Radio Broadcast (May 1928-Apr 1929)

■z. .RADIO BROADCAST ADVERTISER. REAL One -Dial Control The sections of Hammarlund "Battleship" Multiple Condensers are matched to within \\ of one per cent. Absolute precision can be obtained by attaching a Hammarlund Equalizing Condenser to each section. Recesses in the frame provide for this. That means REAL One-Dial Control, with every circuit accurately tuned. Made in 350 mmfd. and 500 mmfd. sizes in two, three and four gangs. Your dealer sells them. Write for Descriptive Folder. HAMMARLUND MFG. CO. 424-438 W. 33rd St. New York ammariund p P, E C I S ION PRODUCTS Reliable ShortWave Reception This tested screen grid tuner will give dependable short-wave reception. Simple to assemble. Easy to Tune. Stations can be logged. Does not radiate. NATIONAL SHORT WAVE TUNER Send for Bulletin No. 132-RB. NATIONAL CO., Inc., MALDEN, MASS. Hr-nE IS A COUNTER CKC TUBE CHECKER Which Requires NO BATTERIES Operates direct from the A.C. LIGHT SOCKET Or any other A. C— 60 cycle — 90 to 130 volt source of supply Proper Voltage Regulation is quickly obtained by means of. the Voltage Adjusting Dial and the Voltage Indicator. Will test every type of tube A. C. or D. C. — having filament voltages of 1.5, 2.5, 3.3, 5 or 7.5 volts, including filament type rectifying tubes. Check Tubes at Time of Sale It prevents comebacks and makes satisfied customers. Your jobber will supply you, or write direct to: Weston Electrical Instrument Corp. 604 Frelinghuysen Ave., Newark, N. J. WESTON RADIO INSTRUMENTS and Polymet makes them" He was buying coils. He knew that Polymet now made coils. He had used Polymet Condensers and Resistances before. Confidently, then, he placed his order for coils with Polymet. This is the sort of good-will we are proud of and intend to keep — the good-will of all, from the largest radio manufacturer to the smallest set builder. Our latest catalogue tells how to build many popular circuits. Send for it. POLYMET MANUFACTURING CORP. 597 Broadway New York City POLYMET PRODUCTS Whatever You Want to Know about RADIO — principles, methods, apparatus — you will find instantly in THE RADIO MANUAL A Complete Course in Radio Operation «n a Single Volume A Handbook for Students Amateurs Operators Inspectors For the first time an entire course of training in one book — the most complete and up-to-date work on radio. Developed simply and clearly from the elementary stage right through all phases of principles, practise, and apparatus so that a beginner with no knowledge of electricity may get all he needs either for amateur operation or to qualify for a government license as operator or inspector. Prepared by Official Examining Officer The author, G. E. Sterling! is Radio Inspector and Examining Officer, Radio Division, U. S. Dept. of Commerce. The book has been edited in detail by Robert S. Kruse for five years Technical Editor of QST., the Magazine of the Radio Relay League. Many other experts assisted them. 16 Chapters Cover: ES^S-KmS: tors and Generators; Storage Batteries and Charging Circuits; The Vacuum Tube; Circuits Employed in Vacuum Tube Transmitters; Modulating Systems; Wavemeters; Piezo-Electric Oscillators; Wave Traps; Marine Vacuum Tube Transmit ters; Radio Broadcasting Equipment; Arc Transmitters; Spark Transmitters; Commercial Radio Receivers; Radio Beacons and Direction Finders; Radio Laws and Regulations; Handling and Abstracting Traffic. Infnvmnitnn never before available such i\ew information as a complete description of the Western Electric 5 Kilowatt Broadcasting Transmitter; description and circuit diagram of Western Electric Superheterodyne Radio Receiving Outfit type 6004-C; Navy Standard 2-Kilowatt Spark Transmitter; etc., etc. Every detail up to the minute. Free Examination "The Radio Manual" has just been published. Nearly 700 pages. Profusely illustrated. Bound in Flexible Fabrikoid. The coupon brings the volume for free examination. If you do not agree that it is the best Radio book you have seen, return it and owe nothing. If you keep it, send the price of S6.00 within ten days. Order on This Coupon I D. Van Nostrand Co., Inc., 8 Warren St., New York Send me THE RADIO MANUAL for examination. Within ten days after receipt I will either return the volume or send you S6.00, the price in full. (Radio Broadcast 4-2o) Name . St. & No City and State • april, 1929 . . . page 411 •