GPSLDO Cannot stabilize

[Moriambar]

Hi,
in my recent spree of failing equipment (I just broke a microcurrent and no replacement is in sight), my gpsldo is starting to behave weirdly.

It's connected to a distribution amplifier and then to my signal gen (and occasionally I use it on a board).
Nothing's changed recently in any of my setups, but the oscillator locks on gps and the alm light stays on. What's worse is that the signal is sh*t, as per the attachment.
Is this one gonsky too?

Cheers

[jpb]

If your GPSDO is an old one or a new one made with an old OCXO then it might be that the tuning range of the OCXO has drifted beyond the range that the disciplining circuit can supply and perhaps it keeps starting at the low end and covering its whole range and still can't reach 10MHz and does this over and over.

If you can measure the applied voltage on the OCXO that might give you a clue.

If this is the problem then you might be able to get a cheap replacement for the OCXO on ebay. I think someone on the forums has posted doing that a little while ago. It might even give you an opportunity to improve the OCXO.

[Moriambar]

If your GPSDO is an old one or a new one made with an old OCXO then it might be that the tuning range of the OCXO has drifted beyond the range that the disciplining circuit can supply and perhaps it keeps starting at the low end and covering its whole range and still can't reach 10MHz and does this over and over.

If you can measure the applied voltage on the OCXO that might give you a clue.

If this is the problem then you might be able to get a cheap replacement for the OCXO on ebay. I think someone on the forums has posted doing that a little while ago. It might even give you an opportunity to improve the OCXO.

It is quite new actually, it has a date code on the case of oct 2020.
I'll try the measurements

[dl6lr]

I'll try the measurements

I assume your screenshot is from the GPSDO, not after the dist. amp?
Your signal shows amplitude and phase jitter, I would check the power supply first. Noise from the PSU will do harm to the PLL lock.

[Moriambar]

I'll try the measurements

I assume your screenshot is from the GPSDO, not after the dist. amp?
Your signal shows amplitude and phase jitter, I would check the power supply first. Noise from the PSU will do harm to the PLL lock.

you think the cheap psu is what has gone?
The signal is the same before and after the amp.
BUT
after unplugging, unscrewing, weeping at the idea of replacing the osx, rescrewing, replugging… well today the signal is clean as a whistle!
It fixed itself.
Maybe I'll investigate the psu though…