开云体育

Craig, did you wind right to the edge? If so, how did you keep the wire from sneaking past? If not, what did you use to fill in the edge?

When I rewound my 453 HT, I wound to the edge, laid a bead of corona dope, laid tape, and waited for the dope to set before starting the next layer. There are other tactics, but that's what I did. I had about 300V (peak) between layers. I used Scotch "Magic" tape, which is polypropylene. I staggered the start/end overlap to avoid humping.

Dave Wise
________________________________________
From: [email protected] <[email protected]> on behalf of Craig Sawyers <c.sawyers@...>
Sent: Monday, May 14, 2018 10:18 PM
To: [email protected]
Subject: Re: [TekScopes] Tek 577 sells for $256 on eBay

Many have come to this forum looking for a solution to the epoxy failing on the 576 HT transformers.
I
went the route of having a run of 5 make by a professional custom transformer supply company. It
was not the most economical solution, but it did keep at least five 576s out of the recycle bin.

That said, you and maybe one other that has posted here, where successful in winding one from
"scratch". Would there be any possibility of you putting together a how-to post with pictures or a
YouTube video of the method you used?

Thanks,
Dave

Hi Dave

I took alas no photos. But what I did was:

(a) Buy the cheapest manual coil winder from eBay. In US-speak we're talking $20.
(b) Found a regular pot core bobbin that would fit the core centre leg. That fortunately had lots of
pins.
(c) Wound using wind-and-retrace. If you wind back and forth, you get twice the voltage at each end of
the wind (found the technique from a google search).
(d) Covered each winding layer with a layer of thin yellow transformer tape both for insulation and to
level the wind.
(e) The additional core pins came in handy because I broke the 0.08mm winding wire three or four
times. So I took the wire out, terminated at a pin, and kept winding.
(f) On completion I potted it in a mix of paraffin candle wax and beeswax. I used something like two
thirds candle (and I mean that I melted candles) to one third (carpenter's) beeswax - which you get as
a solid stick.
(g) After assembling to the core, I immersed it in the molten wax until bubbles stopped, and let it
soak for 15 minutes more. Then let it drip until cold.

The pot core needed to be modified, because it was too long. So I cut off the end cheek, then reduced
the length of the centre tube and reattached the end cheek with superglue.

Any way you look at it, winding 1400 turns of hair thin wire is a royal pain in the ass ;-)

The first attempt was a learning process. The second one is in the 576 and working perfectly.

Craig