Qex Articles By Paul Protas

Fig 6 The Junk Box Special, a low-cost shortwave receiver. circuit's stability for CW and SSB reception. C7 is the throttle-capacitor REGEN ADJUST control. As C7's capacitance is increased, more RF energy is coupled from Q2's drain to ground (and therefore the ground end of L2) this eventually initiates an RF oscillation. RF choke L3 isolates Q2's RF feedback from the detected audio, allowingjust the audio signal to pass on to L4. L4 is the primary winding of a small 6.3 V filament transformer....