The 2N2/20 follows
the general design of many QRP rigs. It consists of a superheterodyne
conversion strip (upper row of blocks) on the receive side and a complete
RF generation strip (lower row of blocks) on the transmit side. Both sections
share a common VFO. Each of these subsystems contains a Local Oscillator
(LO). The receive LO allows one to optimize receiver response by centering
the receive pass band to the center of the crystal IF filter. On the transmit
side, a separate LO provides offset adjustment, resulting in a side tone
matching the received audio. Switching between receive and transmit is
done with solid-state switches to provide QSK capability. When transmitting,
the 2N2/20 is listening to its own signal.
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