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Re: Discharge impedance of a CW Tesla coil

Hi Richie,

At 05:43 PM 03/10/2000 +0000, you wrote:
>Hi Terry,
>
>This is very interesting stuff.
>
>Did you build the RF power generator,  or are you using a linear amp or
>something from work ?  Is its output sinusoidal or is it a square wave ?
>I take it that you are driving the resonator via a primary coil rather
>than feeding the base ?

The generator is like ones we build at work.  I pieced it together from
scrap parts from the dumpster and stuff.  It is pretty beat up and shaky
inside but I seem to have it working at the moment.  Fortunately, I am
pretty familiar with how it works but it took awhile to get it running.
Many of the PC boards went through destructive vibration and environmental
testing, but I think I have everything glued in enough.  It had a burning
smell for awhile but it went away ;-)  The power PC board has had a few
blowups but I think they are cosmetic.  

It is a pure sine wave generator and I have a primary coil driving a base
grounded secondary.  It is a real RF plasma supply and it has all the nice
controls for such.  It is also fully self protecting so it shouldn't blow
up (knock wood).  It is also able to drive reflected power loads and has
built in load match but I don't use that at the moment.  The 50ohm output
seems to work fine.

>
>Sorry for all the questions,  but solid state coiling has always been an
>interest for me.  I am a power electronics engineer by profession and see
>the potential of using a power inverter for a small solid state TC.
>
>Did you try modulating the RF feed ?  I found that the discharge becomes
>more like a dissruptive TC if the RF is modulated with a narrow pulse
>waveform.  More bolts and less of a brush effect.  The buzzing and ozone
>return of course,  but the average power drawn can be slashed greatly.

John mentioned this too.  The generator has electrical remote analog
inputs.  If they are working, this should be easy to experiment with.  It
sounds like a lot can be done by modulating the power level.

>
>There is a paper by Dr. Gary L Johnson called "Input Impedance of a Tesla
>Coil" which covers a similar series of tests to what you describe.  I
>trust you have already seen this,  but could scan it for you if you
>haven't.  It would be interesting to see if your findings agree with his.
>He used a half bridfe MOSFET inverter to end feed the resonator.

I don't remember seeing this paper.  I would be interested in seeing it.

Cheers,

	Terry

>
>Please keep us informed of developments,
>							Cheers,
>
>							-Richie,
>
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