Much Improved Test Results (fwd)
---------- Forwarded message ----------
Date: Wed, 13 May 1998 14:30:43 EDT
From: Esondrmn <Esondrmn-at-aol-dot-com>
Subject: Much Improved Test Results
Bill Wysock has been helping me off line to resolve my problems. He suggested
that I remove the static gap in series with the rotary and to remove the
series resistors in the H.V. feed lines - which I did. He also suggested to
replace the welder with a heavy duty variac. I found a 120 volt 41 amp variac
rated at 5,000 watts (labled Luxtrol, by Superior for use as a light dimmer)
at a surplus store for $20.00 without brushes which I have since bought for
$58.00. $78.00, not bad for a nice unit like this.
Bill's suggestion then was to turn the main power variac up until the rotary
just starts to fire, then adjust the ballast variac for the smoothest rotary
operation. The gaps fired at about 140 volts on the primary of the H.V.
transformer (pole pig)- depends on the ballast setting. The primary current
fluctuated wildly from 15 amps to 50 amps and there was a loud thumping coming
from the voltage control variac. You could also feel this thumping. The cap
safety gap also fired. I could not adjust the ballast to
I added the resistor bank (3.3 ohms) in series with the ballast variac. Now
I can control it. With the best ballast variac setting, the primary current
is about 27 amps and the primary transformer voltage is about 175 volts. The
cap safety gap is not firing!! This is great news. It looks like I now need
to get some lower value resistors, maybe try one or two ohms, in order to get
primary transformer voltage up somewhere around 200 or 220 volts.
The best spark I could get was 52" to a grounded wire. Far from this coil's
best of 80" but at least the tank capacitor should not be in any danger with
this set-up. The primary tap point for best tune has changed from 11.75 to
12.5. As Bart pointed out to me, this seems to support what Malcolm was
saying recently about the ballast inductance being reflected through the
transformer into the primary.