Even Newer NST-sync tests, was LTR Charging vs. Firing Time

In a message dated 99-06-23 04:21:49 EDT, you write:

<< I'll do more tests to try to find a good gap phase setting near 60 or 75 
> DPSVP that causes a small dip, and then a proper rise.
> Maybe I missed it. >>


Adding to my post here:  I did some more tests, but I'm still unable
to find any sync phase position near 60 or 75 degrees that works
well using this 12 - 30 NST.  At a low variac setting, the coil works
OK, but when I attempt to raise the variac, the gap stops firing and
the waveform takes on an unusual waveshape.  I think someone
mentioned this effect in the past, and I also saw it happen in the
past.  I do see the signs of a strong IK rise before this happens 
(I think).  With this setting, the gap firing is delayed past the cap
voltage peak.  The gap stops firing when I reach 200 watts on the 
wattmeter using this 360 watt rated NST.  The biggest problem
might be that the gap fires so far after the supply voltage peak.  The
peak itself has a good voltage level.

I thought that the NST might be failing (when I installed it, I forgot
I was supplying 240 volts, and turned it up too high  :(  )  but I
tried another identical NST, and it behaved the same way.  I'm
still able to get a good output only at 135 DPSVP (degrees past
supply voltage peak).

These results do explain a prior finding:  In previous tests I found
that an NST with LTRC must be turned up past 120 volts input in
order to draw more than it's rated input power.  I did not have a
scope connected during those early tests, but I now realize that
the need for more than 120 volts input might be because of the
135 DPSVP requirements of this system. This phase setting gives
less of an IK build up than 60 or 75 DPSVP it would seem.  

Are others finding that NST with LTRC can draw more than it's rated
input power without going over 120 volts input?  (esp using systems
that can run properly at 60 - 75 DPSVP?)

Maybe I have to set up a system like Terry's with .022uF cap, and
15 - 60 NST, to compare.

I may install the .0077uF cap (still ~LTR since reso = .0066uF) to
see which gap phase positions are usable.

John Freau