New 4" coil: R.Hull and CSN, Secondary Varnish

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Dave Hartwick by way of Terry Fritz <twftesla-at-qwest-dot-net>" <ddhartwick-at-earthlink-dot-net>

Guys,
What is the current thinking on applying secondary insulation, in this case
MinWax gloss polyurethane? There was a time when multiple coats to build a
up a thick layer was desirable for  corona suppression, racing arcs, etc.
Richard Quick was one such advocate.

I note that Richard Hull advocates minimum or no varnish at all, stating
that pretty secondaries with lots of varnish are also lossy. I've got about
5 coats on the new 4" secondary (#26, 1500 turns) and am thinking that's
enough, maybe too much. I've never done A B tests with identical secondaries
that differ only in varnish quantity.

I also wonder how Glyptal and other substabces compare in terms of
lossiness.


Generally regarding Rich Hull's work: I'm now reading his Guide to the
Colorado Springs Notes--1993, 2nd edition 1995). Here he addresses the
secondary insulation matter. He also concludes, for example, that cap size
for a given transformer should be smaller than is generally advocated today.
He says that a 5kVA 14.4 kV piglet won't handle a 0.06 ufd cap, that 0.005
ufd is largest a 15/30 NST will power up. This is certainly at odds with
more recent LTR methods.

The overall question is what is still viable from work generated 8-10 years
ago? And that goes for any theory that is some years old now. Certainly,
much of his conclusions are still valid--Big toroids, magnifier theory.
Dave Hartwick