Grounding
System for DXers
Perhaps
one of the most overlooked aspects of setting up a listening
post is a ground system. Any listener with a table top receiver
will need a good ground system to operate their unit at its optimum
level. This piece will deal with setting up a simple, yet effective,
ground system that can be installed in a short period of time
with a minimum number of tools.
The first
thing you will need three parts:
The first is of course a good ground rod.
You will also need a buss bar if you have more than one unit to
ground.
And finally some ground wire to tie the whole thing together.
Let us
look at the ground rod.
Not all ground rods are created equally. When I went to put in
my present system, I talked with several people from our local
hydro electric company to see what they were using. They all agreed
on one thing: you need a full sized 10 foot ( 3 metre) rod to
be effective.
This length will almost guarantee that the rod will stay in contact
with moisture in all but the driest years. The ground can dry
out to quite a depth during long hot dry periods, leaving shorter
four to five foot rods useless. The rods must be kept moist to
give a good ground, but more on this later.
I also purchased a rod that had a built in connector so I did
not have to purchase one to keep the ground wire attached. These
work best and are easily found.
Next was
the selection of the wire I was to use. I ended up selecting
10 gauge copper wire that was covered in a heavy vinyl jacketing.
What kind of wire to use is open to all sorts of opinions. I picked
the 10 gauge as it was readily available and, although stiff,
you could work with it fairly easily.
A coated or insulated wire was chosen to make life easier for
me. By using a coated wire it meant I could run the wire easier
as I did not have to worry about it touching objects that are
conductive in nature. Your ground wire must never touch any thing
conductive as it will ruin the ground. A clear and unrestricted
path from the radio(s) to the ground rod is a must and coated
wire gives you more options of how and where to run the wire.
The buss
bar can be installed if you have more than one radio to ground,
or if you plan to add to your listening post with other equipment
that may require grounding.
The bar is usually made from copper because of its conductivity.
The bar need not be large. Mine is 3/4 of an inch (2 cm) wide
and 10 inches (25cm) long. I can ground five to six pieces of
equipment on it with no problems at all.
Now that
all of the parts have been purchased we can start on a simple
but effective ground system that will last for years.
You must first of all choose a site for the rod to be put in.
One very important thing to consider is to keep the run of ground
wire as short and as straight as possible. This will insure a
better system.
Keep the rod as close to the side of the house that your listening
post is located. If your home is like mine, you may have underground
hydro, telephone, and gas lines as well as water and sewer lines,
so please call your local utilities to have them located before
you start putting in a ground rod. You do not want to drive your
ground rod into any of these lines. Putting a ten foot metal rod
into a hydro or gas line can ruin your day!
Once you
have selected your spot you will have two options:
1) You can pound the rod into the ground leaving about 8-10 inches
(20 cm) of it above ground;
2) Or you can for the deluxe option.
I have gone for this latter route as it will over time help you
keep the ground rod damp during dry times. This involves more
work but if you live in climate like mine where the weather varies
over a large spectrum or has long dry spells it is worth the extra
effort. Also if you have heavy clay soils during rains the water
will have an easier time to soak into the rock pit instead of
running off.
You can mark the ground where you wish to put the bar and measure
one foot (30 cm) in all directions from this point. Mark the area
off and then dig a hole in the area.
This will result in a two foot (60 cm) square or diameter hole
depending on how you dig it out. Either is acceptable. You should
dig a hole that is about 2 feet (60 cm) deep, more if you wish.
Once the hole is completed place the tip of your rod in the centre
of the hole. You can now pound the rod into the ground leaving
it the 8 inches (20 cm) above ground level (not the bottom of
the hole). Have a friend help hold the rod as it will move around
as you pound it in. Be careful not to hit your friend, as this
may hurt the relationship as well...
Once the
rod is in place test it to insure it is in in tight. Try pulling
and wiggling it to see if it moves.
If it is in tight you have been successful.
If it is close to a foundation or is in loose or sandy soil it
will move around. This will not produce a good ground, so check
it out.
If you went the deluxe route you must now fill the hole with rock.
Insure it is hard rock that will stay loose. Rock such as limestone
is of no use as it will break up and form a hard packed area.
You need loose rock fill that will not pack over time.
You may also want to put is in a bag of rock salt before the rock.
This salt once wet will start working on the rod to give better
conductivity. This rock pit is put into place for one important
reason: moisture.
During dry periods I water the rock pit to insure moisture is
getting down to the lower levels of the rod. The neighbours do
kid me about it so if you embarrass easily do it at night.
The next
step is to install your buss bar is in your listening post.
If you are going to use one it is easy to install. You can make
one or buy one ready made.
To build one just take your flat piece of copper and drill two
holes is in it. One at either end that will act as anchor points
to mount it on the wall near as possible to you equipment. You
can now drill as many holes as you have pieces of equipment plus
one more for the common lead into the bar.
This will mean if you have four pieces of equipment to ground
you will need:
Two holes to mount the bar, one at either end.
Four holes for the equipment between the two anchor holes.
And one hole for the common lead, also between the anchor holes.
Each of the holes, excepting the anchor holes at the top and bottom,
will be drilled to put in a bolt and washer to attach the radios
etc to. Use what ever you have at hand.
Put in the bolts and washers into the pre-drilled holes. Using
the two mounting holes screw the buss bar to the wall near to
your equipment. Try to keep it centrally located to keep leads
to the equipment as short as possible.
Now that
the bar is mounted run short straight pieces of heavy wire
from each piece of equipment to the bass bar.
You should use coated wire here to insure no wires touch each
other or anything else. This is very important. Attach the other
end of the wire to the lowest bolt and work your way up to the
top. Insure the wire is under the washer so it presses the wire
onto the buss bar insuring a tight and solid contact fit. This
is a must.
You can now attach a run of wire to the common at the top of the
bar and run it to the ground rod outside. Once again insuring
a solid contact . If your rod had no built in clap you can use
metal strapping to get a solid tight fit to the rod.
When you connect any end of the wire to any piece of equipment
or the buss bar or ground rod, insure you strip the wire and then
using sanding or emery cloth clean the bare wire to insure there
is a clean contact.
You should use washers on binding posts to wire up the equipment.
This will insure a solid contact. Loose contacts are of no use
so make sure all contacts are good ones.
Your ground
system is now completed. Maintenance is little if any. You
should from time to time check the connections to insure they
are tight and in the case of the ground rod connection there is
no corrosion. It may need to be cleaned once a year.
When it is dry water your rock pit to insure a good ground year
round. I flood mine until I can see the water sitting on top.
That is it.
You now have a good ground system that will last years.
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