[Amps] SB220 cooling was: Re: Coupling a blower to an air system socket

[Pete Smith N4ZR]

For what it may be worth, I seem to have cured a recurrent problem with 
overheated filament pins on my SB-220 (which came unsoldered frequently) 
by putting a muffin fan directly over the tubes, sucking air out of the 
tube area.  The amplifier is used in contestservice at ~1200 watts 
output on the lower bands and around 1KW on 15 and 10.  I had tried all 
the usual fixes - swapping the socket springs, polishing the pins, 
adding the Harbach fan - but this appears to have been an essential last 
step.

73, Pete N4ZR
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On 3/17/2013 2:03 AM, Roger (K8RI) wrote:
> I do not know of any way to achieve the required air flow at a reduced 
> back pressure other than an exhaust fan reducing the exhaust pressure 
> thus making it a little easier to get more cooling air through.
> I believe Emtron and OM both use this approach on some models.