Radio Broadcast (Nov. 1925-Apr 1926)

696 RADIO BROADCAST ADVERTISER and now more stations come m distinctly A UX Power Tube will increase the clarity and volume of your set REWIRING UNNECESSARY NOTE: The UX-120 tube for dry battery sets and the UX-112 for storage battery sets reproduce more perfectly the excellent broadcasting of to-day. These tubes handle the powerful signals of nearby stations so that the quality of the tone is preserved without distortion. You can easily obtain this increase in clarity without rewiring your set. A complete line of Na-Ald Adapters and Connectoralds have been made to meet this purpose. Their scientific design insures a nicety of operation. Below are given three efficient and easily made applications of the new power tubes. For complete details covering these and other applications of the new tube mail the coupon below. No. 920 Connectorald How to improve storage battery sets Clarity and volume can be increased in storage battery sets by using the UX-112 tube in the last stage. Easily fitted to the UV-201A socket by means of the Na-Ald No. 112 Connectorald which provides cables for attaching necessary extra B and C batteries. Price $1.25. Mail coupon below for complete adapter information covering use of new tubes in all sets. How to improve sets equipped with UV-199 tubes To increase volume and clarity in sets using UV199 tubes, use the UX-120 tube in the last stage. Easily fitted to the UV-199 socket with a Na-Ald No. 920 Connectorald which also provides cables for attaching necessary extra 45 volts B battery and 222 volts C battery required for the UX tube. Price. $1.25. How to switch to dry batteries without sacrificing volume or Quality The combination of a UX-120 tube for the last stage with UX-199 tubes in the other sockets provides, with dry cells, results previously obtained only with storage batteries. Fit UX-120 tube to the UV-201A Socket with Na-Ald Connectorald No. 120. Cables provided for attaching extra B and C batteries. Fit UX-199 tubes in all other sockets with NaAld No. 419-X Adapters. Price, No. 120 Connectorald, $1.25; No. 419-X Adapter, 35c. No. 120 Connectorald Alden Manufacturing Company Dept. B 17 Springfield, Mass. All Na-Ald Sockets, Dials and Adapters are protected by patents. Many patents Pending Na-alD ALDEN MFG. CO., Dept. B17. Springfield, Mass. Please send me complete information on how to increase volume and clarity in any set by the use of the new tubes. Name Address City .State. THE GRID int .§ or our QUERIES ANSWERED i . what are the dimensions and number of turns for the coils used in the "universal" receiver recently described in Radio Broadcast? L. T. — Flushing, New York. 2. HOW MAY I ELIMINATE THE REFLEX PART OF THE ROBERTS CIRCUIT? G. C. — Altoona, Pennsylvania. "UNIVERSAL" RECEIVER COILS TH E coil units employed in the "Universal" receiver may very easily be made by winding on a i\ inch diameter cylindrical form, 59 turns of No. 24 d.s.c. wire in the manner shown in Fig. 1 . No 24 D.S.C. Wire FIG. I The first winding put on the coil form is the secondary, and over it, at one end of the form, is wrapped a piece of insulating material, such as ANTENNA COUPLER To Grid Mid-tap ->~To C 4% V. Ant. ToNeut.Cond. Gnd. 2 Prim, o 3 3. WHAT ARE THE SIMPLE LAWS GOVERNING THE CALCULATION OF CAPACITY IN SERIES OR PARALLEL? J. C. — Chicago, Illinois. 4. PLEASE PUBLISH A GOOD THREE TUBE R. F. CIRCUIT FOR A RECEIVER EMPLOYING ONE STAGE OF IMPEDANCE-COUPLED AUDIO FREQUENCY AMPLIFICATION. H. H. McC— Dayton, Ohio. a tap at the 20th turn from the grid end of the secondary. The antenna coil unit has its secondary tapped at the center turn. The circuit connections are shown in Figs. 2 and 3 ELIMINATING THE REFLEX IN THE ROBERTS CIRCUIT THE Radio Broadcast Knockout fourtube receiver has enjoyed widespread popularity for more than a year, and is still going strong. For many it has proven to be the "par excellence" circuit. In such a highly specialized circuit where each branch has its own important role to play, there is bound to be trouble when constructors disregard the simple fundamental rules of receiver design, or where cheap parts are substituted for those recommended. R.F.& DETECTOR COUPLER To Isolating Condenser To Plate of R.F Tube B + To Primary of Audio Transformer To Plate of Detector Tube FIG. fig. 2 paper, cambric cloth, etc. The width of this piece is about inch, and over it is wound 1 5 turns of the same wire for a primary. For the interstage coupler, located between the radio frequency and detector tubes, the coil unit has if Tested and approved by Radio Broadcast -fc Reflex, at its best, is a system of dual amplification that must be handled with utmost consideration and, when installed properly in a receiver, offers advantages, economically and electrically, that cannot be seriously disregarded. However, there are those who, in attempting to rid their receiver of the troubles caused by an inefficient reflex system, desire to eliminate the rellex feature entirely and substitute for it a stage of straight audio frequency amplification. The circuit-changes necessary to make-over a four-tube receiver are few, and are shown in Figs. 4 and 5. In Fig. 4 the regular four-tube circuit is shown. Fig. 5 shows the new circuit,