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Re: NST Ground, RF ground, the whole bit...
Original poster: "Terry Fritz" <twftesla-at-qwest-dot-net>
Hopefully, my other post tonight will help a bit. I separate my coil's
grounds at the AC wiring to the coil. My controller and power switches
(stuff "I" touch) are all connected to the regular AC line ground. High
inductance, but reliable for AC faults. I only carry hot and neutral AC
wires for the motor and NST to the coils. No ground. At the coil, all the
grounds go to the RF ground. Everything at the coil side can take a
streamer hit so it is all RF grounded. I do have MOVs all over the place
to control the motor, filters, and NST case grounds from never going about
200 volts in relation to each other.
I do note that the controller has some RF on it. I have a big RF ground
stud on it but I never seem to use it. When the coil is running full
blast, I can get a little RF bite off the controller. It seems that the
controller should have a good "AC" ground and a good "RF" ground. I bet
there should also be a good primary base RF ground and another AC/RF ground
at the coil side. So we get into a bunch of grounds (like four)...
Perhaps if everything had only one "darn good" single ground point all
would be well. the problem is that the AC hot wire seems to have it's own
idea about where it is referenced and with how much inductance to the
Since my test stuff is all AC line grounded it gets even hard to measure
such things. Although, for an obnoxious sum of money, my Tek 3012 can be
run off a battery pack ignoring the threats about having it floating in
relation to "ground" ;-))...
I am wondering if a big silver plated sheet of copper under my coil would
be the only really good ground (sounds like a shorted turn coupled to the
primary coil...). It seems like other grounds have so many problems.
Maybe careful measurement of the inductances and "controlling" the RF on
the ground voltages is the key...
Since I run coils here in my little area with hot-streamer and the big
computer as well as everything else near by, grounding is always a big
issue here. I have stopped a number of things midstream here as it
appeared that the RF noise was getting out of control...
At 10:33 PM 7/15/2001 -0400, you wrote:
>Jonathan and all,
>I use a bank of three NSTs. The ground lugs are tied together and connected
>to the ground in Terry's NST filter. They are not connected to the AC power
>Nor do I use an RF ground with the bipolar coil.
>Below I have pasted a few of the comments posted on this subject. I am
>Big news, that is. But I think a careful reading of the comments may
>of the inconsistencies. I have interspersed a few of my comments and separated
>the individual postings with the dashed line. I hope this can be followed.
>Terry, the filter works fine and the diagram is clear enuff--almost. There is
>confusion because you do
>not say that when the filter is used the NSTs should NOT be connected to the
>AC power line ground. That then would clear up the ambiguity altho the theory
>may still be debatable.