[Prev][Next][Index][Thread]
Re: grounding problems
From: Mad Coiler[SMTP:tesla_coiler-at-hotmail-dot-com]
Sent: Saturday, September 20, 1997 4:26 PM
To: tesla-at-pupman-dot-com
Subject: 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
>
>
>
>
I do not believe my aprtment bldng is steel, but I might ask the Office.
If someone thinks a counterpoise would work in my case please decribe to
me what a counterpoise is and how to build it. Fell free to contact me
at tesla_coiler-at-hotmail-dot-com or ts5815-at-devrycols.edu
Mad Coiler