Radio broadcast .. (1922-30)

218 RADIO BROADCAST ADVERTISER 200A P OWE R DETECTOR OOWER—and more of it JT«— that's the biggest thing in the tube field today! Son- atron's famous power tubes are giving new life to thou- sands of sets—and new en- joyment to thousands of set owners. The very next thing you should do is to buy this remarkable power detector — and hear the amazing improvement in reception which it brings! It's one of a family of 25 distinct types— the world's largest tube line! SONATROlS-ize your set! The Sonatron Amplifier •with 3 1(fd, White and flue Matched Power Tubes Adds three stages of amplification to any set, even a crystal. One con- nection, made in a moment, and you have this source of amazing power and tone. Adds beauty to your set, and makes your batteries last longer. For dry-cell or storage battery sets, $20 complete. At your dealer's. eONATKON TUBE CO.. Cliloio. NtwYork. N.w.rk, N. J., Detroit Windsor, Out., Canada Nationally Advertised Standard Quality Trade M.ir'i rscltke WORLD'S LARGEST TUBE LINB THE "RADIO BROADCAST" INFORMATION SERVICE How to Write for Technical In/or- motion— The Scope of This Service AS WAS announced in the June RADIO BROADCAST, all questions which were formerly sent to "The Grid" will now be handled by the Technical Information Service, RADIO BROADCAST Laboratory. That service is maintained under the following rules: 1. All questions from subscribers to RADIO BROADCAST will be answered free of charge. 2. Non-subscribers to RADIO BROADCAST will be charged a fee of One Dollar for the Laboratory Technical Service. j. All questions will be answered by mail and none will be published in RADIO BROADCAST. The Technical Information Service of the Laboratory feels that it is important to define the scope of its service to readers. Although the Service is of very general help to our readers, there are certain demands which can not be met. The Technical Information Service: 1. Cannot make comparisons between various kinds of receivers or manufactured apparatus. 2. Wiring diagrams of manufactured receivers cannot be supplied. This information can be secured from the various manufacturers. 3. Complete information cannot be given about sets described in other publications, but in all cases (wherever possible), inquirers will be referred to a source of information where the data can be obtained. In this connection, the monthly department in RADIO BROAD- CAST "The Best in Current Radio Publica- tions" should be of great help, and should be consulted. That department records the most important constructional, technical, and general radio articles which appear. 4. Special receivers or circuits cannot be de- signed by the Technical Service. 5. Those who ask questions which cannot be answered in the scope of a letter will be re- ferred, if possible, to sources where the infor- mation can be obtained. Readers who help by complying with the simple rules of the Information Service will greatly aid us in sending them a complete, accurate and speedy reply to their questions. TECHNICAL INFORMATION INQUIRY BLANK Technical Service, RADIO BROADCAST Laboratory, Garden City, New York GENTLEMEN: Please give me fullest information on the at- tached questions. I enclose a stamped addressed envelope. D I am a subscriber to RADIO BROADCAST, and therefore will receive this information free of charge. D I am not a subscriber and enclose $i to cover cost of the answer. Address R. B. D. The Shielded Dual-Control Receiver THROUGH an unfortunate error, improper C bias was specified in the article on "A Shielded Dual-Control Receiver" which appeared in the October RADIO BROADCAST. On page 498 it is stated that a small 22j-volt B bat- tery should be used as C bias when the plate voltage is supplied from four 45-volt batteries. This should read three 45-volt B batteries, and, if four are used, the proper bias will be 40.5 volts.. Examined and approved by RADIO BROADCAST^ COMPLETE WITH TUBE $25.00 GEORGE ELECTRIC COMPANY "B POWER UNIT" TYPE "M" Delivers the proper voltage at all times with- out a trace of a hum. Sturdily constructed to last as long as the best radio set. Its fine appearance will add to the beauty of your receiver. A full wave rectifier tube is used—no filament to burn out. Three taps with two variable resistances per- mit complete control of both detector and amplifier voltages up to 180 volts. This gives ample power for any set on the market. A George Electric Company "B" POWER UNIT" will remove all your "B" worries. LOWER PRICE HIGHER QUALITY POSITIVE GUARANTEE Sold direct from the factory to you, or through our authorized representatives. Write for complete informa- tion. Shipped prepaid on receipt of $25.00 or C. O. D. $25.00 plus postage. GEORGE ELECTRIC COMPANY 751 Carleton Ave. St. Paul, Minn. Representatives Wanted Why not subscribe to Radio Broadcast ? By the year only $4.00; or two years, $6.00, saving $2.40. Send direct to Doubleday, Page & Company, Garden City, New York. Pkrttex Build the best — Socket Power Devices —A and B Supply Devices Power Amplifiers Impedance Amplifiers And are best — For Filter Uses Rectifiers By Pass Blocking D. C. American made of best of materials to full capacity. All sizes and types. -^ POTTER MFG. CO. North Chicago, 111.