Been having issues with the GPSDO project where I couldn’t get the thing to become stable.
Tried a number of things including putting the OXCO in insulation and putting coax in for all the signal traces.
After looking at the diagram again, I saw the oxco is tuned by a PWM signal and this is sent through a slow Low Pass filter giving a stable voltage out, the main part in this filter is a 100uf electrolytic capacitor.
Decided that it wouldn’t do any harm to change it so swapped it out for a nice quality SMT Tantalum one, mounted on the bottom of the board. 1000% better instantly. the stability is almost rock solid now and its run throuhg the setup phases in one or two goes. its up to PH5 in under 1.5 hrs whereas before it took 2 days to get to PH4.