Lucky for us, there is another kit vendor, who's kits have the potential to replace the ones of Dave.
Have a look at the KN-Q7A kits.
The 20m KN-Q7A operates with an i.f. of 4.194MHz, using a ladder filter made of standard xtals. The transceiver makes us of a moderately pulled VXO of 18.432MHz. All parts a relatively standard and well known, apart from a couple of inductors. The design makes use of subtractive mixing, which increases stability.
Here's what we can learn from Dave's PSK-series, the combination of standard crystals to result in an operating frequency near enough to the PSK bands.
- 30m: 4.000MHz + 6.144MHz
- 20m: 5.0688MHz + 9.000MHz
The 40m KN-Q7A involves two different i.f., dependent on the frequency range ordered, either 8.467MHz or 8.192MHz. The l.o. will make use of any of those frequencies: 15.360MHz, 15.418MHz, 15.500MHz, 15.536MHz or 15.570MHz. I have not yet figured out a combination to reach 7.040MHz, however, I am sure that one can be found.
Further, I am convinced that the design can easily be adapted to the 80m band. Think of 10.000-6.400 for starters.
As to QRSS/WSPR:
- 30m already cover the mod above
- 15m 4.000MHz i.f. and 25.000MHz l.o.
- 15m WSPR: 4.096MHz i.f. and 25.000MHz l.o.
- 20m could be reached by 4.000MHz i.f. and 18.000Mhz l.o.
- 20m WSPR: 4.096MHz i.f. and 10.000MHz l.o.
- 40m best option would be 4.000MHz i.f. and 11.000Mhz l.o. (alternatively 11.059Mhz)