A good lightning ground is a good RF ground, but the converse
isn't necessarily true.
Make sure the cold water pipe is continuously metal and doesn't
become PVC soemwhere. Also jumper all joints to prevent crud
buildup from increasing its resistance, the water meter likewise must
be jumpered. This last step may require a licensed person to do the
job, so check the municipal requirements. Although the cold water
pipe doesn't hit ground for a fair distance, it still carries the current
with minimal inpedance (to any other medium). You should consider
changing the #6 to at least #2; 2/0 would be better; and 1-1/2"-wide
(or wider) copper strap would be the best medium for that jumper.
73,
Bob AA0CY
----------
From: N6CW@aol.com[SMTP:N6CW@aol.com]
Sent: Wednesday, November 03, 1999 9:44 AM
To: towertalk@contesting.com
Subject: [TowerTalk] Another GROUNDING question.
I have been reading with great interest all the comments about grounding a
station. My question deals with grounding when it is not possible to have a
short ground from the rig to ground. My station is located on the second
floor of my house. My current ground system consists of a single 5x2 foot
copper sheet bolted on the back of my desk which all electronics are grounded
to, and conected to, a single 3 foot long #6 wire running through the floor
to a copper cold water pipe directly under the floor and in the garage
ceiling. This cold water pipe runs all over the house and probaly does not
get into the ground for 50 feet or so.
The good news is that I do not have any problems with RF getting into my
equipment. I do have some problems with RFI into phones and on the low bands
I do have some audio rectification in the TV set. And when I force my antenna
(CC X7) to work on 18 and 24 MHz I have probelms I dont have with it on the
resonant bands. Probably this has nothing to do with a poor ground BUT I FEEL
like this ground is not good enough.
So what do people do with an above ground level shack do to insure they have
the best ground possible? I realize I am talking about two different ground
situations here. An RF ground and a single point station ground. Since I dont
have RF getting into my equipment possibly this is an adequate ground for
this purpose. And since I dont have any way to shorten the length of the
ground cable/pipe then maybe I have all I can expect?
Comments appreciated.
Terry/N6CW
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