[time-nuts] 10811 foam enclosure
warrensjmail-one at yahoo.com
Mon Jan 10 16:26:00 UTC 2011
IMHO, The dual oven 10811 oscillators I've seen are not designed as some
hack JUST to do a quick warm-up.
The six sided heater and all the trouble they went thru to insulate the
inside oven from any effects from the outside is a design meant to keep the
inside oven highly isolated from wide ambient temperature changes.
The fact that the outside oven is such an overkill in both the total power
it can supply and how isolated it keeps the inside, It will surely do both.
The outside oven on mine runs at 1/100 of it's max heating power, and any
osc frequency change caused by normal room temperature changes is will below
the oscillator's noise level.
In other words, normal lab temperature variations, have NO measurable effect
on the Dual Oven 10811's frequency, something that can NOT be said of the
single oven unit's I've tested.
At 07:59 AM 1/10/2011, Bob Camp wrote...
>>The spec they were after was a warmup to "on frequency +/- 1x10^-8"
>>from -40 C sort of thing. I believe the warmup time was under 15
>>minutes, but I don't know the exact number.
>Nope. It was only spec'd for operation from 0-50C. It was required to
>achieve satellite lock within 60 minutes of powerup, but only had to
>achieve +/- 1 us (PPS) while locked. Freq spec was < 10E-9 one day
>average. You don't even need an OCXO to do all of that.
>As I already stated, the warmup/training spec allowed 24 hours, after
>which it was expected to be able to holdover for 24 hours within 7 us.
>This, while experiencing temperature cycles (0-30C, 20-50C). The
>successor, the GPSTM, doubled the warmup to 48 hours, but added an
>additional temperature range (35-65C) to the holdover requirement.
>The double oven was there for holdover stability, not warmup time.
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