[R-390] Thermal Stability and Top and Bottom Covers?

[Todd, KA1KAQ]

Pretty sure the covers were meant as dust covers used only for rack
mounting. The side holes would permit ventilation to pass through the
receivers and up through the top louvers via forced air convection. Remove
for cabinet use.

I recently scrapped out an old AF rack used for R-390s, it had a dual
squirrel-cage blower system at the bottom and exhaust fan on top (both of
which I kept). They moved a lot of air through the multiple receivers. I'm
guessing that a single receiver wasn't considered a problem for cabinet
mounting with the cabinet louvers and overall heat sink effect. Then again,
changing tubes or swapping out a defective module was considered routine
maintenance and spares were plentiful.

de Todd/'Boomer',  KA1KAQ/4

On Mon, Oct 17, 2016 at 6:23 AM, David C. Hallam <dhallam at knology.net>
wrote:

> I have never had a 390A, but I have always run my 390 with a small muffin
> fan on the underside directed at the the series pass voltage regulator
> tubes.  Between the rectifiers and the regulators, a lot of heat is
> generated.  I don't know about thermal stability, but the components will
> be a lot happier.
>
> David
> KW4DH
>