Many have reported that the Harbach fan cools less than the original and
leaves hot spots on the tube. The Heath fan has to be cleaned and lubricated
to stay at speed, the blades have to be positioned as per the manual, and
that small aluminum plate on top must be in place to divert the air.
With several hundred SB-220's coming thru here since 1970 Ive yet to see a
filament pin or socket problem when all the above was correct.....and not
used by some CB idiot flat out on AM.
Carl
KM1H
----- Original Message -----
From: "Pete Smith N4ZR" <n4zr@contesting.com>
To: <amps@contesting.com>
Sent: Monday, March 18, 2013 6:29 AM
Subject: [Amps] SB220 cooling was: Re: Coupling a blower to an air system
socket
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
Check out the Reverse Beacon Network at
http://reversebeacon.net,
blog at reversebeacon.blogspot.com.
For spots, please go to your favorite
ARC V6 or VE7CC DX cluster node.
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.
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