dual 833A VTTC, problems

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Original poster: "Steven Ward by way of Terry Fritz <teslalist-at-qwest-dot-net>" <srward16-at-hotmail-dot-com>

Hi all,

I have been working on my dual 833A VTTC project for a while now.  I just 
recently fired it up again (after blowing the power the first time a month 
ago or so) and keep happening upon the same problem.  The tubes are not 
matched, so one gets more red than the other.  Rather, one tube is red, the 
other dark (no redness).  I found that i originally had way too much grid 
feedback, so i cut it down quite a bit.  This made the sparks grow from 
about 10" to about 20".  But even 20" is pathetic for 2 of these tubes :(.
Basically what is limiting me is that one tube is getting red, and the 
other not, so i cant just let all of the stress fall on one tube.  So i 
have 2 ideas that i propose (I think John Freau actually may have told me 
these i ideas, i cant remember).  1, perhaps put a resistor in series from 
the red tube grid to the grid winding.  This would reduce the turn on pulse 
from the grid coil, going into that tube.  2, make a grid coil tap, and tap 
the red tube at a lesser turn until i get them to go red at ~ the same 
time.  This could be tricky, well actually, either way is tricky!

So has anyone ever had this problem?  If so what was the solution?  Also, 
can anyone think of any other solutions?  And which of my proposed 
solutions looks better?

Also, a problem that i thought i would not ever have to worry about.  Well 
several small problems.  The parts are getting warm.  The primary coil gets 
warm after about 30 sec, the 36A RMS doorknob cap array gets slightly warm! 
the secondary base gets rather hot, and the discharge point may need to be 
replaced often, if i dont get tungsten :)  These arcs are white, hot, and 
thick!  So really this coil is becoming a in depth project, when it comes 
to all of the de-bugging(not nearly as bad as the other tube coils!). And 
of course, there is always the possibility of catastrophic faliure when 
running about 2+ KW in a 12"x18" area!

Steve Ward.