Gap Challenger DX Vertical Antenna Survives Severe Winds
This is a follow-up post to the initial posts dealing with the construction of the Gap Challenger DX vertical ham radio antenna and tilt base mount. This post deals with durability and not functionality of the antenna, the gap tilt base mount and the suggested support structure.
I must admit that I was somewhat skeptical about the overall survivability of the antenna and the base after I got the antenna mounted The tilt base worked quite nicely to bring the antenna to its full upright position. My mistake was in having my wife, Jane (KD8KRS) video the process. Reviewing the video was a bit frightening. I could hardly believe what an arch the 30 plus foot antenna had in it on the way to vertical. It seemed quite flimsy. I became concerned for its survivability in high winds.
We did use the Gap rope guy kit. The kit consists of a clamp with screw eyes and bolts plus spools of rope. The rope was quite thin but did contain Kevlar I believe. We went with three guy ropes. We guyed the antenna as high up as we could without having the ropes interfere with the tuning rods of the antenna. For anchors for the guy ropes we used a pine tree, a main support post for our deck and the wall of our garage. For the wall of our garage I obtained a stout metal plate with a hole in the center of it, a screw eye and a bolt. I drilled a hole through the wall of the garage up high – and right through a main support beam for the roof.
The guy ropes worked quite well. Even relatively tight in three directions there still was a good 15 – 20 degree sway in the top of the antenna in 80 mile an hour winds. Now just how do we know that this antenna sustained 80 mile an hour winds? Several ways. One is because those wind speeds were measured during the storm by trained spotters, etc.. Another is by the size of the live limbs that came crashing to the ground near the antenna. See the photo on this page!
After the storm I was able to inspect the dirt support for the Gap tilt base. I was skeptical when the factory suggested using dirt instead of concrete to anchor the tilt mount. I thought it would be flimsy. My mistake! There was a crack in the soil, but the soil was not moved from the sides of the tilt base legs as one would have thought. It was still quite a rigid mount. The ropes were quite intact. The antenna itself sustained zero damage.
I was quite pleased with the results of the mounting system. I do not claim that the antenna can survive unlimited winds. I do believe, however, that if those ropes or their anchor points do ever fail that I have a lot more serious things to worry about than the antenna. For all three guy ropes to fail a large pine tree would have to be gone. The roof of the garage would have to be GONE – not just the shingles ripped off – but the support beams gone as well. And / or the entire deck in the back of the house would have to be gone. Under those conditions the house itself would sustain major damage.
I am not an engineer and I do not know what the exact breaking strength is of the ropes used to guy the antenna. I do know that the ropes likely deteriorate over time with sun and water exposure. I also know that the cost of the ropes is quite minimal given the amount of time and effort to assemble a new antenna. Therefore I likely will add additional ropes next summer. Use of rope has a major advantage over use of metal guys in that rope will not de-tune the antenna! I have used ropes in the past and they have worked well for many years.
We used three anchor points for this antenna simply because there were three almost equally spaced anchor points available that were clear and sturdy. If there were four I would have used four or more. Clearly the more anchor points one uses the less load each of them must carry. In this case more is better – except that there are more points to consider in getting the antenna completely straight.
I have decades of professional Audit experiences in multiple industries. I know how to evaluate the performance of systems. In my opinion, this antenna and mounting / guying system is quite good after this summer’s field testing in the straight-line 80 mile an hour winds of Wisconsin. I can now recommend this antenna as a sturdy antenna system. I can see why others like the durability of this antenna system as well. Good luck with yours!
OH – and by the way – my new favorite song? “I’m Still Standing” by Elton John! smile…
Stay Radio Active!
Jon Kreski – AB9NN – Appleton, Wisconsin / Green Bay, Wisconsin area
http://www.HamRadioResources.com http://www.Twitter.com/AB9NN
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