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Re: [TCML] Secondary self frequency



Jim -

How did you arrive at a topload capacitance of 24.5pF?

I think this is at least 20% higher than actually provided by 4.5 X 18" toroid.

Regards,
Herr Zapp
----- Original Message ----- From: "Jim Mora" <wavetuner@xxxxxxxxx>
To: "'Tesla Coil Mailing List'" <tesla@xxxxxxxxxx>
Sent: Friday, July 03, 2009 4:18 PM
Subject: RE: [TCML] Secondary self frequency


Hi Andrew,

First impression is with a top load that size something sure isn't right.
Let me run Classic TC:
Turns=716
32.6/inch
Ratio 5.5 (lower yet)
DC ohms=12
XL=18763
K=.8472
Self C=8.61
Fo=~583Khz (coil only)
Top Load= 24.5pf
LOADED Fo= ~346Khz

You are measuring it with the top load attached, yes? Perhaps you are
looking at a harmonic? It really should be near 350Khz loaded.

Regards,
Jim Mora

-----Original Message-----
From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On Behalf
Of Andrew Robinson
Sent: Thursday, July 02, 2009 9:45 PM
To: tesla@xxxxxxxxxx
Subject: [TCML] Secondary self frequency

Does this sound strange to anyone. A 4" OD x 22" (windings) secondary
using 22 gauge wire with a 4.5" x 18" spun alum toroid having a self res
freq of around 515kHz? I ran the tests in the lab today and thats what
im getting. For some reason though, I had reason to believe it was going
to be much lower. I'm gonna resubmit this email next Thursday when I get
a chance to get back in the lab and im gonna take a video of myself
taking the measurements. Maybe im just doing something wrong. I just
threw this website (http://www.teslamad.com) together just now for the
purpose of this email. Please go check out the pics to get a better idea
of whats going on. This coil isnt finished yet. You may have noticed the
quickie ghetto gap and, my old rotary disc from an old BIG coil on my
new RSG mount. In addition to my freq question above, I also have
another... im not getting anywhere near what I expected to, performance
wise with this coil. 2 - 6in max off a break out point. By the way, that
toroid i just got in the mail today from OW landergren... Most amazing
craftsmanship I have ever seen and extremely robust and heavy duty! Took
it to the machine shop today to center tap it and it was "over" a 1/4"
thick of aluminum in the center. Just google them.

I know everyone needs numbers to even begin to help me and I figure I'll
resubmit a detailed report of my findings to the list like I said, next
thursday. Hopefully then with plenty of data, pictures, video, etc...
someone out there will say that catchy phrase "Well theres yer problem!"
Thanks everyone! Hope you all enjoyed my new coil pics... even if it
doesnt work hahahaha.

Regards,
Andrew Robinson

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