On Aug 3, 1:52*pm, "KJ4NTS" wrote:
On *3-Aug-2009, Michael Coslo wrote:
http://tinyurl.com/ns7jjd
Is a nice station grounding pdf from Polyphasor. Sorry for the tinyurl,
the original url is a mile long.
Everyone should have a copy, and the writer should get an award for his
or her clarity.
That's a good article, but it is focused on grounding for lightning protection. *I am interested in
that, but I am also interested in having an effective RF ground.
I've been able to get a total of 16 feet of ground rod down in the form of 4 four-foot rods, but I
have a 50 foot run from my office to the ground rods, and I'm concerned about RF impedance in that
connection.
I ran attic mounted antennas for a period time and here is my
experience. First, don't bother running any ground to the antenna,
especially at 50 feet long. It will act more like a radiating element
than a ground, then you will get to meet Mr. RFI as you will discover
all types items your RF can affect. Since your antennas are in the
attic, static and lightning should not be an issue, unless you or a
close neighbor takes a direct hit.
I keep everything disconnected unless I am operating, it is the only
way I know of to keep lightning from destroying your station. If you
or your neighbor takes a direct hit, there is not much you can do to
prevent damage, unless you have everything disconnected, AC/Ground/
Antennas/Control lines/etc.
Second, your four foot ground rods are about useless for both RF and
DC ground. Minimal is eight feet. My current station has 7 eight foot
ground rods, spaced no more than eight feet apart, and all grounds are
tied together, including the panel box ground. This is done to make
sure all grounds are at the same potential.
You did not describe your station so the information someone can
provide is limited. In my case, my station was on the second floor,
so instead of having a ground, I used a tunable counterpoise system as
my RF ground. MFJ makes the tune boxes, and Ten-Tec may still sell
them in kit from too. I used the one from Ten-Tec, it worked well at
my location, but it still was a compromise, when compared to having a
true ground system and outside antennas.
73