Wednesday, June 2, 2010

Mother Nature


For a hundred years radio amateurs have been hoisting antennas up into the air.  Sooner or later Mother Nature knocks them back down.  Or at least she reminds us who's boss.

My Gap Titan DX multi-band vertical dipole stood straight and tall until this past December when my area experienced severe blizzard like conditions.  One of many winter storms that passed through this one brought high winds in excess of 50 mph.  That afternoon and evening as I watched out the back door the antenna oscillated wildly with the top section swinging back and forth six feet or more.  The three guy lines appeared to be keeping the Gap from folding over in the strong gusts.

The next morning conditions were calm and as I peeked out the window I was dismayed to see the bend about one third up the length of the antenna.  The Bottom section of the Gap Titan is made up of three layers of aluminum tubing each telescoping into the next.  It is very sturdy.  The bend occured just above the triple walled section.  I attribute the failure to an inadequate guying system.  I used the Gap guying bracket which is a very sturdy assembly made from aluminum angle and stout 1/4" stainless steel eye bolts. 


 I attached the guy bracket to the spot recommended by Gap.  Because of the space limitations of my lot I did not have many options for anchor points for the guy lines.  The north-east and south-east lines I attached to the corners of the garage roof where I could screw into the wood rafters.  The last guy I stretched out directly west into the back yard and attached  to a steel stake.  This guy was much longer than the other two attached to the roof and ended up being the weak link.  I believe this layout did not provide the support required to keep the side to side swinging of the antenna in check during the strong wind.

In the future I hope to have more space to deploy the Titan and the Eagle and when I do I will certainly use a symmetrical 4 line guy system with the lines spaced 90 degrees apart and of equal length.
   

During Memorial Day weekend after some hedge trimming chores my ground man Wyatt and I lowered and disassembled the Titan for storage.  Another lesson learned is to use conductive grease on all the metal to metal fittings.  Even after being in the air for only about six months the aluminum tubing sections were very hard to pull apart.  Interestingly the Gap Titan continued to work great even with the bend.  In January,  a month after the storm,  I set my record distance radio contact to Orel,  Russia about 5,009 miles away.  

I'm sure this won't be my last run in with the powerful effects of nature.  One of many challenges to getting and staying on the air as a radio amateur.   


5 comments:

  1. I have more or less decided that the Titian will be my HF antenna. My problem right now is figuring how to mount it. I'm not sure I want a ground mount next to the house, as it's out front. It just might be too tempting for those who pass by. Although this really isn't that kind of neighborhood and none of the Handicapped Vehicles that we used to store on the front drive way. Any ideas on how to mount it to one's roof?

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  2. Hi Norm,
    Yes I studied your site pictures. Not many options. Certainly you could mount it on a small tv style roof tripod but you will need to guy it. Not a big deal if you can plant it in the center of your roof and run the guys to the corners. But your electrical drop comes in from the back. Bummer! What kinds of wind conditions do you get there in the SW? I think the Eagle might be ok unguyed with a sturdy mount but I guyed mine.

    The Eagle is just a bit shorter but quite a bit lighter just no 80m. It loaded up on 30 meters ok with auto tuner.

    I would love to try the Butternut verticals but would have to lay a radial field. The XLY says up on the tower fine but no antennas in the yard. I can live with that!

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  3. The Eagle was actually my first thought, then when emailing to Gap, the Titian was suggested. My XYL is telling me, "NO ANTENNAS". Front Yard, Back Yard, Back of Van, Neighbors House, On our Street.

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  4. I had two tall pine trees in my front yard. Unfortunately the city utility wires ran through these trees. They were 40 or 50 ft tall. During a summer storm a few years ago a christmas tree size portion of the very top broke off and I found it in my driveway. Too bad I could not use these pines for antenna supports. If I could I would have run a remote tuner at the base and got a copper wire as high as possible.

    I started my amateur station using commercial antennas to develope a base line. Now am i interested in wire antennas and their low cost and ease of use. Hopefully this summer I can test this idea with the end fed half wave and my qrp rig. I think a pine tree vertical at 66ft with just a coax jumper and the rig as a counterpoise at 5 watt level would be a nice set up. Oh well at 5 watts the neighboring campers will probably be rfi free.

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  5. I like the gap hinge base. that is what I will use the next time I put up a Gap. And a 10 ft mast pipe to make it easy to mow around. Then if a storm comes I can walk it down by myself.

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