[time-nuts] Which GPSDO for an accurate, low phase noise 10 MHz?

[Bill Katz]

Hello.
I found this group last year when I was working on my microwave rover
station (up to 10GHz currently, 24 GHz soon) when I ran into a challenge.

First I bought a small Rubidium standard, hoping that would keep my system
accurate. (Symmetricom x72 from ebay).  It looked fine with some
transverters, but with one brand the phase noise was so bad, one couldn't
make out the primary tone on the spectrum analyzer.  The next step was a
club member sent me an HP 10811A, which has great phase noise, but showed
some drift when I fed my counter from the rubidium standard.

Oh, and once I repaired the (apparently somewhat common) temperature fuse
inside the second 10811A inside the counter, I now had two oscillators that
almost agree.  Almost.

So I'd like to get something that can run the instruments in my house, and
allow me to calibrate the OCXO in my rover equipment.  And tweak in the
various other OCXO standards.

At the high end, there are used HP Z3801As that seem to have excellent
phase noise, but are somewhat expensive.  At about half the price are used
Thunderbolt units.  and there are a myriad of other options.  What are the
pros/cons of some of these units?

Thank you,
Bill Katz
KA1TZ