[time-nuts] Z3805A cooling requirements?
SAIDJACK at aol.com
SAIDJACK at aol.com
Fri Dec 21 02:35:23 UTC 2012
Wish I had more time to play with this setup.
How about fellow time nuts spend some time and present similar test data on
their OCXO's to compare?
I was interested in the 1s to 100s ADEV, and my runs were from 8 minutes to
20 minutes, certainly enough time to capture data for 1s to 100s ADEV
measurements..
bye,
Said
In a message dated 12/20/2012 14:17:59 Pacific Standard Time,
magnus at rubidium.dyndns.org writes:
On 12/20/2012 01:34 PM, Bob Camp wrote:
> Hi
>
> Temperature transients are not a good thing for an OCXO. If you
deliberately use the fan to create a transient, then yes the OCXO will not be
happy. The question it - what happens after the transient has settled out? The
plot you have still looks a lot like a step function.
I agree. Temperature steps stresses the OCXO oven loop and easily
creates a gradient over the crystal. As the oven loop tracks in, the
frequency returns to around normal. The trouble with forced air over a
crystal is that the metal shield couples very well and acts like a heat
sink. A think plastic cover over it and forced convection doesn't have
the same effect. There is even being used by at least one vendor. Works
very well for the extra cents of manufacturing cost.
The HP10811 is recommended to be put in a airflow-quiet corner of the
world. Look at it's mounting in the HP5370A/B for instance.
Cheers,
Magnus
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