From: Paul
Date: Wed, 22 May 2002 21:20:49 +0100
Subject: Re: [TSSP] Topload breakout potentials
Bart wrote:
> The start of the first turn from the center is 10.44/2"
That's good. In fact I've put it into the model as 11.1/2"
because that little tweak gives a good match on the primary inductance,
Measured Modeled
Lp: 102uH 102.1uH
and the secondary matches as before,
Measured Modeled
f1 69.7 kHz 69.6 kHz
I ran the model with this but the mode frequencies came out quite a
lot higher than measured - about +3%. In the end I obtained a the
best match to the tuning with a Cpri increased by 6% to give 65.9nF.
This setting gives:
Measured Modeled
f1- 60.1 kHz 59.6 kHz (-0.8%)
f1+ 71.7 kHz 72.3 kHz (+0.8%)
f3 237.9 kHz 234.7 kHz (-1.3%)
f5 366 kHz 366.3 kHz (+0.1%)
which matches the real coil's tuning but with a slightly higher
coupling. I'm not too worried about the error in k, but that
apparent shift in Cpri needs accounting for.
Can you confirm that your primary Fres (sec removed) is close to
61.4 kHz? If so, then the 61nF cap is really 66nF and the bang
energy goes up with it. Has the cap been measured recently?
The frequency has hardly changed with your new arrangements at the
coil top, but that high surface field at the top rim of the secondary
has reduced considerably and it is no longer the 'hottest' spot on
the sec.
I've updated ba0 in
http://www.abelian.demon.co.uk/tssp/cmod/
with the new settings, but I'm still at the full firing voltage.
Your tuning is at about -12%.
> strike rod about 4 feet from edge of toroid
> placed a breakout point on the toroid
When you go back to a smooth toroid, no breakout point, and no strike
rail, does the tuning remain the same? I guess that's the hard one
to do inside the garage! It would be interesting to know at what
variac setting the smooth topload is just breaking out.
The sec surface field has fallen a little, from around the 18kV/cm
mark down to 15kV/cm.
--
Paul Nicholson,
--
Maintainer Paul Nicholson, paul@abelian.demon.co.uk.