From: "Terrell W. Fritz"
Date: Fri, 01 Sep 2000 21:15:31 -0600
Subject: Re: [TSSP] Mystery of the missing loss
Hi Paul, I patched up the ground plane. It is now solid and NON-SPLIT again. I decided to violate the "pristine" ground plane area and get right on in there with some equipment to see what was what. So with a load of equipment and wires in there the numbers shifted but I was able to get some Q data with a "rough" ground plane. Bare Coil f1 = 148.3kHz Q = 57.7 f3 = 347.87kHz Q = 33.3 f5 = 513.76kHz Q = 20.3 45 inch Torroid f1 = 97.93kHz Q = 80.9 f3 = 322kHz Q = 36.6 f5 = 491.2kHz Q = 23.8 Then I tried to measure the coils AC resistance with a 41pF fixed super high Q ATC ceramic cap in series with the coil, generator, and a 50 ohm RF resistor. Even though the Q of the ceramic cap is "so high it can't be measured", the Q of the circuit was only 14.1! I played with it awhile and discovered that if I put the coil up on a plastic bucket, the Q shot up to 75! I was powering the coil upside down so the high voltage end would have been near the ground plane. That probably had a big effect. But I was thinking the fixed cap would pretty much keep the fields in check. So I am know wondering if the very close ground plan is have a "devastating" effect on the coil's Q. I was thinking of looking at the Q with the coil and terminal on the bucket about a foot away from the plan and seeing what happens. This is yet to be done but it appears to be in important thing to look at... For reference, two pictures of the "mess" are at: http://63.225.104.218/test/TeslaCoils/Misc/PaulNich/P9010007.jpg http://63.225.104.218/test/TeslaCoils/Misc/PaulNich/P9010009.jpg BTW - This site was down for the last 48 hours but should be fixed now. Cheers, Terry
Maintainer Paul Nicholson, paul@abelian.demon.co.uk.