[time-nuts] Good GPSDO on eBay?
holrum at hotmail.com
Sat Jul 9 20:39:12 EDT 2016
They are based upon a telco surplus "UCCM" GPSDO board. Both Symmetricom and Trimble made (mostly) compatible units. I prefer the Trimble units... they store their settings in EEPROM. The Symmetricom units don't... and have to do a long re-survey every time you power them up. Plus the firmware in the Symmetricom units has a couple of minor glitches (occasionally drops a time stamp output message and can send the time stamp message in the middle of other message outputs). That said, the Symmetricom is rumored to have a slightly better oscillator)... but it is driven by a 6V to 12V DC-DC converter that is known to be somewhat unreliable. I have not measured the output ADEVs, etc.
A little shopping on Ebay (search Trimble GPSDO) will turn up some units for less money. I bought one of these and it arrived quickly and safely in good condition (BTW, you used to be able to get them for $50):
There are unscrupulous sellers shipping damaged units.
This thread on EEVBLOG covers the units pretty well:
I now have Lady Heather working with both models.
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