[time-nuts] getting a grip on 10811 drift (beginner-ish question)

[David McQuate]

If you can measure the 10811 frequency as a function of the control 
voltage with the 10811 control voltage input disconnected from 
everything else, you'll have a curve that will allow you to translate 
control voltage changes into frequency drift.
My impression is that the 10811 ageing is generally all in one direction.

73,
Dave
wa8ywq

On 11/5/2012 6:49 AM, Chris Howard wrote:
>
> I built a GPSDO using my own power supply,
> a VE2ZAZ board, a Trimble Resolution T GPS
> and a surplus  HP 10811 oscillator.
>
>
> I'm having a bit of trouble with it.   I have it set up and
> it locks ok and stays in lock so far.  But the recommended
> long-term integration setting is not working for me.
> I think it is about 3 hours.  At the end of every cycle
> it does a control voltage adjustment, always in one direction.
> If I understand it right, the oscillator is slowing and needs
> an incremental bump downward of control voltage every time.
>
> That seems like it is more than just long term drift.  But
> I don't have my head around the quantities I'm looking at.
>
> I can measure the control voltage change over time.  Can I convert that
> into a frequency drift?  Or do I need to stop the voltage
> adjustments and allow the drift to occur then do a measurement
> of that directly somehow?
>
> Is this type of behavior an indication of dire problems
> with my 10811 oscillator?
>
> Chris Howard
> w0ep
>
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