[AMRadio] Drying out HV transformers / Chokes


John Coleman ARS WA5BXO wa5bxo2005 at pctechref.com
Sun Sep 18 12:37:37 EDT 2005


	I have a modulation XFMR that was under muddy water for 6
months.  I thought it had some how floated away in the "Spring, Tx flood
of 94", But I just didn't understand how it would be possible.  That's
another story, where was I, Oh yeh, the XFMR was found and the mud was
off of it.  It was let to stand in the sun for about 3 months under
shed.  I then measured 1000 ohms from any winding to another and to
ground.  I took the end caps off exposing the coil, rust and mud.
Washed it out some more and decided to put it on the shelf in a un-air
conditioned office that no one used, where the temp would reach 120-140
every day in the summer.  I was thinking I would rewind it some day.
But alas, 6 months later all the readings were infinite.  To be safe it
was mounted on a wooden shelf in the XMTR and has been working for the
last 7-8 years.  Modulator is four 813s with 2500 volts on the plates,
800 on the screens and about -100 on the grids.  This modulator will
pump out some PTP voltage.  I was really surprised at the come back of
this XFMR.     

-----Original Message-----
From: amradio-bounces at mailman.qth.net
[mailto:amradio-bounces at mailman.qth.net] On Behalf Of Don Lemley
Sent: Saturday, September 17, 2005 11:51 PM
To: amps at contesting.com; glowbugs at piobaire.mines.uidaho.edu;
AMRadio at mailman.qth.net
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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