[AMRadio] Transformer Lead Dress


Jim Candela jcandela at prodigy.net
Tue Dec 11 10:19:19 EST 2007


Bill, KB3DKS/1 wrote:

Message: 4
Date: Tue, 11 Dec 2007 01:00:48 -0500
From: DOXEMF at aol.com
Subject: [AMRadio] Transformer Lead Dress
To: amradio at mailman.qth.net
Message-ID: <3F8ECD96.6491B6C8.0004326F at aol.com>
Content-Type: text/plain; charset=iso-8859-1

Hello,
 I just stripped out a basket case VK II transmitter for rebuilding.
 Most of the transformer leads are brittle and even carefully removing
 them thru the chassis hole, I can feel the rubber inner jacket breaking
 up.
 I would expect to replace the wires near as I can get to the windings.
 
 The plate transformer will need good HT wire.
 
I have quite a bit of different sizes of silver teflon.
for most of the windings but not quite sure what to do about the HT
 wires.

 This is a project transmitter, not a restoration.

  Suggestons? Sources of suitable wire in an affordable put up. I have
 other large transformers with the same problem as well.

 Thanks,
Bill, KB3DKS/1



Reply by Jim, WD5JKO:

Bill, I went through this a few years ago on a Sherwood tube type stereo amplifier. See link below for some pictures.

http://pages.prodigy.net/jcandela/Sherwood_S8000/Transformer/

I spliced new wires onto the tinned leads, and used heatshrink for the insulation over the joint. Then I folded the wires back and taped them over the winding area. What started out looking like a total loss ended up good. I skipped dipping in transformer varnish along with a vacuum chamber to suck out the air so that the varnish would fill all the internal pores that have been created since the old potting material had disintegrated. So far after nearly 4 years, my trusty Sherwood S800 is working fine.

Jim
JKO





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