[time-nuts] EFC info on Trimble 34310-T OXCO

EWKehren at aol.com EWKehren at aol.com
Sun Aug 24 20:36:00 EDT 2014


Charles
I use double bobble pack inside the Alu channel and I always start out by  
monitoring the OCXO and make sure it is at least 10 C below the spec range. 
The  tbolt is center located and I use a combination of rubber mounts but 
suspended  that they sell for hard drives and squares of double bubble pack. 
Vibration and  thermal.
Bert Kehren
 
 
In a message dated 8/24/2014 8:26:02 P.M. Eastern Daylight Time,  
csteinmetz at yandex.com writes:

Bert  wrote:

>As I said before am waiting for the small spheres and will  see what 
happens.

Monitor carefully, as I suspect the spheres will pack  too tightly 
leaving too little airspace.  You could easily burn down  an OCXO if 
this proves to be the case and the oven control loop goes  
unstable.  I'd put a thermal sensor on the OCXO itself for  testing.

Even if it doesn't burn down, you could find that the oven  
performance is degraded by (i) instability or quasi-instability of 
the  oven controller, or (ii) too much thermal resistance (remember, 
you want  to add as little thermal resistance as possible).

On the other hand,  mounting the OCXO as centrally as possible inside 
the outer enclosure on  thermally non-conducting standoffs (teflon or 
nylon), with at least an  inch of air on all six sides, has proven to 
work extremely  well.

When I described using packing peanuts (or similar) to break up  the 
airflow, it was in the context of having already mounted the OCXO as  
centrally as possible inside the outer enclosure on thermally  
non-conducting standoffs with at least an inch of air on all six  
sides.  And as I said, I have not found the additional step necessary  
once you have done this.  It may even be  counterproductive.

Best  regards,

Charles



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