It's normal for the R-4B power transformer to run hot. And to Carl's point,
the audio tube, running class A near the transformer adds even more heat.
I really dislike cabinet heat and rather than use a fan, I went to the extreme
last year and made several circuit conversions. The first phase involved
replacing the power transformer with the type found in the R-4C, then
converting all 12.6v tubes to their 6.3V equivalents. This was followed by the
installation of the Sherwood PS-4 upgrade to further reduce heat by eliminating
power-hungry resistive dividers. The last phase involved complete removal and
replacement of the class A audio stage with a discrete, audiophile-grade Class
AB push-pull audio board.
After the mods, the R-4B is cool to the touch, like a Sherwood modified R-4C.
This was an extensive experimental exercise and I don't recommend it as a
casual upgrade. Probably with even a modest amount of air flow, the cabinet
will run significantly cooler.
Paul, W9AC
----- Original Message -----
From: gypsym...@aol.com
To: euge...@nni.com ; Drakelist@zerobeat.net
Sent: Monday, June 18, 2012 7:09 AM
Subject: Re: [Drakelist] R4B Transformer temp
euge...@nni.com writes:
R4B. I
noticed that even the transformer seemed very warm - virtually hot.
Probably the tube just to the right of it, a small fan on top of the case
helps a lot.
Carl WD8NHK that's what I do with my R4
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