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On 3/25/15 7:52 AM, Timothy Gilmore wrote:
The secondary bottom will go to electrical house ground.
Uhh.. not necessarily. Yes, it should eventually connect to electrical
safety ground (aka green wire or third prong ground), but you do not
want to use that as your only RF ground.
Even a small coil (especially a small coil, which will have a higher
operating frequency) should have a counterpoise or good ground *plane*
under it.
If a larger sized
coil is made - it will go to both electrical ground and RF ground (made
with a 4-8 copper pipe in the earth or large sections of Hardware
cloth/Chicken wire directly placed under the tesla coil - ensuring its
considerably larger than the top load).
I'm not a big fan of ground rods. They're not a particularly good
connection to "ground".
I am a fan of a screen counterpoise. Hardware cloth, chicken wire,
aviary netting, reinforcing mesh, sheets of aluminum foil, etc. Radius
of counterpoise should be comparable to the height of the topload above
the mesh.
So if you have a table top coil that's 2'-3' tall, you'd have something
like a 4 foot diameter or square conductive plane under the coil on the
table top.
If you have a 5 foot secondary on top of a 3 foot high equipment cabinet
with your rotary gap, etc., so the topload is 8-9 feet high, then you
want a 20 foot diameter counterpoise.
another alternative is a fence or cage around the coil, connected to the
bottom of the secondary.
The secondary top "should" go to a top load of either a sphere for smaller
distributed multiple sparks or to a donut shaped toroid which provides some
additional minimal capacitance and will allow build up of sparks to be
longer in length.
Tim
On Wed, Mar 25, 2015 at 8:01 AM, Doug <doug11642@xxxxxxxxxxx> wrote:
Gentlemen; I am building my first Tesla Coin rated at around 250.000 volts
and would like some advice on routing and connecting the secondary coil
wires top and bottom.
Thank you for any help you can provide.
Doug Johnson
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