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Re: 2 questions on resonance (new tests)

Gary, Malcolm, Terry, Bert, Reinhard, all,

I did some tests on my sync gap TC using larger than resonant
sized caps, and the results were excellent.  Everything is working
as some of you have suggested; strong current draw, more efficient
operation, narrower safety gaps, strong output, etc.  I've actually 
been using this larger-than-resonant cap size in my 64" spark 
15kV, 60ma NST powered TC for some time since it has a .0147uF
cap, (the matched value is .011uF or so). 

But I wanted to test a larger cap in the "42" spark TC", so I first 
installed a 12kV, 30ma NST and verified that I'm getting 42" sparks 
using a .0077uF cap, and drawing 740 watts.

Then I changed the cap value to .0147uF to test the power draw.
(This was an attempt to test the large type cap size in similar fashion
to a .023uF or so for a 15kV, 60ma NST).  At 140 volts into the
NST, I obtained 42" sparks using only 620 watts, at 640VA.
This is better than my previous results using the resonant sized 
cap.  Thanks guys for persisting on this issue.  My 42" spark coil
is now more efficient than ever with the NST, and the NST should
be even more protected now without the high resonant voltages.  I
was able to reduce my safety gaps from 7/16" to 1/4" now.  Very
nice.

I did notice one concern with this cap size, which is actually larger
than Terry recommended, which is, to get max output, the sync
phase has to be set near to the point where the gap fails to fire.
But it did seem OK when I backed it off a little for steady firing.
I also noticed as Terry said, that I had to turn the variac up a little
higher to get the same current draw compared with a resonant
charging setup.

I also did some tests using static gaps, but the results were poor
and erratic.  I used a multi-pipe
static gap, with various numbers of gaps from 5 to 21.  With few gaps,
the spark output was only about 4" long, and this gradually increased
to about 21" with more gaps being used.  Operation was erratic, and
I could not accurately verify the firing rate using the static gaps.  But
the firing rate sounded low.  With the static gaps, the NST drew
about the same amount of power, as using the sync-gap.

It is possible that the static gaps cannot take advantage of the
charging that occurs during the downside of the half-cycle that
Malcolm mentioned, so this might be still another advantage of
sync gaps when used with these large caps.

I tried with and without PFC caps, but didn't see much difference
either in power draw, or results.

I also tested the TC using static gaps with the .007uF cap, this 
resulted in up to 34" sparks, but operation was somewhat erratic.
It does seem to me that using static gaps, longest sparks can still 
be obtained from NST's by using resonant charging.  Although the
transformer will probably be destroyed.

I also tested a .0118uF cap in the coil.  This size worked OK, but
not as well as the .0147uF.

I did see a difference in power draw between resonant charging
sized caps, and these larger caps.  The resonatnt sized cap drew
640 watts at 120 volts input, but the larger cap needed 140 volts
input to draw 640 watts.

I do like to use large caps with a low break-rate, and to me, all
these results support that approach even more strongly.

I will also do some work using the potential transformers
and the larger capacitor sizes.

John Freau