[R-390] Tube Shield Painting

[rbethman]

Just remember to etch or sand the surface to get the best adhesion.   Do 
it OUTSIDE - especially if it cadmium plated!  You sure don't want to 
inhale the plating dust!

Otherwise you'll end up with it flaking off.

Bob - N0DGN

On 4/19/2013 1:20 PM, Nick England wrote:
> 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.
>>