Radio age (Jan 1927-Jan 1928)

RADIO AGE for May-June. WZ7 Trouble Shooting on Supers (Continued from page 7) fied for your particular circuit. Sometimes mistakes occur in packing and a .00035 mfd may be found in a .0005 mfd box, or vice versa. Loop may be too large or too small. [f the loop is to large you will have trouble in tuning in stations on the lower waves if it has not enough inductance it will not tune up to the higher bands. (38) Wrong type condenser. If a condenser with a metal shaft is used in a super with an oscillator tuned from grid to plate, you will have trouble with body capacity. With this type; of tuning use a condenser having insulated rotor and stator so the shaft coming through the panel is not a part of the circuit. (See oscillator method used by Radio Age in its latest 9 tube design — Editor). (39) Grid connected to rotor of condenser. Always connect the grid to the stator of the variable condenser. If the grid goes to the rotor body capacity may be encountered. (40) Rotor not grounded to negative filament. The regular type of condensers can be used where the tuning is from grid to filament of the oscillator. In this case be sure to connect the rotor to the filament negative to eliminate body capacity when the set is being pushed for distance. Of course the grid goes to the stator as usual. Notes On Above Do not use the schematic in this article for wiring a set. It is only reproduced here for reference in trouble shooting. The test methods outlined here will help you considerably in solving your own problems. Many trivial mistakes made in originally building the set will show up under these tests and should serve as a guide for your construction of an excellent super of which you will be proud. Be sure to use quality material in a super. Tts the best economy in the long run Please 45 Radio Under Watei HARRY L. PAIGE'S business is going down to the sea in a diving helmet, but he insists upon taking his radio along — at least, he takes the ear phones with him below the waters of Corpus Christi Bay. Paige is a member of a crew running a barge and placing pipe for a sewer outfall on the bottom of the bay. Harry's job is to go down and buckle the pipes together after they have been placed in their positions. He found after a while that the very programs he wished to hear usually were broadcast at those hours when he was engaged in diving operations. He decided to remedy the situation. Others on the barge out in the bay, about a mile from the mainland, were skeptical about Paige's experiment. He procured some heavily insulated wire, ran it from the instrument to his sleeve and up to the ear phones. Then he tuned in on the particular station he wished to hear. When he went down about fifteen feet to the place where he was working he found that he received the programs as clearly as if he were sitting on the deck of the barge. Now, whenever he has to wait for the heavy concrete piping to be lowered into place, he can while away the time beneath the waves by listening to jazzy tunes from far-away stations or he can take swimming lessons by radio from Gertrude Ederle. Anyway, Harry says the radio adds to the companionship of the deep when the only visible animal life is jelly fish. — E. G. Fischer. Mlentitvn Tta/lin Aae When Wiriti.no tn A A PUSH-PULL FOR POWER . Two new audio frequency transformers have just been released by the SilverMarshall laboratories, which, used with two 112 or 171 type tubes, will provide greater power output without overload distortion than the most powerful 210 amplifiers heretofore used. One 230 and one 231, with two 171 tubes', will give greater undistorted power output with but 180 volts than a 210 tube operated at 400 volts or morel Type 230 input transformer may be used as a 3:1 or 6:1 ratio audio transformer, or as a 3:1 push-pull input transformer. Its characteristics are very similar to those of the famous 220 — effective primary inductance 100 henries, with falling curve from 30 to 5000 cycles. Type 231 output transformer may be used as a push-pull output transformer, or to obtain accurate matching of output impedance of all standard power tubes when used as an ordinary output transformer. Its characteristics are similar to the popular 221, plus an additional primary winding. Price, either type, $10.00. SILVER-MARSHALL, INC. 850 West Jackson Blvd., Chicago, U. S. A. Worlds Record Supers Custom Built for Power and Quality Ten Kilocycle Selectivity BREIT RADIO COMPANY 417 LAKE ST.. MAYWOOD, ILL. B Eliminato*^ _ Battery Eliminator. Power up to 90 volts. Works perfectly on any set. Direct or alternating current. Send only $5.00. Postpaid. Money back if not delighted after 10 DAYS TRIAL. Order today. PERFECT ELIMINATOR CO., Dept. V6 National Theatre Bldg., Cln'tl. o.