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Re: Fair Radio Sales HV cap---cool with liquid N2?
Tesla List wrote:
>
> Original Poster: Doug Brunner <dabrunner-at-earthlink-dot-net>
>
> I'd like to be able to use one of these caps in my next coil, but I'm
> concerned about the dielectric heating. I had the idea of immersing it
> in liquid nitrogen. Do you think it would work?
>
> --
> --Mr. Postman (Doug Brunner)
> <dabrunner-at-earthlink-dot-net>
Doug,
Many technical components do not take kindly to the thermal shock and
differential contraction/expansion, as well as the brittleness which
occurs in materials when cycled from and to room temperature and
cryogenic temperatures. As a radio astronomer building and maintaining
my own cryogenic receiving equipment I learned that once one
successfully accomplished a cooling cycle (got the temperature down) and
still had a working receiver, you didn't dare let the dewar run low of
LN2 and accidentally allow the receiver to warm as it might then fail.
The 78K of LN2 was bad enough. Things got even more unreliable when
cooling to 14K.
I'd forget the complexities and expense of trying to make a mylar
capacitor do what it was not intended to do. If it gets as cold where
you live in the winter as it does where I live, just run your system
outdoors in the winter. That should be plenty cold enough to extend the
runtimes of that capacitor. Keep them stored in an unheated outdoor
shed between runs.
Robert W. Stephens
Resident - Great White North