Radio Digest (July 1924-Apr 1925)

18 RADIO DIGES T— Illustrated January 31, 1925 THE ANTENNA BROTHERS Spir L. and Lew P. We Agree with Mr. Hoover LOW LOSS INDUCTANCES (fjontinued from page 15) that the insulation on the coil will not be injured. After slipping this piece of bakelite into the coil the loop made at the twelfth turn can be untwisted and cut at its middle point. We will then have two separate windings, one of 1 2 turns and one of OS turns. The method of mounting this coil on condensers cannot be shown, as this will vary with every type of condenser used. It is suggested, however, that small right cond leal enser in pleasure shunt to the secondary, is a as the selectivity is remark Pigure 4 © K. & H. angle brackets be made of heavy brass or aluminum, to be attached to the bakelite or hard rubber strip at the ends and to the rear end plate of the condenser. The condenser will then have to be mounted on the panel in such a way that the coil just described will be at an angle of 57.4 degrees with the baseboard. In the near future the writer hopes to give full details for the construction of a receiver utilizing these inductances. Tuning with these inductances, and a good low loss Figure 6 ably good and stations that were formerly found over 10 or 15 degrees on the dial will then be found on only 2 or 3 degrees Handsome ~ Safe ~ Fast EAL OVER 250,000 Radio fans have found the big capacity 5 ampere GOLD SEAL HOMCHARGER ideal for keeping their Radio batteries fully charged and operating at top efficiency. Connects to any lamp socket and charges all Radio "A" and "B" and Auto Storage Batteries over night for a nickel. Simple, reliable, fool-proof. Can be operated _ by any one. Contains no bulbs, acids or fast wearing carbon PER Radio's most popular Battery/ ^Charger/ contacts. Only one moving part, replaceable for $1.00 after thousands of hours' use. Absolutely safe — no danger of shock or fire. Approved by Insurance Underwriters everywhere. Beautifully finished in mahogany and gold. May be used right in the finest living room. Price, $ 1 8 . 50 complete for all currents. Sold by all good Radio dealers, or shipped charges prepaid upon receipt of purchase price. &ree THE AUTOMATIC ELECTRICAL DEVICES CO. 215 W. Third, St. Cincinnati, Ohio Largest Manufacturers' vibrating rectifiers in the world. Write for booklet, "The Secret of Distance and Volume In Radio," containing information on this subject and fully describing the GOLD SEAL HOMCHARGER. fjree M4»»HH»»»HK»K«« of the dial and a vernier adjustment is necessary to get on the very sharp resonance peak. This unit, as described above, can be used as the antenna coupler and the air core transformer in a receiver comprising one stage of tuned Radio frequency detector and audio frequency. If more than one stage of tuned Radio frequency is utilized, and three of these units must be built into the set, care should be taken to see that they are well spaced and all at exactly the same angle to the baseboard. It may prove necessary also to remove from one to four turns of the primary of the second or third unit to prevent oscillation on low wave lengths. Another method of preventing oscillation might be that shown by the writer in the issue of December 20, utilizing three neutrodons. Vernier Attachment A plumber's fitting called the Puller ball when mounted on a screw with some play to touch the edge of the dial makes a very desirable vernier attachment. When used for a vernier it is pushed toward the panel front so that it will come in contact with the edge of the dial. This device is inexpensive, easy to apply and it gives a delicate touch without cramping the fingers. — H. W. Brown, Cleveland, Ohio. JIIIIIMIIIIIIIIIIIII Ill 1 1 II lilHIH) 1 1 1 1 1 || 1 1 t.l Ill li 1 1 1 1,, in in i ii I [ I mil | | | illiliilllllll I II : I DIETZEN^^IOUD SPEAKER I I At the Price of an Ordinary Pair of Head Phones I °"T: Jbk SEND NO/ i details MONEY' ORDER BY MAIL If your dealer cannot supply you we will ship you a complete DIETZEN JR-65 speaker ready for use Written money back guarantee with each loud speaker. COMPLETE with specially built DIETZEN adjustable loud speaker unit and plug1. NOT a Head Set Unit SPECIAL FEATURES Absolute non-metallic sound. Permanent Crystalized finish. No batteries necessary. Specially constructed adjustable unit with gold plated diaphragm. Unconditionally guaranteed for one year from date of purchase against mechanical defects of any kind. specifications: Diameter offfom 9 INCHES Height IETZEN /RADIO LOG BOOK WRITE FOR YOURS.' DIETZEN inc 71CortlandtSt. x Dept. D. New>brk MAKERS Of PRECISION INSTRUMENTS^SINCE_I8S9 lllllllllllllllll Illl Illlllllllllllllllllllll IIIMIIIIIMIIIIIIIIIMIIMIIIIIIIIIMIIIIIMIIIIIIIIIIIIIMIII II I MUM I Ml I II 1 1 II I II 1 1 1 1 II I III 1 1 1 1 1 II I II I II 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 II 1 1 1 1 1 1 1 1 1 1 \ oc-'r'J'J MAGNATRON A GOOD set deserves Mag r* natrons. If you want clearer reproduction and greater volume, then use Magnatrons exclusively. MAGNATRONS know no su ,pc-2oT*o> I ffif)^W\ Perior to<iay. They have been im 1 proved to the point where their continued leadership is assured. Your dealer will be glad to show you the MAGNATRON DC-199, the MAGNATRON DC-201A, and the MAGNATRON DC-199 (large base). Each of these types d» A lists at only ...*r* CONNEU/EY ELECTRIC LABORATORIES « .99 _ M Z>\ J09 Fifth Avenue NEW YORK CITY