Gary Schafer wrote:
>>
>
>Interesting thoughts Ian. Would you think that pressurizing the output
>compartment on an hf amplifier with a tube like a 4CX250 or a 4CX1000 would
>be practical?
Just as practical as it is on VHF and above, where it is the standard
method. The only reason it isn't used so much on HF is because many
people feel it's OK to let RF wander all around the insides of HF
amplifiers, so they don't make a sealed output compartment.
>It sure would help on the 4CX250 if some back pressure relief could be had.
Certainly would, because that tube is one of the worst in terms of the
pressure:flow ratio required.
>Looking at that tube though it seems that most of the air would go out the
>bottom rather than the dense plate heat sink.
Sure it would - that's why you have to *seal* the input compartment and
then provide one controlled outlet. A hole of 1.0-1.5in diameter (mesh
covered) is about right for two 4CX250s or similar.
--
73 from Ian G3SEK Editor, 'The VHF/UHF DX Book'
'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.com/g3sek
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