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RE: primary tuning

Original poster: "Mark Dunn" <mdunn@xxxxxxxxxxxx>


David:

I'm no expert, but I have a spreadsheet that I developed to do my calcs.
I plugged in your data and here is what I get:

119 mH Sec L
21.2 pF Sec C
61 pF Toroid C
Secondary Xc = Xl = 38,161 Ohms
51 kHz Resonant Frequency

For a .2 uF(200nF) tank cap you need:
7.9 turns on your Primary gives 48 uH(Note my Primary calc is rough)
Primary Xc = Xl = 15.5 Ohms
51 kHz Resonant Frequency

My formulas typically predict a higher primary inductance than actual
and thus less primary turns than required so your (10) turns makes sense
to me.

I can send you the spreadsheet if you want to play around with values.

Mark



-----Original Message-----
From: Tesla list [mailto:tesla@xxxxxxxxxx]
Sent: Monday, April 18, 2005 10:02 PM
To: tesla@xxxxxxxxxx
Subject: primary tuning


Original poster: "David Rieben" <drieben@xxxxxxxxxxxxxxx>

Hi all,

I need to get some input from
you guys on the tap point of your primary coil vs. the size and # of
turns of your secondary coils and the physical size of your toroids. I
ran the specs of mine through Bart Anderson's Java TC program and after
it "crunched the numbers" it stated that my primary should tune in at
only a little over 4 primary turns. That's assumng my 12x56 toroid for
the top hat and .2 uFd for the primary tank capacitance. However, I have
to tap up to about 10 primary turns before i start to get any output off
of my massive toroid. I have about 1260 turns of #19 wire on 12.75" x
48.5"  of a gray PVC duct pipe for the secondary coil and have a spiral
of 12 turns of 5/8" OD copper tubing for the primary w/ ~ 1/2" turn/turn
spacing and the innermost turn at about 15" in dimeter and the outermost
(12th) turn at about 40" in diameter. I'm starting to think that I may
have to either add to my primary coil or go to an even higher pri- mary
capacitance. I am using a 14.4 kV, 15 kVA pole pig for the primary power
source and of course, I was tuning in at a much reduced voltage input to
the pig via a variac.

Thanks,
David