From: "Barton B. Anderson"
Date: Sun, 13 Oct 2002 16:05:49 -0700
Subject: Re: [TSSP] Top Voltage
--Boundary_(ID_B8NGhbVqWfASsbeWwAhvSg) Content-type: text/plain; charset=us-ascii Content-transfer-encoding: 7BIT Hi All - Measurements on ba1: Fres = 238kHz (gap open) Upper Mode = 248kHz (gap closed) Lower Mode = 206kHz (gap closed) f3 = 832kHz (gap open) f3 = 846kHz (gap closed) I seem to be breaking out at lower V&I than expected. The gap = 2 sphere electrodes at 1.2522" diameter spaced at 0.1" = 7.228kV (North) Base current varied all over the place between firings (1 to 5.6 amps). Definate breakout, sparks ranging 3 to 8 inches. Setup is the Pearson (1V=1A) current monitor fed directly to the scope. The secondary base wire is fed through the Pearson on it's way to RF gnd. I don't know if I'm doing something wrong or what. This procedure seems simple enough. I ran an AC load (10.7A) to check the Pearson vs. scope reading and the scope was right on the money. So I don't think anythings wrong in the arena. Possibly, not the best top load (Al corregated flex tube with Al tape to smooth out those little ridges). The only other topload I have is the spun alluminum - but 9" x 30" is a bit much! hmmm, wonder if John F. has anymore of his small spun toroids left. Any ideas? Bart Paul wrote: > Bart wrote: > > my smaller 4.5" coil is already in place...think I'll start > > measurements with it. > > Ok, I put in the details as coil ba1. The predicted mode > frequencies are 212.2 kHz and 250.0 kHz, with Fsec coming out > at 234.9 kHz, an error of -1.3%. You got 248 kHz with > the gap shorted. That's the upper mode, with an error of +0.8%. > You'll find another around 2% below 212 kHz, say 208 kHz. > > f3 should be up at 849.5 kHz with the primary gap closed, and > 836.6 kHz with the primary gap open. > > Modeled Lsec are > Ldc: 18.84 mH (measured 18.67, model is +0.9%, ok there) > Les: 18.69 mH > Lee: 18.44 mH > > All very close together because of the huge amount of toploading. > This coil must be one of the most heavily loaded that we've seen. > > Fpri comes out at 223.4 kHz, so a 5% detune is predicted. > > ba1: Bart's small coil, > Predicted breakout: @ 320kV, equating to 10.7kV firing volts. > > Base current should be a smidgen under 12 amps peak at 10.7k Vfire. > > As regards calibration, even though the probe is known good, it's > nice to get an end to end check. > -- > Paul Nicholson, > -- --Boundary_(ID_B8NGhbVqWfASsbeWwAhvSg) Content-type: text/html; charset=us-ascii Content-transfer-encoding: 7BIT Hi All -Measurements on ba1:
Fres = 238kHz (gap open)
Upper Mode = 248kHz (gap closed)
Lower Mode = 206kHz (gap closed)
f3 = 832kHz (gap open)
f3 = 846kHz (gap closed)I seem to be breaking out at lower V&I than expected.
The gap = 2 sphere electrodes at 1.2522" diameter spaced at 0.1" = 7.228kV (North)
Base current varied all over the place between firings (1 to 5.6 amps). Definate breakout, sparks ranging 3 to 8 inches. Setup is the Pearson (1V=1A) current monitor fed directly to the scope. The secondary base wire is fed through the Pearson on it's way to RF gnd. I don't know if I'm doing something wrong or what. This procedure seems simple enough.
I ran an AC load (10.7A) to check the Pearson vs. scope reading and the scope was right on the money. So I don't think anythings wrong in the arena.
Possibly, not the best top load (Al corregated flex tube with Al tape to smooth out those little ridges). The only other topload I have is the spun alluminum - but 9" x 30" is a bit much! hmmm, wonder if John F. has anymore of his small spun toroids left.
Any ideas?
Bart
Paul wrote:
Bart wrote:--Boundary_(ID_B8NGhbVqWfASsbeWwAhvSg)--
> my smaller 4.5" coil is already in place...think I'll start
> measurements with it.Ok, I put in the details as coil ba1. The predicted mode
frequencies are 212.2 kHz and 250.0 kHz, with Fsec coming out
at 234.9 kHz, an error of -1.3%. You got 248 kHz with
the gap shorted. That's the upper mode, with an error of +0.8%.
You'll find another around 2% below 212 kHz, say 208 kHz.f3 should be up at 849.5 kHz with the primary gap closed, and
836.6 kHz with the primary gap open.Modeled Lsec are
Ldc: 18.84 mH (measured 18.67, model is +0.9%, ok there)
Les: 18.69 mH
Lee: 18.44 mHAll very close together because of the huge amount of toploading.
This coil must be one of the most heavily loaded that we've seen.Fpri comes out at 223.4 kHz, so a 5% detune is predicted.
ba1: Bart's small coil,
Predicted breakout: @ 320kV, equating to 10.7kV firing volts.Base current should be a smidgen under 12 amps peak at 10.7k Vfire.
As regards calibration, even though the probe is known good, it's
nice to get an end to end check.
--
Paul Nicholson,
--
Maintainer Paul Nicholson, paul@abelian.demon.co.uk.