Erich wrote:
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

I was thinking of several layers of milled-from-billet cabinets between
the signal and the receiver. I suppose I should have mentioned just
what I meant by "enough".

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

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