OLTC update

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

Original poster: "Terry Fritz" <twftesla-at-qwest-dot-net>

Hi All,

I have verified two import things the computer models predicted (apparently
very well ;-))

I tested my primary coil today and it measures 439.5nH.  So you "can" make
a big single turn primary with less then 500nH inductance ;-))  That is
critical for getting a high top voltage since Vo = ~1/2 SQRT (Ls/Lp).  A
lower Lp also allows higher operating frequency and a lower inductance
secondary (which is already pretty high at about 500+mH).

More importantly, I measured the coupling to my present big coil secondary
at k=0.125!!  I am not sure anyone realized that a single turn primary
could have a high coupling like that!  That is, of course, key for this
thing to work.  

http://hot-streamer-dot-com/temp/P8100020.jpg

I used the simple (with nice test equipment) method on page 14-11 of John's
"Tesla coil Construction Guide". 

A few weeks ago, I just happened to punch the single turn primary case into
Mark R.'s program and was stunned the coupling was that high.  That was a
key factor that started this whole thing...  Apparently, the coupling
"really" is that good!  These may seem like odd technical points, but they
pretty much insure the OLTC will work.  Just a matter of details now.

In another note.  I think I figured out how to insure that the IGBTs share
current perfectly evenly!!  No fancy stuff needed at all.  I just thought
of it like 15 seconds ago so let me think on it *:-))  It would be "tooooo"
simple...  Eliminates some rather critical IGBT mounting stuff...

I also need some way to verify the very low loss of the primary circuit but
I think I need the IGBTs and all running first since the loss is like 0.03
ohm and not at all easy to test.  Probably need to test that for real but
at low power...

Back to work now ;-)

Cheers,

	Terry