[time-nuts] getting a grip on 10811 drift (beginner-ish question)
Chris Howard
chris at elfpen.com
Mon Nov 5 14:49:27 UTC 2012
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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