Alex Collins wrote:

"Harold E. Johnson" wrote in message

Well, you don't specify the frequency coverage of your other VCO's, MCL's
have a very high MHz/volt tuning rate and unless the tuning voltage is
absolutely quiet, they'll look pretty bad.

But surely if the Minicircuits datasheet says the trace will fall to less
than -75dBC at 1,000Hz away I should see that, or something close to it?
Irrespective of the frequency (800MHz)?

Well, Harold is pointing out that noise on the tuning line will
show up as broad phase noise. What are you using to drive the
tuning voltage line?

The old Ramsey FX440 UHF transceiver had a horrific noise floor on the
transmitted audio, since the VCO had about 10MHz/volt sensitivity and
the audio modulation was fed from an ordinary op-amp into the tuning
line. You could be seeing a very similar problem.

Dana