On 9/28/2012 8:45 AM, Gary Smith wrote:
All that to say; since I have no choice but to run the wire over the tree tops, what would be a better wire?
I'm near the Pacific coast, and also get some pretty good winds. K2RD showed me a really nice method of dealing with your problem. It takes more work to get it done, but it stays up. First, launch fairly small diameter line or rope over your high branch, then use it to pull up some of the nice support rope that DXE and others sell. I use the 5/16-in diameter size. My neighbor, W6GJB, an aeronautical engineer who works in the space program, recommends Vectran rope, which you can buy from sailing supply stores. It's pretty pricey, but quite strong. Use enough of that rope to make a continuous loop, secure a pulley (a marine pulley) to it, put your antenna wire through it, and pull the pulley up to the top. Put an insulator at the far end and tie down at a suitable point. Somewhere in that system, use a weight to control the tension on the wire so that it can move in the wind. Now, when the trees move, the motion is at the pulley, and there's relatively little rub on the rope going over the branch.
In my 160M Tee vertical, I have a "mechanical fuse" at the base in the form of mating banana plug and jack. There's a bottom insulator tied down with a length rope that is slack under normal conditions, but which secures the wire when the wind opens the fuse.
BTW -- my current favorite wire for high antennas that see a lot of stress is #10 THHN. It will stretch with a lot of tension on it, but that's easy to deal with if it's up with pulleys. Every few years I lower my 80/40 fan and trim the 80M elements.
73, Jim K9YC _______________________________________________ UR RST IS ... ... ..9 QSB QSB - hw? BK
