Tube coil success story (and still more puzzles)

[cwillis-at-guilford.edu (by way of Terry Fritz <twftesla-at-uswest-dot-net>)]

Greetings tube coilers,

Thanks to the helpful suggestions of several list members, I fearlessly ran
my 833A coil at full power today for the first time since last year.  I was
having problems losing the microwave oven diodes I had been using in my
doubler, but I now have a string of 20 6-amp 1 KPIV diodes (.001 cap and 10
meg resistor across each for balancing) that shows no signs of being
blowable.  I introduced about 0.4 microF of capacitance across my MOT, as
suggested by Dave Sharpe, and kept 0.4 as the main RF bypass across the
output of the level shifter.  I kept 1.2 microF as the level-shifter
capacitor.  

I also had lots of time to improve other aspects of my coil as well.  It
has a new secondary, actually wound on dried and sealed PVC and coated
three times with polyurethane.  I made a little stand so I can easily
switch position of plate and grid and secondary coils and change the
coupling between them.  And I replaced my 1900 pF "RF Parts" doorknob with
an MMC of two strings of 8 .0082 microF, 1600 V caps from digi-key. I am
about to add a 50 ohm, 100-watt resistor as a plate protection resistor as
well.

The end result of these improvements, as seen in today's run, are a long
writhing discharge that can get about 20 inches long from the toroid.  The
MMC cap gets slightly warm but not nearly as warm as the doorknob, which I
had thought was doing a pretty good job.  I solved a few problems: first, I
had put a little plated-steel tab at the bottom of my secondary to connect
the ground lead to, but the steel was getting smoking hot near the primary
coils- basically it was being induction-heated.  So I switched to a thin
copper braid lead and solved the problem.  Another issue was RF in my
homemade filament transformer, which caused a ruinous arc in the primary
winding.  I made another transformer for the few days until my commercially
made one comes.  The final problem (which I have not solved yet) is my MOT-
it gets very hot, very fast now.  Somehow, in the combination of capacitor
across it and new diode, it is getting too hot.  I certainly expect it to
warm up a bit like it used to do, but maybe it resonates with the
capacitance in its secondary and causes high current in the windings.  And
we have 20-amp breakers in these dorms, and that (for some reason!) is just
not enough for the tube coil every now and then.  I have never had this
issue in the past, but I have it now.  I plan to move the coil to the
physics building, where breakers of higher current are used.  But somehow I
cannot believe my coil eats 2400 W when it used to eat a lot less!  Power
factor correction required maybe!?

Oh- I am going to be recieving a new 833A shortly.  My current one is fine,
but I think it was a pull and I want to see what the real thing off the
shelf does here.

-Carl