[time-nuts] Thermal insulation choice?

Tom Van Baak tvb at LeapSecond.com
Fri Jan 6 22:33:10 UTC 2012


> I am looking for a readily available (from Home Depot or other local 
> source) insulating material to use in a chassis that's housing a 
> sensitive OCXO.  My goal is just to slow down any external thermal 
> transients so the oven loop has time to react gracefully.

Hi John,

Once I used several inch thick polystyrene sheet from Home Depot
for this very purpose, sealed it up all nice with tiny holes for the
power and RF wires. It turns out I nearly burned out the oscillator
because the insulation was so good. The temperature stabilized
somewhere between the crystal set point and the melting point of
solder.

So the lesson is good insulation is not necessarily what you want.
How many watts does your OCXO put out?

What I did instead was to buy a bunch of cement paving blocks
from Home Depot and made an air-tight sarcophagus (Egypt or
Chernobyl-style). Lots of thermal mass.

This was all placed on the concrete basement floor to reduce the
effects of vibration and shock on the oscillator; something else
you may want to consider for best long-term performance.

/tvb




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