[R-390] Equipment heat (WAS: Case Comments)

[2002tii]

Tim wrote:

>My personal solution was a 240VAC 10-inch Rotrons
>that don't spin fast at all at 120VAC.

Interesting that 120 V is enough to get them to start - good to 
know.  Most 120 V fans won't start on 60 V.

>>Why no one has suggested putting the resistors on top and
>>the filter caps inside the audio module is a mystery to me.
>
>In fact others have. But I've never seen a 390A audio module with "bad"
>dropping resistors or failed/charred components around the dropping resistors.

The whole debate regarding heat in tube electronics is sustained by 
two truths that leave a huge area of satisfactory operation:  (1) 
Cooler is always better for component life, and (2) Most electronic 
components found in tube-type military electronics can run for many 
decades at obscenely high temperatures and still perform perfectly 
satisfactorily.  In theory, it is better to cool tube electronics, 
but except for certain specific problem areas (around the R-390 
regulators, for example) it is not really necessary even if you 
define mean time between failures in terms of multiple decades.  So 
be as kind as you want to be to your gear, but in general you aren't 
abusing it if you don't force-cool it.

Best regards,

Don