Radio Broadcast (May 1927-Apr 1928)

RADIO BROADCAST ADVERTISER 191 Improve Reception! ELECTRAD Certified Lead-Ins Eliminate insulation troubles at the entrance point of your aerial and have better reception by usins this superior constructed Lead-in. Bends any shape to fit around the corners and under locked doors or windows. Triple-ply insulation full 10 inches, covered with waterproof webbing. One piece copper strip heavily tinned to prevent corrosion. Protect yourself by looking for the Electrad name. Price 40c each. At your dealers. Write for Descriptive Circulars Dept. 61 B, 175 VarickSt., New York, N.Y. ELECTRAD FROST-RADIO OFFERS RADIO BROADCAST READERS TWO VALUABLE NEW BOOKLETS FREE! Write for Them VyE OFFER readers of Radio * V Broadcast two valuable new Frost-Radio publications free on request : "What Set Shall I Build?" the answer to a question which puzzles many set builders, and the new Frost booklet "For Better Reception," a complete and helpful manual of Frost Parts. Every set builder should have both of these booklets. They will be found chock-full of useful information that is right up to the minute. FROST-RAM) What they Contain "What Set Shall I Build?" tells much about the newest and most popular circuits "For Better Reception" tells you proper size rheostat for multi-tube sets, has wiring diagrams for high resistance unit, and contains valuable facts about Frost-Radio Parts. FROST RADIO W'%$q\o^ Mail Coupon NOW ^nistsi^iMl lets FKEE mi out and mail ,(G* HI , AN\1 I <iiui>"ri Im Iuu. iirinliim '. h : ^ \a?/' ^ : / // name and address carefully. / \ /' TIjchj brink will amaze you ^t^^^Sp^v ill with their completeness. wM&ttoVWMtl Write for them to-day — £mo°° mm// now. HERBERT H. FROST, Inc. Elkhart, Indiana f ROSTRAMO Chicago New York HERBERT H. FROST, Inc. 160 North La Salle Street, Chicago Please send me free your two booklets, as advertised in Radio Broadcast for January. Name Street Address City State Power a Quality A PUSH-PULL amplifier in that last stage provides the speaker with ample power to sustain a high volume level without tube overloading, transmitting the full effects of large swings in intensity common in orchestra music. This balanced type of amplifier draws no alternating current from the plate supply, a fact of great importance if socket power is used, as the impedance of the power unit does not affect the amplifier. This results in improved reproduction of sustained notes, particularly of low frequency. Other advantages of the push-pull system are, a reduction in hum when alternating current is used for filament supply and for equal power outputs, a reduction in the plate voltage required. The amplifier is supplied completely wired. Type 441 amplifier For use with UX 226, CX 326, UX 171, CX 371, UX 210, or CX 310 tubes. Input inductance 30 henries. Input turns ratio 1:2.25. Output impedance ratio 12:1. (whole primary to secondary) Price completely wired #20.00. Licensed by the Radio Corporation of America for radio amateur, experimental and broadcast reception only and under the terms of the R. C. A. license the unit may be sold only with tubes. mmlm mm Fw LABORATORY EQUIPMENT PARTS and ACCESSORIES If we can be of help to you in supplying technical information, we welcome your correspondence. Write for our Series A of amplification booklets describing various amplifiers, circuits and units. GENERAL RADIO CO. Cambridge, Mass.