%. Tubing has 5/32" wall. matters too confidential and important to VARIABLE B. BATTERIES Radio Supplies. entrust even to a private secretary. Women 22+/y Volts $2.50 45 Volts $5.00 of this class would learn radio just as easily Postage Extra- Circular for Stamp. DETROIT ELECTRIC CO. and it JEFFERY -CRAWFORD CO. 434 Shelby St, Detroit, Mich, find equally useful. For competent 2173 Milner Ave. Detroit, Mich. instruction they gladly pay from 42.5 to $S.00 per lesson. Such women must spend some time each season at the first -class $ $ RADIO and MODEL hotels in order to maintain social connec- $ $ $ tions which are of importance to them, but S A V E D ENGINEERING By ordering thru us Edited By M. B. SLEEPER they do not spend their time in mere social frivolity. They might b° secured as pupils 10% discount on practically all radio goods. Money t and might help in organizing classes. Women orders only accepted. JUNE ISSUE -Unusually good who have helpt THE AMERICAN RADIO SALES & SERVICE CO. their husbands to success Box 356 ideas for the construction of tuning ` are sure to be interested in young men who Mansfield, O instruments. For the Experimenter are ambitious and sound as to character. of average means and shop equip- They have longer memories ment. than men and STANDARD RADIO EQUIPMENT they have an adroit way of mentioning the AGENTS FOR MAY, JUNE and JULY issues, 25e. young fellow whom they are helping at MURDOCK FEDERAL TEL. you BRANDES AMERICAN RADIO Did see the telephone article times when it will do him the most good. BURGESS AUDIO TRON. in the May number? GREBE CHICAGO RADIO LAB. Published by An amateur who could meet such friendli- BENWOOD SPEC. DUBILIER The GENERAL APPARATUS CO.. ness with common sense and genuine ap- DE- FOREST TRESCO AND OTHERS Inc. preciation, one whose mouth U. of I. SUPPLY STORE, Inc. 570 -N West 184th St.. New York was less ready 627.29.31 SOUTH WRIGHT STREET than his brains, would find valuable friends CHAMPAIGN, ILLINOIS among the gentler sex at exclusive hotels regardless of his own social position. DODGE LEARN WIRELESS SHORT CUT VACATIONS 1N CAMPS. at the largest radio school MADE POSSIBLE in the Central States. IT Every organized camp needs radio serv- Modern complete equipment. ice. Camp managers may not appreciate Experienced instructors. Dor- TO MEMORIZE mitory in connection. Stu- that fact, but they do need it. Camp phy- dents may earn expenses it WIRELESS CODE IN sicians usually are medical students or necessary. Write today for catalogue and full informa- ABOUT ONE HOUR young practitioners. At any moment they tion WHAT WAS A TIRESOME TASK may be confronted by a situation in which CENTRAL RADIO SCHOOL IS NOW A PLEASANT PASTIME the prompt assistance of an older man is Independence. Me Thousands have, So simple everybody can. needed to save a life and to save the repu- Complete chart 50 cents. Testimonials from 36 States free. Investigate and profit by tation of the camp. experience of others. Generally speaking, the record of boys' C. IL DODGE, Boa 200, Mamaroneck, N. Y. and girls' camps in the care of their campers is good, but the leaders in this as in other fields will be using radio as a further (SPRUCE) The Midget "FIVE- IN -ON E" Slide Ride is a combination Mannheim, Log- means for safety as soon as they appre- OUR WIRELESS \\ Log, Add and Subtract, Polyphase ciate its value. Some are using it now but urnished and erected at reasonable rates and Binary Slide Rule. It will 578 Gates Ave. instantly add, subtract, multiply too often the sets are inefcient and the op- . BYRNES and divide any combination in- Brooklyn, N.Y . volving whole numbers, fractions. erators too inexperienced. pOLES decimals and mixed numbers. Competent amateurs who will secure va- Gives every possible root and power of every quantity. The cation positions in camps and give reliable "The Trans - Pacific Radio Operators Log" graduations are printed on metal service will make reputations for themselves is a fascinating booklet crammed full of press, time, coated with whits celluloid and and weather -schedules, distance tables, speed records, are grease and waterproof. While and do a lot for radio. LD records, and information of all kinds that you tt is the most versatile calculator radio "bugs" have been waiting so long for. Your ever Invented, its operation L simple and easily under - POSITIONS ON YACHTS. copy will be sent postpaid by return -mail upon ars'.. stood. Diameter receipt of 50 cents. - Price with 18- pe ction B Leather- Yacht owners need radio. Some of atte case 60e them Address carrying extra. ta ok. $1.80. have it but more have not. Even some big W. BRENIMAN are not Gilson 701 Remington Street Fort Collins, Colo. vrouu wed. SiMe line CO, Niles, Mich. yacht clubs are still asleep on this propo -

www.americanradiohistory.com Radio News for June, 1921 927

sition, not realizing the value of a radio station at the club house. An amateur who likes the water ought to have no difficulty in landing a vacation job on a yacht, especially if he is willing to do other work around the boat besides radio. Here again ICÉÑ-14EBY the acquaintances made may be of greater value even than the recreation. On fishing boats and sailing craft of all EQ.JIPNT sorts a radio man could earn his passage. He would need to be a rough and ready f el low and he would have a wonderful time if he was. An op. who likes the sea but not its funny motions could scrape acquaintance with a Thousands of Dollars light keeper and spend a few weeks at the light. Lightkeepers and their families are lonely folk and they like company of the have been spent by radio amateurs and experi- right sort. A radio set would be a wonderful new plaything for them. Lighthouse in- menters for inferior apparatus. There was a spectors are not so agreeable. for reasons which can be appreciated when the necessity time when they could get nothing else. for absolutely perfect servic3 at the lights is considered, but i have spent many a day and night at a light station without getting- anybody into trouble. TODAY it is different. The up -to -date experimenter is IN THE WOODS. no longer content with his former limitations. With the Forest rangers and fire wardens get lone- some too. A radio man who knows how development of the high -grade equipment now available to get along with country folks could un- doubtedly secure an invitation to share a he demands apparatus built according to real professional log cabin in the wilds, eaten trout and live high on backwoods dainties such as rasp standards. berries and blueberries. Or, coming bac toward civilization, he might choose a farm or ranch. In many sccti;;ns guests are invited to spend six months or a year as a IN this development the Colin B. Kennedy Company has matter of course. No man likes to sponge his way or impose upon hospitality, but even been a leader. From its very beginning its policy has been tho an operator out of health needed so long a period for rest and recuperation, his to manufacture apparatus which is "built to a standard, set and a willingness to lend a hand in such not to a price." ways as he could would enable him to ac cept an invitation with a clear conscience. AT SUMMER SCHOOLS. There arc schools which would have made ASK your dealer for a demonstration of Kennedy Re- arrangements long ago for radio courses ii Give it a in the managing boards had thot such ceiving Equipment. thorough examination courses within their reach. Even tho comparison with the best of other makes on the market. appropriations were lacking, citizens might make up a purse of reasonable size or at Form your own opinion of its design, workmanship and least provide entertainment for a man who was competent to teach even the elementary performance. Our unreserved guarantee on every item principles of radio and help beginners to is final construct simple receiving sets. School pe- bearing the Kennedy trade -mark your protection. riods vary in different parts of the country and whenever an amateur could take a vacation he would be likely to find an opening If your dealer has not yet put in a stock send somewhere. for list. Then there are Farmers' Weeks at agri direct our catalog and price cultural colleges and many gatherings last ing for a week or more which would be glad to pay the expenses of a man who could give demonstrations with a radio outfit, if THE COLIM COH PZAMY the matter were brot to the attention of KYINCORPORATED the committees in charge. RIALTO BUILDING SAN FRANCISCO WHAT WILL I DO? By the time this story is in print I will be enjoying my own radio vacation. In the little town where I lived when a boy I will have my Grebe CR -7 receiver working and show GALENA SILICON will be endeavoring to a rural com- Galena Crystal Mounted $0.50 Silicon Crystal Mounted $0.50 munity what radio can do for it. I intend to broadcasts from Galena Crystal Unmounted .25 Silicon Crystal Unmounted .25 give the constable the police Galena Crystal Mounted in Std. Silicon Crystal Mounted in Std. KUVS so he can catch some o' them slick Murdock Detector Cup Murdock Detector Cup auto thieves from New York, b'gosh. I am .55 .55 going to try to give the farmers the weather Every Crystal Tested Under Actual Working before it happens. They get the forecasts Conditions and GUARANTEED SENSITIVE now by visiting the postoffice but the weather DEALERS WRITE FOR DISCOUNTS. always gets there before the forecast! ROLAND BROWNLIE, Mfg., 27 Oakland Avenue., EVERETT, MASS. For the village paper I am going to pick up the Navy Press so that once a week it can crow over the city dailies. I am reliably informed that these government "EVERYTHING IN RADIO" QST's are public property and that publishing them is no violation of the law or of WESTERN RADIO ELECTRIC COM`PANY my oath of secrecy as an operator. The SEND FOR OUR MARCH jeweler shall have the correct time by radio STOCK BULLETIN AND PRICE LIST daily. Nobody is going to pay me for any of this 550 South Flower Street Los Angeles, Cal. service, but I will have free board, including

www.americanradiohistory.com Radio News for Juno, 19?1 SPEC AL 30 DAY OFFER Save Money -Get a FREE Premium Besides The subscription price of Science and Invention has mium you prefer; you are at liberty to send as many been $3.00 per year. For 3o days, not only will we subscriptions or renewals as you desire, and you can give you a full year's subscription (12 big numbers), pick out a free premium for each year's subscription. for $2.50, but we will also give you absolutely FREE, You may also take subscriptions of your friends your choice of any of the well known books shown and earn the free for yourself. below. Read the special offers. If you want more than premium one book free take a two or three -year subscription. You must act at once - Today. For each year you can take advantage of one offer. These sensational offers are made by us at a tre- If you are already a subscriber to one of our mag- mendous sacrifice in the hope that your acceptance azines, take advantage of this opportunity and send will make you a life -long friend of our magazines. in your renewal subscription, stating what free pre- ! ! Please use order blank below! !

Z:ije experimenter Vutirígfjíttg Co., 31iYc. 236 FULTON STREET, NEW YORK

Special Free Premium Special Club Offer Special Free Premium Offer No. 1 RADIO Offer No. 3 The How and Why Wireless Course in of Radio Apparatus NEWS 20 Lessons By H. W. Secor, E.E. By S. Gernsback, A. Lescarboura This newest of Radio Works has THE 100,0 WIRELESS MAGAZINE and H. W, Secor, E.E. 160 6 9 inches. (10th Edition) pages. x AN D Size of book is 7 x 10% in., 160 OFFER No. 1 pages, 350 illustrations, 30 tables. Above Book, bound in crence and OFFER No. 3 special cloth, flexible, hand Above Book, bound in sewed. FREE with a year's Invention special cloth, flexible; hand subscription to Science and sewed. FREE with a year's Invention for $2.50. subscription to Science and THE UNDISPUTED AUTHORITY ON SIMPLI- Invention for $2.50. FIED SCIENCE AND MECHANICS Special Free Premium BOTH MAGAZINES Special Free Premium Offer No. 2 With any one of the FREE Premiums, as described: Offer No. 4 A Thousand nd $3.50 Experimental Electricity SCIENCE & INVENTION One Formulas Offer 6A and RADIO NEWS with Premium 1 Course in 20 Lessons By S. Gernsback By S. Gernsback and Offer 6B It contains 160 pages. The pa- with Premium 2 H. W. Secor, E.E. per has been especially selected The book contains 128 pages to stand rough handling in labora- Offer 6C with Premium 3 and more than 400 illustrations. tories. Size 6 x 9 inches. Size of book is 6 x 9 inches. OFFER No. 2 Offer 6D with Premium 4 OFFER No. 4 Above Book, bound in in Offer 6£ with Premium 5 Above Book, bound special cloth. flexible, hand special cloth, flexible; pocket sewed. FREE with a year's The Biggest Bargain size. FREE with a year's subscription to Science and Clubbing subscription to Science and Invention for $2.50. Ever Offered. Invention for $2.50.

I= ma . MIS _°°_ EXPERIMENTER PUBLISHING COMPANY, Inc.

236 New York City, N. Y. DESIGN- CONSTRUCTION 4 Fulton Street, HOW TO MAHE Special WIRELESS Gentlemen: SEHDING WPPRRent Enclosed find $ for which send me: Free Offer No. i Offer No. 6A Offer No. 2 Offer No. 6B Premium Offer No. 3 Offer No. 6C Offer No. 4 Offer No. 6D Offer No.5 Offer No. 5 Offer No. 6E Design and Construction of Audion Amplifying Transformers Radio and Audio Frequency Type MARK SQUARE ABOVE FOR ITEM WANTED. 1 How to Make Wireless Sending Apparatus Name How to Make Wireless Receiving Apparatus Address 1 OFFER No. 5 Above three Books as described FREE with a Year's Sub- Town State scription to Science and Invention for $2.50.

www.americanradiohistory.com Radio News tor June, 1921 929 apple pies like mother used to make, griddle cakes and maple syrup, and fish out of the creek. I can eat them in that order if I want to, when and as I please. For I will be stopping with two young people of sev- enty who have been encouraging me in my the Message hobbies for more'n forty year-my father Hear and mother. all Over the House Who's Who in Radio (Continued from page 867) I,III,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,1111111,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,_ With the Radio Magnavox you can perfected the device which prevented inter- receive the message altho away ference by other signals sent on the same wave -lengths. from your Station. When the Today Radio control is successfully used is used with a in several ways, among which may be men Radio Magnavox tioned an airplane which, without a pilot, suitable amplifier -you will get may be sent up and directed entirely by Radio. radiophone music that you can Professor Branly has been awarded several prizes in appreciation of his work. In dance by; and the volume is greater 1899 he was awarded a prize by the Acad- emy of Sciences, and in 19)3, he shared than any other receiver. with Mrs. Curie the Osiris prize given by the Press. In 'gm, the National Society for Radio Magnavox works on the Industrial Help awarded him its highest The prize. Dec. 15, Iglu, he was elected asso- same electrodynamic principle as ciate member of the Belgian Royal Acad- emy, and on Jan. 23, 1911, the Academy of the Magnavox Radio Telemegaf one, Sciences of the French Institute made him a member in the Physic Section. and will reproduce signals with the Within the last few years Professor Branly has started investigations on the same volume. modifications causing the electric conductibil ity in an imperfect contact, and in spite of has been operated on three or his actual material difficulties that are added It to the out -of- dateness of his laboratory, he four dry cells with good results, and pursues without aid, but with his usual will and perseverance, both his teaching and his its success is widespread. Especial- experiments. ly desirable for wireless clubs and teachers. Write for Bulletin 27 and A Mental Telegraf get full details, or better, send $45 (Continued from page 864) ; and get the Magnavox. ..,,.,,,,,.,,,,,.,,,,,,, III ,,,,,,,,,,,,,,, ,,,,,,,,,,.,,,,,,,,,1,,,,,,,,,,,..,,.,,,,,,,,,,,,,,,,,.,. the receiving is done on the stage where concealment is not so necessary. A woman with the most recent head -dress can wear the fones without their showing in the least. When the sets are completed and in opera- the / tion, the transmitting units walk about / ti tib,o audience collecting the whispers of the in- 4 tc1 dividuals, which are relayed with the ve- / ot on locity of light to the receiving medium oe{yey the stage, who is given the appearance of / / et having supernatural power. e3 e for anything else Can the idea be used J. O. MORRIS CO., Inc. 4 Oto but mere fruitless mystifying and fun? Yes. / It could he used for special detective work, 1270 BROADWAY / e+2, interviewing personages. The ingenuity oye tio for NEW YORK / 09 the readers of this article will no doubt o~ o Se of Eastern Distributors / ô suggest further applications. S. e`bGo., 15

,11111111,11111111111111111111111- Washington's Birthday Relay Results Business is Good on GOOD "B" (Continued from page 864) Batteries - Because GOOD "B" ,,,,,,,,,,,,,,1,111,,,,,,,,,,,,,,,,1,1111111111,1 Batteries Make Good Business., as getting the message across the country was Stuart Batteries bring in the signals until the last bit concerned, no trouble was experienced; but the of energy is gone. Then you realize that Stuart Batteries fact still remains that without, say about six sta- give you longer life, more PEP and better service at a tions, the relay would have been a failure, par- reasonable cost. ticularly in the East where there was the most PEP. These stations are No. 5677, Small price -popular size -tremendous noticeable QRM, QRN, QSS. lbs. Price $2.25. NSF, 8XK, 9ZN, 9LR, 5YH, and a few others. Size 5" x 3" x 24". Weight 24 Nearly all the reports show that signs were hard to read and the boys waited until either one or Send us the name of your dealer, and receive the other of these stations sent in order to check our latest Bulletin on Radio Batteries postpaid. slip -up occurred somewhere be- up the MSG. A DEALERS WE HAVE AN AT- tween 9LR and 8XK of one word only and even do otherwise, sent the word TRACTIVE PROPOSI- STUART PRODUCTS CORPORATION NSF, who could not TION FOR YOU as they received it. This caused a lot of stations 663 WEST WASHINGTON BLVD., CHICAGO, ILL. to get one word not correct and naturally marked for the error, as there was no other way to do it. twelve issues, each of which INCIDENTS OF THE BELAY. iGet a Handy Binder for your RADIO NEWS. Holds and preserves can be inserted or removed at will. Price 65e, Experimenter Pub. Co., Inc., Book Dept., 236A Hertz, of Washington State, who was to sen1 Fulton St., New York. the relay East, got into trouble at the last minute,

www.americanradiohistory.com 930 Radio News for June, 1921

but we had him covered by 7YS, St. Martins Col- One enterprising amateur had the nerve to give lege, Lacey, Wash., who sent in his stead. Bessey, to the then President Wilson at Washington, D. C., of Sunnyvale, Calif., who was to start the MSG a copy of Mr. Harding's message. This was car- TUSKA C. W. INDUCTANCE east from California, went fishing and forgot it, rying out orders in great shape. Twenty-two but was located thru our frantic efforts and put United States Senators, 35 State Senators, over the southbound MSG thru in great shape. 500 Chiefs of Police, Selectmen, City Councilmen, Type 181 Personally I want to thank each and every one Sheriffs, Postmasters and News Editors, received Unmounted who helpt in this relay for their wonderful as- the message. This was a most wonderful showing PRICE sistance and co- operation. I do not believe that and some of the reports sent in were really mas- there is in this world a body of men or boys that terpieces. Some made errors in time of sending works closer together for the common cause, than stations, call leters, etc., and will have a whole $5 our amateur radio workers. year to improve their receiving in order to get H. P. Maxim's station in Hartford, Conn., the next national message correctly. Some ama- started the west- bound MSG and was considerably teurs worked in pairs, but the results were only handicapped by local QRM, but his sigs were put in the name of the one to whom the receipt clearly read in the Middle. West, as the report was given. Everyone in the United States en- shows. gaged in the wireless business was solicited for The reason that the relay results were prizes and willingly gave to the limit allowed, that not printed sooner, boys, is on account of the was one prize only from each one. All the send- magazines wanting the story about two months ing stations that helpt in the relay have been sent before you get your magazine, and after crawling a complete report of it by the writer and can tell thru about two tons of letters and sorting them, easily who read their signals and just how far Use a Tusks C. W. Inductance in your reading, checking, tabulating, marking, etc., I they went under the bad conditions prevalent. new tube set. Send your found The tabulated report on the relay was submitted dealer's name that two months were gone. to and 5 cents for our illustrated C. W. the Prize Committee, A. N. Goldsmith, Institute Booklet. of Radio Engineers; E. H. Armstrong, of Yonkers, RESULTS OF RELAY. N. Y., whom you all know, and Hiram Percy Maxim, of Hartford, C. Fourteen Governors of as many States read this Conn. All three agreed on THE D. TUSKA COMPANY message from the amateurs, several of them be- awarding the prizes on the basis of speedy and HARTFORD, 3 - CONN. ing called out of bed by the amateurs to sigr for correct reception, together with the marks for the the message A certain Catholic priest got the perfect wireless report about the conditions. All governor of his State out of bed to sign for the of this figured down to miles per minute in re- message, and this Governor, who lives in the ceiving and delivering. South, thot it was a message from the "night Very few of you will be able to comprehend riders," but our friend the priest told him it was the great amount of work in connection with this Have you something to sell or ex- relay and hope that the awards will meet change? A the "radio riders." with your classified ad in Radio News Two hundred and forty -seven mayors of as approval and that you all will thank the many will reach 40,500 for only 6c a word. many cities were disturbed at all hours to sign dealers who made the distribution of prizes pos- for the message and did so like real fellows. sible. The first prize winners were consulted as to their pick of the prizes and the others awarded on the basis of their report marks and the relative value of the prizes. The prize winners are Charge Your Own Batteries With a Union Rectifier for Only listed below without their addresses, which the writer has, and to get your prize merely send a 10e. 12c. PER CHARGE letter to W. H. Kirwan, Box 148, Davenport, Iowa, to stating what prize Get a Union Rectifier to charge your filament you get and the writer will battery and MagnavoX battery and your station approve it and send it on to the donor of that will operate at the highest efficiency. Connect prize. If anyone has any trouble getting his prize, rectifier plug to 110 volt. 60 cycle A. CL light- merely drop another line and we will get you ing socket and connect clips to battery and turn straightened out. All the possible advertising you on current at socket. The ammeter on rectifier can do with your prize please do, as it will shows the current flowing and the rectifier the show operates automatically and with a little care real world who the co- operative dealer is should last for years. who takes enough interest in the game to make the Type A. Rectifier 6 volts, 5 to 8 amperes, com- relays worth while. Do not judge the prizes by plete with ammeter and battery clips....$20.00 their value, but by the fact that they are prizes. Type B. Rectifier, 12 volts, 6 amperes, complete As stated before, the only lady in the United with ammeter and battery clips - $27.00 States who received the message correctly and Descriptive bulletin on request. made good time and turned in a good report was Order one of these rectifiers today - and keep. Miss Winnie Dow, of Tacoma Wash. I have not your batteries charged. written to anyone yet about the prizes, as the magazine they read is the place to find out all UNION RECTIFIER1 COMPANY about it. Do hope that the magazines will pub- MONROE, N. C. lish Miss Dow's foto so we can all take a look at her and hear something of her work. Lots of ladies sent in reports but a great many considered the report as a joke and their marks were likewise. A certain man in the Middle West sent in a report as a lady and used a lady's name, but a VARIABLE -ACE "B" BATTERIES- PLAIN little wireless detecting soon found him out and we sent his report back to him to frame and show his children when he grows up, how he nearly won =Use the Best- a prize -almost. The first prize was won by Leander L. Hoyt, of Hayward, Calif., whose report decided all the judges. Hoyt worked with S. D. Browning in his city and says that he also deserves credit. Mr. Hoyt also won in 1917 the Ace "B" Batteries long wave Chambers coupler as fifth prize. Mr. Hoyt says nothing will satisfy his craving but the Clapp- Eastham ZRF regenerative receiver, and Dealers when he complies with the request in the story, we will see that he gets it and tells us all later how Sell the `Best" it works. The complete list of the prize winners will be with our Special publisht in the next issue. Inducements 111111111111111111111111111111, Write for Catalog No. 15 New Daily Radio Weather Cat. No. Size. Voltage. Hrs. Ser. Lbs. Taps. Prise. 623 Report Plain 2/z x 2 x 3% 22%z 400 I $1.50 623 Variable 21/2 x 2 x 3% 221/4 400 I 5 1.75 625 Plain 3 x4x6s/8 22%z 1400 5 2.50 (Continued from page 874) 625 Variable 3 x4x6s/e 22 %z 1400 5 5 3.50 626 Plain 3 x8x6a/e 45 3000 10 5.00 .1,,,,,,,1111111 11111111111111111.111,1111111111111111111111111 626 Variable 3 x8x6s/s 45 3000 10 5 6.00 1,11111,114 1111,111111,11 111 11111..111,,,, ,,,,,,.., ACE "B" BATTERIES are made according to government specifications, and are especially adapted for Plate Circuit In Detector or Amplifying Tubes. The bulletin is divided into two parts and invariably begins with Guaranteed not to Depreciate more than 10$ in I year when not in use Absolutely Moisture the letters USWB proof (U S. Weather Bureau). The first part A few of the dealers handling Ace "B" Batteries consists of surface weather conditions based Am. Electro Teoh. Appliance Co.,. New York. David Killoch, New York. upon observations taken at 8 a. m., 75th Continental Radio & Electric Corp., New York. Manhattan Elec. Supply -Co., New York. meridian time, and of upper Drefuss Corporation, air observa- New York. M. Muller, Boston, Mass. tions begun at a. m., 75th W. B. Duck, Toledo, Ohio. - Vimy Supply Co., Thronte, Canada. 7 meridian time. Whithall Elec. Co., Springfield, Mass. of the date of distribution. The second part of the bulletin consists of synopsis of general atmosferic pressure distribution, in- ACE !BATTERY MFG. CORP. cluding the locations of high and low areas, andthe barometer readings at their centers; 44 COURT STREET Phone Main 8373 BROOKLYN, NEWT` YORK wind and weather forecasts for Atlantic AGENTS WANTED and east Gulf offshore areas ; storm and hurricane warnings for these areas ; and flying weather forecasts for each of six aviation zones.

www.americanradiohistory.com Radio News for lune, 1921 931 ```` Wireless Shop Variable Condensers:: 4s "' "THE QUALITY INSTRUMENTS"

E4`t,fi4 Put "Wireless Shop Variables" in your set and end your condenser " troubles. They are made right and will stay right. Heavy aluminum - E plates and spacers, accurately die stamped, formica end plates, and .c, t ribbon connection to movable element are points of superiority worth `* _ -,, considering. Our prices may not be quite as low as some but the price is low considering the superior instrument we give you. Entire satisfaction or your money back. Prices listed below include knob and pointer and mounting screws. Write for Bulletin No. i illustrating and describing the complete line of wireless shop variable con - SERIES "T" densers. PRICES No. 20 2 plate Vernier Condenser $2.00 No. 7o 7 plate, approximately .000r m. f. maximum capacity $2.35 No. 13o 13 plate 0002 m. f. $2.75 No. 170 17 " " .0003 m. f. . $3.15 No. 23o 23 " " .0005 m. f. $3.60 No. 310 31 " .0007 m. f. " $4.30 No. 430 43 " .001 m. f. $5.25 No. 63o 63 " .0015 M. f. 44 4C $7.50 Include postage for one pound to your postal zone, and insurance, with your remittance.

° lag A.J. E D G C O M 104

511 WEST WASHINGTON STREET LOS ANGELES, CAL. 131,TTEPIZINT'S SHORT WAVE RECEIVER ARMSTRONG AMPLIFYING to 1000 METERS This data is not available in any text book or publication. NOT A TWO VARIOMETER RE- CEIVER. Design GUARANTEED to be at least equal in efficiency to the best receivers on the market covering any part of this wavelength range. Has every advantageous feature known today. Developed and designed in our laboratory by COMMERCIAL RADIO ENGINEERS, not only to operate perfectly but to be built ECONOMICALLY and at a REASONABLE PRICE. Electrical Data, Mechanical Details, Assembly Views, Firing Diagram and List of Material shown on four blueprints 21" X 28 ", price $4.00 set. CONSIDER THIS When You Build When You Buy Dealer's Discount 3oVo Manufacturer's Profit 20% Manufacturer's Overhead 20% Raw Materials 20% Raw Materials 20% Other Items Ica

Saving Approximately 8o% List Price Instrument Ioo /c

Also available, blueprints of, 25o to 2 000 meter regenerative receiver; Io, zo, o, loci, zoo or 500 watt Radiophone, CW, ICW Sets, Quenched Rotary Spark Gap, 64 volt Storage B Battery and others.

EXPERIMENTERS INFORMATION SERVICE Suite 551 45 Pinehurst Ave., NEW YORK CITY

CHARLES R. LEUTZ, Director, Formerly Designing Radio Engineer, Marconi Wireless Tel, Co, of Am, and Liberty Electric Division of Mallory Industries, Inc.

www.americanradiohistory.com 932 Radio News for June, 1921

taiwiv..tul,.:, ...,..,wl1.vitulwllvlw,1. lvwaw.11vllvllvlw.iwltvr vawl,,,lwllvaluuá i, a OPPORTUNITY AD -LETS Follow these advertisements every month. Reliable advertisers from all over the country offer you their most attractive ape- - vials in these columns. Classified advertising rate six cents a word for each insertion. Ten per cent discount for 8 issues. 20 per cent discount for 12 R issues. Name and address must be included at the above rate. Cash should accompany all classified advertisements unless placed by an accredited advertising agency. No advertisement for less than 10 words accepted. Objectionable or misleading advertisements not accepted. Advertisements for the August issue must reach us not later than July 10. THE CIRCULATION OF RADIO NEWS IS OVER 40,000 ?,, EXPERIMENTER PUBLISHING CO. INC., 233 and 238 Fulton Street, New York. N. Y. ñYíYltrlINkilfr.YlYiNgfailtritI IlrtiltYlhitllrelffitlhi infltaftt raitti ilffi ll7i0YtRacltiraclhaillni lr/l lhitlAkdrYítlffitlf52(Irr.Ylfflira` ltrahlheiYU7A4Yíatiilift erse lllrkltra1r/ícm.ltiNifikkrteu

Automobile Accessories. Electrical Supplies and Appliances. Books. Autoists- "Saviorgas"; easily mixed. Saves gas. Navy Test Galena Crystals- Supersensitive, We Buy and Sell back issues of Radio Amateur Decarbonizer. Recipe, 10c coin. Hawthorne Co., mounted crystals, value 50 cents each. Sale at 30 News and Electrical Experimenter. Boston Maga- Roslyn, Wash. cents each. Harry T. Gleich, 490 Sixth Ave., New zine Exchange, 109 Mountfort St., Boston, Mass. Auto Motora Supplies- Buick, Michigan, Stod- York City. The Amateur Electrician- Pocket size, 20c, dard- Dayton, E. M. F., Cadillac, Overland, Con- Electricians- Wiremen, linemen, send your coin. Joe Tillberg. Proctor, Vermont. tinental and Buda Motors. All types, $50 each name and address for descriptive literature of our high "Ten Days "-Stories from Boccaccio's "De- and up. New Dixie magnetos, $20; Splitdorf modern blue print chart method of electrical wir- cameron, best you ever read; 85c postpaid. Mar- Auto - tension magnetos, $10; Kellog pumps $3.50; ing. Over 350 practical diagrams. Electrical Wir- tin, Box 67R, Pontiac, Mich. Lite generators, new, $10; air gauges, 65c; Remy ing Diagram Co., Box C-173, Altoona, Pa. ignition coils, new $3; electric and gas head- Concordia Magazine, Quarterly, 9 \Vater, York, Storage Batteries for automobiles. We furnish Penna., prints essays, stories, current events, lamps, coils, distributor heads, air compressors, etc. all parts and moulds for making them. Sample Write for catalog. Motor Sales Dept., 16 West poetry, formulas and plans. Send $1 for three -year plate, 40c. Foreign countries, 50c. Windsor subscription. End, Pittsburgh, Pa. Specialty Co.. 5419 Windsor Ave., Chicago, Ill. ,,o.noomounlimummiu,.u.,.ummIsItnutntenuu,,,,,,,, tti, men,,emill 1113113.1emeoe The How and Why of Radio Apparatus, by H. Motorcycles-Bicycles. Used Magneto Telephones, thoroughly over- W. Secor, E. E. This newest book on radio mat- hauled, like new, 1,000 ohm bells; will work 12 ters fulfills a distinct gap in wireless literature Don't Buy a bicycle motor attachment until you on a line; instruments guaranteed. Worth twice in that, while the treatment is made as under- get our catalog and prices. Shaw Mfg. Co., Dept. the money, $5 each. Two or more $4 each. G. standable and as free from mathematics as 1606, Galesburg, Kans. Walter Varrell, Laconia, N. H. possible, it at the same time incorporates a wealth Used Parts for all motorcycles. Schuck Cycle of technique and instruction for the Radio Ama- 1111 ll 1,,,1 1111111111.,,,,1111111111,,,11, ll,,,, 1111111111111111111111111111111111 ll1 ,l,,,,,,,, W,,,9:,1,111111 Co., 1922 Westlake, Seattle, Wash. teur -the Radio Operator -the Installation and Designing Expert -as well as teachers and students of the subject in general. A very broad field Motors, Generators and Dynamos 47 Drullard Ave., has been covered by the author, at the same time Special Garage Motors-Manufactured by the Lancaster, New York, giving a great deal of information not found in General Electric Co.: 1 H.P., $78.50; 2 H.P., $110; other text books. If you are engaged in any 8 H.P., $128.50; 5 H.P., $166.50. All sizes botti February 7, 1921. branch of the Radio or allied arts at all you will single and polyphase motors for immediate deliv- surely need this latest contribution to radio litera- ery. Special charging generators all voltage.. Experimenter Publishing Co., ture, which is destined to be found on every Write for catalog. Motor Sales, slept. 16, West radio man's book shelf before long. A glance at End, Pittsburgh. Pa. 233-236 Fulton St., the following list of chapters gives but a very

, 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 11 11 1 1 . 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 111 1 1 1 1 .111111111111111111111 l 11,,,,,,,, 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1, u 1, 1 1 1 1 1 1 1 1 1 1 1 scant idea of the extensive and useful radio New York, N. Y. knowledge provided in its text: The Induction Agents Wanted. Coil; The Alternating Current Transformer; Big Money and fast sales. Every owner buys Gentlemen: Radio Transmitting Condensers: The Spark - gold initials for his auto. You charge $1.50; Gaps; Radio -Transmitting Inductances; Radio make $1.85. Ten orders daily easy. Write for Please put the attached adver Receiving Tuners; Radio Receiving Condensers; particulars and free samples. American Mono- tisement in the March issue of Detectors; Telephone Receivers; Radio Amplifiers; gram Co., Dept. 133, East Orange, N. J. Construction of a Direct Reading Wavemeter and NEWS. Beginners -Complete mail order system, R. Box RADIO Decremeter; Antenna Construction; The Calcu- 1005, Atlantic City. It is a ten -word ad-let and I en- lation and Measurement of Inductances; Appen- lady dix containing very useful tables, covering all Inkeehtal Most dependable protector for close sixty cents in stamps in pay subjects treated in this very unusual book. This or gent. Saves worry and annoyance. Send 50c Kerita newest of Radio Works, cloth bound in Vellum de for sample and agents' discount. Specialty ment. I would like it to be in Luxe, Gold Stamped and Hand Sewed, has 160 Co., 21 Prospect St., Holyoke, Mass. Ill llll1111 111ullll 1u1111111111111111111 1u,,,,,,,,,,,,,,,,,,,, the March issue. pages. Size of book 6x9 inches. The How and ll Why of Radio Apparatus, Postpaid $1.75. Ex- Help Wanted. My brother received Perfect re perimenter Publishing Co., Book Dept., 236a Ful- Detectives Earn Big Money. Excellent oppor- suits with the ad -let he sent you tcn St., New York City. tunity. Travel. Great demand everywhere. Fas- last month. cinating work. Experience unnecessary. Particu- Correspondence Courses. lars free. Write, American Detective System, Yours truly, 1968 Broadway, New York. Dollars Saved correspondence courses of KENNEFH -Used Be a Mirror Expert. $3 -$10 a day; spare tinte (Signed) SWANSON. all kinds sold, rented and exchanged. List free. home at first; no capital; we train, start y.au (Courses bought.) Lee Mountain, Pisgah, Ala- making and silvering mirrors, French method. bama. 111111111111111 : ,,,,,,,,,,,,,,,,lll 111111111llll 111/11ll,,,,,,,l,,,l,,,,,,,,,,,,,,,,,,,,,,l,l,l,,,,lll 11111111111111M 14 1111111111111111 1111 1 Free prospectus. W. R. Derr, Pres., 579 Decatur ,,,,,111 lll lllllll,,,,, lllll1111111111111111iiimimmm1111111111111111111.11111111 ,,,,,,,,,, St., Brooklyn, N. Y. Motion Pictures Earn $25 Weekly, spare time, writing for news- Business Opportunities. papers, magazines. Experience unnecessary; de- Substantial Manufacturing Corporation wants Motion Picture Cameras, $30; projectors, $10; tails free. Press Syndicate, 5865, St. Louis, Mo. capable men to establish branch and manage sales- particulars, 5c. Werner, High Ridge, Missouri. Wanted-Experienced amateur operators east men; $300 to $2,000 necessary. Will allow ex- Motion Picture Machines and Films. Bargain of Chicago having or who can rig up for long penses to Baltimore as explained. Address Mr. lists. National Equipment Co., Duluth, Minn. wave up to 4,000 meter receiving apparatus with Clemmer, 603 N. Eutaw St., Baltimore. Md. 1 ll,lu.11 111u1111uuuu11u,.111111,,,,u,u,,,,,,,,..,,,,,,,u11111u111111111111111111111111111111111111111111111111111u, 2 -stage audio -frequency amplifier, vacuum tube Make Big Money -Start a business of your own. For Advertisers. detector, 2 storage batteries A and B. Address We give full instruction to succeed. Guaranteed G. Kummer, 116 Nassau St., New York. F. Von formulas how to manufacture: Silverplating pow- Don't Wait for Business.- Advertise and get Radio Operators- Amateur radio operators der, liquid court plaster, straw hat bleach, re- it. We will help you. Jacobus Service, 41 Bruen, wanted to form a communication division 1st Ba- silvering mirrors, dressing and polish for tan Irvington, N. J. tallion Naval Militia and U. S. N. R. F. Practi- shoes, luminous paint, toothpaste for collapsible cal work and instruction radio and radio tel ^- tubes, soap babble liquid. All for 50 cents. The pltones. Many summer advantages. Week -end Sydney Specialty Co., 43 Murray St., New York Instruction. and fifteen -day cruises in Eagle boats to West City. Indian ports. Retainer pay while serving, full Convert Each Spare Moment into cash. My Recharge 25 dry cells, no expense except for pay when cruising. No interference with civilian new, dignified methods, requiring no investment, 10c worth alcohol. Directions, dime. Gilbert, duties Inquire any Mondry evening, Communica- ro merchandise nor peddling, will enable you to 746 Chenango, Binghamton, N. Y. tion Officer. U. S. S. Granite St., foot W. 97th St. increase your income 100 per cent immediately, Mathematics Taught By Mail -Spare time (via 96th St. and Broadway), North River, Man- without study or experience. Robert Stokey, 2206 home study course, including arithmetic, geometry, hattan. Elm St., Dallas, Texas. algebra and trigonometry. J. A. Harding, 76 Be Moving Picture Operator -Big pay. My Brighton Ave., Highland Park, Mich. Health. system helps you qualify. Answers to important Locksmiths -Get valuable chart for cutting questions, $1. Chief Operator Stepanik, 58F West tumbler padlock keys, $1.00. Globe System, 136 Tobacco or Snuff Habit Cured or no pay: Si St., New Britain, Conn. Sixth Ave., New York. if cured. Remedy sent on trial. Superba Co., SB, Baltimore, Md. "The Schemer, Alliance, Ohio, prints big -producing Pyorrhea (Riggs disease -bleeding or swollen profit schemes; one subscriber making Novelties. helped $25,000 from three schemes; another $10,000 from gums)-hundreds have been by "Pyorrdent one. See for yourself. Trial three months, 25c. Genuine Indian Baskets. -Wholesale catalogue. the successful home pyorrhea treatment. Puri- Marion Gilhams. Highland Springs, fying, healing, preventative. Full month's treat- Boys-Earn plenty money in spare time. Let California. ment, consisting of a very beneficial massage us show you how. Write today. Meirock Lab- paste and an antiseptic tooth -cleansing paste to be oratories, 5129 Marmora Ave., N., Chicago. Ill. News Correspondents used in place of your ordinary dentrifice, to. If You Want to Sell or exchange your farm. gether with full directions for treatment. $1 unimproved land, city property or patent, write Earn j25 Weekly, spare time, writing for news- postpaid. Or write for free booklet "R. Pyorr me. John J. Black, 194th St., Chippewa Falls, papers, magazines. Experience unnecessary: de- dent Mfg. Co., 489 Seventh St., Brooklyn, N. Y Wis. tails free. Press Syndicate, 566 St. Louis, Mo.

www.americanradiohistory.com Radio News for June, 1921 933

Patent Attorneys. Wireless. (Wireless continued) Millions Spent Annually for ideas! Hundreds If This Should Catch the Eye of radio amateurs Must Sell -Clapp -Eastham receiving set, cheap. and profit! Write to- in mechanics; it would be to Complete information sent. Hallam Meeder, now wanted! Patent yours or experimenters Pa. day for free books -tell how to protect yourself, their advantage to call at 2082 Lexington Ave., Girard, how to invent, ideas wanted, how we help you near 125th St., New York, and look over the line Baldwin Phones-The U. S. Navy, the British, sell, etc. 301 Patent Dept., American Industries, of wireless apparatus, condensers, cabinets, parts French and several other European governments, Inc., Washington, D. C. and odds and ends. Also machines, motors, ex- in addition to most professional operators and description offered E. T. Brandenburg (former patent expert, Ord- perimental material of every amateurs, have adopted Baldwin phones as their War Department), Attorney -at -law for sale. Only reasonable prices asked. Can be standard of electromagnetic receiver excellence. nance Division. 9 A.M. to 8 P.M., Saturday and Solicitor of Patents, 927 Loan and Trust Bldg., seen all day from The reason for this preference is apparent. Ex- Washington, D. C. Send sketch and description, and Sundays included. ceptional sensitiveness, combined with ruggedness model of your invention for careful investiga- equipped with gives Baldwin phones their popularity. The dia- or Alkaline Storage "B" Batteries mica Office and unbiased report as to switches. Thirty - phram is made of the finest quality selected tion at Patent rectifiers and single cell control as patentability. two volts, $8; 50 volts, $10; 70 volts, $12; pic- with the force concentrated at the exact center further information upon request. Esti- in high grade - phonograph reproducers. This fea- Patents -Send for free book. Contains valuable tures and highly important in the reception of radio- information for inventors. Send sketch of your mates given on unmounted cells. Kimley Electric ture is Winslow Ave., Buffalo, N. Y. phone music. The small armature is pivoted and invention for free opinion of its patentable nature. Mfg. Co., 290 to the Prompt service; twenty years' experience. Talbert designed to act as a fulcrum when connected D. C. Complete Wireless Telephone of 2 W N. Mo- diaphram by a small link. There is no tension & Talbert, 440 Talbert Bldg., Washington, of metal as in ordinary receivers. 1111, 111111111111 ,1 H11,,,,,,,,,,,.,., tor- generator gives 350 D.C., operates on 110 A.C. or springing Complete filter system designed for this generator, Four pole prices of a single solenoid act upon both Personal. absolutely no hum. Filament transformer for 4 sides of a highly balanced armature. Signals be heard with the best types of re- Astrology- -Stars tell life's story. Send birth - tubes. Two five -watt tubes. Microphone desk that cannot Eddy, Westport stand. Remote control relays. Weston and Roller - ceivers of conventional construction become easily date and dime for trial reading. for book- Station, Kansas City, Mo., Suite 30. Smith instruments. General Radio sockets, rheo- readable with the Baldwin phones. Send stats. Bus wiring. Everything first class. Heis- let and reasonable prices on these well known re- ing modulat'm with Acme transformer. This set ceivers. The Kehler Radio Laboratories, Dept. R. Phonographs. must be seen and heard to be truly appreciated. Abilene, Kansas. Build a genuine Choraleon phonograph and save Price $150. Kenneth Bainbridge, 823 Riverside Audion Detector and Amplifier, V.T., 50 cents. over half. Fine profits building and selling. We Drive, New York City. Honeycomb coil mountings, 25 cents. Back mount- tone arms and necessary parts. furnish motors, Dodge Short Cut made it possible to memorize ed rheostats, 40 cents. Composition for molding Send for our catalog and free blueprint offer. in one hour. your own knobs, panels. etc. 35c pound. Send Co., 621 15th St., Elkhart, and master Continental code about Choraleon Phonograph Thousands have. So simple everybody can what stamp for particulars. Palmers Electrical Equip- Indiana. was tiresome task now pleasant pastime. Send 50 ment Co., Palmers, Minn. Phonographs Direct From Factory- Complete cents for complete chart or ask for free testi- as and Variometers-You can now have as many or knockdown. Send today for large circular. monials from thirty -six states. Investigate you need. Why spend a lot of money for one Everett Hunter Mfg. Co., McHenry, Ill. profit by experience of others. C. K. Dodge, Dept. variometer when you can have three for the same 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 111 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 11 1 1 1 1 1 1 1 1 1 1 1 1 1 111 1 1 1 1 1 1 1 11 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1111 1 1 1 1 1 1 1 11 1 1 1 1 11 1 1 11 1111 111,11111111111 N. C., Mamaroneck, N. Y. price if you use our coils and make the other two Postcards and Pictures Aluminum Condenser Plates 5 cents. Washer parts easy according to our system. Send and we will send you four precision "egg- return 5 cents dozen. 10 cents for samples. Gravenstede, dollars Ten New York Views which you may 84 Hancock Ave., Jersey City. shell" variometer coils, blueprint instructions for bere for mailing. Two dimes. Fullofun, 136 Sixth completing the variometer, cement for attaching Ave., New York. Variocouplers on Bakelite Tubes, $5.25; vario- the coils and colored descriptive circular. These meters, inside windings, $4.25; complete for panel coils are something new. They are, light, strong, mounting; also carry all parts for above units, self -supporting and have high efficiency. Money Printing. oak cabinets with and without bakelite panels, back if you are not delighted! Send two dollars Everything Printed. -Long run specialists. bakelite tubes, magnet wire, DCC No. 24, 'A lb., now. Precision Radio Equipment Co., 120 Christie Samples. Quality Printery, Marietta, Ohio. 40e.; No. 26 DCC, 50e.. V lb. all other sizes in St., Ridgefield Park, N. J. proportion. Meade Bakelite and Radio Apparatus, Sta- Introductory Offer -As an inducement to those Labels, 60e per 1,000 up. Irvin J. Wolf, 522 Central Ave., Brooklyn, N Y. with our service, we E, Philadelphia. who are not yet acquainted tion All Kinds of Radio and electrical apparatus. will supply free of charge with each Radiotron 100 Letterheads and Envelopes, $1.50; 100 List sent free. Audion control panels with cabi- detector V.T. $5, or radiotron amplifier V.T. $6.50, cards and case, 75c prepaid. Crown Mail Order net, $7. Monte Radio Laboratories, 2221 Hunt or A -P. V.T. detector $6, or A -P V.T. amplifier Print, Station A,A11 Columbus, Ohio.1o1111111111111111 Ave., Monterey -Park Calif. $7, a Remler bakelite panel mounting rheostat of latest type $1, or an Amrad panel mounting V.T. Stop! Look and Think! 5 to 30 per cent dis- socket 90e. All tubes are shipped postpaid and Stamps and Coins. count on well -known makes of regenerative sets, insured and are guaranteed to arrive in perfect variometers, variocouplers, vacuum tubes, radio- Radio Laboratories, Dept. 1000 Different Stamps, $3.00; 500, $1.25; 200, grade condition. The Kehler 5602 Prairie, phones and accessories. Only new and high R, Abilene, Kansas. 25c; 100, 12c. Approvals. Michaels, apparatus carried in stock. Remember us when- Chicago. Lab- Intermediate Wave Tuners, no extras needed, ever you need anything. The Kehler Radio East and Colombia Dept. R, Abilene, Kansas. $35; description for stamp. C. Phipps, 407 California Gold Quarter size oratories, Brooklyn, N. Y. coin 30c; Italy 10 Centimes and catalog Eighteenth St., nickel Eldredge Meters. These meters are excellen' -High voltage gener- 10c. Homer Shultz, King City, Mo. in radiophone sets. The Advance Radio Phonists' Attention ,1111111111111111111111111111. for incorporating motor generator units in vari- .11111,111111111111111111111,11111111111111,11,1,1111111,111111,.1111111,,,,,,111111111imi,l111111111, voltmeters, 12 ranges A.C. ators. We supply "Midget" ammeters and ous capacities especially designed for radio phone Stammering. and D.C. may be used for controlling both direct dynamo- current, from transformers, on the work. Low powered rotary converters, tering and Stammering cured at or alternating tors. Fractional H.P. motors, storage batteries. St- Stu -t -t- filaments of your vacuum tubes or power tubes. condensers, spark gap home. Instructive booklet free. Walter McDon- and milliammeters Various types of meters, Bldg., Washington, D. C. The radio frequency ammeters rotors. The new synchronous spark gap. Get ac- nell, 121 Potomac Bank are just the thing for the radiation, grid and plate N. individual- quainted with our service. Ray- di -co. 2653A, Stammerers -My simple and natural method circuits. Each one has hand -calibrated, Ill. indi- ly engraved scale dimensions, distinguished by Clark St., Chicago, will correct your impediments. Instruction amplifier, $10. Wins- Robbins, 246 Huntington Ave., their high polish nickel finish, unvarying accuracy Bargain -New one stage vidual. Samuel I. prices. Sizer, Port Washington, N. Y. Boston. over 25 years of service, and at reasonable ton

1 1 X11 X1111111111111 11 1 11 The 111 X1111111 one 1 these meters. 411111111111.111111111111111111111111111111111111111111 11111111111111111111111 11111111111111111111.111 Send for a booklet describing Sacrifice large cabinet set, tube detector, Kehler Radio Laboratories, Dept. R, Abilene, stage amplifier, B batteries, $6.80; battery table Telegraphy. Kansas. Baldwin phones and transmitting set all mounted washing basket full and Wireless) and Blue Prints put your favorite hook -up on on white marble panel having Telegraphy (both Morse -We of miscellaneous, all for $100. Also ammeters and Railway Accounting taught quickly. Big salaries. tracing cloth, 9 x 12 inches for 50 cents, three for Call or write. R. and largest school; want. milliammeters calebrating set. Great opportunities. Oldest $1.25. You can then make all prints you Strauss, 1381 Avenue A, between 73d and. 74th established 46 years. All expenses low -can earn you obtained our VT diagrams for receiving Dodge's Institute, M. Have St., New York. large part. Catalog free. and phone sets? They' are making a hit. 50 cents cannot af- St. Valparaiso, Indi range Regenerative Set for amateurs who ,1111111111111111111 set of 12 separate sheets. Full 1im11111111111111111111111111111 .11111111111111111111111 for either ford the variometer type. Use these staggerwound of circuits at your finger tips. We prepare draw- pancake coils with the tickler circuit and obtain Scenery for Hire. ings, carrying out your ideas for any kind of greater selectivity and signal strength. Mount Collapsible Scenery for all plays. Amelia apparatus. Finest drafting at dirt cheep rates. on your old panel. Set of 150 -375 M, $7; 600 M, Grain, Philadelphia, Pa. Cabinet sets planned. Send sttinp. Fine wall $7.50; 1 K.W. O.T., $9; loops, $4. West Phila- 11111111111111111111111111111111111111111111111111, 11111111111111111111101111111111111111111. 4054 Chestnut St., Philadelphia, 1111 11111111111111111111111111111 print of Continental Code, 6 by 28 inches, 25 delphia Radio Co., Song Writers. cents. Readable 30 feet. No stamps with orders. Pa. The Plan Bureau, 1929 McCausland Ave., St. Variometers (2) and variocoupler in cabinets demand with Bakelite panels, complete but unwired, price Song Writers! -Learn of the public's Louis, Mo. make for songs suitable for dancing and the oppor- '$45. Send stamp for description. We changed conditions offer new writ- Slab Inductances -Set of eight, tuning with .001 special apparatus. Stratfield Radio Laboratory, 9 tunities greatly 30,000 meters. For- 1, Conn. in our "Song Writers' Man - MF condenser from 300 to Flushing Ave., R. F. D. Bridgeport, ers, obtainable only orders, $4.00, made payable at Atlantic ual and Guide, sent free. Submit your ideas for ward money Special Sale of Parts for radio apparatus. In free criticism and advice. We Road Brixton to Perry 9 Jelf Road Brixton, Lon- songs at once for England, and secure a set post free by return. order to liquidate a large stock we are offering revise poems, compose music, secure copyright and don, at practically half price the following sets of com- facilitate free publication or outright sale of Pure Hard Drawn copper strips for oscillating plete units ready for assembly. This is an excel- songs. Knickerbocker Studios, 319 Gaiety Bldg., transforme primary two inches wide, fifteen feet lent opportunity to make a start in wireless. We New York]; long; secondary, one inch wide twenty -three feet have the following ready for immediate shipment rum tttttt 11111111111111111111111,1111111111111111111111111111111111111111111111111111111111111111111111111111111111111 long. Makes the best of transformer; price per by parcel post prepaid, on receipt of remittance: Wanted to Buy set of two, $5 F. O. B. facory; shipments ten days Receiving tuner, 60e; 2,000 meter loose coupler, direct from factory. C. S. Newcomb, Mars Hill, $2; variable condenser, .0005 mf., $3; crystal de- It is Like Finding Money when you mail us Maine. tector, 70e; No. 14 antenna wire, 100 ft. coil, 60e; teeth, brooches, brace- helix, $2; % inch spark coil (com- 'old or broken watches, false directions for mak- transmitting lets, old or broken jewelry, old gold. silver, plati- Amateurs' Attention-Full plete assembled), $3.50; zinc spark gap with nol- platinum wire, ing latest U. S. Navy battleship cage type-antenna, 70e; hand key, 50e. 'l K.W. num, diamonds, magneto points, drawn, No. 14, lobed bakelite base, contact points or crucibles, mercury and anything free with every order for hard radio transformer, $8; 1,000 ohm head phones, highest prices in cash by pure copper wire at 90e per hundred feet. Postage ohm head phones, double, $3.75; valuable. We pay the 1st St., Brooklyn, single, $2; 2,000 return mail. Goods returned in ten days if prepaid. S. Weiss, 87 South strain insulators 8c each; mica transmitting con- you're not satisfied. The Ohio Smelting and Re- N. Y. densers .002 mfd., $2.50. No catalogues. Send & Clark Mfg. Co., fining Co., 207 Lennox Bldg., Cleveland, Ohio. Have Large Quantities of usedeond hand orders immediately. Kilbourne Write for Seattle, Wash. Want to Hear from party having farm for sale. material at big savings to the amateur. lowest price. John J. Black, Price list. Send postage for I. Krieger, 931) Give particulars and City. (Continued on page 194th St., Chippewa Falls, Wis. 2120 4

www.americanradiohistory.com 934 Radio News for June, 1921

(Continued from page 933) (Exchange continued) (Exchange continued) continued) Sale -One kilowatt 42 volt 24 ampere Robins For Sale -Wireless receiving apparatus, audion, (Wireless & Myers dynamo; cost $80; guaranteed good as coupler, etc., also printing press 5 x 8 in. Call new. Make me an offer. J. W. Thomas, Jr., after 7.30 P. M. Leonard Beck, Lafayette, 6211. Navy Test Galena Crystals. Supersensitive, Shelby, Miss. mounted crystals, value 50 cents each. Sale at 30 Exchange-Harley twin motorcycle engine, ex- cents each. Harry T. Gleich, 490 Sixth Ave., New For Sale- Regenerative receiver CR1 style, beau- cellent condition, for 1 kilowatt transmitting ap- York City. tifully made, brand new, $50 and. express. A. P. paratus. Russell Cronkright, Waseca, Minn. Southworth, Chestnut St., Wakefield, Mass. For Sale -Tresco tuner, amplifying transformer, Eaton oscillator, four volt storage kilo- For Sale battery, g -The record breaking receiving set, watt transmitting set, audion and Holtzer & Cab - 3,300 miles, used by 2KF, as illustrated in March bot phones. C. R. Bradley, 90 Birdsall, Winsted, Navy Test Galena Crystals-Supersensitive, issue RADIO NEWS, consisting of detector and '3- Conn. mounted crystals, value 50 cents each. Sale at 30 stage amplifier, hardwood cabinet, bakelite panel. cents each. Harry T. Gleich, 490 Sixth Ave., This For Sale- Complete receiving set, $23. Sam outfit is a beauty and a bear for long dis- Bronstein, Boston Massachusetts. New York City. tance. Perfect working condition is guaranteed. 48, Tunes from 175 to 600 meters Tresco Tuners, AS, BS and CS, $8 each. Law- 19 Electrostatic Condensers- Capacity .2 micro - sharp. Will take $110 cash, or send $40, balance C. O. D. Selling rence Alden, 5 Clifford St., Binghamton, N. Y. farad each. Will stand discharge over a parallel because 1 -16 in. of installing radio -audio set. H. D. Sel- For Sale- 1 0 -125 voltmeter, and 1 0 -10 am- gap of 2.5 mm. (.1 in.) between flat faces vage, 45 x 4 in. Good for high frequency work; $45 Durand Place, Irvington, N. J. meter, Eldridge type, new. Each $9. Lloyde Berkner, Sleepy Eye, Minn. each. Ajax Electrothermic Corporation, Trenton- Bargains-Detector and 2 -step amplifier. detec- N. J. tor cabinet, g K.W. sending set; 110 volt motors; Bargain -New receiving set, $15; navy coupler, $10, list. Bill Booth, 1300 Elizabeth Dirt receiving set comprising aerial wire; everything complete. Enclose three Ave., Char- Cheap -Cabinet red stamps for photo, if you mean business. Alon lotte, N. C. 2,500 meter loose-coupler, 21 primary switch taps, Shewman, 11 secondary., high selectivity; 43 -plate aluminum 662 Highland Ave., Meadville, Pa. For Sale- Doolittle amplifone, $12. used about two weeks; reason for selling loud variable condenser; 3 point battery switch, rheo- For Sale 2 have large -No. Junior omnigraph, perfect speaker. S. W. Brown, Mechanicville, N. Y. stat; audiotron- adapter, $15 complete. Have heard condition, $16. C. H. Tanner, Canton, Ill. conversation from Cape Cod, 410 miles away, using Must Sell- Unused $60 short -wave regenerative indoor aerial L. R. Ferguson, LeRoy, N. Y. Sell -Croft elec. Library, new, $20. W. L. receiver, $30; unused $65 long-wave undamped re- Pucket, Cave City, Ky. ceiver, $32; complete parts for $400 radiophone 3,000 Meter Coupler, $6; 600 meter coupler, and complete receiver, $150; $10; coil transmitter complete, $15; buzzer, Exchange -Dealers stock postage stamps and Spalding "Domino" spark tennis racquet; $3; post -card projector. $3.. $1.75; key, 75e.; detector, $1.50. All good con- supplies; will catalogue about $500, for 2 -step amplifier Brownie No. 2 camera, $1.50; Tresco variable condition. Hawkins, Alden, Minnesota. with tubes or other high grade radio denser, $1. apparatus in first class condition. Philatelist, 326 Terms C. O. D. P. H. Craig, 3397 Sale -$11 Rogers jig -saw, $6 (f.o.b.); good High St., Watertown, N. Y. Glenmore Ave., Cincinnati, Ohio. condition. Kuper, 407 W. 21st St., New York. Complete Wireless Outfit Cheap. List on re- ab- DeForest Unit Panels -Variable grid condenser quest. Dehert, 867 McPherson St., Brooklyn. Amateurs by a very few changes you can and leak, filament rheostat, single coil mounting, solutely get rid of all capacity effects of your body For Sale- Detector and two -stage amplifier, in- audion socket panel, battery switch and telephone cluding phones and, when operating your set controls and get louder 35 per cent prices long wave tuner, $70. Send signals than you ever heard before with no dis- posts, off. DeForest catalog D; for picture and description. Wm. Davis, Stanley instruc- Chelsea variable grid leak, $2; all good condition. Ave., tortion. Results guaranteed. Complete Wanted, Magnavox. Wesley Robinson, Jr., St. Canon City, Colo. tions with blue prints how to make or change your Marys, Georgia. Sell- Complete tuner detector and one -step set, only $1. David Monroe, East Orange, N. J. panel. Tuner has three variables, $32. W. Daniel, Bargain -National Radio Institute correspond- Q.S.T, -% K.W. Acme, $23; high speed rotary 430 Cedar St., Owensboro, Ky. ence course instruments, $20. Literature $25. All, with sawtooth rotor, $10; oil condenser, .007 mfd. 8AOA, Walter McCoy, Dormont, Pittsburgh, Honeycomb Coils Wanted (plug type) ; lowest $42. One -half inch coil (gap), $3.50. Books, etc., Pa. price. Bowers, 531 Madison St., Brooklyn, N., Y. stamp. Charles Moore, Kenton, Ohio. For Sale- Honeycomb coil tuner, $25. Clarence For Sale or Trade -New $35 professional punch- Sell -2 Murdock 366, $3.75; 3 coil mount, $4.50; Ott, 2121 Sheffield Ave., Chicago, Ill. ing bag stand, will trade for two amplifying bulbs Murdock and other apparatus cheap. Ed Page, and transformer or set of triple honeycomb coils Baliv; insville N. Y. Stamp Collection-Two collections of 800 stamps with mounting. each; $10 each, prepaid. R. Osborn, Darien, C. Halberg, 1445 Rascher Ave.,, Two Inch Spark Coil, $7; gap, $1. Both new. Conn. Chicago. Arthur Post, Harrison St., Passaic, N. J. Sell -Three toy casting forms for $8; cost $15. S-11-Chicago Radio Laboratory's audion control Stop! Look! and Think! -5 to 30 per cent Unused. Investigate. Aaron Vanatta, Houghton cabinet, listed $22; sell $10; new. Walter Pfeifer, discount on well-known makes of regenerative Ave., Manistique, Mich. Ind. sets, variometers, variocouplers, vacuum tubes, Dgdgp's Institute, Valpariso, radiophones and accessories. Only new and high For Sale-Complete navy standard receiving set, s.,. Swap! Buy! Sell!- Whatd'ye got? grade apparatus carried in stock. Remember us, consisting of 1P -500 tuner, Audion control box, Whatd'ye want? Forward price, description and two -stage amplifier and three external loading coil. whenever you need anything. The Kehler Radio This has quarter for listing, including year's subscription, Laboratories, Dept. R, Abilene, Kansas. navy set been in use a very little. Price Swap. Bulletin, New York- Detroit -Wichita Falls, $500, including 4 AP -tube. Just the kind for school Te:.o. For Sale -3,500 meter crystal receiving outfit or college. Photograph of set upon request. D. W. Murdock phones, $18; 10,000 and 3,500 meter Toy, 200 14th St., Milwaukee, Wis. Unmounted Long Distance receiving indue- loading coils, $8; 1920 issue Science and Inven- For Sale -Ace regenerative, 150 to 600 meters, Tb.ese are duo lateral wound coils, each tion, $4. Louis London, 3109 Cumberland St., ..f: !ice prints. Two coils with a tickler $50; Tusks C.W. inductance type 183, $9. appa- Philadelphia, Pa. ratus good _ al,ie receiving combination. Range in condition. Transportation prepaid. .meters, Arlington to Lafayette. Bargain -K.W. transmitter. Best distance All letters answered. Ray Thompson, Canton, 1,800- -gen. So. Dalc. i- rices: p many and secondary coils, $3.50 each. C.W. motor Kohnitz, Navy Radio, Du- Tickler coil. $2. Send $9 for the three coils and luth. Sell -Colby, $12.50, 200 -3,000 meter loose coup- diagram, and make a guaranteed receiving set. For Sale -Direct- reading ohm meter 0- 1,000; ler, for $8.25. Meader Pattington, Aurora, N. Y. P. J. Sro.1 -veil, Reading, Mass. bargain, $11. E. F. Gard, 24 Cedar Ave., Eliza- Detector and One -Step Amplifier panel, beth, N. 0 to 150 rl,. : oil set with audiotron variable, J. voltmeter, oak panel board for 18 DeForest panels, '.. ,n es, coils, etc. dial controls, price $32. 1 Amrad 6 volt induction coil, $30; % K.W. amplifying transformer. Sell cheap or swap. Write except A and B batteries. D. Shepard, quenched gap, $9. one -inch spark coil, $3. Items Leitch, Park Drive, West Orange, N. J. Ylat9`tsville, Conn. will be sent C.O.D. A. Hubner, 1842 Westwood Big Bargain- Browns 4,000 ohm phones, new, Bargain -New audion control, $5; amplifier, Ave., Cincinnati, Ohio. $15; condenser, 43 plate, $3; audiotron with hold- i. o - erat.. ,. 150 600. M., $15. Money back For Sale- Emerson motor, 3 speed, 110V, 60C, er, new, $4; 6 amplifying bulbs, pliotron type, . r r: s e J. Tygert, Hyattsville, Md. HP, $15; 110 and 6 portable test set, $10; new, $8 each; amplifier and detector, home made, S:ngle cylinder Harley Davidson motor- 4x5 (Bausch Lomb) rapid shutter and rectilinear works perfect, $20; navy crystal detector, $3; ., for radio apparatus. Write Warren lens, $10. Cash please. Marvin Harold, West - Perikon detector, $1.50; large sounder, $1.50; one MSe_lord. Okla. plains, Missouri. set I. C. S. electric engineering books, $15: other For Sale -Coil mounting and 5 coils, Will big bargains. Wireless, 139 Fountain Ave., Brook- iaar'air -- Detector and one step, with phones, $17. lyn, N. Y. bulbs, "B" batteries, $40. Regenerative receiver, trade. DeWitt Harris, Clarkdale, Ark. Imagine It! plate . -17 panel variable condenser, , Isadore Wolf, 1829 Evergreen Ave., Chi- Will Exchange -$100 chemical outfit for wire - ,less apparatus or will sell for $60. E. P. John- postpaid, $1.25. Jurek, 2642 Ballou St., Chicago. r .Eastham half K.W. Hytone trans- son, Oakdale, Tenn. Bargain-Complete receiving, sending set and rotary gap and motor complete, $50; one For Cameras, rectifier, punching aerial parts. Stamp for list. W. C. Grubb, Au- Sale- bag, mo- burn Jet., Indiana: Simon % K.W. 500 cycle generator and tors, Hawkins guides; send stamp for list. Law - combined, $25; one 'A K.W. 500 cycle rence Johnston, Fairfield, Ill. Sell or Exchange -Knapp dynamo, $3; large .,:nsfonner, $20. Sinclair Raynor, 8 N. Main For Sale -DeForest ten panel set with bulb, D.C. fan, $6.50; water motor, $2; Edison cylinder St., ,,reer, T I.. N Y. phonograph, fine for recording signals, $7; $448.. William Kivimaki,.517 Independence, Fair - tele- Now ar.;t. Comlete wireless'set, for sale.. port Harbor, Ohio. phone transmitters, 50c. Postage extra. Write, D. Vallow, 636 W. 38th St.. Indianapolis. Ind. ...rr^.culars .rite James Roff, Box 177, Bellaire For Sale -1 K.W. type RThordarson, new, $28; glass plate oil condenser, $10; oscillation trans- For Sale -1 K.W. transformer, $20; 1 K.W. Young & :c'Jr Sale -% K'VA transmitting station, $20, former, $3. A transmitting set at a sacrifice. McColmb gap, $12; Dubilier condenser, ,omplete. Robert Champion, 517 Park Ave., Wil- 9YAE, D. O. Kime, Le: Mars, Iowa. $20; oscillation transformer, $10; rotary gap in- liamsport, Pa. closed in home made box, $8. You pay postage. Marconi Wireless Records (6), $4; $35 Victrola, Daryl McClung, 1221 Ninth Ave., Huntington, "ri4l Volt D.C. direct from 110 volts 60 cycle best offer goes. Pair Murdock phones, $3; key and W. Va. r rldáopsour_." trans, issiòn., Capacity 50 buzzer, $1. P. Krawiec, 15- Woodbine St., Brook- i+ts price $30. Order ea *;,for quick delivery. lyn, N. Y. Brand New Colby long wave tuner. $12.50: J. Fitch, 181 W. Housatonic St., Pittsfield, Turney spiderweb inductance. $5.50. Will ship Bargain- Regenerative receiver, has Corwin C.O.D. or on receipt of first Postal Money Order. dials, tube, tube controls, 2 condensers. bakelite I. Krieger, 2120 Mapes Ave., New York i r4.less Apparatusus at remarkably low prices.. panel, variocoupler, variometers, City. $36; Willard 6 Variable Condensers Cheap, al l.' out. Write me. Earnest Fuller, V. 150 A. battery, $22 3,000 meter panel with knob, scale re- and pointer; suitable for panel or table mounting. n, .Ill. ceiver, has coupler, tube, tube controls, 4 con - densers, $27.50. 11 plate condensers, $2.30: 21 plate, $2.75: 41 -Notary spark gap, $12; aerial switch, Send for list. D. H. S. Science plate $3.75. Association, Dover, Ohio. e only Add parcel post for 1 lb. Henry estca .0115 MFD glass plate condenser, F. Robbins, 93 Mamaroneck Ave., White Plains, ampliatif panel with tube. "B" batteries and Will Trade wireless for high-powered field glass, N. Y. connected, $15. -'Ray'Raymond iedÏér, 70 Sargent St., preferably; or other goods.- Dave Ducks Arlington I..a;ralice, Mass. loose coupler, Murdock phones, Bargain -Short -wave regenerator, paragon type, condensers, and fine condition, $18.75; two Potentiometer, $1,95; Eastham 43 complete vacuum tube, and crystal detectors; navy standard Dubiliers, Clapp- plate all little used, $12.50; cabinet type two -step amplifier, condenser, $4.75; Tresco 11 plate condenser, as- new. Send particulars for same. Waler Scholz, Mignon sembled, $1.50; storage 6V, 60 $12. La Crosse, Wash. transformers, Al 'ondition, $19.50. Other battery, amp., new and slightly used apparatus. Also have some Fv. r +thing guaranteed. F. O. B. Edward Beaver, Rotary Condenser; 2 in. coil transmitter com- brand new power tubes. "1'+ Milwaukee, Wis. Leo Rostenberg, 15 Chest- Third St., plete. J. Swank, R. R. 16, Dayton, Ohio. nut Hill Ave., White Plains, N. Y.

www.americanradiohistory.com .. 10 `'--; ., _: ; T -`.,... s NFRSf ' - F Volumes S iNAWKIN .. Ilk IHAWKI1Sf[ii*-'-- KAWKIItiS' tHAWKII'x-. fIAV4hI1S ;NAWKIIS! HAWKINS I0'01 Ill ` :EECTRI(lí- 'ELEQRI(AlE" £LELTRI(A IflE(TRI(R ELECTflIEIiI, çLE(TRI(I+L !ELECTRICAL! EETRIfA¡i olirsA 3504 Flexible s; GUIDE, ¡GUIDE ; LGUIDEj, IGUIDE; .GUIDE'. !GUIDE GUIDEr jGUIDE1I(,0ÈS1,.NATI01100,01'-i', 1: Pages , r ,--,..-...,..::1 I. Covers ; 1LUsT6. .. 4700 Ne6' S 4e8 f0 (i N° N `N:9 }I .., Pictures Handy "- __ 1r' .. .=

t'' A.C. i AC' C IEIECfRICITY MANACENENT WIRING t r A I S 1Per E S fAETERNATIN MOTORS r SYSTEMS WIRING TELECRAPN N `MA6ÑETI5M -IAMPPOEIDCA[TRION Pocket DYÑAMOS , OISTRIBUilOq; I uflcmr POWEfl $ Volume TRAÌOFORMERS' i WIREIESS EYS ¡mignon % CURRENTS TLWUORAN MOTORS BREAKERS STATIONS ELETJiC gPERÏMENfS BELLS ; AUOMOSES. INSTRIIMENT MEASllAINGrr Size DYNAMOS S "CONPEgTQBS TEIEPHONE CE Per ALTEANATORSÍ LIGHTIN; s ,ARMATURES TESTING , RECñEIERS jtINSTRUMEHis% -WOHK. t;',' WINOIN j Montó Volumes É/. j ` --_....._.-3 .._GNII .ION 1 ',--"---'"-----1 "-----'-'.1- % PAGES 696 r 1266 8=; :'',..'t 1884 .._ -:+. .^. -... /..ri. . _ Just what you need to ktaow to succeed in ELECTRICITY EVERY electrician, every engineer, every mechanic should know READ THIS PARTIAL LIST OF CONTENTS about these wonderfully helpful instructive books, which give in 1 Contains 348 pages, 388 illustrations. Electrical plain words a complete working knowledge of electrical engi- No. signs and symbols -static and current electricity - primary Cells -- conductors and insulators- resistance and neering in all its phases. conductivity- magnetism--induction coils --dynamo. prturiplas -classes of dynamos- armatures -windings-- commutption -- You run into some new electrical problem almost every day. The brushes, etc. - Contains 348 pages, 394 illustration. ï Ito.

information you need to help you in your every day work is In No. 2 principles-armature - reaction-mot - v r *gas' :;.;3 ì1 calculations-brake horsepower -selection and msuaorttic., rt dynamo and motors- galvanometers-standard cells...corr ot, measurement resistance measurement voltmeters -- watt- meters --watt -hòur meters-- operation of- dynamos-operation of motors. etc: 300 pages 423 illustrations. Distribu. No 3Containslion systems -wires and wire calculations -,.. - side, outside and underground wiring -sign flasher, -l' , HAWKINS ntng protection -rectifiers -- storage battery systems. om. Contains 270 pages. 379 illustrations. Alternat- No. 4 ing current principles -alternating current dia- ELECTRICAL GUIDES grams---the Dower factor- alternator principles- alternator These books place electricity at your finger ends. They cover every imaginable etc. subject, prfliciple, theory, problem, trouble, and way of doing things electrically. Contains 320 pages, 614 nlustratlons. A. C. Motors Every subject is indexed so that you can turn right to Lt. They are a study course No. -synchronous and induction motor :Tin- C. commutator motors induction motors, tras:;form. c; fosse, and a reference guide in one, written in plain every day language -no wasted words construction, connections.- tests-converters you need to know-chock full of up -to- the-minute electrical knowledge. -rectifiers etc. -only what Contains 298 pages, 472-illustrations, Al,,erns', :,:e.. The guides are a complete course in electrical engineering. They will help you in No. 6` current systems-switching devices -circuit bre;:. .f every detail of the day's electrical work. You can't ask an electrical question that ers-relays - lightning protector apparatus-- regdlating dec,,, ) Hawkins Guides can't answer. -synchronous condensers- indicating, devices-mete,r; po'9,.. G...,1 factor indicators-wave form measurement -- switch boards. etc. Contains 316 pages. 879 illustrations. Alternat- Noe . 7 ing current, wiring power stations turbines] Pocket -Size Flexible Covers management, selection, location, erection, testing,- running. care and repair telephones, etc. books are enough coat - The small to slip into your Contains 332 pages, 436 illustrations. Tel . ßì:'a E.. pocket- handsomely bound in flexible black covers. No. 8 -simultaneous telegraphy and telephony -wire- What Electrical Men Say You can carry each volume with you until you have less - electric bells - electric lighting - photometry. eta Helped Good mastered its contents. 3,500 pages of actual information Contains 322 pages. 627 llluswations. Elec- S:, Him Make and 4,700 illustrations. Once you see these books and No. 9 trio railways-electric locomotives-car light- "It is only right for me to recom- put them into actual use you will never again want to be ing-fro ?ley car operat ion-míscellaneous'applications- 4 mend highly the Hawkins Guides, for without them. Try it at our expense. onction pictures= -gas engine ignition- auton:1bn,, se!r ,, they have been ofthe greatest assist- sta';ters and lighting systems. electric ,chic!',, P., ance to me in placing me in nay Contains 513 pages. 599 iiivauazzons, present position as Superintendent of No. 10 Elevators- cranes-pumps -air com- Construction Department of one of pressors-electric heating-electric welding Ohio's largest Companies. soldering - Electrical and brazing - industrial electro.. - ¿: I would like to see every man have a SEND NO MO lysis- electro plating electro- therapeutic ,ly set of Hawkins Guides." It will cost you nothing to receive these books -to leek -% -reps, etc. - & Co. Geo. Knecht, Columbus, Ohio. them over -ask them all the questions you "can think of -; Also a complete 126 -page ready 72 Fifth Ave. -use them in your work-study them-pick ud some reference N 72 Av . In the Naval Electrical Dept. informatioh that will increase your earning ability: We index of the complete will ship you the entire set of 10 volumes entirely FREE. library. This index has been "The Hawkins Guides are great This is a sign of our confidence in the guides. Pure planned to renfler easily ac- y,le 3e sábxd!. r help to me in the Naval Electrical gold does not object to being tested. thsaat fort examination Department, which they cover very Keep cessible all the vast Lnfor- Hawkins seven days and if you do not decide that you can't deo. YS mat(on contained in Electrical Guides (price thoroughly." C. J. Cornell. along without them. return them to us and owe ,us the r ® U. S. Receiving Ship, Brooklyn. N. Y. nothing. 10 - electrical guides. / $I each). Ship at once, re There are over 13: t6 Superintendent, When you decide to keep them you only hav, ro Day paid, the 10 numbers. ::!a $1.00 down and remit the balance of $9.30L on die easy. 500 cross refer - factory I agree Bawl v, am now superintendent of the ences. to I payment of $1.00 a month till paid for. You find seven days and to Dunnville Hydro - Electric Systems. Use this coupon to get the books. It will pay you what you want ., within f.: and Hawkins Guides were a great many mall $1 each month ü/'::. help to me in holding down a re- times over .. to know In- you sponsible posittbn." stantly. / W. E. Swartz, Dunnville, Ontario. Signature...... ,,,....,....,,...,.....,. Wireless Operators THEO. AUDEL & 'CO 'T have worked wireless for ten 72 Fifth Ave. New York, N.Y. Occupation yearn -but I wish I had these books years ago. as they have saved me a Employed by great deal of trouble." H. Marshall. Steamer M & B No. 2, Residence 9 Walkerville, Ont. SEND NO MONEY- USE THE CCU°ICIN Ir Reference .r, - -. R. N

www.americanradiohistory.com Do .Amateurs Realize the Wireless Opportunities that Await Them? How the President of the National Radio Institute Answered this Question When It Was Put Up to Him. What Would You Have Said ? Is the World's Fastest - Growing Field Actually Going to Slip Away From Those Best Able to Cash In Big On It ? These Are Questions Which Will Interest Every Radio Amateur.

+HAT was one of the questions re- that `the fastest -growing field in the world' cently put up to me by a well -known besides being a fascinating hobby is a won- Ii authority visiting Washington. "In derful, opportunity -filled field offering splen- your opinion," he said, "do amateurs real- did present advantages-and growing su ize the wireless opportunities that await rapidly that the future is beyond estima- thorn:" For a moment I was stumped! tion!" Then I replied, "Yes, with just one `but.' I wonder if many amateurs have ever I think that amateurs are well aware of considered the fact that what is to them a the tremendous expansion of wireless that fascinating hobby is also a fascinating pro- is daily going on. They realize that it is fession, filled with big opportunities that sweeping the world like wild -fire. BUT they can easily share whenever they are I do not think that they realize what this ready to do so. It's only a short step for means to them -they do not realize that them now to a splendid field that they can they can easily get the 'plums' that the put their hearts into -and offering a bigger field offers. They `have the jump' on future than older businesses which are everyone else, and they should realize now overcrowded. Mr. Taux E. Smith. President, Big Opportunities Are Knocking National Radio - Institute Are Some of Us Saying "Please Go 'Way What I Jotted Down After the caller who started me think- Here are the items I jotted down on my pad, and Let Me Sleep ?" showing how Wireless is growing by leaps and ing about this matter had left, I jotted bounds all over the world. Let nor tell you clown on my pad some of the items which our graduates five to ten points credit when taking what this world -wide sweep of wireless expansion means to you to I had recently noted regarding wireless First Grade Government License examinations. We and your futtre. have graduates in almost every part of the world expansion. On land and on sea big op- A. $20,000,000 American corporation has been formed who have quickly qualified through the special to establish wireless stations in every part of the portunities are opening, and even greater method through which we make Wireless amazing- globe. uses for wireless are being found every ly easy for anyone to learn completely at home in The U. S. Merchant Marine operates over 30,000 spare time. vessels. Wireless is now a necessity on sh:ps. day. No doubt you too have read these The Chicago Tribune now receives foreign news by items, I going These are some of the main points about this wireless. Other papers are calling upon Wireless too. hrt am to have them printed Huge wireless here I Institute and I am sorry I haven't room to tell you stations are springing up all over the because want to impress upon you all of them. I should like to tell you more about world. Saint Assise, France; Bordeaux, Ville Juif, what this can and Lyons, France; Pelting, China; Geneva, Switzer- tremendous expansion mean our wonderful new methods of teaching, about our land- Shanghai, China; Fiji Islands; Warsaw, Poland to remarkable new invention, the "Natrometer," which -and these are but a few. each student gets free, and which almost cuts in Many railroads are calling upon wireless to dis- `úrn I read every day how wireless expansion half the time necessary to learn Wireless thor- patch trains and carry on communication. The Lacka- is sweeping over the world I often say to myself, oughly. Then too I'd like to tell you about our wanna, The Louisville & Nashville, The Canadian - Pacific, The Nashville, Chattanooga & St. Louis, are "Big opportunities are knocking -I wonder if ama- free Post-Graduate Course and about "Dots and some of them. -New York, Cleveland, Chicago and teurs realize that they can cash in big on this Dashes," about our Diploma, our Relay League, Detroit are connected by an inter -city wireless service. growing field. While opportunities knock, I won- Employment Service, and about our special easy - Criminals are being intercepted by wireless through der if some aren't saying, 'Please go 'way and let payment plan. But there is not enough room here the Police Department of New York, Dallas, Chicago, me sleep.'" Of course, they aren't sleeping by to tell y,u about all these things so I am going to and other cities. Brokers, Bankers, Merchants, Manufacturers and any means, but I want all of them to know just ask you to write me for a new interesting booklet other business Now easy is to fully a field we have gotten up. concerns are calling upon wireless. it qualify for which is John Wanamaker, Goodyear Rubber Co., Standard undeniably filled with greater advantages than most Oil Co., New York Stock Exchange, are only a few. others in the w : ' _ io.la... Write Me For Farmers are getting Market and Weather reports Booklet daily by wireless in all sections of the country. Easy to Qualify A little coupon is being put here so that you can New wireless stations are springing up in every part save yourself trouble in sending for this illustrated of America. Belfast, Maine; Cape May. N. J.; East Pittsburgh, Pa. ; San Francisco, Cal.; Helena. Mon- In Spare Time -At Home booklet, " Wireless. the Opportunity of Today." By tana; Seattle. Washington; Mobile, Alabama-these mailing the; coupon you will not he obligating your- are but a few. I want to tell you -without obligation to yourself in any way and no solicitor will call upon you. The Aerial Mail Service of the Post Office Depart- self in any way-more about wi. c'era But the coupon will bring you some mighty inter- ment already has 12 radio stations in operation. ties aid how you can take advantage of them. I esting facts about Wireless Opportunities and The Japanese are constructing a powerful station would like to tell you abrut our Institute. which about how you can quickly and easily qualify for in the Orient. if officially A big new wireless service is being established recognized by the U. S. Dept. of Com- them -at home and in your spare time. between England and merce and whcsc name heads the list of the France. VlTon't you mail this The Federal Telegraph Co. is establishing a com- schools recom'o.eoded little coupon at once? plete chain of by thee.S. Shipping Board. Whether you are a junior Radio stations on the Pacific Coast. This National Radio Institute was the original and Amateur and want Messages are sent from the Philippine Islands to to learn all at out Wireless or whether you are Washington (10,000 is today the oldest and largest school in America anxious to fully qualify miles) in 3 minutes. teaching wireless by mail. The government allows so as to enter the wireless Daily wireless service between the United States profession now in cue of the fine opportunities and Japan is in full operation.-St. Johns, New open on land or on sea-write me for Foundland, is operating a large service. Danzig, in Europe, is carrying on large wireless ,M this booklet. All that I ask is that you TODAY-- write as soon as possible. operations. And- -since Three tremendous stations are operating on Long 11Ir, James E. Smith, President, there is no obligation-why not write Island at Easthampton, Port Jefferson, and East National Radio Institute, me today, Moriches. Dept. 16, Washington. D. C. South America is planning to establish a chain of me stations at Rio de Janeiro, Asuncion, Buenos Aires Send your FREE book. "Wireless, the Opportunity P. S. -By the way, we are making a and Montevideo. of Today." Tell me about your Institute and your special short -time offer, special for a strictly One single American concern offers wireless com- g short -time offer, limited time, in which we are giving all munication between the United States and France, rew students, our complete England, Germany, Norway, Denmark, Sweden, Fin- !i' Name new course land, Poland, Honolulu and Japan, in Wireless Telephony FREE. Mail the And these are II Age Occupation coupon direct to me, today, and let me only a few of the examples tell you about showing how Wireless expansion is spreading Address it by return mail. Mr. over the James E. Smith, President, whole earth. It brings you amazing The Na- opportunities-and you can now easily grasp State i tional Radio Institute, Dept, 16, them. L City Washington, D. C.