From: "Barton B. Anderson"
Date: Mon, 20 May 2002 23:51:04 +0000
Subject: Re: [TSSP] Racing arcs
Hi All, Just to add to my latest. I adjusted coupling tonight by raising the primary. I ended up at a primary base height of 28.75" which puts the secondary bottom winding near even with the primary top plane. So, the sec is about 0.1875" above primary center plane. At this primary base height, coupling is obviously higher. At low power, the coil ran fine, but at higher voltages, sparks from the top of the secondary would spark out about 1/3 down the secondary. Meaning, not a straight flash down, but it protruded out about 10" and curved back to the secondary 1/3 down a couple times. I believe these sparks eminated from the wire which connects the toroid. The wire is straight up vertically and is part of the secondary 24 awg wire. Rather than move the toroid down to add shielding, I configured a corona ring between the top of the secondary and toroid. Corona ring dimensions ended up at 4" x 14.875" and a nice fit. The top 1/3 of the corona ring was actually inside the toroid and the corona ring bottom plane was 1.375" above the top winding. The coil now ran fine at higher powers and with similar coupling as when we first started this adventure (but didn't measure it). I'll scope it another day because the air is moist (rain), although it didn't seem to affect performance. I'll take a frequency check anyway. Ok, it hasn't changed. At least the coupled mode frequency's haven't changed. I think the coupling is as close as I dare get. It may still have problems if I were to truely open it up. Tonight I took some pics of low (100V input) and moderate (180V input) power (sorry, no digital - I'll have to scan if they turn out). Guestimate is 7 feet at times. I think I'll stick with low power for garage running in the future as it's getting a little too close. One thing that seemed to change is the arcs are kind of branchy. Still good power in the branches, but thinner with the branching affect (maybe crisp is the word). I even took some pics of the little flat coil running on a single MOT (~3.5" arcs). Most I've got on the single MOT is 5" (no air on simple 2 electrode static gap made up of 2 tungsten rods gapped at 0.07"). Tonight it ran for at least a minute very well (but the electrodes were very hot). Take care, Bart
Maintainer Paul Nicholson, paul@abelian.demon.co.uk.