[Hammarlund] vibrating hum on sp600?

[Schichler, Alfred]

I had a similar noise coming from the power transformer in the HQ-100 I
restored. 
I found out that if I pushed on the paper-like material that is wrapped
around the windings, the buzz would go away, so I squirted some RTV in
between some of the layers that were accessible from the bottom of the
transformer where there is no cover, then pushed down in different places
until the buzz would go away and stay that way.
So far it's been pretty quiet.


-----Original Message-----
From: Eugene Hertz [mailto:ehertz at tcaf.org]
Sent: Thursday, March 31, 2005 12:04 PM
To: hammarlund at mailman.qth.net
Subject: [Hammarlund] vibrating hum on sp600?


Hello all,

Just received my GenRad 1001A rf generator and have been starting to learn
about how radios work and how to use test equipment with them.  Had a
question.

When I turn on my sp600 with the rf and af gain set to "0" I can hear an
audible hum coming from either the big transformer or the shorter one right
next to it, I am not sure. It is 60Hz, but appears to be a mechanically
produced sound vs from a speaker or any audio chain.  Kinda like if you walk
by some of the very very large transformers used in power distribution, even
tho there are no speakers you can hear these transformers "buzz"  In my
case, the sound is very low, but somehow annoys me!  Question is, is this
normal? Is this portending some disaster with a transformer? Could
additional caps help this? The audio of the radio is very quite with no hum
whatsoever.




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