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Re: Optimal toroid elevation
Jeff & Marco,
I just measured this, and it is definately large enough to be significant.
However, as Marco pointed out, if the toroids out of reach, then it's out of
reach (definately stick with the primary).
Here were the results of my test. The winding dimensions are 12.5" x 44.5",
18awg,
CS=21.6pF, Ls=87.6mH.
Ctop = 34" x 7.4" and calcs to 36.9pF (70.3kHz)
Test #1:
Toroid at top plane of secondary. Measured 86.2kHz.
Ctop then calcs to 17.2pF (53% error from original calc).
Test #2:
Toroid raised 22" up. Measured 75.7kHz.
Ctop then calcs to 28.2pF (23.5% error from original calc).
This test also held true for a 16" sphere. Of course, capacity's were different
but the results were the same (11pF gain in Ctop is significant). Jeff, did you
model this with E-Tesla5? I took E-Tesla5 to work today to run on a faster pc
and ran the setup mentioned above (true measured values were input into the
program). The program showed 76kHz for Test #1 (but this is not what I
measured). I need to rerun E-Tesla5 for Test #2 as I put in the wrong toroid
height. I have a feeling it is going to be near 73kHz. I'll post this result
tomorrow.
Take care,
Bart
Tesla List wrote:
>
> Original Poster: "Jeff W. Parisse" <jparisse-at-teslacoil-dot-com>
>
> Barton & Marco,
>
> > Marco, you may want to consider making the toroid movable up and down.
> Malcolm
> > posted in a reply this week about fine tuning the resonator simply by
> raising
> > or lowering the toroid. Makes a lot of sense to me.
>
> I modeled this with E-Tesla 5.1 and tested with real parts. The amount of
> Fsec
> shift due to different toroid heights is too small to be significant on a
> big coil
> (like the Model 9J).
>
> Jeff
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