Radio broadcast .. (1922-30)

.114. RADIO BROADCAST ADVERTISER TRIMM Headsets For Short-Wave Receivers L Dr. Donald B. MacMUlan used Trimm Headsets in his last three expeditions to the Arctic re- gions in the ship Bowdoin. Here, isolated from the rest of the world, with no chance to make repairs, Dr. MacMillan depended on Trimm 'phones, maintaining unprecedented communication over tremendous dis- tances. Short-Wave Radio is growing in interest. The new con- quests, the big promise of the future are definitely tied up with these ex- periments. At least three American stations are broadcasting short-wave voice and music. The most pro- gressive of the amateurs are construct- ing short-wave sets. And their ex- periences are writing a chapter of modern miracles. Trimm Head 'Phones are the choice of the leading am- ateurs and ex- pert radio men. The Trimm Professional leads the line. Trimm Professional Headsets at #5.50 The Trimm Dependable at #4.00 is the best low-priced headset on the mar- ket. At a price but little higher than that of a cheap, inefficient headset, you may buy this real quality instrument. At all Radio Dealers or -write to us direct A Varied List of Books Pertaining to Radio and Allied Subjects Obtainable Free With the Accompanying Coupon 'S may obtain anv of the booklets listed helow by »s- '^ ing the coupon printed on page 322 Order by number only. 1. FILAMENT CONTROL— Problems of filament supply, voltage regulation, and effect on various circuits. RADIALL COMPANY. 2. HARD RUBBER PANELS —Characteristics and proper- ties of hard rubber as used in radio, with suggestions on how to "work" it. B. F. GOODRICH RUBBER COMPANY. 3. TRANSFORMERS —A booklet giving data on input and output transformers. PACENT ELECTRIC COMPANY. 4. RESISTANCE-COUPLED AMPLIFIERS —A general dis- cussion of resistance coupling with curves and circuit dia- grams. COLE RADIO MANUFACTURING COMPANY. 5. CARBORUNDUM IN RADIO —A book giving pertinent data on the crystal as used for detection, with hook-ups, and a section giving information on the use of resistors. THE CARBORUNDUM COMPANY. 6. B-ELIMINATOR CONSTRUCTION —Constructional data on how to build. AMERICAN ELECTRIC COMPANY. 7. TRANSFORMER AND CHOKE-COUPLED AMPLIFICA- TION —Circuit diagrams and discussion. ALL-AMERICAN RADIO CORPORATION. 8. RESISTANCE UNITS —A data sheet of resistance units and their application. WARD-LEONARD ELECTRIC COMPANY. 9. VOLUME CONTROL —A leaflet showing circuits for distortionless control of volume. CENTRAL RADIO LABORA- TORIES. 10. VARIABLE RESISTANCE —As used in various circuits. CENTRAL RADIO LABORATORIES. 11. RESISTANCE COUPLING— Resistors and their ap- plication to audio amplification, with circuit diagrams. DF.JUR PRODUCTS COMPANY. 12. DISTORTION AND WHAT CAUSES !T —Hook-ups of resistance-coupled amplifiers with standard circuits. ALLEN- BRADLEY COMPANY. 15. B-ELIMINATOR AND POWER AMPLIFIER— Instruc- tions for assembly and operation using Raytheon tube. GENERAL RADIO COMPANY. 153. B-ELIMINATOR AND POWER AMPLIFIER —Instruc- tions for assembly and operation using an R. C. A. rectifier. GENERAL RADIO COMPANY. 16. VARIABLE CONDENSERS —A description of the func- tions and characteristics of variable condensers with curves and specifications for their application to complete receivers. ALLEN D. CARDWELL MANUFACTURING COMPANY. 17. BAKELITE— A description of various uses of bakelite in radio, its manufacture, and its properties. BAKELITE CORPORATION. 19. POWER SUPPLY— A discussion on power supply with particular reference to lamp-socket operation. Theory and constructional data for building power supply devices. ACME APPARATUS COMPANY. 20. AUDIO AMPLIFICATION —A booklet containing data on audio amplification together with hints for the construc- tor. ALL AMERICAN RADIO CORPORATION. 21. HIGH-FREQUENCY DRIVER AND SHORT-WAVE WAVE- METER— Constructional data and application. BURGESS BATTERY COMPANY. 46. AUDIO-FRF.QUENCY CHOKES— A pamphlet showing positions in the circuit where audio-frequency chokes may be used. SAMSON ELECTRIC COMPANY. 47. RADIO-FREQUENCY CHOKES —Circuit diagrams il- lustrating the use of chokes to keep out radio-frequency currents from definite points. SAMSON ELECTRIC COMPANY. 48. TRANSFORMER AND IMPEDANCE DATA— Tables giving the mechanical and electrical characteristics of transformers and impedance*-, together with a short description of their use in the circuit. SAMSON ELECTRIC COMPANY. 40. BYPASS CONDENSERS —A description of the manu- facture of bypass and filter condensers. LESLIE F. MUTER COMPANY. so. AUDIO MANUAL —Fifty questions which are often asked regarding audio amplification, and their answers. AMERIRAN SALES COMPANY, INCORPORATED. 51. SHORT-WAVE RECEIVER —Constructional data on a receiver which, by the substitution of various coils, may be made to tune from a frequency of 16,660 kc. fi8 meters) to !<r>'' kc. (iso meters). SILVER-MARSHALL, INCORPORATED. 52. AUDIO QUALITY— A booklet dealing with audio-fre- quencv amplification of various kinds and the application to well-known circuits. SILVER-MARSHALL. INCORPORATED. 56. VARIABLE CONDENSERS —A bulletin giving an analysis of various condensers together with their charac- teristics. GENERAL RADIO COMPANY. 57. FILTER DATA —Facts about the filtering of direct current supplied by means of motor-generator outfits used with transmitters. ELECTRIC SPECIALTY COMPANY. so. RESISTANCE COUPLING —A booklet giving some general information on the subject of radio and the applica- tion of resistors to a circuit. DAVEN RADIO CORPORATION. 60. RESISTORS —A pamphlet giving some technical data on resistors which are capable of dissipating considerable energy; also data on the ordinary resistors used in resistance- coupled amplification. THE CRESCENT RADIO SUPPLY COMPANY. 62. RADIO-FREQUENCY AMPLIFICATION —Constructional details of a five-tube receiver using a special design of rad o- frequency transformer. CAMFIEID RADIO MFG. COMPANY. fu. FIVE-TUBE RECEIVER— Constructional data on building a receiver. AF.RO PRODUCTS, INCORPORATED. 64. AMPLIFICA i ION WITHOUT DISTORTION —Data and curves illustrating the use of various methods of amplifica- tion. ACME APPARATUS COMPANY. 66. SUPER-HETERODYNE —Constructional details of a seven-tube set. G. C. EVANS COMPANY. 70. IMPROVING THE AUDIO AMPLIFIER —Data on the characteristics of audio transformers, with a circuit diagram showing where chokes, resistors, and condensers can be used. AMERICAN TRANSFORMER COMPANY. 72. PLATE SUPPLY SYSTEM —A wiring diagram and lay- out plan for a plate supply system to be used with a power amplifier. Complete directions for wiring are given. AMER- TRAN SALES COMPANY. 80. FIVE-TUBE RECEIVER —Data are given for the con- struction of a five-tube tuned radio-frequency receiver. Complete instructions, list of parts, circuit diagram, and template are given. ALL-AMERICAN RADIO CORPORATION. 81. BETTER TUNING— A booklet giving much genera! in- formation on the subject of radio reception with specific il- lustrations. Primarily for the non-technical home construc- tor. BREMER-TULLY'MANUFACTURING COMPANY. 82. SIX-TUBE RECEIVER —A booklet containing photo- graphs, instructions, and diagrams for building a six-tube shielded receiver. SILVER-MARSHALL, INCORPORATED. 83. SOCKET POWER DEVICE —A list of parts, diagrams, and templates for the construction and assembly of socket power devices. JEFFERSON ELECTRIC MANUFACTURING COM- PANY. 84. FIVE-TUBE EQUAMATIC— Panel layout, circuit dia- grams, and instructions for building a five-tube receiver, to- gether with data on the operation of tuned radio-frequency transformers of special design. KARAS ELECTRIC COMPANY. 85. FILTER —Data on a high-capacity electrolytic con- denser used in filter circuits in connection with A socket power supply units, are given in a pamphlet. THE ABOX COMPANY. 86. SHORT-WAVE RECEIVER —A booklet containing data on a short-wave receiver as constructed for experimental purposes. THE ALLEN D. CARDWELL MANUFACTURING CORPORATION. 88. SUPER-HETERODYNE CONSTRUCTION —A booklet giv- ing full instructions, together with a blue print and necessary data, for building an eight-tube receiver. THE GEORGE W. WALKER COMPANY. 89. SHORT-WAVE TRANSMITTER- —Data and blue prints are given on the construction of a short-wave transmitter, together with operating instructions, methods of keying, and other pertinent data. RADIO ENGINEERING LABORATORIES. oo. IMPEDANCE AMPLIFICATION —The theory and practice of a special type of dual-impedance audio amplification are given. ALDEN MANUFACTURING COMPANY. 93. B-SocKET POWER— A booklet giving constructional details of a socket-power device using either the BH or 513 type rectifier. NATIONAL COMPANY, INCORPORATED. 94 POWER AMPLIFIER —Constructional data and wiring diagrams of a power amplifier combined with a B-supply unit are given. NATIONAL COMPANY, INCORPORATED. 100. A, B, AND C SOCKET-POWER SUPPLY— A booklet giving data on the construction and operation of a socket- power supply using the new high-current rectifier tube. THE Q. R. S. Music COMPANY. 101. USING CHOKES —A folder with circuit diagrams of the more popular circuits showing where choke coils may be placed to produce better results. SAMSON ELECTRIC COMPANY. ACCESSORIES 22. A PRIMER OF ELECTRICITY — Fundamentals of electricity with special reference to the application of dry cells to radio and other uses. Constructional data on buzzers, automatic switches, alarms, etc. NATIONAL CARBON COM- PANY. 23. AUTOMATIC RELAY CONNECTIONS —A data sheet showing how a relay may be used to control A and B cir- cuits. YAXLEY MANUFACTURING COMPANY. 25. ELECTROLYTIC RF.CTIFIER— Technical data on a new type of rectifier with operating curves. KODEL RADIO CORPORATION. 26. DRY CELLS FOR TRANSMITTERS —Actual tests given, well illustrated with curves showing exactly what may be expected of this tvpe of B power. BURGESS BATTERY COMPANY. 27. DRY-CELL BATTERY CAPACITIES FOR RADIO TRANS- MITTERS —Characteristic curves and data on discharge tests. BURGESS BATTERY COMPANY. 28. B BATTERY LIFE— Battery life curves with general curves on tube characteristics. BURGESS BATTERY COM- PANY. 20. How TO MAKE YOUR SET WORK BETTER —A non- technical discussion of general radio subjects with hints on how reception may be bettered bv using the right tubes. UNITED RADIO AND ELECTRIC CORPORATION. 30. TUBE CHARACTERISTICS— A data sheet giving con- stants of tubes. C. E. MANUFACTURING COMPANY. 31. FUNCTIONS OF THE LOUD SPEAKER —A short, non- technical general article on loud speakers. AMPLION COR- PORATION OF AMERICA. 32. METERS FOR RADIO— A catalogue of meters used in radio, with connecting diagrams. BURTON-ROGERS COM- PANY. 33. SWITCHBOARD AND PORTABLE METERS— A booklet giving dimensions, specifications, and shunts used with various meters. BURTON-ROGERS COMPANY. 34. COST OF B BATTERIES —An interesting discussion of the relative merits of various sources of B supply, HART- FORD BATTERY MANUFACTURING COMPANY. 35. STORAGE BATTERY OPERATION —An illustrated booklet on the care and operation of the storage battery. GENERAL LEAD BATTERIES COMPANY. 36. CHARGING A AND B BATTERIES —Various ways of connecting up batteries for charging purposes. WESTING- HOUSE UNION BATTERY COMPANY. 37. CHOOSING THE RIGHT RADIO BATTERY —Advice on what dry cell battery to use; their application to radio, with wiring diagrams. NATIONAL CARBON COMPANY. S3- TUBE REACTIVATOR —Information on the care of vacuum tubes, with notes on how and when they should be reactivated. THE STERLING MANUFACTURING COMPANY. 54. ARRESTERS —Mechanical details and principles of the vacuum type of arrester. NATIONAL ELECTRIC SPECIALTY COMPANY. 55. CAPACITY CONNECTOR —Description of a new device for connecting up the various parts of a receiving set, and at the same time providing bypass condensers between the leads. KUR?-KASCH COMPANY. (Continued on page 322)