In the past, I've actually "injected" silicone into the innards of
bell-ended transformers, in anticipation of (possible) vibration from older
such units...
I don't know if this notion really works, or not --- they were, after all &
in all instances, pre-emptive moves on my part --- but, I can honestly (and
happily!) say that whenever I've done this, I've never once had a
"...vibrator" in the bunch.
Perhaps a better idea might be to tip the transformer upside down, & then
simply pour something a little more viscous --- like maybe varnish? ---down
in between the end bells & the windings themselves...let it soak in a tad,
then pour in some more...
Last but not least, the thing should be allowed to thoroughly dry --- a
process that'd no doubt take several days to complete.
As I say, I've never personally tried this last trick myself, but in the
final analysis, aren't transformer windings sealed with some sort of a
shellac, anyway? And if the original stuff dries hard over time, & becomes
brittle (resulting in vibration), what harm could a "fresh" application of
varnish / shellac like this be...?
~73~ Eddy VE3CUI - VE3XZ
**************************
----- Original Message -----
From: "W5CUL" <w5cul@sbcglobal.net>
To: "'Van K7VS'" <wa7fab@cdsnet.net>
Cc: <amps@contesting.com>
Sent: Sunday, June 10, 2007 1:19 PM
Subject: Re: [Amps] HV transformer buzzing!! Help Please
> 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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>
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