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Re: Primary Q's and Spark Gaps
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To: tesla-at-grendel.objinc-dot-com
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Subject: Re: Primary Q's and Spark Gaps
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From: mrbarton-at-ix-dot-netcom-dot-com (Mark Barton)
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Date: Sat, 2 Dec 1995 01:29:55 -0800
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>Received: from ix2.ix-dot-netcom-dot-com (ix2.ix-dot-netcom-dot-com [199.182.120.1]) by uucp-1.csn-dot-net (8.6.12/8.6.12) with ESMTP id CAA19124 for <tesla-at-grendel.objinc-dot-com>; Sat, 2 Dec 1995 02:25:35 -0700
You wrote:
>
>O.K., here are some real figures based on measurement of my coil.
>Stats : Lp = 11.8uH (including a couple of feet of stray wiring)
> Cp = 102nF (extended foil)
> Static Gap firing voltage = 7.5kV
>
>Measured Q (using sig gen and scope - i.e. no spark gap) about 50
> => Rp about 0.22 Ohms
>
>Measured Q (operational using ping test and decrement calc.) =11.5
> => Rtot = 0.95 Ohms
>
> => Rgap about 0.73 Ohms!! (accounts for 3/4 of all losses)
>
I guess this means your Fo ~= 150KHz. That 0.1uF cap seems a bit large
for that freq. Tesla ran the Colorado lab at 80-100KHz with 0.12uF.
You know what to do now. Switch to 0.015uF, about 1/10 what you are
using now and use a rotary gap. The reactance of the primary
components will be 80ohms instead of 10ohms. Your Q should go way up,
tuning get tighter, and (hopefully) sparks get longer.
Zap,
Mark