KC6ASA - Kirk


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13-watt MOSFET Xmtr

Kirk's astounding 13-watt, breadboard MOSFET transmitter.  The D-104 mike feeds a cassette recorder preamp/agc amp which then drives an automobile stereo-amp modulator.  The modulation transformer (above left) is a multi-tap, 60 Hz power transformer whose poor audio performance is compensated for by the graphic EQ in the modulator.  The RF chain is a handful of IC's driving a pair of MOSFETs in push-pull.  The final output is transformed up to a usable impedance level and then matched to the antenna by a pi network (tuning/loading caps in upper right).  

(Click here for medium res. photo ~350K)

(Click here for large photo ~1.5 Meg)

(Click here for original photo ~3.3 Meg)

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