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| Failed Vertical |
Greg Ordy
This page is more about Mother Nature than Amateur Radio. It describes an incident that happened on September 4, 2004.
My 6-element vertical array is described on a number of web pages. The basic antenna element is an 80/40 meter trap vertical. The vertical is not free-standing, a single set of guy lines supports the aluminum tubing.
It's not enough to build and set up an antenna system, you have to keep it maintained. With 6 verticals, I always wondered and worried about the first failure. When would I look out and see something less than 6 verticals?
My first assumption was that a vertical would fail due to a design flaw. Some part of the vertical would be under more stress than expected, and then fail. Coming in a close second was a construction flaw. Perhaps a bolt was not tight enough, or, a knot would give way and fail. My third concern was vandalism. Although I live in a rural area, and the array is removed from the street, and hidden behind a number of trees, a few seconds of vandalism could bring down all 6 verticals with very little effort.
During the early morning hours of September 4, 2004, I woke up, and decided to turn on the radio to check for DX. As I rotated the array, I did not see the normal front to back ratio, which can be over 20 dB. I then applied some power to the array, and observed the SWR on both 80 and 40 meters as I rotated the antenna through its six directions. At the target frequencies, the SWR is low, and, in particular, the same in all 6 directions. I found that the SWR was higher than expected, and moved up and down as I changed directions. Something was wrong.
But, it was 3:00 AM, and dark outside, so I went back to bed, knowing that I had some sort of problem to deal with when the morning arrived.
When I got up, I went to the window that faces towards the array. As feared, I saw 5 verticals, not 6.
As I waked towards the array, I saw element #1 on the ground. It seemed to be bent in half, which I certainly didn't expect. I had always assumed that any element failure would require a guy line failure. After all, if all of the guy lines were in place, how could an element fall and fail? When I got to the element, I immediately checked the three guy lines, and all were in place. Now I had two facts that didn't make sense - the element was bent in half, and all three guy lines were in place.
Here is a picture of how I found the element. Please click on the picture for a larger view.
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| Failed Vertical |
A fourth rope is attached to the vertical. It is a pull rope that is used to raise and lower the vertical. During normal operation, the rope simply hangs down the side of the vertical, and the slack is hung from a cleat on the vertical wooden base. It started to become clear that the vertical failed because this rope was pulled away from the base of the vertical. This caused the vertical to buckle. At some point, the bottom broke free from the hinge at the base. The vertical collapsed on the ground. All three guy lines remained attached. They actually provided an anchor above the pull rope attachment point. This led to the vertical buckling, as opposed to simply falling over.
One thing was clear, somebody did this on purpose. This was not the the result of weather or mechanical failure. Somebody grabbed the pull rope, and kept tugging on it until the 2" diameter aluminum tubing buckled, and then broke away from the base, as it collapsed to the ground. I should mention that the guy lines and the pull rope were both made from Dacron rope with a black UV-resistant jacket. I have found this to be the only choice for outside use, since it seems to last forever. The guy lines are only 3/32" in diameter. The pull rope is 5/16" in diameter.
I started to follow the pull rope, which headed off from the element in the direction of the arrowhead formed by the bent tubing. About 20 feet away, I found the rope making a nearly 90 degree bend around the trunk of a small tree. The bark of the tree was heavily abraded, as if the rope were rubbing against the trunk for a long time. Here is a picture of the trunk wear.
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| Trunk Wear |
Now what sense did this make? Not much to me. I continued to follow the rope, which was now heading off in a new direction. After another 15 to 20 foot distance, the rope was tangled around another small tree. This tree, however, was lying on its side, and almost pulled free from the ground.
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| Second Tree, Almost Pulled Out of the Ground |
As in the case of the first tree, the bark was worn off of a portion of the trunk. Near the ground, I saw something hanging from the end of the rope. As I got closer, I could not believe my eyes - it was a deer antler!
Now, this all became clear, and was hardly what I would have ever expected.
A buck, sporting a small set of antlers must have been grazing around the base of the vertical. His antler got tangled in the pull rope hanging off of the cleat. As the deer panicked he must have ran from the element, turning after the first tree, and then running around the second tree. The antenna probably gave way early on in the process, but then I had a deer tied to a tree by a short rope connected to its antler. The second tree was nearly pulled from the ground, most of the roots were snapped. At some point, the antler gave way, and the deer was free.
Here is a picture of the antler, and the naturally forming knot.
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| Knotty Problem |
Finally, here is what a normal vertical base looks like. The spare pull rope is collected, and hung from a cleat.
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| Normal Vertical Base |
The deer must have found a way to get their antler caught in the rope windings, and the ended up tied to the very end of the rope.
Although I thought of a lot of possible problems, I must confess, this one caught me completely off guard. I believe that antlers will grow again if lost. If you find a one-antler deer chasing you around your Field Day site, perhaps it was this one - I suspect he has no love for Amateur Radio.
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