Re: Grounding

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

Original poster: "Herbert Mehlhose by way of Terry Fritz <twftesla-at-qwest-dot-net>" <herbert.mehlhose-at-kdt.de>

Hi David,
I have made the same experience with my 500W coil when I once
forgot to connect the groud cable to the copper rod I use as ground.
With my Bonsai coil (secondary about 6 inches high and 1.2 inches
diameter), which runs at about 1MHz, I use a "capacitive coupled"
RF ground. I just put an aluminum plate, 10 by 15 inch, on the
floor and connect this to the base. This capacitively couples to
the ground. I found this effect, when observing corona effects from
a vice (the small ones to mount on a table) to the concrete floor on
the spots where it had contact to the floor.
For Bonsai, I need to use something connected to the secondary
base, if I leave it completely open, I get severe arcs from the secondary
base to the inner primary turn.
This shows, that an RF ground is needed in this case. The question
is, if such kind of capacitive ground would be good for bigger and
much lower frequency coils also (using larger metal plates).
Regards,
Herbert

You can see photos of the effect on my homepage,
http://home.wtal.de/herbs_teslapage/index.html



Tesla list wrote:

> Original poster: "David Boss by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<d.boss-at-Center7-dot-com>
>
> I have a couple of questions regarding grounding my coild.  I've read
> conflicting information about what and where to ground.  I understand that
> the secondary needs to be grounded to a seperate RF ground, by seperate I
> mean seperate from my house ground.  Where should I ground the nst case and
> safety gap?  Also, right now, my coil is producing 12" to 18" sparks and
> that is consistent weather or not I have the secondary connected to ground.
> I can have the secondary ground wire dangling in mid air and still get those
> sparks.  Makes me wonder if my ground does anything at all.  I'm going to
> pound a new rod into the ground and try that.  Any ideas?
> Thanks
> Dave