Hi Fred,
Thank you very much for email and the video. I watched it and took a look at
the MFJ 4603 – that won’t do it for me but it gave me some ideas that I might
want to try. Many thanks!
73
Bob KQ2M
From: Fred Keen
Sent: Wednesday, May 30, 2018 3:07 PM
To: towertalk@contesting.com ; Bob Shohet, KQ2M
Subject: Re: [TowerTalk] Replacing station ground
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!
Building the shack - window feed thru panel done!
Plexiglass window feedthru panel
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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