Interesting problem!
I ran across a posting somewhere in the past 6 months on some reflector about a
guy who was having hum nightmares with his 2 x GI7B amplifier. He tried all
sorts of cures. It would of course disappear with DC on the fils. He tried all
sorts of bypassing and choking to no avail.
The final solution turned out to be a simple matter of "crossfeeding" the
filaments rather than parallel feeding them. I don't know whether you have
tried that or not. Maybe it might work. It worked for him.
73, Lee ZL2AL
Date: Sun, 6 Aug 2006 16:23:31 -0400
From: "hamguy2" <hamguy2@fuse.net>
Subject: [Amps] Henry 2KD-5 120 Hz Hum
To: <amps@contesting.com>
Message-ID: <006a01c6b996$3166c710$6400a8c0@RONSCOMPUTER>
Content-Type: text/plain; charset="Windows-1252"
It could be 60 Hz. It sounds like 120 though. A local ham with
band scope said 60 Hz and not a perfect sine wave. He said it was
riding on the signal about 20 dB down. This is an amp I acquired
recently and the hum problem has existed since I started using it.
This may be related. Previously, I also replaced both blocking
doorknobs. One of the them was cracked and blew the CB when it
arced the first time I first used it.
----------------------
Ron Schuster N9RC
Cincinnati, OH
----------------------
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