RE: RF grounding (fwd)

["Tesla list" <tesla@xxxxxxxxxx>]

---------- Forwarded message ----------
Date: Sat, 23 Jun 2007 11:51:28 +0100
From: Colin Dancer <colind@xxxxxxxxxxxxxx>
To: 'Tesla list' <tesla@xxxxxxxxxx>
Subject: RE: RF grounding (fwd)

I agree with the "there's always an RF ground somewhere" sentiment.  The
charge pumped up to the top of the coil has to come from somewhere, and if
there is no explicit ground connection you're going to end up with a very
large potential difference relative to ground across some stray capacitance
at the bottom of your coil.  I think the only exception to that would be a
perfectly balanced bipolar coil where the voltage difference ends up between
the two toploads, and the midpoint stays near ground voltage.

Practically though, even with a bipolar coil it still makes sense to ground
the mid point of the common secondary or magnifying driver, to deal with the
imbalance from a ground strikes or one coil having a stronger ground
coupling that the other.  I've accidentally run a largish magnifying bipolar
without a ground and while it initially seemed fine, when I got a strike
from one coil to an overhead light it got very "exciting" round the driver
coil area!

Colin.
-----Original Message-----
From: Tesla list [mailto:tesla@xxxxxxxxxx] 
Sent: 22 June 2007 13:34
To: tesla@xxxxxxxxxx
Subject: Re: RF grounding (fwd)


---------- Forwarded message ----------
Date: Fri, 22 Jun 2007 02:35:41 -0400
From: Dave Pierson <davep@xxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: RF grounding (fwd)


>RF Grounding.. hmm in my experience it is quite overrated.  Now don't 
>get me wrong, it definitely is necessary for optimal performance and 
>safety.  But in my work with tesla coils it hasn't been an overwhelming 
>difference.  I actually won my 8th grade science fair by comparing the 
>operation of tesla coils with and without RF grounds (connected at the 
>base of the secondary coil).  I will have to dig up the data, but in my 
>results the difference was relatively small.
     It would be interesting to see the data/methodology.

     I suggest there is 'always' an RF ground.  A good, visible, designed
     one, or, if not, an invisible, accidental one.  The voltage will rise
     at the base, until something punches thru (I note the references to 
     counterpoise sheets sparking round the edges....).  Another 
     'incidental' ground is one provided by stray capacity between
     windings of power transformers, etc...  This may, or may not,
     involve damage to the power transformer....  Stray capacity from
     connectig wires to 'real ground' can also be effective.

     It would involve substantial effort to design a 'system without 
     a ground'.

      best
       dwp