In 1995 we built our new house.
It was negotiated with the builder that the tower base would be priced
in with the building of the house. Luckily the cost incurred was
only the concrete. The project started out with a drawing from Pirod
(the tower manufacturer) and it called out for a  7'
x 7' x 6' (L x W x H) base. This would yield around a 11 cubic yards.
I wanted the tower away from the house, so I located a spot near the hill
behind our house that would accommodate the tower. Because the tower
was near the woods, I had to cut some of the trees down to allow for the
antennas to be raised and tuned. I made a trip to pick up the anchor
bolts at Pirod (Plymouth, IN) and then found a sheet of scrap plywood from
our home construction site. I made two templates to hold the bolts
as vertical and parallel as possible. The primary template was installed
around the threaded area of the bolts (see picture) and the second template
was installed about 8" below the primary template (the picture does not
show the 2nd template). The area where my house was built has more
gravel than expected and caused some installation issues with the builder.
As you can see, from the above picture, the builder used his back
hoe to hold part of the collapsing walls. By the time the base was completed,
the hole size was around 9' x 9' x 7' and the cement trucks were empty!
The final volume was just over 19 cubic yards... a bit more than required!  Although
I did not have to worry about the base going anywhere.... This last
picture shows a portion of the tower base above the ground. The main
base is around 6" below ground level (enough to grow grass on). The
black flexible tube is for the coax. It is 4" corrugated pipe with
small slits for the water to drain. If you can guarantee no water in the
tube then I would consider the use a solid pipe, but here in Indiana where
water and ice are abundant I opted to allow the water to escape..
I used three 8' grounding rods positioned off each tower leg and connected
them together with heavy gauge wire. I also connected each of the
rods together in a triangle pattern in order to decrease the chance of
a lightning strike...
Each person has to take their own environment into account to determine the best way to complete the installation. |