Re: Grounding. Oh joy.
Subject: Re: Grounding. Oh joy.
From: Terry Fritz <twftesla-at-uswest-dot-net>
Date: Fri, 23 Jul 1999 17:35:51 -0600
At 12:36 PM 7/23/99 -0700, you wrote:
>1. I have heard that it can be a good idea to epoxy a flat piece of copper
>to the base of a secondary to serve as a ground terminal. Would a piece of
>aluminum tape work also?
I have not heard this. Be carful not to make a shorted turn that would
look like a short circuit and drain power from the primary to secondary
coupling system. I have heard of using a thick copper strap at the base of
the secondary as a nice connection point but those are never complete
loops. Apparently, top terminals that form a solid loop are far enough
away from the fields not to have much problem with the shorted turn effect.
I would skip this copper plate thing. Sounds like a load of trouble...
>2. I have heard that I can use something vaguely like chicken wire called RF
>Grounding Strap to ground the secondary. Where do I get this? THe local
>hardware store? Home Depot? Or the ends of the Earth?
Chicken wire may have some use for building a Faraday cage to contain the
RF noise, but as a grounding wire, it would be terrible. Thick copper
strap, Litz wire, the braid from a coax cable (not super good) all work
well. However I just use 14 gauge wire and it seems to work fine for me...
I just got a roll of Litz so I'll probably change to that now.
Perhaps they meant to put the chicken wire on the floor as a ground plane
for the coil?
>3. I have heard that I should not ground the secondary to a water pipe. Why?
>I'd like to know, because I don't feel like diging a six-foot-hole when
>there is an iron well in the backyard that goes a whole lot deeper than six
As long as you are sure the water pipe goes straight out into the ground
from where you connect to, it should be an excellent ground. Hot water
pipes are usually insulated at the water heater to prevent electrolysis
effects from eating up the heater so hot water pipes are very bad. There
is a chance that your house wiring is grounded to the cold water pipe too
(mine is) so RF could get into the AC. However, I don't seem to have a
problem with it. The iron well would work fine too. Any conductor that is
in good contact with the round should do fine. The current is low, it is
at RF frequencies, and the voltage is high so grounding a TC is fairly easy
compared to some things. Any lighting or standard ground rod should do
fine. If you system is really high power you may want more...
>4. I have heard of coils "failing" when they are not properly grounded. Is
>this failing as in "not doing anything," or as in "blowing up beyond all
>hope of repair and forcing me to wind another three pounds of magnet wire on
>another ten dollar PVC pipe?"
It the secondary were not grounded, the same high voltage at the top of the
coil could appear at the loose end on the bottom. This could cause a power
arc from the primary to the secondary. If a streamer were to hit a
grounded object at this time the damage could be great. It could also
present a fairly dangerous electrical path. All this could occur if there
were NO ground. However, even a "poor" ground should prevent this. A poor
ground typically diminishes the output power and adds to RF noise to the TV
>Thanks for advice.
>Who has heard