Re: Tesla Coil RF interference

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Original poster: "Jim Lux" <jimlux-at-earthlink-dot-net> 


----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Wednesday, May 19, 2004 7:18 AM
Subject: RE: Tesla Coil RF interference


 > Original poster: "Paul Marshall" <klugmann-at-hotmail-dot-com>
 >
 > I noticed this with small out of tune coils. Actually, the first coil I
 > ever built was on a 1 1/2 inch form. At low power 450 watts, It would
light
 > a neon tube at a distance of 30 feet. Metal objects that were not grounded
 > had induced voltages as high as 3kV. My neighbors complained about their
TV
 > just looking like a blizzard. On the other hand my 6.5" coil running at 10
 > kW wouldn't do that and I was getting 8' streamers. I think it has a lot
to
 > do with frequency. You seem to have just hit the right one.
 >

Perhaps smaller coils are higher frequency, which aggravates the incidental
coupling effects.  The harmonics will also extent higher in frequency for a
higher frequency coil.

I too have noticed that when out of tune, EMI is a lot worse than when in
tune.  Maybe because less power is making it to the secondary, and the
primary is actually the primary radiation/interference source.  Certainly,
there's an appearance of more energy in the primary spark gap when out of
tune.