Agreed!
There is a new version of the Motorola R56 manual. Make sure you find it.
The older version (early 2000s) is good too. The new one is twice the size.
Thanks
73
Jim W7RY (Motorola Solutions)
-----Original Message-----
From: Bob Matthews
Sent: Wednesday, May 30, 2018 2:38 PM
To: Fred Keen
Cc: towertalk@contesting.com ; Bob Shohet, KQ2M
Subject: Re: [TowerTalk] Replacing station ground
Hi Bob
You may want to download the Motorola R56 pdf file online. Also QRZ dot com
has a 3 part forum on station grounding hosted by a PE who installs and
inspects cell tower sites. Both are a very interesting and informative read.
Whenever I pass coax or hardline through box enclosures or panels, I find
1/2” - 1” J-cord connectors work great in keeping out the insects and
moisture. Just pick the size that suits your feedline diameter. They are
available in standard and Liqui-tite. Home Depot and any electrical supply
house usually stock them.
Usually #4 solid copper wire is adequate for grounding.
Hope this helps you out some.
Bob Matthews KT3RR
Sent from my iPhone
On May 30, 2018, at 15:07, Fred Keen via TowerTalk
<towertalk@contesting.com> wrote:
Hi Bob,
I like the MFJ 4603 thru window approach. If your window is not wide or
tall enough to get all the connections with it, you might consider making
one with plexiglass,
see one here: Building the shack - window feed thru panel done!
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Building the shack - window feed thru panel done!
Plexiglass window feedthru panel
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Be sure to post some pictures of your antenna farm.
Fred KC5YN
On Wednesday, May 30, 2018, 1:04:14 PM CDT, Bob Shohet, KQ2M
<kq2m@kq2m.com> wrote:
I am planning to completely revamp my station placement and station ground
and have been thinking about and researching different ways of doing this
for several years. I have also studied what was done at many stations at
which I have operated, but that only confuses the issue more as each house
and terrain is different and every station owner has their own way of
doing things. :-) I have also spend considerable time reading the
Polyphaser material and W8JI and K9YC’s websites. So I have several
questions and would appreciate your help.
First, here is what I am planning to do:
Install a metal Hoffman box at each tower and then ground the coaxial
cables, rotator cables and control cables at the box (the control cables
are already grounded to the tower) with a #2 Copper wire grounded
connecting to multiple short ground rods (because of the ledge right
underneath) and the tower.
Then I will run all the cables to a larger metal Hoffman box grounded just
outside the shack and a few feet from the utility ground, telco and cable
grounds. Then, in a trench ~ 1’ deep around two sides of the house to
form a perimeter ground, I plan to connect a series of 8’ copper clad
ground rods culminating with a connection to the Hoffman box outside the
shack and to the utility, telco and cable grounds, so that I will have a
single-point-ground connected to a perimeter ground in the trench. I will
then fill in the trench when done.
Questions:
1) How far away should the trench be from the house foundation? 6”? A
foot? more? I know that there should be some separation but do not know
how far is best. I live in Western CT near the NY border where we get a
lot of ice and snow and it has gotten down to –20 F; so frost heaves are
always an issue.
2) I assume that the best and safest way to connect all the grounds would
be to use #2 copper wire running between the Hoffman box and the
utility/telco and cable grounds. Since these ground wires are all
connected ABOVE ground, is there any risk to removing the wires and
replacing them with a single #2 Copper wire below ground? If there is
risk with removing the utility ground temporarily to do this, then should
I simply dig down and then connect #2 copper wire to the same utility
ground rod below ground – thus avoiding the need to remove the utility
ground above ground to connect all the grounds? Is there a problem that
could be created by having an oxidized copper clad ground rod of the
utility ground with connection above ground and then simply sanding a spot
lower on the same rod below ground in the trench and then connecting the
Hoffman box to that below ground?
3) I need to get about 6 control cables, 6 rotor cables and 8 coaxial
cables into the shack. How would you suggest that I do so without
allowing critters and insects in?
I see two potential options:
A) There is a small window to the shack about 12” high and 24” wide – if I
replaced the window with an aluminum plate (which would be grounded to the
single point ground), I will use standoff coaxial connectors to get the
coaxes inside, but I don’t think that I have enough room to mount
everything on the plate, so how do I get the control cables and rotator
cables inside without making another hole and allowing the critters in?
B) If I don’t replace the window with a panel, then how do I get all the
cables inside without allowing critters and insects inside other than
making a big hole in the house above the top of foundation and then
stuffing it with steel wool and other material? This would allow cold air
and humidity to get into the basement as well and provides a potential way
in for all kinds of insects and mice. Not a desired outcome.
4) Due to the extremely violent wx that I get at my qth I still like the
idea of disconnecting everything when not in use. With this in mind, does
it make sense to have another aluminum panel inside the shack mounted on
wooden beams near the window (and grounded to the spg with #2 wire) to
which I attach all the coaxial, control and rotator cables inside the
shack and then simply disconnect them and move them away when not in use?
These outside and inside cables would also be disconnected from all the
equipment and outlets and ground inside the shack would be disconnected
from the single point ground outside.
I would appreciate any thoughts, suggestions or warnings about what I
propose. Thank you for your help!
73
Bob KQ2M
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