[RFI] Ground Rod Replacement

tduffy tduffy <tduffy@sygnet.com>
Sun, 03 May 1998 00:46:53 -0400

>Reply-To: ka5s@saber.net X-Mailer: Mozilla

     I'll jump in here because some of this is a misunderstanding
(IMHO!) of what a ground is, at RF.

 With a field strength meter I determined the ground strap and rod were
both radiating RF.

Yes. RF currents flowing along any wire will radiate. This isnormal and
often not a problem.

 I ask all this because I get complaints now when running 60 watts
output from some neighbors

and one day I would like to run an amplifier with about 500 watts or so.
I understand that the RFI

is coming from the  antennas, Force 12 C4 and home brew wire antennas
off the tower, and not

the rig in the basement but I want the station to be as RF clean as

So I know I will need a ground rod at the rig/amplifier which I  do not
have now. Emphasis

added. You do NOT need a ground rod at the rig. What you need, is a
"ground," a common point

where RF currents flowing on all equipment connect to each other and
prevent the system from

becoming a radiating structure itself. This will keep RF off your
microphone, key, phone patch and

so on, but does NOT require a ground rod anywhere near the equipment.
The ground rod is only

for safety, NOT for grounding RF. I will add that a good RF ground will
also absorb RF that might

otherwise flow into your power wires, a very important effect. If you
want to insure equipment is at

the same RF potential, a good bet is to cover a floor and wall with a
metal sheet and the connect all

the gear grounds and your safety ground  to one point on that sheet. The
purpose of the sheet is

to provide a non-resonant, mainly capacitive sink for RF. If it works,
it will also keep RF from the

outside of the coax, another good effect. My elmer suggested to run the
station without the ground

> rod at the rig and use the braid of the coax, that is my feedline as
my only ground which is

grounded at the base of the tower approx 45ft down  the feedline. This
sounds like a good way to

make the RF all follow the same path. However, you have not dealt with a
station ground, and for

that, I suggest a large metal plate as above. If you get all the RF to
radiate from the antenna, and less

from the rig, the feed line and the power wires, your neighbor's
problems MIGHT go away. A

couple of rolls of chicken wire under the carpet could be the answer you
are looking for. Of course,

if he's getting RF that you radiate from the antenna, then it won't
help. that is a subject for another

message thread, I think. And for God's sake, don't drill a hole in the
basement! People spend lots of

money sealing those things.

Cheers, Cortland, KA5S

Submissions:              rfi@contesting.com
Administrative requests:  rfi-REQUEST@contesting.com
WWW:                      http://www.contesting.com/rfi-faq.html
Questions:                owner-rfi@contesting.com