[volt-nuts] plastic caps on 3458A reference board

[Charles Steinmetz]

Poul-Henning wrote:

>I've often wondered what would happen if you put one of these
>circuits (xtal, vref etc) in a suitable small box, and filled
>the box with with aerogel powder:
>      *   *   *
>I'm pretty sure you'd get very stable temperatures, my worry is
>that you'd get too high stable temperatures...

I think over-insulation is a very real worry, given what the web site 
says about the thermal insulating properties.  The properties they 
described seem to be those of a solid block or sheet -- the powder 
may not be quite as good -- but still, it seems like you'd be going a 
long way toward emulating a dewar, and it is very easy to 
over-insulate an oscillator or other circuit with a dewar.

Another possibility is glass microballoons (also called 
microspheres), which are just what they sound like.  They are a very 
common filler for epoxy when a featherweight composite is required.

Either one would probably be kind of messy....

Best regards,

Charles