HELP ON SB401 HUM

[Glen Zook]

I had that problem on my first SB-401 that I built in
November of 1967.  Added additional filter capacitors
across the two that are there now.  However, the hum
was noticed several hundred miles away.

I also have a similar problem with my SB-110A when I
run up the microphone gain.  Cured this by using the
amplifier in my D-104 so that I don't have to run the
audio gain past about 10 o'clock.  Although the hum
was definitely within specifications, stations a
couple of miles away could hear it (I was about 50 dB
over 9 and the hum was about S-5 which means over 80
dB down).  By using the preamplifier the hum drops to
less than S-1 less than a mile away.  In either case,
stations more than a few miles away could not hear
anything.

Glen, K9STH


--- Dan Pividal N4VET <OTAKEBI at AOL.COM> wrote:

Another station I talk to all the time told me he also
noticed a hum. Both of these stations are about 2
miles from my house and both told me that since I was
hitting them at 20 over and a station further away
would probably not hear the hum.

=====
Glen, K9STH

Web sites

http://home.comcast.net/~k9sth
http://home.comcast.net/~zcomco

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