[time-nuts] Thunderbolt E failing

[Matthias Welwarsky]

On Samstag, 12. September 2020 23:53:39 CEST Bob kb8tq wrote:
> Hi
> 
> As far as anybody knows (which *is* a big qualifier indeed ….), the TBolt
> family only does it’s “temperature compensation” stuff when it’s in
> holdover. While it’s locked, there *appears* to be no compensation being
> done. If it’s doing anything while locked, it’s learning what the TC is, so
> it can use that information while in holdover.

That is interesting, why wouldn't they use the information if it's available? 
Watching the temperature gives you a prediction of what is going to happen, 
while watching the phase only shows what has already happened. And knowing 
what's about to happen is always very favorable in control theory.

> 
> Bob
> 
> > On Sep 12, 2020, at 3:52 PM, Matthias Welwarsky <time-nuts at welwarsky.de>
> > wrote:
> > 
> > Kevin,
> > 
> > how long has it been in storage? I expect the GPSDO doing quite clever
> > things to compensate for temperature effects. There may be some
> > parameters stored on the device and the characteristics of the OCXO may
> > have changed after being turned off for an extended period.
> > 
> > Regards,
> > Matthias
> > 
> > On Samstag, 12. September 2020 18:13:35 CEST Kevin Schuchmann wrote:
> >> Matthias,
> >> 
> >>    You are correct, having spent hours looking at all the stable areas
> >> 
> >> and cooling and heating the gpsdo I find that when it reports that it is
> >> 116.25 F then it is stable.
> >> So now I guess I need to figure out why it is so picky. I will measure
> >> the current draw from a cold start and see if I see the oven warming up
> >> and then stabilizing and then heat and cool it and see how it reacts,
> >> and also look at the electronics and see if an area is overly sensitive
> >> to temperature.
> >> 
> >> Thanks
> >> Kevin
> >> 
> >> On 9/11/2020 2:26 AM, Matthias Welwarsky wrote:
> >>> On Freitag, 11. September 2020 01:08:09 CEST Kevin Schuchmann wrote:
> >>>> Guess my image didn't make it, I will add it as an attachment this
> >>>> time.
> >>> 
> >>> The temperature curve seems to show some correlation to what is
> >>> happening
> >>> with the DAC. Seems that the DAC and OSC jumps are mostly during periods
> >>> of some thermal perturbation.
> >>> 
> >>> Regards,
> >>> Matthias
> >>> 
> >>> 
> >>> 
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