[Lowfer] LOWFER receiver conundrum.

[JD]

>>> Does it have to be a PLL?

In principle, a DDS could work.  On the upside, a DDS LO can even be built 
to have two outputs that are in phase quadrature continuously throughout its 
frequency range...handy for SDR work.

In practice, though, I don't think the 9850 family would be the best choice 
for a receiver.  It's probably adequate for most transmitters, but with only 
a 10 bit DAC, it would be like a receiver LO with phase noise issues.  IMO, 
it's not a good option for weak signal work.

Also, a DDS chip requires communication with a microprocessor to do 
anything.  Even if one is capable of constructing and programming a 
controller (not too difficult these days), there is the matter of having 
even more digital hash to keep out of the RF path.

It can be done, but these are a couple of concerns to be aware of.