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Re: Cushcraft 738XB



On Sun, 16 Jan 2000 jbblack@mindspring.com wrote:

> Yesterday, I climbed my short tower (23') and removed the switchbox on the
> antenna.  I had sealed it with silicon to keep water out.  

I'm no expert, but I think that if you seal anything, then it must also be
100% hermetically sealed (air tight) or you will get more problems than if
you just leave it open.  Here is what I have heard about making things
"water proof":

1) Guarantees failure when the thing leaks on the top and cant drain out
the bottom.  Floods all exectronics
2) Day heating (high humididty) and nighttime cooling (condensation) will
keep the circuits bathed in mositure..

My rule of thumb, is:

1) NEVER completely seal the "bottom" there must be a drain hole.
2) Let it breathe freely
3) Paint it white to keep it cool...
4) NEVER leave exposed aluminum boxes if you want to keep it cool.
Aluminum in sunshine can reach very high tempratures.  White will stay
cool in brigh summer sun... (difference between absorbtivity and IR
emissivity)  The factors are a factor of 10! between aluminum and white.

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