[time-nuts] GPSDO won't lock: OCXO aged out?

[paul swed]

Newell its all a gamble at this point so go with the 6V and see if you gain
a few hz.
Its a serious cheat. But it just gives you a sense of how bad is bad. Does
a olid volt maybe move you 1 hz or 5 hz?
In the can you could actually look at the crystal and in general several
caps around it. One of those caps either increasing or decreasing will
shift the oscillator into range. I have had to do that some time ago on a
oscillator. Granted it was a old piece of test equipment.
Regards
Paul
WB8TSL

On Mon, Jan 11, 2021 at 11:01 PM Scott Newell <newell+timenuts at n5tnl.com>
wrote:

> At 09:01 PM 1/11/2021, paul swed wrote:
> >Can you see what the xtal unit actually is.
>
> Trimble "73090".
>
>
> >I suspect there is not a hole to a trimmer cap. But potentially if you can
>
> I peeled the sticker from the top--no holes hidden there or on the four
> sides.
>
>
> >open it you could get to a cap or at least see the xtal and what caps are
> >around it.
>
> The can is partly soldered--not a full seam around the lid. It might
> be possible to open it up without too much damage. (Looks easier that
> the MV89 I opened years ago.)
>
>
> >Other more difficult approach is to insert a purposeful offset. Maybe 6 V
> >very current limited. Opamp would be the best way to do that. Just to see
> >if you can pull it to 10 MHz.
> >But it would also mean you have traced the efc control pin to some extent.
>
> The EFC trace on the GPSDO board is accessible and wouldn't be hard
> to cut. EFC swings it about 8 Hz right now, but I'd need another 4 Hz
> or so. Not sure 50% is doable.
>
>
> --
> newell  N5TNL
>
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at lists.febo.com
> To unsubscribe, go to
> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
> and follow the instructions there.
>