ZYT GPSDO (Trimble) incorrect frequency

[jacekowski]

I've got an odd one.

I've got ZYT GPSOD with trimble guts that used to work fine but recently started to have 0.3Hz error.

Powers up fine, locks and reports frequency as 9999999.7Hz while producing almost perfect 10MHz then after few hours reported frequency changes to 10MHz with mHz error. but actual frequency is 0.3Hz high

53131A in the photo is running from different GPSDO and this ZYT GPSDO is the only odd one out so, unless 4 other clocks are producing same error, the fault is with this one.


Any suggestions on what the issue might be?