Radio Broadcast (May 1929-Apr 1930)

. RADIO BROADCAST ADVERTISER. (passu* Zinnias** FROST-RADIO RHEOSTATS The original air-cooled Bakelite Rheostats. Have many unique features, including moulded Bakelite frame, resistance wire wound on die-cut flexible Bakelite strip, and smooth-working constant pressure contact arm. Made with or without D.C. switch, and supplied in a wide variety of resistances to meet every tube requirement. List prices range from 51.00 to $2.50. FROST-RADIO VOLUME CONTROLS We can furnish these famous Volume Controls with or without A.C. Switch, as desired. They are housed in Bakelite shell, with dust cover and have the only positive, nonwearing, stepless roller contact arm adjustment in the field. Switch type handles 2 50 volts at 3 amperes. Prices range from $2.00 to $3.00. Write for catalog showing the complete Frost -Radio line HERBERT H. FROST, INC. Main Office and Factory: ELKHART, IND. Chicago San Francisco Wire Your Home for Radio For every radio need, in brushed brass or Bakelite. Fit standard electrical switch or outlet box. Single plates and in gang in many combinations No. 135 — For Loud Speaker $1.00 No. 136 — For Aerial and Ground. . . i.oo No. 137— For Battery Connections. . 2.50 No. 138 — For A C Connections 1 00 {Bakelite, 25c additional per plate) YAXLEY MFG. CO. Dept B. 9 So. Clinton St., Chicago, III. HOOK-UP WIRE "The Draid Slides Back" At All Dealers 25 Feet Stranded 35c 25 Feet Solid 30c Red, Green, Yellow, Blue, Black PRFF Send us the name and address of your dealer r and we will send you a sample package of Braidite FREE. Include JOc for postage. CORNISH WIRE CO. 38 Church Street New York City ' > 0 g O.g-PJLftJk TONE QUALITY NOW the Carborundum Detector is adjustable. A turn of the pressure screw gives you perfect balance — gives you perfect tone. The detector then remains fixed and permanently sensitive, by tightening the lock nut. Tone Quality is everything in radio; here is another improvement that further assures it. Recommended by noted radio-circuit designers. DEALER OR DIRECT, $1.50 IN U. S. A. Send for Free Book "Carborundum in Radio" — D-2 THE CARBORUNDUM CO., NIAGARA FALLS, N. Y Canadian Carborundum Co., Ltd., Niagara Falls, Ont. Carborundum is the Registered Trade Mark of The Carborundum 7 Company for its Silicon Carbide and is its exclusive property I E CARBORUNDUM REG. U. S. PAT. OFF. DETECTOR A Two Year Subscription Saves You Two Dollars It saves you the bother of renewing next year. It is the most economical way to subscribe. You simply write six dollars instead of four when sending your check or money order. Try it for two years. Form the habit ! RADIO BROADCAST Garden City, N. Y. Jenkins & Adair Level Indicator Panel Type B (Calibrated) For Broadcasting, Electrical Recording, and Power Speaker Systems The Type B Level Indicator Panel is designed for direct reading of the voice level on any 50 0-ohra telephone circuit, the range being from minus 10 TU to plus 2 0 TU, in steps of 2 TU each. The parts consist of an accurately built input transformer, a specially designed potentiometer, a filter retard and condenser, and direct current galvanometer calibrated for this work. The use of this panel is essential wherever a specific level must be maintained. The calibration is highly accurate, and cannot alter while the tube constants remain normal. The potentiometer is built up of nichrome wire units, held to an accuracy of 1/10 of 19r. The panel is extremely simple in operation, is direct reading in TU's, and minimizes the change of load on the measured circuit when the level settings are changed. This last feature is a great improvement over present types. The dimensions of this panel are 19 x 7 Vz in. It is of 5/16 in. black sanded bakelite and weighs, complete, 18 lbs. It operates on 12 volt A battery and 135 volts B battery, and requires a 102E tube (not furnished by us). The parts of this panel are NOT sold separately. Bulletin 8 gives a more complete description and will be mailed on request. The net price in the United States and Canada is $2 50.0 0 f. o. b. Chicago. J. E. JENKINS & S. E. ADAIR Engineers 1500 N. Dearborn Parkway Chicago U. S. A. Manufacturers x>f Recording Amplifiers The Shielded Filtered AERO-CALL SHORT-WAVE A.C. and D.C. CONVERTER BOX Factory-Built, Ready to Plug Into Any Present Radio Set The Aero 1929 Converter is a compact factory-built short-wave adapter equipped with special short-wave coils. It is designed for both A.C. and D.C. sets. Operates on A.C. or D.C. sets without motorboating, by an auxiliary filter system control, an exclusive feature (patent applied for.) It can be plugged into any regular radio set. This amazing radio instrument now makes it possible for you to reach 'round the world. Morcroft of Pa. received England, Australia and Holland on his initial test.) Permits you to enjoy international programs and many others from coast to coast that your regular receiver cannot get. What a thrill it is to plug this into a tube socket on your regular set and instantly be in another world! No change or wiring required. All complete, ready to operate, tubes and coils hidden, no apparatus in sight, except the neat, golden-brown, compact metal cabinet in crackle finish. Size, 9 x 5 % x 2 % in. Cushioned feet. The only converter we know of that really works on all sets. Two models — A.C. and D.C. Write for Catalog and literature, or send $25.00 less 40% and name of your jobber. New Aero Supplement now ready. Ask for it. Model A, without tube, for A.C. sets List Model D, without tube, for D.C. sets List $25.00 INCORPORATED 1 V# 4611 E. Ravenswood Ave. CHICAGO, ILL. Dept. 259 • may, 1929 . ♦ n page 55 •