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Re: grounding problems


From: 	Geoffrey Schecht[SMTP:geoffs-at-onr-dot-com]
Sent: 	Friday, September 19, 1997 12:06 AM
To: 	tesla-at-poodle.pupman-dot-com
Subject: 	Re: grounding problems


<Snip>
> > >
> > > Mad,
> > >
> > > Because of the use of plastic plumbing in many areas, your ground may
> > > not really be a ground. To determine if it is, take an ohmmeter and
> > > carefully measure the resistance between the ground connection (the
> > > third prong on a nearby AC outlet) and your cold water copper pipe
> > > ground. If you get good continuity (say 20 ohms or less), then you
> > > should be OK. Another alternative ground is the ironwork of the
building
> > > you're in if it happens to be an iron-concrete type structure, or as
a
> > > last resort, the AC ground itself if you have a small coil.
> > >
> > > -- Bert --
> > >
> > 
> > Hello All:
> > 
> > I've used soldered-together sections of "chicken wire" as a form of
radial
> > system (counterpoise) for my vertical ham antennas from time to time.
It
> > works fairly well in that application and is quite cheap. Any
> > opinions/experience from other list members about how this might work
with
> > a TC that needs a grounding system? It's an RF ground, though, not a
safety
> > (green-wire, in the US) ground.
> > 
> > Geoff (NQ7A)
> 
> Geoff,
> 
> Good point, Geoff. I considered suggesting a counterpoise, but it wasn't
> clear if Mad Coiler's apartment was wood/frame construction or steel
> beam/concrete. A counterpoise could work very well, especially if Mad
> Coiler lived on the first floor. Since Mad Coiler lives on the second
> floor, an elevated counterpoise would still work very well if he was in
> a steel/concrete building, and less so if he lived in a wood/frame
> environment.  
> 
> -- Bert --
> 
Hi Bert:

I suppose that any counterpoise is better than nothing but at the
frequencies a TC operates at, it's hard to imagine a 1/4 wave radial
grounding system being installed in a 2nd story apartment! I've read about
tuned radial systems for limited-space applications....I wonder if
something like that would be applicable to a small counterpoise system like
a "chickenwire carpet"? Tuned radials probably only make sense when you're
dealing with a coherent oscillator due to their relatively high Q (and a
coherent oscillator is something that a TC is _far_ from :) ).

A chicken wire counterpoise should at least provide an efficiency-enhancing
current node point for the cold end of the TC and it gives the arcs
something to strike other than the TV, sofa, cat, etc.

Geoff