[AMRadio] Drying out HV transformers / Chokes

Bob Bruhns bbruhns at erols.com
Sun Sep 18 09:00:34 EDT 2005

Low-voltage DC on the windings would do it.  It would
be tricky to figure a current that would produce enough
heat without toasting anything, though.  Probably
something around the maximum operating current would do
it, over time.  I would put the primary and secondary
windings in series, and heat the whole core.  You might
try to arrange the connections to approximately cancel
the DC flux in the core.

Put the core in a blanket so the heat builds up, and
monitor its temperature.  My guess is it will take days
to build up the heat.  You want to heat it up so it is
warm to hot to the touch, (maybe 140F / 60C), but you
don't want to scorch it.

Another thought is to get a few electric space heaters
and point them at the unit, and let them heat it up.
Again, monitor its temperature.  With this kind of
heating power, you really need to watch it closely.

  Bacon, WA3WDR

----- Original Message ----- 
From: "Don Lemley" <w8hrq at lemleys.org>
To: <amps at contesting.com>;
<glowbugs at piobaire.mines.uidaho.edu>;
<AMRadio at mailman.qth.net>
Sent: Sunday, September 18, 2005 12:51 AM
Subject: [AMRadio] Drying out HV transformers / Chokes

> Hi all,
> Ok, I know this has been covered here before,
> but is there a consensus on how to get the moisture
> out of HV plate transformers and chokes, so they
> won't arc on me.  And before everyone jumps in
> with the quick "just put it in an oven on xxx degrees
> for yy hours", I am working with the iron from a
> Broadcast transmitter, specifically, the Gates
> BC-1G so these things are 100, 150 lbs each,
> and my XYL would REALLY not like it if I tried
> to put them in her fancy oven.  They have been
> sitting in an un-conditioned but dry hanger/garage
> for several years, so I am certain they have soaked
> up a good deal of moisture over that time.
> Thanks for any suggestions,
> Don - W8HRQ
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