[R-390] Tube Shield Painting

[Ted Breaux]

Remember from Thermodynamics, a good absorber is a good emitter.

----- Original Message ----- 
From: "Nick England" <navy.radio at gmail.com>
To: <Chuck.Rippel at cox.net>
Cc: <r-390 at mailman.qth.net>
Sent: Friday, April 19, 2013 12:20 PM
Subject: Re: [R-390] Tube Shield Painting


> And painting the outside of the shield flat black actually helps too.
> Black surfaces both absorb IR better from heat sources (tube) and emit
> IR better to heat sinks (surrounding chassis/components).
> It's like low SWR....
> Cheers,
> Nick K4NYW
>
> On Fri, Apr 19, 2013 at 1:10 PM,  <chuck.rippel at cox.net> wrote:
>> Painting the INSIDE of the nickel shields flat black helps.  Its an old
>> trick used in RF amplifiers which employ glass tubes.  The idea is to 
>> paint
>> the
>> surfaces around the tubes flat black so that infra-red heat from the 
>> tubes
>> is absorbed and not reflected by what may be shiney metal surfaces back 
>> into
>> the dark structure
>> of the tube itself.
>>
>> Its not an IERC or WPM shield which actually wicks heat off the tube bulb
>> itself but better than nothing.
>>
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