[Amps] transformer winding

[Bryan Swadener]

Hi Paul,

When I rewound a transformer for my GS35b amplifier project,
I found NMN333 "paper" from:

OTS Wire & Insulation
9155 SW Barber Street
Wilsonville, OR 97070
503-682-7050

It wasn't terribly expensive but, they had a minimum
order of (IIRC) $40.  That was A LOT of paper. I have
several square feet left over!

My xfmr uses a split bobbin, and the tapped primary windings
allow use on 100/120/200/240V sources - I didn't need to
do anything with them.  The multiple secondaries were
removed and replaced with one 18ga secondary with 3 taps.
I used polyimide (Kapton) coated wire that came from eBay.
I bought 10# - about twice as much as I needed.
I used bits of Kapton tape, too.  It has high temperature and
dielectric withstand characteristics, and is mechanically
tough, too.  See http://en.wikipedia.org/wiki/Polyimide and
http://www2.dupont.com/Kapton/en_US/assets/downloads/pdf/summaryofprop.pdf
for more info.

You're welcome to any/all of the above extra for a song.
If interested, email me off-list.

I was fortunate to have a local xfmr rewinder perform
vacuum impregnating of my xfmr using a polyester
material. I offered to pay for the service but, they
would have none of it.

Lastly, Manfred and his website are a wealth of
information!

vy 73,
Bryan WA7PRC

--------------------------------------------

 Date: Mon, 17 Mar 2014 20:41:46 +0000
 From: Manfred Mornhinweg
 To: amps at contesting.com
 Subject: Re: [Amps] transformer winding
 
 Hi Paul,
 
 
 > Q2.  What sort of paper insulation should
 > I use between the primary and secondary?
 
 If you want to be professional, a good choice is
 nomex-mylar-nomex 
 laminate. It comes in different thicknesses. After winding,
 the whole 
 thing should be impregnated with insulating varnish. The
 porous nomex 
 soaks up the varnish very well, while the non-porous mylar
 provides safe 
 insulation even where the varnish doesn't reach.
 
  > I do have some Kapton tape I could use?
 
 Probably, but I have never tried it, I don't even know the 
 characteristics of it.