NST Resurrection

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

Original poster: "B2 by way of Terry Fritz <twftesla-at-uswest-dot-net>" <bensonbd-at-erols-dot-com>

Hi Garry, All,
    I tried barbecuing and soaking about 25 years ago and gave up in
disgust. 15 years later the battle was rejoined.  Samples of tar were
placed in various solvents and left overnight.  Toluene was found to be the
best.  The lid was removed from a 12-30 NST.  The NST was placed in the
ultrasonic cleaner at an angle with one insulator sticking out because it
was too big to fit completely.  The ultrasonic cleaner was filled with
toluene and turned on High for a few days.  This was done under a fume hood
with 2 fire extinguishers nearby and while wearing goggles and a gas mask.
Toluene burns on contact with skin and the fumes will damage the lungs. It
can be bought at the local hardware store.  Neoprene gloves must be used
with toluene.  It agressively attacks all others.

    Came back in a few days and the NST innards had dropped to the bottom
of the ultrasonic cleaner, ripping both wires out of the HV coils (Duh).
The wires were cut and the case was removed.  The toluene and tar was
removed and replaced with fresh toluene.  The ultrasonic cleaner was
allowed to run for another few days until the bolts holding the cores
together could be accessed.  The cores were separated from the coils.  The
cores were cleaned for a few days until spotless and then set aside.  The
coils were cleaned over the time of a week.  The toluene was replaced every
few days.  The coils were turned every hour or two.  Everything was given a
final cleaning in reagent grade ethanol for a few hours.  (A druggest can
order this.)

    The HV coils were unwound (with surgical gloves on hand) until the wire
breaks were found and pulled out a few inches.  The coils were set aside to
dry, in a dust free environment, for a few days.  The HV coils were then
coated with "RED GLYPTOL" HV insulating varnish available in small bottles
from mail order electronic supply houses.  I used this because it could be
redissolved if a repair was ever needed in the future.  The coils were
placed on aluminum sheets so that they could be pealed off after the
varnish had hardened.  The coils were then flipped over and varnish was
added to the other side.  This process was continued until the coils became
solid blocks. They were allowed to dry in a warm, dust free enfvironment,
for 2 weeks.  

    40 KV flexible wires (20" long) were then soldered to the broken ends
and held onto the coils with clear mylar tape.  The coils were wrapped in
more insulating tape and assembled onto the cores.  Sheets of teflon were
inserted between the HV windings and core, where they were closest, to
prevent arcing.  

    This transformer is very rugged.  I have run it in open air for hours.
I keep the shunts in to keep the temperature below the insulation melting
point.

Cheers,

Barry