[time-nuts] Low phase noise affordable GPSDO

[Ethan Waldo]

Hello time afficionados.  I've tried my best to scan through the archives to see if this has already been answered, so apologies if I missed something relevant.  I am going to be experimenting with >10Ghz microwave frequency grounded coplanar waveguide phase combining/cancellation/detection across a number of generated signals.  That being said, I am in the market for a GPSDO that has the least amount of phase noise.  A secondary factor in my choice is how many 10Mhz references the GPSDO can provide to sync all my signal generators; not as concerned about what amplitude is provided.

Most of the cheap GPSDOs on eBay seem to have only 1-2 sine outputs with no understanding of expected phase noise.  A solid option seems to be the TrueTime XL-AK but something tells me there might be options out there better than 1x10-12.  Price is the right ballpark though I could justify spending a little more for better phase noise specs.  I have no need to run without GPS lock so Rubidium source doesn't seems as necessary compared to something with a high quality (D)OXCO, but it would be nice to add that as an external source at a later time.  Build vs. buy is an option, but I would like to avoid making costly mistakes so would favor buy if specs are comperable.

I would really appreciate advice from folks around here who already have some hard-earned experience on what my best options are. Whatever I get I'm likely to be stuck with for a while so I would rather take the time and research than to do a knee-jerk buy.  Thank you ahead of time for any replies.

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