Radio age (Jan-Dec 1926)

RADIO AGE for February, 1926 The Magazine of the Hour 61 Maximum Receiver Efficiency C Continued from page 24) iron should be heated, the point filed bright, rubbed in paste, and then in solder so it will acquire a coat of tin. Rosin on a joint does not hurt it, providing there is solid solder underneath. Do not try to wire with anything but perfectly straight bus bar rolled flat. Many constructors prefer to use flexible wire in connecting up sets. In this particular receiver, this is permissible only for the filament battery, and audio amplifier sections. All r. f. amplifier wiring should be of stiff bus bar. After the receiver has been completed , and the wiring checked against the circuit diagram, it may be connected up. The ends of the color cord are terminated at the batteries, with the exception of the B45 and B90 leads. With these unconnected, a tube inserted in a socket should light, if the switch is on, and the rheostat turned on. With a water-pipe ground connected to either 1 or 2 of the left coil socket, and a 25 to 40-foot single wire indoor or outdoor antenna connected to whichever post (1 or 2) the ground has not been connected to, the set may be tuned, using the three dials. It should first be operated with headphones. The modulator or volume control should be turned all the way to the right, or at maximum. The antenna coil rotor should be so adjusted its axis is parallel to that of the stator coils. All three dials will read practically alike — that is, they will all be set at within one or two degrees of each other for a given station. Since each dial division may be assumed to represent approximately 10 kc. with S. L. F. condensers, a station might be located approximately as follows: For simplicity, let us assume zero on the dials equals 500 kc. and 100 degrees equals 1500 kc. Thus, we have 10 kc. per dial division. Suppose we want WHT, 750 kc. (400 meters). Then 500 kc, our lower limit, subtracted from 750 kc. — WHT's frequency — gives us 250 kc, which divided by lOkc — the frequency variation per dial degree — gives us 25. Thus, setting the dials at 25 degrees plus or minus one or two divisions will tune the set to 750 kc. (400 meters). Suppose we were using straight line wavelength condensers. The process is different. Our wavelength range covered by 100 dial degrees may be assumed to be 200 to 550 meters, or a range of 350 meters. Thus, each dial division represents 3.5 meters. Suppose we want WHT again, at 400 meters. Then 200 — our low wavelength limit — ■ subtracted from 400 — WHT's wave — iives 200, which, divided by 3.5 — the number of meters per dial division — gives us approximately 57 — the setting at which the set will be tuned to 400 meters. It must be remembered that these figures are at best but approximate, due to unavoidable variation in individual receivers and tubes. * Illustration shows Model 7 — 5 tubes — ' battery compartment underneath. f^\"D Tf^T Th f Tne Most Amazing Performer WrVXWl^JJ/ I You've Ever "Tuned In" Oriole radio receivers step right out and make astounding records on distant stations — they give exceptional volume — unequaled for clarity and sweetness of tone. The most selective, sharpest tuning set you ever played with — you'll be "sold" on the ORIOLE the minute you turn its dials. Model 7 — 5 Tubes, with "B" battery compartment. Model 7-B— 5 Tubes. Model 7-C — 5 Tubes; — Console. Model 8 — 4 Tubes. Write for folder illustrating and describing all models. Dealers: There is some exclusive territory open — ask for details. W-K ELECTRIC CO. KENOSHA WISCONSIN Van Horne-Musselman Adapted Mogul 5 V C Power Amplifier NEW! The Van Horne-Musselman Mogul 5 V C Tube is the latest and most advanced tube in the Power Amplifier Field. The Patented Adapter enables you to enlarge the receiving range of your set — increases your loud speaker volume from 50 to 100% and completely eliminates distortion WITHOUT CHANGING YOUR PRESENT CIRCUIT. Send for detailed information or see your nearest dealer. JOBBER— DEALER Write for our cooperative merchandising plan THE VAN HORNE CO. Factory and Sales Office 286 Center Street Franklin, Ohio (near Dayton) Tell them you read it in Radio Age