The tuning voltage of the OCXO after
3 days of measurements (this morning) has now reached 5.24963 VDC as shown by my labs DMM. The unit itself is up and running continously for almost 23 days already as stated before...
I checked the frequency output of the "new" BG7TBL GNSSDO frequently during that period (22-days +) and both displays (Fluke PM6685 + external star 4+ ATDC ref. freq. and the built-in LCD-display) -
always - show frequencies below 10 MHz, which made me wonder, because the shown frequencies by my other GPSDOs usually "oscillated" around 10 MHz during that "startup" period (more or less), when arrived, after a few days run-time. Even my older BG7TBL GPSDO from 2015 provided a much "better" stability and accuracy measured by the instruments I got. I contacted the seller already in China by e-mail but got no satifying answer from him, because he refered me to BG7TBL.
I relate those experienced differences to the C-MAC OCXO installed in the "new" GNSSDO. This was the main reason for wanting to exchange the installed OCXO against one of those Oscilloquartz 8662-XS I got, which show a date code of "08/47" and which seemed to be much more stable after only several hours of runtime than the one installed, judging by the oscilloscope i hooked up to it. But due to the new and only partly populated PCB I have not been able to do this for various reasons.
How long would you expect me to wait for the OCXO to stabilize during retracing ? 30 days, 40 days or even more
I wonder how those units and their OCXOs have been tested by BG7TBL, if reaching stability of the OCXO will take that long ...
What made me wonder too, that the tuning voltage multiplier was set for "x3" right from the beginning although current measurements (see above) show only a need for "x2" including some proper headroom as a reserve.