Radio News for April, 1921 673
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CIRCULATION LARGER THAN ALL OTHER RADIO MAGAZINES COMBINED RADIO 20April Cents 1921 Over 100 Illustrations NEWSREG. U.S. PAT.OFF. Edited by H. GERNSBACK A NEW RADIO INSTRUCTOR SEE PAGE 686. --f-, .r a J- _ - -- immitadan... _,-, THE 100% www.americanradiohistory.comWIRELESS MAGAZINE" CUNNINGHAM POWER TUBES Type C ®302 Demand 5 watt output Cunningham Tubes Price $8.00 The Name is etched on the Tube CW TELEGRAPHY AND TELEPHONY WITH CUNNINGHAM TRANS- MITTER TUBES OFFERS THE ADVANTAGES OF COMPACTNESS - RELIABILITY - LONG RANGE LOW POWER SHARP TUNING f RANSMITT ER TUBE SPECIFICATIONS Output Filament Plate Delivery Conservative Model Rating Amps. Volts Voltage Price Date C 302 5 watts 2.35 7.5 350 -400 $8.00 immediate C 303 50 watts 6.5 Io. Ioo0 30.00 Mar. 10th C 304 25o watts 15. 12. 4000 Max. 11 0.00 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. CUNNINGHAM 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 excess of their rated outputs. GENERAL ELECTRIC QUALITY PLUS CUNNINGHAM SERVICE Address All Communications to TRADING AS AUDIOTRON MFG. COMPANY 35 MONTGOMERY STREET SAN FRANCISCO, CALIF. www.americanradiohistory.com Radio News for April, 1921 673 Specify No. 766, Eveready Wireless Station Specify No. 763, Eveready Airplane Wireless Battery. Standardized for use in the U. S. Navy Battery. Standardized for use in the U. S. Signal Corps Aviation Section Here's your power-plant! 'THE Eveready Vacuum Tube All the skill and experience of the Plate Battery was especially de- Eveready engineers have been poured signed for radio outfits. It is packed into this battery and sealed up. tight with electrical energy that will Once you know the power and en- send your message singing through durance of the Eveready Vacuum space to the receptive antennae miles Tube Plate Battery, you will never away. be satisfied with less. But be sure The Eveready is known every- you get the genuine. Sold by lead- where as the battery of endurance. ing dealers everywhere. Name of It stays on the job till the last second. dealer in your locality on request. AMERICAN EVER READY WORKS of National Carbon Company, Inc. 226 Thompson Avenue, Long Island City, New York Chicago Atlanta San Francisco Makers of Eveready Flashlights and Batteries, Storage 'Batteries, Miniature Mazda Lamps, Dry 'Batteries, and Meters FIJE fly VACUUM TUBE PLATE BATTERIES A19-TE www.americanradiohistory.com \ ß \ V L,\` r Zt % ,.c\ \w3 -_---- --- CONTENTS VOL.1a2 FOR APRIL NO. 10 /,; PAGE PAGE Underground Loops...By H. Gernsback 677 The H. C. of L. and Burned Out Ampli- fying Transformers Radio Communication By Cyril O. Smith 691 By J. H. Dellinger 678 An Ideal Receiving Set for Short and eat Get Your Friends Interested 680 Long Wave- Lengths By E. G. Shalkhauser 692 New Universal Range Receiver By Arthur H. Lynch 681 Short Wave Radio Vacuum Tube Trans- mitter and Regenerative Receiver with Tests of Insulating Material for Radio Two -Step Audio Frequency Amplifier Use at the Bureau of Standards By Walter Hyndman 693 By S. R. Winters 682 Conduction of Electricity Thru Vacuum Aeroplanes and Radiogoniometers and Gases with Application to Design By Armstrong Perry 683 of Radio Apparatus. First Part By E. M. Sargent 694 $10o Portable Radio Prize Awards of ia`1 0_ Ì Contest . 684 Who's Who in Radio -Sir Oliver Lodge 695 A "B" Battery of the Edison Storage With the Amateurs 696 Type By W. H. Farr 685 Correspondence from Readers 698 A New Radio Instructor 686 Club Gossip 699 First Annual Amateur Radio Show and Radio Digest 700 Convention 687 Found by Radio 701 The Radio Dealer and the Beginner By Armstrong Perry 688 The Radio Constructor 702 Junior Section 704 Quenched Gap Transmitters 689 By Jesse Marsten A Complete Receiving Set for 25c 1111111111E1 111111UI1UIUIIII IIIIIIr rl1111: Rillt By D. Adams 705 )11. John ^\\ .. 4 -. Non -inductive Resistances and How to V Make Them By P. F. Geagan 690 Junior Constructor . 706 'I Continuous Wave Multi -Stage Receiving I- Want -To -Know 707 -Taggart 690 Circuit By John Scott News from My Statior New German Radio Recording Device.. 6ó1 By G. Ridleak V. T. 708 --aaa;01 of each month at included. ALL accepted contributions are paid for on Publication. NEWS is publlaht on the 25th novel RADIO are 12 numbers per year. Subscrip- special rate is paid for experiments; good photographs accompanying 233 Fulton Street, New York. There them are highly desirable. tion wonted (ne i2.ó0 a09year. II S. coin as well as S. Stamps RADIO NEW S. Monthly. Entered as second -class matter June Single copies, 20 cents each. A sample copy will 6th, 1919, at the Post Office at New York, N. Y.. under the Act of foreign coins or stamps) be drawn to sent gratis on request. Checke and money orders should March 3, 1897. Title registered U. S. Patent Office. tbpyright, 1921, by be ENTER PUBLISHING CO., INC. If you should E. P. Co., Inc., New York. The Experimenter Publishing Co., 233 Falten seder of EXPERD copies be not mis- The change order that Street, N. Y., N. Y. Contents of this magasine are copyrighted and sent amer y, ins must not be reproduced without giving full credit to the publication. carried youro L.drÑo copies be ad- communications and contributions to this journal should RADIO NEWS, 233 Fulton Street, New York. P. A D I O NEWS is for sale at all newstande in the United States dreat to Editor, full postage has been and Canada; also at Brentano's, 37 Avenue de l'Opera. Parla. Unaccepted contributions cannot be returned unless Pnbliaht by EXPERIMENTER PIIBLISHING CO., INC. 233 Fulton Street, New York City _2 H. GERNSBACK. President S. GERNSBACX. Treasurer R. W. DE MOTT. Secretary aSIlY:/j \. A \SL, -a^.. l'_. =i-=-`.= , \\__ , ^' /11_li- .:"-\__\ - www.americanradiohistory.com Radio News for April, 1921 675 50,000 NAVY TYPE OHMS A. C. 50,000 ohms A.C. at 800 cycles. Weight 9 oz. com- plete with headband and RESISTANCE in our polarity indicating cord, Price $14.00. Navy Type HEADSET Special attention of all who are using Vacuum Tubes How We Get An Impedance To get the highest efficiency from a station equipped with vacuum of tubes it is absolutely necessary to use a headset of very high im- pedance. In our Navy Type Headset with an impedance of 50,000 Ohms 50,Ooo ohms A.C. at Boo cycles we have accomplished something There are four bobbins in each headset- never before two to each earpiece. Each of these bob- possible in a commercial headset. The extra high bins is wound with 10,000 turns of insu- impedance of this new model makes it ideal for vacuum tube lated copper wire. Because of the difficulty reception. of winding small wire the greatest number of turns in any other headset is less than 7,500. No other manufacturer has been This headset is exceedingly high pitch in tone and is -consequently able to approach 10,000 turns without mak- ing his headset too bulky, heavy and fragile very sensitive to high pitch signals. To anyone wishing to receive for practical use. Consequently no other trans -Atlantic or Pacific signals our High Impedance Navy Type headset has over 25,000 ohms impedance at Headset is indispensable. 800 cycles. In spite of the fact that there are over 40,000 It is the most sensitive headset built regardless of price and it is turns of wire in our High Impedance Navy Type Headset it weighs only 9 oz. backed by one of the most liberal guarantees ever written. Read complete with headband and cord. Its our offer below. compact, sturdy build insures comfort, re- liability and long life. BRANDES Matched-Tone HEADSETS 100c% Receiver Satisfaction While Brandes Matched Tone Headsets on the diaphragm less current is required justable to any size head. Check nuts hold are very light and comfortable they are so to produce audible signals and the space the adjustment. built that there is no This headband is rust- sturdily danger of and weight of unnecessary amplifying proof, strong and light. them losing their adjustment through hard mechanism is eliminated. usage. The shell is made of thick, rigid Our headsets are aluminum and the cap of hard vulcanized Brandes also now equipped with Matched Tone Headsets are new style conducting cords which indicate rubber. The parts are all securely anchored carefully matched in tone and permanently the polarity by hand by skilled workmen of the receivers. This elimi- who do noth- adjusted at their highest point of efficiency. nates any danger of ing but make Brandes Headsets. All of our models are demagnetizing the re- equipped with im- ceiver when used in connection with vac- Because the action in our headsets is direct proved headbands which are instantly ad- uum valve detectors. You can try our High Impedence Navy Type Headset without We want you to give our risk High Impedance Navy Type Headset a trial. comparisons with the headset you are now using. We want your judgment on it. We back this headset with the most liberal set in If it isn't a better head - every way than any you have ever used or seen, or if guarantee ever placed behind a wireless instrument.