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>

dwp,
Interesting comments. 30-50 radials may be excessive. I'll have to consult
my ARRL antenna handbook on that one since it's been awhile since I've
considered such designs. A dozen may be appropriate.

A properly designed counterpoise for a Ham antenna may be overkill for Tesla
duty. I don't see a problem with this discontinuity.

Of course, the arrangement will be such that the Ham antenna will be fully
disconnected prior to Coil connection and operation. Obviously! I've already
fried the front-end of the receiver section of my Yeasu FT-102 with my
coils. Terrible sensitive FETs, IIRC. I think my 80 meter dipole was
connected to the 102 and operation at 4-5 kVa was too much for it. About a
week ago, I fried the front end on my Radio Shack DX-390 shortwave radio. It
was not attached to an external antenna and was some distance away from the
coil. I actually have 2 of these radios and the same thing happened some
years ago on the other 390. Not a prob to replace the FETs, but now I put
all potentially sensitive devices in the upstairs bathtub for coil firing
sessions...Hasn't failed me yet....

You said: "Ham freqs are higher, and purposes modestly different:	what is
needed for ham work may not be required for	Tesla system."
Of course, but once again--that which is sufficient for 1/4 HF vertical Ham
installations will probably be more than adequate for coil operation--your
strays warning (and otherwise any coupling twixt coil and ham equipment
caveats) is assiduously noted! Thanks for your input, as always.
Dave H









Dave H




Original poster: "davep by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<davep-at-quik-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.


	Have any tests been run with a BETTER ground?


	The necessary ground complexity depends on local soil
  	conditions.  What works in one place may or may not
	in another.

	That Said:
	A full on counterpoise, as outlined below, while
	admirable maybe overkill, for may applications...


>>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.
	It would work nicely.  Likely to be 'overkill'.


>>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.
	IF the counterpoise is going in anyway, i would use it

	for both WITH DUE CAUTION that strays from the
	Tesla system not find their way to the Ham gear.


>>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,

	It will be.  Its not clear that the advantage
	will be significant, possibly not worth such
	elaboration solely for coiling.  IF the counterpoise
	exists ANYWAY (or will) seems reasonable to use it.
	(might compare both sorts of ground...)

	Ham freqs are higher, and purposes modestly different:
	what is needed for ham work may not be required for
	Tesla system.

>> 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.

	best
	dwp

...the net of a million lies...
	Vernor Vinge
There are Many Web Sites which Say Many Things.
	-me