[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  
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.


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