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Re: [Amps] Drying out HV transformers / Chokes

To: w8hrq@lemleys.org
Subject: Re: [Amps] Drying out HV transformers / Chokes
From: R.Measures <r@somis.org>
Date: Sun, 18 Sep 2005 04:37:18 -0700
List-post: <mailto:amps@contesting.com>
Hello, Don -- I heat large xfmrs by shorting the primary with an AC 
ampere meter and connecting the secondary to a variac that is connected 
to the electric mains.   I increase the the sec. V until I arrive at 
the normal pri. current.  I put a folded in half bath towel over the 
unit to hold in heat.  After a few hours, the xfmr should be almost too 
hot to touch.  Continue for a few days.  At this point, the xfmr should 
be dried out.  At this point, polyester laminating resin can be poured 
into the windings to fill the air spaces.  When the resin hardens, the 
xfmr will not absorb moisture, it will be able to get rid of internal 
heat better, and the insulation will be improved.
- note - xfmr potting is covered in:
http://www.somis.org/D-amplifiers3.html
cheerz

On Sep 17, 2005, at 9:51 PM, Don Lemley wrote:

>
> 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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>
>

Richard L. Measures, AG6K, 805.386.3734.  www.somis.org

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