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Re: grounds, was RE: capacitance of homemade caps
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- Subject: Re: grounds, was RE: capacitance of homemade caps
- From: "Tesla list" <tesla@xxxxxxxxxx>
- Date: Sat, 09 Apr 2005 12:33:07 -0600
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Original poster: Karl Lindheimer <karl@xxxxxxxxxxxxxxx>
A counterpoise ground consists of material like chicken wire or metallic
window screen. It should be sized so that it's diameter is at least as
tall as your secondary. Larger is better. It is placed directly under
your coil, and the bottom turn of the secondary is connected to it. It
works by capacitively coupling to the underlaying material and providing
your secondary with a return path.
It sounds as if your current ground system is more than adequate. You
could try your coil with the ground rod only, then add a counterpoise and
compare performance. Another experiment would be to ground your
counterpoise screen to the ground rod, and compare as well.
Basically, a counterpoise ground system is used when it would not be
practical (or possible) to connect your coil to an earth ground. Coils
running on the third floor of a large building, would be perfect candidates
On Apr 8, 2005, at 11:06 PM, Tesla list <pbbrodie@xxxxxxxxxxxxx> wrote:
So, after reading your post, I'm a little confused about grounding my
small coil, 15 kV, 30 mA NST, 4" diameter by 21" tall secondary. I have
driven an 8' by .5" ground rod approximately 10' from where I plan to run
the coil, the front part of my garage on a concrete slab. The bottom of
the secondary is connected to this ground rod by 10' of two 15' long auto
jumper cables, four conductors of 4 AWG.
I asked this question once before with no responses. Should I use a
counterpoise ground? Can someone please explain how a counterpoise works?
Is a counterpoise an either or proposition or should I use both? Thanks. I
really appreciate any help.