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.

Thanks,
---Joel Koltner