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Re: Calorimeter response #1



Original poster: "Terry Fritz" <twftesla-at-uswest-dot-net>

Hi Gary,

At 10:05 PM 1/16/2001 -0600, you wrote:
>Paul, Barry, Duncan:
>
>Thanks for the suggestions.  The major influence of humidity on input
>impedance was a surprise to me, but I think I am going to be able to use
>this feature to explain some of the measurements that have been puzzling me
>up to now. I am going to defer answers on humidity until I think I
>understand its effects.
>
>The 14 gauge coil is wound on a tube made of 1/8th inch polyethylene sheet.
>The 16 gauge and the 22 gauge coils with the same resonant frequencies are
>wound on polyethylene barrels claimed from the local salvage yard. The other
>three coils are on PVC pipe. Ground consists of three 1 inch copper water
>lines spaced a few feet apart and buried a foot or two deep in some very
>hydrophilic clay. The lawn around the building is beautiful from all the
>water I put on it. Inside the building is basically a dirt floor, covered
>with a poly vapor barrier and about 4 inches of asphalt millings (no
>concrete, no rebar).
>
>Input impedance is measured two ways. One is the ratio of the rms voltage of
>the applied square wave to the rms of the sinusoidal current as measured by
>the voltage drop across a 0.02 ohm resistor, with the appropriate factor to
>correct for the fundamental component of a square wave. The other is to
>apply a sinusoidal voltage, (10 V rms) and measure the sinusoidal current
>with a Phillips PM 9355 current probe. The rms values are read from a HP
>54654D scope. I have a couple of 50 ohm dummy loads that I use for
calibration.
>
>Resonant frequency stays rock solid as humidity changes, so the capacitance
>of the coil is not changed by humidity.

That IS interesting!

>
>The input impedance is not a function of power below breakout. It acts just
>like the resistance of a linear RLC model ought to act. Above breakout,
>however, the coil changes from constant impedance to constant current. If I
>get a 3 inch plume at 300 V and 1 A input, then at 400 V input the plume is
>somewhat longer, but the input current is still 1 A. And no, the phase
>between voltage and current has not changed. I am still thinking about a
>good explanation for that. If anyone has a good explanation, I would
>appreciate hearing it.

If you have not already seen it, check the note I have below.  Perhaps it
will help add something to help this investigation.

http://hot-streamer-dot-com/TeslaCoils/MyCoils/CWCoil/CWImpedance.txt

It is one of my "to do's" to get my CW coil going again.  I'll have to get
to that...

Cheers,

	Terry


>
>Gary Johnson
>