Radio broadcast .. (1922-30)

RADIO BROADCAST ADVERTISER 25.5 PURCHASE OLT WOUND CONDENSERS WOUND condensers for use in the filter circuits of current supply units should be rated for continuous duty at their full marked voltage. "Flash tests" are valueless. Con- densers can be made of the cheapest materials which will not break down under a "flash test" of 1500 volts, yet they may fail after 6 hours of continuous duty at 400 volts! Paryolt Wound Condensers are made in 3 service voltage ratings: Type A-400 Volts d. c.) Type B-800 J. continuous duty Type C-1000 i ACME WIRE COMPANY NEW HAVEN - - CONNECTICUT RADIO PANELS OF GENUINE BAKELITE Cut, drilled and engraved to order. Send rough sketch for estimate. Our complete Catalog on Panels, Tubes and Rods—all of genuine tfakclite—mailed on request. STARRETT MFG. CO. 521 S. Green Street Chicago, III. Amperite alone can supply automati- cally, the self-ad- justing filament control your tubes require for perfect _ rlu-ostat regulation under all varying conditions. Insistupon Amperite, andaccept nothing else. Simplifies wiring. Eliminates hand rheostats. {specified by leading engineers in every popular circuit. Types for all tub-s. Price $1.10 mounted (in U.S.A.) At all rs 60 FRANKLIN ST.. NEW YORK FREE Write for Hook-UDS to Dept. R.B.-8 WHAT KIT SHALL I BUY (Continued) 220. BROWNING-DRAKE —Five tubes; one stage tuned radio frequency (Rice neutralization), regenerative detector (tickler control), three stages of audio (special combination of resistance- and impedance-coupled audio). Two controls. 221. LR4 ULTRADYNE —Nine-tube super-heterodyne: one stage of tuned radio frequency, one modulator, one oscillator three intermediate-frequency stages, detector, and two transformer-coupled audio stages. 222. GREIFF MULTIPLEX —Four tubes (equivalent to six tubes); one stage of tuned radio frequency, one stage ol transformer-coupled radio frequency, crystal detector, two stages of transformer-coupled audio, and one stage ol impedance-coupled audio. Two controls. Price complete parts, $50.00. 223. PHONOGRAPH AMPLIFIER —A five-tube amplifier de- vice having an oscillator, a detector, one stage of trans- former-coupled audio, and two stages of impedance-coupled audio. I he phonograph signal is made to modulate the oscillator in much the same manner as an incoming signal from an antenna USE THIS COUPON RADIO BROADCAST SERVICE DEPARTMENT Garden City, New York. , Please send me information about the following kits in- | dicated by number; Name. .. Address (Number) (Street) (City) (State) ORDER BY NUMBER ONLY. This coupon must accompany each order. RB827 She "SELF-ADJUSTING" Rheostat TECHNICAL INFORMATION INQUIRY BLANK Technical Service, RADIO BROADCAST LABORATORY, Garden City, New York. GENTLEMEN: Please give me fullest information on the attached questions. I enclose a stamped addressed envelope. D I am a subscriber to RADIO BROADCAST, and therefore will receive this information free of charge. H I am not a subscriber and enclose $i to cover cost of the answer. NAME. ADDRESS R. B. Aug. USE THIS COUPON RADIO BROADCAST SERVICE DEPARTMENT RADIO BROADCAST. Garden City, New York. Please send me information about the following manu- factured receivers indicated by number; Name. Addr -ss (\'umbtr) (Street) (C'l/.v) (Slate) ORDER BY NUMBER ONLY This coupon must accompany each order. RB 827 The Famous AERO Short Wave Kit Now Improved! Even greater volume, selec- tivity, tone quality and flexibility assured by this season's sensational coils! AERO LOW WAVE TUNER KIT Code No. L. W. T. 125 Price $12.50 Always the prime favorite of all experts and amateurs insistent upon the very best in short wave reception, the AERO Low Wave Tuner Kit for this season has been made even better than ever! Flexibility to a degree never before thought possible has been embodied into the new kit so that it has a gapless range (when used with INT. Coils No. o, 4 and 5) of 13 to 725 meters! Used by 2 Famous Expeditions The performance of this AERO kit is so flaw- less, so satisfactory in every way that it has been selected as standard equipment by the Uni- versity of Michigan's Expedition to Greenland (1926-1927-1928) and by the MacMillan Arctic Expedition. No greater proof of its efficiency could be offered than by its selection for these important tasks. The AERO Low Wave Tuner Kit illustrated above is completely interchangeable. The kit itself includes 3 coils and base mounting covering U. S. bands 20, 40 and 80 meters. You can in- crease or decrease the range by securing the AERO Interchangeable Coils described below. All coils fit the same base and use the same con- densers. New AERO Inter- changeable Coils Int. No. 0 Range 13 to 29.4 meters. This is the most efficient inductance for this low band. Code num- ber INT. No. 0. Price X4.00 Int. No. 4 Range 125 to 250 meters. Fits same base supplied with low wave tuner kit. Code number INT. No. 4. Price j!4.00 Int. No. 5 Normal range 235 to 5 SO meters. However, by using .0001 Sangamo fixed con- denser across the rotor and stator of the .00014 vari- able condenser, the maxi- mum wave band of this coil is increased to 725 meters. This gives you cov- erage of the following bands: Airplane to Airplane, Land to Airplane, Ship to Shore (Great Lakes) Ship to Shore (Atlantic and Pacific oceans). Code number INT. No. 5. Plan for D. X. Records NOW Order any of these foils direct from us if your dtalfr doein't happen to have them. Specify <Wc nttmhi-n tvhfn ordering, AERO PRODUCTS, Inc. Dept. 109 1772 Wilson Avc. Chicago, 111.