At the risk of further extending a non-AMPS discussion... John mentions
'rebar' below - I assume (yes, I know what ASSuME spells) this refers to the
rebar in his tower base. It is not a good idea to provide a path to ground
which goes THROUGH the concrete base. Lightning passing thru a tower base
can do strange things, like blow it up. Best to provide a good low impedance
path AROUND the base.
I'll go back to sleep. 73 all Bill N2BC
----- Original Message -----
From: John T. M. Lyles <jtml@lanl.gov>
To: <amps@contesting.com>
Sent: Friday, October 08, 1999 12:57 PM
Subject: [AMPS] cheap copper wire, and glass failure
>
> At 11:46 PM -0400 10/7/99, Amps Digest wrote:
To: <amps@contesting.com>
> >Date: Thu, 7 Oct 1999 19:33:44 EDT
> >From: K4ZDZ@aol.com
> >Subject: [AMPS] Ground rods?
> >
> >I live on sandy soil into which I can easily "water jet" scrapped copper
> >plumbing pipe. It would seem that using such a grounding method would be
> >superior to copper plated electrical ground rods since I don't need to go
> >down very far to hit water. As I understand it, the larger the surface
area
> >on a ground, the better! Anybody using this relatively cheap material for
> >grounding?
>
> I am using inexpensive 1/8 inch refrigerator tubing from the hardware
> store for a series of radial grounding conductors, from the base of
> my tower out in 5 directions, each about 25 feet long. This was much
> cheaper than using real ground wire, multistranded stuff. You can get
> scraps of this from heating/refregerant suppliers also.
>
> I use it to give my tower a reasonably low impedance to ground,
> besides the rebar and several standard copper clad ground rods at the
> base. Our soil is sandy and caliche, and dry in New Mexico. We have
> frequent lightning. So far, after 6 years, no problems. Anyway, it
> has nothing to do with needing an RF ground, as the yagi on top
> doesn't need that. Its for lightning currents.
>
>
>
> At 11:46 PM -0400 10/7/99, Amps Digest wrote:
> >I have a few QST's from 1954 with an Eimac advertisement on the page (the
> >pages were smaller then). They were demonstrating the advantages of
> >ceramic/glass power grid tubes (ie. 4cx150 ect) vs. glass envelope
triodes
> >(ie. 250TH etc). The picture shows the 250TL in a lump of molten glass in
an
> >oven while the newer style still retains it shape. I wish I had that
picture
> >as a poster. But it was an advertisement for Eimac.
> >Cheers,
> >Mike
> >W3SLK
>
>
> Only time I saw a glass suck in was an 833 triode, in a Gates AM
> radio TX. Lost grid bias in the class B modulator I think. The tube
> got real white, according to the chief engineer, followed by a pop
> and voila, the glass had a very nice hole sucked in (cannot remember
> if it was near the plate stud).
>
> K5PRO
> John
>
>
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>
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