The antennas at this QTH are the best overall set of aluminum that I have had
up in the air. The antennas are held in the air by a pair of U.S. Towers
HDX-589-MDPL crank-up towers. These towers are remote controllable and motorized
permitting full operation from within the radio room ( "ham shack" ). The towers
nest fully down to a minimum height of 23 feet above the tower bases, and extend
upwards to a total of 89 feet. These are seriously heavy duty towers and can
easily hold the stacks of antennas that I have on them. The towers are about
400' from the ham shack making a very long run back to the towers. The towers
are located in the leased 14 acre abandoned sand pit. The first picture shows
the back yard looking from the house up to the back fence, The towers can be
seen through the trees. South tower is on the left and the north tower is on the
right.
The second picture shows the two towers and antennas from the vantage point
of the sand pit looking toward the back fence of the property. The house is to
the right of the towers and beyond the fence. In this picture, the north tower
is to the left and the south tower is toward the right. Antennas are described
below.
The third picture shows the two towers extended up to about the 65 foot
level. The antennas can be seen fairly easily. We shall call the tower on the
left the south tower, and the tower to the right as the north tower. The north
tower has an M2 7 element six meter yagi ( the 6M7-JHV long boom optimum spaced
seven element 6 meter yagi). This yagi is located 10 feet above a Force - 12 C31-XR tri-band trapless yagi antenna. Both antennas are oriented to fire in the same direction.
The C31-XR is a hot tri-bander which provides three elements on 20 meters, 4
elements on 15 meters,. and 7 elements on 10 meters. The bands are interlaced on
the same boom. The mast is a 1/4" wall galvanized mast, and both yagis are
rotated by a Hy-Gain Ham-V rotator unit. The south tower holds a Cushcraft A3WS
WARC duo-bander providing three elements on 17 meters and three elements on 12
meters. This antenna was modified to extend the driven element of this yagi and
a second trap to provide a rotatable aluminum dipole for 30 meters. The A3WS+30
is positioned on a 1/2" wall galvanized mast 10 feet above the top of the tower.
At the top of the tower is a Force-12 620/340 which provides an optimized 6
element yagi on 20 meters interlaced with a three element linearly loaded 40
meter yagi. Again, both antennas fire the same direction and are rotated through
360 degrees by a Hy-Gain Tail-twister rotator.
The Force-12 620/340 appears to be somewhat oddly constructed if you don't
know the reason. A good friend, K5JZ, owns the same yagi and I helped him put it
up and take it down several times. The first time that it had to come down was
because several of the telescoping elements on the 40 and 20 meter elements came
loose and fell to the ground. The element sections telescope together and hold
together with three rivets, all on the same side of the telescoping pieces. The
problem is that although the aluminum telescopes nicely together, there is a
slight amount of "slop" (movement) in the inner telescoping tube. The amount of
slop is very slight, but enough to let the smaller element section move very
slightly in the wind as the element vibrates and resonates in the wind.
Eventually, the slight vibrations worked on the rivets, and sheared
the rivets and let them drop out of the elements and to the ground.
Then it was just a matter of time for the telescoping element sections to jiggle
apart and drop to the ground. After discussions with Force-12, George ( K5JZ )
developed a process of doubling the number of rivets, and counter-balancing the
"stock" rivets by placing three additional rivets directly across the element from the
initial three rivets. In this way, one set of rivets worked against the other
set of rivets, and held the telescoping sections much tighter and with no
evident "slop" or movement. Then the entire joint was wrapped with Scotch 130 to form a
moisture barrier, then coated with three coats of Scotch liquid electrical tape,
and then final-wrapped with a double wrap of Scotch 88, topped with a double
wrap of Scotch 33. This process produces the black bumps at each joint of
telescoping elements. Using this modification of the Force-12 assembly process,
K5JZ has experienced no additional loosening of element sections, and it was
decided to build this yagi using the exact same process. The wrapped junctions
are clearly seen in several of these pictures. This process undoubtedly
increases the wind load of the yagi but I believe substantially improves the
element design.
The vertical element that appears above the trees and to the right of the
North tower is actually a 1200' tall television tower and antenna that is
located about a quarter mile from this QTH, as I said earlier, I discovered that
this QTH is just about the best location that one could have in this entire
parish. The clear take off angle for the yagis is amazing, and a terrain
analysis of the tower locations shows the performance of these yagis to be
exceptional.
In addition, the antenna system uses a Carolina Windom - 160 160 meter
antenna. The antenna is hung in trees in the back yard and is about 65 feet off
the ground. The short side of the Windom is between trees while the long side of
the Windom travels from a tree to the north tower. The Windom, with an antenna
tuner is used on 160 and 80 meters. The Windom functions a lot like an "Inverted
- L" on 160. There is also a Butternut H9V vertical mounted on the back lot
fence support pipes.
This QTH will also support four bi-directional Beverage receive antennas
which will be erected next year ( 2007 ). The cable and equipment has been
purchased, but will be held until next fall to erect. The bi-directional
Beverage antennas will each be 590' feet long, made up of 450 ohm ladder line,
and using DX-Engineering switching control units to reverse the direction of the
Beverages. Beverage antennas are very directional wire antennas that are mounted
close to the ground. The Beverage normally receives in a single direction based
on a traveling wave absorption. I used 6 directional Beverages in Hattiesburg
with great success. At this installation, I will erect four Beverages:
North/South, East/West, North-East/South-West, and North-West/South-East. This
will permit a highly directional Beverage every 45 degrees around the compass.
The North-South and East-West Beverages will be permanent installations and the
NorthWest/SouthEast and NorthEast/SouthWest Beverages will go up each fall and
come back down each spring.
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