A Stable Relay Switched VFO

This VFO was described in Sprat 75 and I used it in a three band superhet transceiver for 80, 40 and 20 metres. It uses reed relays to switch in the various Toko coils and polystyrene capacitors as shown above. Coil A is KANK 3333 plus 100pF and B is KANK 3334 plus 220pf..

Yes, the VFO is stable!. One relay selects the tuned circuit for 5mHz (80 and 20m) and 2mHz (40m), the other relay switches in a pre set capacitor, so the tuning capacitor (20pF) can be used on both 80 and 20m.

The VFO tunes:

5.0 - 5.07 (20m), 5.43 - 5.5 (80m) and 1.96 - 2.00mHz (40m).

Back to the first page