Don,
I found a source for transformer varnish on the internet. That
varnish is very volatile and you may have trouble getting it as an
individual. (the flash point is around 70 degrees with a spark as I
remember and it has a short shelf life according to the mfgr.). I had
no trouble but I am a licensed Professional Engineer. An option for
the units is to find a motor rebuild shop. They usually have a 55
gallon drum of it that they dip the rewound motors into when they are
done. I sure they would do it for you for a modest fee. I have no
source on the tar or fish paper etc.
Larry
At 01:00 PM 9/18/2005, you wrote:
Hello Larry and All,
I have several 2.5v and 10v rusty,dirty, and rattling UTC small can
S series filament transformers that I want rebuild and would like to
know a source for transformer varnish and potting material, wax,tar,
or whatever.
On pulling the cover off the most rattling around one I found only
sections of corrugated cardboard to be the
"packing/potting" material !!. I would like to use something better
and improve the heat transfer as these seem to be really small
construction for the rated current. I intend to use the 10v units
for 813/814/805 family.
Any suggestions would be appreciated.
Bill KB3DKS/1
-----Original Message-----
From: Larry Will <[EMAIL PROTECTED]>
To: [EMAIL PROTECTED]; Discussion of AM Radio <[email protected]>
Sent: Sun, 18 Sep 2005 10:41:41 -0400
Subject: Re: [AMRadio] Drying out HV transformers / Chokes
Don,
Here is the section in my article from ER Magazine on rebuilding an
RCA BTA-1R1 on the homemade over I used with great sucess. all you
need is a thermostatically controlled hotplate a thermometer and a hood.
.from my RCA BTA-1R! article in ER.
A check of all the iron with a 1000V 1000 megohm ohmmeter showed
excessive leakage (less than 1000 megs) in the modulation reactor,
the driver plate transformer, and the control transformer. The
control transformer makes 110VAC for relays and lamps from the 240V
input. The smaller transformers were baked in the kitchen oven at
140 degrees F for 5 hours. For the very heavy 50 henry modulation
reactor, I fashioned a homemade "oven" using a thermostatically
controlled single burner hotplate and a hood made from an old water
heater jacket (Figure 1). This allowed me to cook the transformer
out in the garage near the rig. An oven thermometer allowed me to
set the oven temperature to 140 degrees F and after 25 hours of
"baking", the leakage was cured. All of these transformers and
chokes were then dipped in transformer varnish to re-seal the
winding from new moisture incursion.
Regards,
Larry W3LW
______________________________________________________________
AMRadio mailing list
Home: http://mailman.qth.net/mailman/listinfo/amradio
Help: http://mailman.qth.net/mmfaq.html
Post: mailto:[email protected]
AMfone Website: http://www.amfone.net
AM List Admin: Brian Sherrod/w5ami
