Wrap your head around this:
- 9.600MHz (modulated) oscillator
- 6.000Mhz down conversion LO
- 9.600MHz local oscillator
- 6.000MHz crystal filter
- 3.000MHz subharmonic BFO
- or a 6.000MHz BFO (e.g. w/ NE612)
Now, seeing it, I think 3.5999MHz should be the natural choice anyway, since all crystals involved are off shelf standard....
For reasons of performance I would prefer subharmonic mixing. Simplicity, however, would be found in a single 6MHz oscillator approach.
Hmmm, if only I got the energy to build all my concepts....