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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