|This is a 90 foot tall top
loaded vertical for 160 meters. It is
constructed from aluminum irrigation tubing and has four sets of four
guys each. The top guys also serve to support the top load wires.
has a "temporary" wire stub about 68 feet long hung off the
provide operation on 80 meters. More details are pictured below.
|The most important part of
any vertical antenna system is the ground. I like to put the radials in
the ground before putting up the antenna so that the antenna and guys
are not in the way. This is the implement I used to form shallow
trenches for the radial wire to lay in. The local farmers use these to
form corrugations in the field for irrigation water to run through.
|Here is one of the shallow
trenches formed prior to inserting the radial wire. The orange baling
twine is streched out between the vertical base and far end of the path
I want the radial to take. That gives me a guide to follow with the
tractor. I tried to insert the wire in the ground as I pulled the
trench but there were too many rocks. Wound up inserting each wire by
hand. I figured that I walked about 18 miles putting in the radial
|Construction was started by
first locating and pouring five concrete piers for the guy
anchors and base. All five are similar except the guy anchors have
rings instead of a threaded stud. After the cement work was done,
conduit was placed in the ground for the coax and control cables. You
can see the conduit in the upper left of the photo. Next the radials
were placed in the ground using the implement shown above, and
terminated in a ring around the base. The green wires are used for
connection to the tuner box to be installed last. The wires are all
soldered to a ring formed from copper wire. When all the soldering is
completed the ring was painted with several coats of common PVC pipe
cement and then sprayed with Krylon paint to weatherproof the solder
joints. There are 82 radial wires, each 100+ feet long.
|The mast is constructed from 4
inch irrigation tubing. The guy lines are fastened to the mast
with a "wheel line" hub clamp. Using a clamp allows adjusting the
placement of each guy set to minimize mecahnical resonances. When the
mast was first stood up, I watched as the wind caused vibrations. The
mast was then lowered and the position of each clamp was adjusted. The
distance between each guy set is now different and vibration is minimal.
The guys are temporary baling twine. I used it to establish the proper lengths and when the design was stable, changed to Dacron.
|The base insulator was made from
pieces of PVC pipe. I turned various pipe fittings on my small lathe
and used PVC pipe cement to bond them all together. The 1/2 inch
diameter hole is for the hinge pin. The first insulator was made from
ABS. The ABS got brittle when the temperature dropped way below
freezing and cracked. So far the PVC has not failed.
|The mast is fabricated from
aluminum irrigation tubing. The bottom 40 foot is 4 inch diameter,
0.075 inch wall tubing. The next 30 feet is 4 inch diameter, 0.05 inch
wall tubing. The top 20 feet is 3 inch diameter, 0.05 wall tubing. I
tried a couple different approaches to splicing the sections together
before it became obvious that more internal support was required to
keep the tubing from collapsing under severe load conditions. This
was made from PVC conduit. The pieces were turned on my small lathe and
make a snug fit inside the two pieces of 4 inch tubing. It didn't need
to be made from insulating material but that's what was handy. A
sleeve made from a 1 foot long piece of 0.05 wall tubing to fit over
the outside of the joint. Sheet metal screws through the tubing and
into the PVC keep the whole thing together and provides
|A base was formed from 4 inch
steel "C" channel. The pieces were welded to form hinge points for the
mast and gin pole. The base plate is bolted to the cement footing. 1/2
inch diameter bolts form the hinge pins. In this image, the tubing on
the left is the gin pole in the lowered position and the antenna is on
the right in the raised position. The black base insulator is the old
ABS insulator that failed after this photo was taken.
|The gin pole is a single 40 foot
piece of 0.075 wall tubing. Although difficult to see in this image,
the 90 foot vertical is on the ground to the left with all guys in
place. The top of the gin pole has a guy on each side, a triple line
pulley system to the rear, and four guys to the mast. As the pulley
system pulls the top of the gin pole down, the vertical is raised up.
This is a one man operation. I wanted to get a photo of the thing half
raised but couldn't figure out how to hold the rope and run the camera
at the same time!
|In this image, the gin pole is
in the lowered position. The side guys are the orange baling twine. The
four rasing guys on the mast are black dacron. The yellow rope is part
of the two line pulley system. It was later changed to a three line
system to allow raising the mast with less effort on my part. The rope
is tied off to a board. Not shown in the image is the tractor parked on
the board! This was later changed to a pemanent concrete anchor point.
The four raising guys are tied off after the mast is raised. Another set of full length guys are used to secure the mast from the "forward" direction
|This is the tuner box at the
base of the vertical. There are four open frame relays used to switch
in different "L" networks. Only two are used now, for 160 and 80. The
relays and network parts are mounted on a sub-chassis so that it can be
easily removed and modified in the shack/shop.120 VAC
is provided for soldering irons and test equipment. In the lower left
the bottom of the mast can be seen in the shadow. You can see part of
the stand off
insulator for the bottom end of the 80 meter side mounted stub.