[Amps] Roller Inductor Choices

[Glen Zook]

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 at 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.