. QST . April 1955 35 Communications Receiver Hints for the Man Simple Modifications To Improve Results with Crystal-Con trolle d Con verters BY EDWARD P. TILTON, WIHDQ ONCE youve used a crystal-controlled con-verter for reception youll never besatisfied with less. The stability afforded bycrystal-controlled injection has probably been thegreatest single factor in the vast improvement inreliable coverage that men have achievedin the last few years. But this has not come aboutwithout introducing a few objectionable featuresalong with the benefits. Spurious responses, for in
. QST . April 1955 35 Communications Receiver Hints for the Man Simple Modifications To Improve Results with Crystal-Con trolle d Con verters BY EDWARD P. TILTON, WIHDQ ONCE youve used a crystal-controlled con-verter for reception youll never besatisfied with less. The stability afforded bycrystal-controlled injection has probably been thegreatest single factor in the vast improvement inreliable coverage that men have achievedin the last few years. But this has not come aboutwithout introducing a few objectionable featuresalong with the benefits. Spurious responses, for instance are muchmore troublesome when the is tuned and thefioiit piid of tlio i-pfoiving system is 1 iiR luniiij; ul llic goiioral-cox erati,e dial on most com-munications receivers can be accomplished through theinstallation of a vernier drive mechanism. This can bemounted on a plate that can be removed at any time,thus preventing any permanent defacing of the recei\ er. And, as many a converter user has found out toolate, there are very few communications re-ceivers that have both tuning rate and tuningrange adequate for the job of covering a 4-mega-cycle spread at 7 or 14 Mc. The problem of unwanted signals has alreadybeen treated in some detail in QST by Van Duyneand Treptau.^ Their discussion was concernedmainly with converter circuit features that helpto solve the problem. They showed methods formaking the converter response curve flat-topped,with steep-sloping skirts. They also pointed tothe need for keeping harmonics and subharmonicsout of the energy supplied to the mixer stage fromthe ostdllator-multiplier chain. After the measures they describe have beentaken, if there is
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectradio, bookyear1915
