|The completed tower in extended position against a grey sky.
My reasons for choosing this construction method were (in order of priority!):
The specifications are as follows:
|Here is the tower almost horizontal, ready to be raised to the vertical
The foot of the tower is hinged and bolted to a small concrete base.
Note that this structure does not require a large concrete pedestal as the tower is supported by the bracket arrangement on the wall of the house at a height of about 3,5 metres. (Top right in the photo)
|Here we have raised the mast to an angle of about 25 degrees. This
done using the lower winch mounted on the mast. The steel cable runs up the mast,
around a pulley, and then through a pipe in the wall and into the ceiling cavity.
I did not want to pull up the full weight of the mast at right angles to the outer wall in case it cracked, so I ran the cable along in the roof cavity and anchored it to a wall which is in line with the lifting cable.
|At last it's starting to look like a tower!
Here we see the mast nearing the vertical position, with guy wires hanging straight down.
Oops! Looks like the director is not quite horizontal. Will have to lower it again and straighten that out sometime!
|Here we are at last in the vertical position, but not yet extended to
No guy wires are necessary in the lower (unextended) position. It moves a little in the wind, but is extremely stable.
One unexpected side effect is the strange noises which you hear when there is a bit of wind. The inner pipe moves within the outer pipe and makes weird creaking noises. As the bracket on the side of the house is bolted firmly to the shack wall, the sounds are transmitted directly into the shack!
|Here is a view of the tower with beam attached, ready to be raised to the
There is some bending of the upper pipes, but it can handle a much heavier weight without permanent bending . . . Provided there are no sudden shocks!
|Another view still on the ground, showing the two winches.
The lower winch (Bottom right in photo) is used only to raise the mast into the vertical position. Once there, it has not load on it, and I remove the handle for safekeeping.
The upper winch is used to raise and lower the upper section of the mast. The leverage here is extremely high, and it takes no effort at all to wind it up. However, it requires lots of turning, and the arm gets quite tired by the time it is at maximum extension!
In this picture you can see the temporary ski ropes which I used for guy wires. These have been replaced by 3mm steel cable once the lengths and angles were determined.
|Detail showing the point at which the inner pipe exits the outer pipe. The little skirt is to limit the rain water from running into the lower pipe. The small wheels are intended to guide the pipe but probably don't serve any useful purpose - The leverage of the inner pipe is far too large, and the wheels are simply bent back.|
|Here is a nice detail shot showing the rotator and mounting of the boom.
Currently I do not have a balun, and a few turns of RG38 suffice as a choke.
The rotator is mounted in a cage which is boxed in. This is not really necessary in our climate. Again, there is a small skirt around the pipe to keep the water off the bearing at the top of the rotator cage.
|Here is a detail showing the bracket on the wall of the house. It is
anchored to two walls at right angles, so extending a rigid frame out beyond the gutter
overhang. I used 50mm angle - Probably an overkill, but it was lying around getting
in the way.
The angle piece below the bracket is simply to hold the bracket up when the tower is not in position!
|This shows the tower in vertical position and anchored to the wall bracket.|
This was taken on our last trip to the Kruger Game Reserve. It was towards the end of the dry winter season, and the water in this dam had almost all disappeared. This picture shows an amazing variety of game all present at the same time. In the picture you can see: Giraffe, Blue Wildebeest, Impala, Zebra, Bush pig and possibly one or two other varieties of buck. You will not be able to make them out, but there were three young lions on top of the earth wall at approximately the centre of the photo.
The water looks still in the picture, but it was continually disturbed by the remaining fish thrashing about. These are catfish, which are able to survive when there is almost no water left. When the water finally dries up, they burrow into the mud and go into a sort of hibernation, and come out again when the rains reappear.
We watched this scene for over an hour. During that time a Leguan of about 1 metre in length slipped into the mud on the far side, flopped around the puddle, and came out on the side nearest us. He may have grabbed a small fish in his travels.
At another waterhole on the same day we saw a Fish Eagle pick up a nice sized catfish and carry it off into the distance. Easy pickings for some during the dry seaon!