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Re: [TCML] Using tree as RF ground



On 9/24/12 9:40 AM, Dave Leddon wrote:
Hi all,
I have recently moved to a new house which, as near as I can tell, sits
on top of a granite hill.  I've tried pounding in an eight-foot ground
rod at various locations only to hit impenetrable soil at a depth of
about one to two feet.  The property has numerous large pine trees with
diameters ranging up to 4 feet and it occurred to me that such a tree
might make a great RF ground by driving a spike into the trunk near the
base.  Does anybody have experience using trees for grounding Tesla
Coils and is there any likelihood that the current could damage the tree?
Dave





How big is your coil?

You're not putting up a vertical radio transmitting antenna, so a "earth" ground isn't all that important. What *is* important is that whatever is under the coil is connected to the bottom of the secondary. If your soil is highly conductive, then driving a stake into works ok, but there are much better ways to provide the RF return for your coil.

I'd look at getting some chicken wire to roll out and lay on the ground. The capacitive coupling from the mesh to the ground is pretty good, and, in any case, the mesh itself works as a better RF return than the soil. (unless you are in the proverbial hypersaline marshland.. for all we know, you're on the shores of bonny Salton Sea.. although a big tree would be unusual there)

The usual rule of thumb is that your counterpoise/ground mat should have a radius equal to the height of the top of your coil above it. So if your coil stands 4 feet high, you want about 4 foot radius. What I've done is stick the chicken wire to some cheap carpet (it makes it easier to roll up, and it provides a visual cue of "where NOT to stand"..)

I wouldn't hook up to the tree, unless you want to kill it.


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