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Show VACUUM TUBE SET BEST FOR GENERAL USE I This Equipment Used for All-around Efficiency by Amateur . n R i bu Director, andio pttltnte or America I in erecting or assembling an amateur ama-teur wireless transmitting nation, it Is KURgested that the vaeuum tube bo used for all-around . ffl, p.. v All the records made by amateurs in the recent trans-Atlantic teat were rrom stations using the tube A tube transmitter will .over three times the distance of the old type parli set of the same pov. . f l or sending out all lengths of un- dampened waves the arc method the Aiexanderson alt. tnator and the ..sell-! ia im. vacuum i ub. rui the only practical form of undampened wave generator for the short amateur ! length Is the oscillating vacuum tube I This method of transmission also permits the use- of a combined radio ; telephone and telegraph set. By simply sim-ply throwing a few switches, tho op- erator may change from speech to telegraph coie. WAVE TVPl.s There lire three general types of wave which may be sent out by tho tube transmitter: Continuous wave (C. V ). interrupted continuous wave 1(1. C. W.. and telephonic C W. can only be received by nta-! nta-! tlons using a vacuum tube receiving j aparratua. Since there are a large, number of amateur using crystal receiving sets, the antenna oscillations of a tub-' transmitter arc modulated by a "grid chopper" which la a rotary interrupter di Igned to interrupt the grid circuit of an oscillating tube approximately' ,1000 times a second This converts the output oscillations Into a current with .the same receptive efficiency ns a quenched spark set. termed I.J C. Wii and may be received on either a vacuum tube or crystal receiver. Voice signals aro received on either ( URREMT STTFPLt In s vacuum tube transmittinR set' a low voltage source is us.-.l to heat the filament. When possible this volt-I volt-I age should be of alternating currant, i for that tends to prolong the life of the filament. A high voltage is Used to energlzo the plate circuit. The current Tor the J plat'- may be obtained In throe ways. 1 From a high-voltage dlrect-cui -rent generator. 2 From a rectified alternating cur rent: 3. From an alternating current source applied directly t0 the plate ' and l.nowri - 'h. -, I: ro,-t ! r.'e.uion cjurcuitt |