. QST . shielding and the 115-volt and keying leads (theonly ones that have external connections) arefitted with harmonic filters for the TV frequen-cies. The transmitter is available only in kit form,and the only accessories required are a key andcrjstals. There are two tubes, a 6AG7 oscillator and807 amplifier doubler. The oscillator uses thePierce-type circuit with the crystal connected be-tween grid and screen, output being taken fromthe plate. Conventional parallel tuning with ca- pacitive coupling to the 807 grid is used in theoscillator plate circuit. The 807 plate tank is api netw
. QST . shielding and the 115-volt and keying leads (theonly ones that have external connections) arefitted with harmonic filters for the TV frequen-cies. The transmitter is available only in kit form,and the only accessories required are a key andcrjstals. There are two tubes, a 6AG7 oscillator and807 amplifier doubler. The oscillator uses thePierce-type circuit with the crystal connected be-tween grid and screen, output being taken fromthe plate. Conventional parallel tuning with ca- pacitive coupling to the 807 grid is used in theoscillator plate circuit. The 807 plate tank is api network with constants selected so that loadsranging 50 to 600 ohms can be fed. In both tanksthe various bands are covered by tapped tankcoils, the unused portions of which are shortedout by the bandswitch. Both coils are sectional-wound to reduce the coupling between the activeand shorted portions and thus minimize losses in. « The oscillator and amplifiertank coils arc wound on ceramicforms, with sections for the vari-ous bands separated as shown toreduce losses. The higher-fre-(piency sections are phono-type connector at theleft on the rear lip of the chassis isfor coaxial output from the ampli-fier tank. the dead turns. The oscillator and amplifierswitch sections are ganged, but are separated bya shield partition to prevent unwanted couplingbetween the two circuits. In the main, the circuits conform to stand-ard practice and are quite straightforward. Theoscillator operates straight-through on the band, 80-meter crystals being specified (al-though presumably a 160-meter crystal could beused for this band if one happens to be available).For 7-Mc. operation, either 80- or 40-meter crjs- August 1955 39 tals may be used, with frequency doubling in theoscillator plate circuit in the former case. Forty-meter crystals are recommended for 14-Mc. andhigher-frequency operation; the o
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectradio, bookyear1915
