The fan that I used came out of an industrial 13.560 MHz amplifier which used
an 8877. It does move some air! However, it isn't that loud.
I positioned the fan so that it blows across the entire tube including the
heater and heater/cathode.
Glen, K9STH
Website: http://k9sth.com
--- On Fri, 4/15/11, Jeff Blaine <keepwalking188@yahoo.com> wrote:
Yes, you are right. As a practical matter, I ran a set of GI7b using the stock
coolers in RTTY service for about 6 months before moving to some custom coolers
which were optimized for lateral cooling. At that time, I had access to a
friends IR analyser which would produce fantastic and cool pictures.
The hottest spot on the GI7b in severe duty (abuse duty?) is just a bit down
from the anode cap on the ceramic. The fan location was roughly similar to
what Glen has done. That worked out and the temps were under spec. So for SSB
service, which I think is Glen's focus, this kind of fan arrangement will be
really enough even with serious compression use as long as the idle current is
not cranked up too high.
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