[time-nuts] 10811 foam enclosure
warrensjmail-one at yahoo.com
Mon Jan 10 00:41:47 UTC 2011
>Does anyone have actual measurements with and without the outer oven
>controlled by a PID?
> To avoid misunderstanding could you clarify which of those specifications
> you can get 10 to 100+ better performance?
a) Aging Rate spec <5e-10, easy to find ones that are 100 times better
b) Temp TC for small changes, easy to find/Made them 100 times better with
c) Load change 5e-10, easy to make them 500 + times better (add a good
d) Allan at 1 sec, 5e-12, Not so easy, but you can find them >10 times
Tom Van Baak tvb at LeapSecond.com
>>Q) None of the hp/Agilent bench test equipment that uses these
>>oscillators uses insulation. Perhaps that's a clue.
> a) It is not much of a clue, considering that a patent & knowledgeable
> time-nuter can get 10 to 100 + better performance out of them.
The spec page for the 10811A is here:
To avoid misunderstanding could you clarify which of those
specifications you can get 10 to 100+ better performance?
> Look inside a HP Z3801 GPS.
Right, that's why I wrote "bench test equipment". None of the
hp test & measurement products use insulation around the
The Z3801A is unique; that was a 1st generation telecom unit;
the only piece of hp gear with a custom heat blanket wrapped
around a stock OCXO.
The outer oven was a hack so Z3801A could meet telecom cell
tower cold weather warm-up specs. In other words, the better
performance they were looking for in that case was warm-up
time; not a tempco or frequency stability spec.
The external blanket is reminiscent of the 115 VAC fast warmup
heater in the vintage 00105 brick oscillators (a predecessor of
the 10544 and 10811).
But unlike the 00105 the Z3801A reportedly uses PID control on
the blanket. For that reason I would expect that the outer shell
could improve the tempco of the oscillator, but I haven't seen
data on that. Does anyone have actual measurements? A long
run with, and without, the outer oven circuit connected would
tell the story nicely.
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