Original poster: "Barton B. Anderson" <bartb@xxxxxxxxxxxxxxxx>
Hi Russ,
I coat my coils similar in manner as Dr. R., however, I use Marine
Spar Varnish (AC-43 I believe is superior from a dielectric
standpoint and Spar Varnish is superior from a elastic standpoint).
I wouldn't coat while winding. It just sounds unnecessary. For
myself, coating involves (1) sealing the form prior to winding and
(2) applying a nice smooth outer coating after winding. Almost all
coils are close wound. The coating will do little for turn to turn
arcing (this shouldn't occur anyway). The coating will however help
with corona, help prevent contaminants from handling, and help
prevent buildup of moisture between turns. The voltages levels of
primary and secondary strikes are usually high enough that
penetration to the winding is possible if a point charge on the
winding is the source. It would take a large coating to prevent that
type of damage. Early on I caused a turn to short about 3/4 up on
the secondary on a 13" diameter coil due to a secondary strike. It
charred 1 turn and also charred the varnish around that turn (easy
to fix however). I haven't had that occur since. Tuning I believe
was the reason. I had that "throw as much power at the beast as
possible" attitude. Fine for a tuned coil. Not so fine for a poorly tuned coil.
It should be noted in this thread, that the greatest damage to a
coil is a coil that is not tuned correctly and/or a coil where
breakdown between primary and secondary is occurring (even
periodically). Do whatever is required to stop this (reduce coupling
if necessary, but start with tuning).
Before I fire up my coils, I am disciplined to wash the coil down to
remove dust and handling contaminants. Sometimes with a simple wet
rag, and other days, with soap and water. The smooth surface on a
coated coil is very helpful here. Towel dry and allow a little time
for any remaining moisture to air dry before firing it up.
Take care,
Bart
Tesla list wrote:
Original poster: Russell L Thornton <Russell.L.Thornton@xxxxxxxx>
Would someone kindly explain to me the process and purpose of
varnishing the windings of the secondary? Specifically, it seems
to me that when we are varnishing the coil form raw and letting
that cure and then varnish again after we wind the wire then the
back of the wire still remains vulnerable with just the enamel
insulation of the wire. Of course this assumes close spaced
winding. Or am I just not seeing the purpose of this exercise. If
we were doing this for insulation purposes I would like to put a
layer of varnish on the form mounted to the winding mechanism and
while still wet wind the wire.
What's up here?
Russ,
Monitoring Lightning at the Cape