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Radio Broadcast
TWO RADIO, DETECTOR, AND TWO AUDIO
C, 75-volt batteries for biasing A.F. tube grids; Gi, earth ground; G2, capacity ground (counterpoise); V, detector tube voltmeter; SPi, series-paralled antenna condenser switch; SP2, switch for cutting R. F. in or out; S, stabilizer; P, A-battery potentiometer; L, loop which may be used instead of outside antenna when desired
have found them to give very good results. These tubes are not critical as to filament voltage, although 5 to 5I volts on the filaments works as well as any higher voltage. These tubes "fry" less and oscillate more freely, than any other tube I have used.
Tuning the set is accomplished as follows: for wavelengths up to 375 meters, the correct size coils are placed in the coil-mountings (about 35 turns in the primary, 50 in the secondary, and 75 in the tickler). The bulbs are turned to their right temperatures and the aerial condenser is switched to series with the aerial, and the R. F. switched in. The primary condenser is then turned to somewhere between o and 40 on the dial (usually about 25), and the secondary condenser is slowly rotated from o to maximum until a shrill whistle is heard. The stabilizer is then adjusted until voice or music is distinct and clear. Usually the secondary condenser, vernier and stabilizer must be re-adjusted slightly, and then the concert or address "picked up" may be enjoyed to the greatest extent. Moving the coils and changing the stabilizer and vernier will enable a
person to hear different stations operating on nearly the same wavelength. If the primary condenser be turned farther toward maximum and a larger coil inserted in the primary circuit, stations of different wavelength may be brought in. For 400-meter stations I have found that 50 turns in the primary and secondary, with 100 turns in the tickler give the best results, the signals being clear and loud, with a minimum of interference from 360-meter stationsand amateur stations. Flat-wound pancake coils seem to give quite the best results.
In the short space of the half-hour in the evening while local broadcasters are quiet, I have been able to tune in as many as 18 different stations. Those within 500 miles may usually be brought in while local broadcasters are in the air, with no interference from the latter. This is especially true when using a loop aerial. The loop used with this set is two feet square and has twelve turns of wire.
In conclusion, I will say, that for one who wishes a set that is sensitive, selective, powerful and easy to operate, this set gives great satisfaction.
REPORTS FROM OTHER ENTRANTS IN THE "HOW FAR?" CONTEST
FINE WORK FROM A REMOTE CORNER OF THE U.S.
MR. LESTER WITHERBY, who lives in Ferndale, Washington — a hundred miles north of Seattle, near the Canadian border, has done some remarkable receiving with a 3-circuit two-bulb set, for which he wound his own
multi-layer coils. His list of stations is too long to publish here, but his three greatest jumps are WGY, Schenectady, N. Y., 2,500 miles; NOF, Anacostia, D. C, 2,475; and KGU, Honolulu, 2,300.
Mr. Witherby has supplied the following "dope," which, with the photo and circuit