. QST . monitor and code-practice oscillator. QST for Bottom view showing the con-necting cable. The crystal diodevoltage triplet can be seen in llicupper left corner of the ehassi-;.. the necessary operating voltages. A novel voltagetripler composed of one-half of the 12AU7 andtwo crystal diodes supplies the voltages for re-ceiver squelching and the audio oscillator. Thisvoltage is controlled by the transmitting key andis turned on when the key is closed. At this in-stant (when the key is closed) the sidetone isproduced and the receiver is squelched by placingthe negative voltage on the
. QST . monitor and code-practice oscillator. QST for Bottom view showing the con-necting cable. The crystal diodevoltage triplet can be seen in llicupper left corner of the ehassi-;.. the necessary operating voltages. A novel voltagetripler composed of one-half of the 12AU7 andtwo crystal diodes supplies the voltages for re-ceiver squelching and the audio oscillator. Thisvoltage is controlled by the transmitting key andis turned on when the key is closed. At this in-stant (when the key is closed) the sidetone isproduced and the receiver is squelched by placingthe negative voltage on the grid of the input am-plifier tube. When the key is opened the receivedsignal is amplified and heard in the phone.;, whilethe sidetone is off. The frequency of the sidetone audio oscillalorcan be adjusted by changing the grid capacitoi,Ci. If the audio oscillator fails to oscillate, theprimary leads of the interstage transformershould be reversed. High voltage is obtained from the 115-voltside of transformer 7i. This is followed bj aselenium rectifier and RC filter which providesenough voltage for good amplification in theamplifier-mixer stage. Operation It is a very simple matter to
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectradio, bookyear1915
