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RE: Mini coil earth?



Original poster: Thomas <tom-at-pwrcom-dot-com.au> 

The very first coil I ever built used the building earth, was poorly tuned,
and gave off about 4" sparks (from an 880VA NST).

It destroyed a number of 10 base T network cards, as well as a Commander
phone system.

Fortunately my boss (who owned the smoking mess) helped build and operate
the coil.

So you can see why I was a bit hesitant to use the building earth this time.

BTW, the same power supply now gives ~39" streamers from my latest coil.

I use a good RF earth and I use a custom 40kA version of this filter on the
mains (I'm a design engineer for this co.):

http://www.novaris-dot-com.au/products/powerline/specs/pp10-2.html


This saved me once when I forgot to hook up the RF earth. The coil seemed to
work fine except for arcs jumping between turns of the primary.

My home theatre set up and PC survived too, my heart nearly didn't.

I've never bothered using a filter to protect the NST, and its had heaps of
abuse.

So I guess with the mains filter and a counterpoise (as proposed by Jim) I
should be ok to run a 180VA mini coil using the building earth.


 > Original poster: dhmccauley-at-spacecatlighting-dot-com
 >
 > No problem.  I run my minicoil using both a 4kV/32mA and a
 > 6kV/30mA NST
 > using only the house ground (3 prong of plug) for my RF ground with no
 > problems.
 > Gary Laus also does this using his 4kV/32mA minicoil.  Any coil under
 > 200-300 watts should be fine using house ground as your RF
 > ground. Above
 > that, and you should start
 > looking at a dedicated ground.
 >
 > Also, I don't use any type of filtering or surge filters.  In
 > fact, I run my
 > minicoil at work for deskside demonstrations probably every
 > few days when
 > new people visit or customers
 > come in etc.  And the outlet I use is connected to both my PC
 > and UNIX work
 > computers.  No problems whatsoever, at least not yet!
 >
 > The Captain