Radio today (Sept 1935-Dec 1936)

that they will be introduced before long. Heralding a step in this direction is Raytheon's announcement of a metal (shielded) gaseous rectifier for automotive use; it is of the filamentless type, thereby reducing battery consumption. The tube operates as the result of the ionization of a permanent gas and with the low potential drop of 24 volts; in basic principle it is similar to the "B" eliminator tube used a few years ago. The use of this tube will probably decrease the cost of receivers slightly because a non-synchronous vibrator can be used with a high over-all efficiency. German radio receivers * Circuit practice in German radio sets follows closely that on this side of the Atlantic. While the sets have different features, much attention has been paid to adding more or less important gadgets, refining the controls, and improving the appearance. In direct contrast to American receivers with their many tubes, the German sets usually employ only three or four tubes. Loudspeakers have definitely been made better. Permanent-magnet dynamic speakers are proving to be popular; a more advanced design provides high efficiency and superb performance. It is reported that magnetic fields used in the air gaps are as high as 12,000 gauss. One set uses an elliptical shaped cone, for which a high fidelity of response is claimed. Acoustical tests reveal -that the mantel cabinets previously used for table models brought about a decrease in the quality of reproduction because of cavity resonance. This cabinet design has been partially replaced by a new one, a rather flat and horizontally elongated design. The loudspeaker is not mounted above the chassis but alongside it. The cabinets are extremely simple, unnecessary ornaments which catch dust and dirt being eliminated. Cabinet features German cabinet design is not a copy of furniture, but represents a style created by technical necessities. The beauty of the sets lies in the application of wood with varied and unusual grain effects. One manufacturer presented a receiver with a cabinet made of a black moulded material; all the fittings and tuning knobs were made of an ivory white material. The set received much attention from A feature of several 1936 receivers is the cathode-ray tuning indicator. Among the sets using the device are Pilot, RCA-Victor, and Sparton. visitors at the Berlin Radio Show, who gave it the nickname, "The man in evening dress." The tuning dials are made with the names of the broadcast stations themselves, and size seems to be of no concern. The chassis illustrated has one of these dials; a hair-line indicator which moves vertically shows to what station the listener is tuned. Dualspeed vernier dials are employed, some with a reduction as great as 150 to 1. Another arrangement is the use of a mirror system which projects name of the station in large letters upon a ground-glass screen. One designer has used the telephone dial mechanism as a tuning means; one has only to dial the station by a number and the station is automatically received. Perfect tuning results. A switching arrangement employing fixed condensers is the principle of operation. TUBES TODAY Metal production up * Metal-tube production is now keeping pace with demand. No longer working hand-to-mouth on shipments, some of the plants are now making deliveries to warehouse stocks, so that the replacement-tube business is again assuming normal aspects. Total metal production is running at least 160,000 tubes a day, with rejects further under control. One factory which increased its output on metal tubes to 20,000 a day, actually had to cut production in half, to 10,000 tubes a day. Big-gun salvo in the metal-tube assault was fired early this month in full-page newspaper ads in 67 cities throughout the country, listing the 47 radio set makers who now employ metal tubes in receivers which they manufacture. Glass tube stand * Meanwhile the glasstube advocates stand their ground, and report that glass-tube sets are selling well right through the Fall season. Wide publicity on the metaltube issue, they say, has resulted in the public's coming into retail stores to get first-hand advice from dealers, with the result that the customer buys the set for which the retailer puts up best sales argument. Announcement of replacement metal tubes under the Philco trademark caused considerable predictions by trade prophets, until the receipt of the letter to the trade sent out by Larry Gubb, general sales manager of Philco Radio & Television Corp., specifying that Philco radio sets for the spring season of 1936 will be equipped only with Philco highefficiency glass tubes. November, 1935 13