SSTC not working as expected

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

Original poster: "Alan Sharp by way of Terry Fritz <twftesla-at-qwest-dot-net>" <AlanSharp-at-compuserve-dot-com>

Rob,

Your topload maybe too big - have you got a breakout point?

Another possibility (though unlikely from your description) is that
you are at a harmonic frequency - not the fundemental.

how do you stop the flyback transformer from saturating with DC?

Is that snubber big enough?

Alan Sharp






Message text written by INTERNET:tesla-at-pupman-dot-com
>Here is my setup:  

1. 18" of #26 on 4.5" form with 8" semi-sphere on top

2.  160V applied to latest generation IR IRFP50LC 600V reduced gate
charge MOSFET, in a flyback configuration. A 100pF-500ohm snubber is
used.

3. TLC555 oscillator with UC2710 6A driver, coupled to MOSFET with an
isolation tranformer.  I get very square 8V p-p on the FET gate.

4.  Output tranformer is 10 turns primary, 30 turns secondary, which
then bottom feeds the coil.  This tranformer core only gets hot after
very long use. It is 1.5 sq cm core area.

I get lots of RF voltage out of the tranformer.  Enough to create a very
small arc with a screwdriver.  Yet hardly any output from the coil. 
I've checked it with a scope and I  appear to be applying voltage at its
resonant freq.  It lights up a neon bulb quite a distance away, but no
streamers at all.

Perhaps it is a matching problem.  I will see if I can come up with the
S-Params with the Ansoft Serenade eval version.  The FET only gets
slightly warm, so it appears that little energy is being coupled into
the SSTC.  I may have to just go with a primary SSTC winding instead of
the bottom feed.

Rob.<