[TowerTalk] Ground resistance
Stone, Gary R.
Gary.Stone at va.gov
Thu Jun 8 16:17:49 EDT 2006
Here is the info I sent to Roger (with a drawing - but I don't think I
can include attachments to TT?)
I have two LMR-400 lines coming into the shack from the tower. I also
have 2 control lines with one being the rotator control (I have an
I.C.E. MOV device mounted on those 8 wires at the base of the tower) and
the other is another 8 line control line for my remote antenna switch
(Rat Pak). I don't believe there is a ground connection on the rat pak
switch inside the shack.
OK, one of the LMR400 lines is coming directly from the (single) dual
antenna for VHF/UHF at about 60 feet on the tower. It is routed to a two
position switch to control it going to either my Icom 746 (2 meter
input) or my Yaesu dual bander VHF/UHF radio.
The other LMR 400 is from the rat pak switch relays at the base of the
tower (which I understand has MOV protection) and it goes to a 5
positive antenna switch. That switch sends the HF to either of two
radios - the IC 746 or and Icom 703.
Now, I have a single grounding bar mounted on the wall of the shack and
a single wire from that goes to an 8 foot ground rod right outside the
shack window (not connected to the 12 or so grounds rods installed
around the tower base). Then I have a 'bus line' or whatever it is
called that runs behind the main portion of the shack. I have anything
that has a ground line connected to the line and then a single wire
going to the grounding bar.
I had planned to put the new coax protectors on the tower side of the HF
switch and the VHF/UHF switch respectively and then to another ground.
Any ideas appreciated very much?
I could put a cooper plate panel to the right side of the shack and
mount the coax protectors there and then run a single heavy wire from
that panel to the ground bar on the wall and also a heavy wire to the
already installed ground rod outside the shack? Would that be the best?
Again, thanks for your help.
From: towertalk-bounces at contesting.com
[mailto:towertalk-bounces at contesting.com] On Behalf Of Roger D Johnson
Sent: Thursday, June 08, 2006 3:09 PM
To: Jim Brown
Cc: Tower Talk List
Subject: Re: [TowerTalk] Ground resistance
Jim Brown wrote:
> On Thu, 08 Jun 2006 14:06:27 -0400, Roger D Johnson wrote:
>> 'm trying
>> to keep it relatively simple for Gary until he comes up to speed.
> Simplicity is good only if it is CORRECT. Simplicity that is wrong
> leads to (or reinforces) the myriad of misconceptions about the
> of earth connections. We've all seen posts here and elsewhere from
> pursuing that perfect earth connection that is going to make their
> antenna work better, or that they need a different earth connection
> power and their ham station. Both are wrong.
One of the problems is that "ground" means different things to different
people. It's rather like using Ohms to describe resistance, reactance
and impedance! Proper lightning protection involves more than just
pounding in a few ground rods. As I stated, my objective was to steer
Gary to some good info on the subject and not get bogged down splitting
hairs or arguing terminology. After he has gone to some of the
recommended sites and has a good idea of what is involved, I'm sure he
will have more detailed questions that we can answer with detailed
Remember the USS Liberty (AGTR-5)
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