Van,
Transformers will vibrate when voltage is supplied, specifically the
windings. This can happen if the primary and secondary windings are not
wound tightly. Or if the winding as a whole does not completely fill the
window of the iron, and thus is a little loose, you can develop some
buzzing. I would check the HV transformer for shims (wooden wedges) between
the windings and the iron core. If there are no shims, I would make some
out of wood and place them between the winding and the iron core such that
the windings are tight within the assembly. If there are shims already in
place, then readjust them until the noise is abated. Now all of this advice
is without actually seeing the transformer, but from what you describe, it
certainly has the symptoms of loose windings. Hope this helps. I will
defer to Tom and others if this does not solve your problem.
73,
Mike
W5CUL
-----Original Message-----
From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com] On
Behalf Of Van K7VS
Sent: Sunday, June 10, 2007 1:14 AM
To: amps@contesting.com
Subject: [Amps] HV transformer buzzing!! Help Please
I just finished tearing down and rebuilding a HV/LV supply for a Globe King
500A. Galvanized the chassis and repainted all the xfmrs. Looks great,
works great BUT the supply is buzzing quite loudly. I know it is coming
from the HV supply on this deck. LV supply quiet. The buzz is there when I
turn on the HV supply switch and become quite a bit louder when I load the
HV supply down (loading and running the transmitter section).
Any thoughts of what might cause this noise. I don't think its any kind of
arcing but a mechanical noise and probably around 60 cycles...maybe. It is
low pitched. This supply using a filament xfmr for the 866A retifiers, a
350 ma choke and large High voltage transformer. I know I have to isolate
the noise to one of the xfmrs but then what do I do? Any help/thoughts
would be appreciated.
Thanks much. Van, K7VS
PS. Next step is to clean off the modulator deck, remove all the rust and
rebuild it. The RF is pretty clean but doing the same to it. I fired up
the transmitter section today and got 300+ watts into a dummy load thru bird
wattmeter. Pretty good for an old boy that probably hasn't been on the air
for thirty or forty years with a very rusty modulation section and very
rusty power supply deck that now looks like it just came out of the factory!
HI HI.
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