RE: Ground system for outside operation: Counterpoise?

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Dave Hartwick by way of Terry Fritz <twftesla-at-qwest-dot-net>" <ddhartwick-at-earthlink-dot-net>

Dan,
The larger question may be: What constitutes an adequate tesla coil ground,
an optimum tesla ground, and what are the characteristics of both? Then, for
the selected proposed physical ground arrangement--ground rod(s),
counterpoise, etc.--how must that ground be constructed to meet the
conditions demanded by the answer to the first question.

My tendency thus far has been to think that the lowest possible ground
impedance should be pursued. Therefore, as of this writing, my inclination
is to go with a more extensive ground rather than one that is modest. The
primary concern is safety, the a close second is performance. I want to sink
that sec base current as transparently as possible.

I DO agree with you on your one point: I do not think massive grounding
cables are necessary to connect the main RF ground to the secondary base. I
just don't think the base currents are that large. The base of my 4"
secondary (1500 turns #26) is typically only barely warm after extended
operation at the 3-5 kVA level. A more fundamental imperative may be
connecting the coil system as close as possible to the ground proper central
locus.
Dave






Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<dhmccauley-at-spacecatlighting-dot-com>


Why bother?  Just get a six foot grounding rod from your local Home Depot,
pound it into the ground, and attach a thick braided wire from it to your RF
ground on the tesla's secondary.  No need for fancy or heavy grounds.  Sure,
a lot of people on this group think you need some serious ground with
serious ribbon type grounding cable, but I operate my coils (currently up to
5kVA) with a simple set-up shown above.  Also, one coiler I know runs his
coils (up to 20kVA) using only a 12 AWG solid ground cable to a similar rod
and that guy is getting some serious output - no problems there.

Dan



> I'm wondering how well a counterpoise type ground would work as the main
RF
> ground for outside coil operation? I'm thinking of something very similar
to
> counterpoise ground used for amateur radio vertical antenna installations.
>
> Something like a counterpoise roughly 30' in dia with 30-50 radials buried
> just beneath the sod?
> The beauty of this for me is that I'm planning to install a ground plane
> vertical antenna for HF Ham operation in the same spot I'm thinking would
be
> a good site for  outside coil operation. Thus, the counterpoise may serve
> dual purposes.
>
> I've got a hunch that such a large counterpoise ground may be superior to
> multiple ground rods driven into the the ground for coil operation, though
I
> can't offer specific theory in the here and now. One notion I'm thinking
is
> that capacitive coupling to earth may be quite substantial.
> Dave H
> KA3STE
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