Tim Wescott wrote:
Joel Koltner wrote:
I'm thinking it'd be a rather poor idea to make a reference oscillator
for a DDS (or PLL) equal in frequency to an IF somewhere in your
radio... right? Since you're just asking for it to get into the IF
itself?

In the ideal world, would one choose reference oscillator frequencies
that weren't harmonically related to IFs? I've seen those "IF
planning" spreadsheets (that calculator where mixer spurs are going to
fall), and such a choice seems like a good start.

I would certainly avoid it. With thorough enough shielding you can keep
just about any signal out of any circuit, but there's no need to tempt
fate.

If you have a decent receiver, you would need over 100db of isolation.
That is very hard to get in a small space. One of the arts of receiver
design is taking care that all of the frequencies and mixing products
don't show up in the passband.

Erich N6FD