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Re: [TCML] Minimalistic Secondary Ground (was Grounding NSTs (Special Case?))



Hi Brandon,
     To be honest you don't need a ground or counterpoise at all, for
decent performance, but that energy has to go somewhere, and when you fry
half the electronics in your house because of RF noise, you'll wish
you had used a better ground...  Grounding doesn't in my experience effect
performance, only safety and emissions, the coil will in fact make a ground
where none is available, you cannot stop this; in fact I've run
coils with no ground at all and they work just fine until the transformer
smokes.  I always can tell by little sparks where they don't belong that I
have poor grounding, sometimes I ignore it, because I can pop in a new MOT
and be fine, and because I use line filtering which seems to do it's job,
but if you are getting an expensive transformer, I'd ground the living crap
out of it.  Just felt like chiming in, seems like something to consider.

Scott Bogard.


On Thu, May 2, 2013 at 3:42 PM, Brandon Hendershot <
brandonhendershot@xxxxxxxxx> wrote:

> Interesting.
> That could explain why my tiny 1"coil worked at all. I had the coil set up
> in my windowsill with a ground wire draped out the window to a broken 3"
> knife blade staked in the garden.
> Can anyone else share their thoughts on this? If a ground can be as 'poor'
> as that, I'd like to be able to get away with one or two 3'ish pieces of
> copper pipe staked in the ground around my coil. I don't think it would
> replace the counterpoise entirely, but if it would be plausible enough to
> supplement it, then I'm all for it.
>
> Brandon H.
>
> On May 1, 2013 9:01 PM, "Carl Noggle" <cn@xxxxx> wrote:
> >
> > Hey---
> >
> > Jim is right.  But it doesn't take much to make a good ground for the
> secondary.  We've used a screwdriver pounded into the dry desert soil and
> caliche with a drip set up to wet the area around the screwdriver, out on
> the end of 20 feet of wire.  Sounds pretty kludgey (sp?) but it worked
> fine. The secondary impedance is pretty high.  It's a good idea to have the
> counterpoise grounded, hopefully to the actual Earth, but to the green wire
> if you can't do that.
> >
> > ---Carl
> >
> >
> >
> >
> >
> > -----Original Message----- From: Jim Lux
> > Sent: Wednesday, May 01, 2013 3:08 PM
> > To: tesla@xxxxxxxxxx
> > Subject: Re: [TCML] Re: Grounding NSTs (Special Case?)
> >
> >
> > On 5/1/13 12:41 PM, Brandon Hendershot wrote:
> >>
> >> Something else I should mention, since I have no way of installing a
> real
> >> ground rod, I use a counterpoise as the RF ground in my system.
> >> Everything else in the coil is finished and ready to run, as soon as we
> >> resolve where to ground the NST's (if anywhere (I read that leaving the
> >> NSTs ungrounded causes permanent damage)) I can fire it up for the first
> >> time. Hope you guys can come to the rescue again ;)
> >>
> >
> > Cases of NST to electrical safety ground (aka green wire ground) in the
> > power cord.
> >
> > Bottom of secondary to counterpoise
> > Counterpoise to greenwire ground.
> >
> >
> > The idea here is that if you have a spark(s) that touches the primary
> > (at 15kV) AND the counterpoise (or NST case) at the same time, you don't
> > want anything you touch to be at 15kV.  Think of a spark as a temporary
> > low resistance connection.  So imagine what currents would flow or
> > voltages would be reached it you took a long cliplead and hooked it from
> > anything to anything. In particular, you want anything that *might* wind
> > up connected to the primary (several kV with a fair amount of current)
> > to be bonded to a good safety ground.
> >
> >
> > Two reasons to ground the cases..
> > 1) If the case shorts to the power line, you want the case at a safe
> > voltage to touch.
> > 2) The insulation on a NST is on the HV windings. A spark that bridges
> > HV to case (e.g. spark to primary and case at same time) will put 15 kV
> > on the case, and the insulation to the powerline might break down. If
> > you get a spark going between power line and case, that might be *very
> > exciting* (for a while)
> >
> >
> > Reason to ground the RF counterpoise
> >
> > 1) You might touch it.  If a spark touches counterpoise and primary at
> > the same time, and the counterpoise isn't connected to safety ground,
> > then the counterpoise is at several kV relative to you.
> >
> > You could, if you like, ground the RF counterpoise to the green-wire
> > ground using a big RF choke to block the RF, but to let line frequency
> > power work pass.
> >
> >
> >
> >
> >
> >> Thanks,
> >> Brandon H.
> >>
> >>
> >> On Tue, Apr 30, 2013 at 11:06 AM, Brandon Hendershot <
> >> brandonhendershot@xxxxxxxxx> wrote:
> >>
> >>> Hi All,
> >>>
> >>> I know this topic has been beaten like a dead horse, but I can't seem
> to
> >>> come to agreeance with the final verdicts in the archives.
> >>>
> >>> I know that the NSTs should NOT be grounded to safety/third prong
> ground
> >>> since that would inject tons of lovely RF into mains and since the
> operator
> >>> shouldn't come into contact with them for any reason during operation,
> >>> grounding them there wouldn't be any more beneficial than at RF ground.
> >>>
> >>> My only qualms with tying into RF ground is that any strikes to a
> target
> >>> or strike rail would connect the HV streamers to the core of the NSTs.
> >>> Nothing about that sounds particularly pleasing in my mind.
> >>>
> >>> So, I'm wondering if the NSTs need to be grounded at all. My NSTs are
> >>> situated out of reach of both the operator and any secondary streamers.
> >>> (While I feel this may also be an asinine assumption,) I don't see any
> need
> >>> for a ground in this situation.
> >>>
> >>> Hope someone can clear this up for me
> >>>
> >>> Thanks much,
> >>> Brandon H.
> >>>
> >>>
> >>> P.S, I'm thinking about following another list members advice and using
> >>> coaxial cable to connect the NSTs to the spark gap and connecting the
> >>> shielding of the coax to RF ground to protect the NST's secondaries
> from
> >>> any secondary strikes. My concern with this is similar to what I just
> >>> mentioned; any strikes to RF ground would be connected to the coax
> >>> shielding. I don't know that I trust the insulation in the coax (which
> has
> >>> gaps/cracks from what I can see) to stand off the voltage of the TCs
> >>> output, let alone the 7.5kV from the NSTs.
> >>>
> >
> >
> >
> > I wouldn't use coax for that..
> >
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