OLTC update

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

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

Hi Everyone,

Many thinks for all the kind words :-))

I thought I would be ordering replacement FETs and pondering "what
happened" today :o))

I have found that I set the secondary capacitance to 37.3pF in error last
night.  It should have been 30.5pF.  The secondary frequency was 34.7kHz
instead of 38.3 like it should have been.  So the tuning was 10% off in
frequency resulting in only 25% power to an air streamer.  That explains
the short streamers to air but big arcs to ground.  I may have to pull a
few turns off the secondary eventually.  The primary inductance is only
like 410nH!  That is how I am getting such a nice high Fo frequency.  I
think the coupling needs to be around 0.10.  The input power was about 225
watts.  The IGBT heatsink got just slightly warm (30C) with a long run.  If
the coil is not breaking out, I really have no idea where the power goes.
Perhaps into secondary heating.

So I'll tune things up and work on it some more to see if the streamers
perform more as expected.  I will be writting all this up too.  I will
probably get everything running at 120VAC and do destructive IGBT testing
before going up to 240VAC.  Now that the coil is working, I find I would
like to keep it that way ;-))

Cheers,

	Terry