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Re: Secondary Resonance LC and Harmonics.



Original poster: "Bart B. Anderson" <bartb@xxxxxxxxxxxxxxxx>

Hi Chris,

JAVATC showed 197.8 kHz using a 9" sphere topload, 2k turns of 24 awg on a 4" x 42" winding geometry.

An h/d of 10:1 is high. It has been done, but most coils are in the range of 5:1. I haven't built a coil (for TC use) higher than 5:1, but most reports indicated that high h/d coils did not perform as well (there are always exceptions out there).

Take care,
Bart

Tesla list wrote:

Original poster: "Chris Rutherford" <chris1@xxxxxxxxxxxxxxxxxxx>

Hi All,

I've just done some more measurements, this time with a square wave and looking at the harmonics on that. This time it resonates at 200KHz (wave superimposed on square wave). For this test I connected my sig gen to the base of my TC using a 1K resistor, and put my scope probe on the resistor to TC connection. I injected a square wave and there was a harmonic at approx 200KHz. I then set the sig gen to sine and tuned up to 200KHz, where sure enough there was a resonant area.

So now my TC has 3 resonant frequencies, which one is the one that most people go by??

Thanks

Chris
----- Original Message -----
From: <mailto:chris1@xxxxxxxxxxxxxxxxxxx>Chris Rutherford
To: <mailto:tesla@xxxxxxxxxx>Tesla list
Sent: Saturday, June 25, 2005 6:34 PM
Subject: Secondary Resonance LC and Harmonics.

Hi All,

I've just wound my first secondary, and in my eagerness I ignored most guidance and just wound as many turns as possible on a piece of 3.5' x 4" tubing. It turned out to be approximately 2K turns (gulp).

I managed to get my hands on a nice stainless steel sphere, which sits nicely on top. I was just 'playing' with my scope and signal generator, when I discovered that when I set the sig gen to oscillate at 76KHz or 416KHz I don't need to connect it to the coil in order to show the signal on my scope, I only need to touch the probe and the signal magically gets on to the coil and scope! - I'm guessing that my coil and top sphere are acting as a tuned LC tank circuit, with a resonant frequency of 76KHz and a harmonic of 416KHz. Either side of these frequencies the signal drops off.

Does this make sense? Has anyone else experienced something like this? How *badly* tuned is my coil? Should I take some turns off it (not yet varnished)?

Thanks

Chris