I've gotten my fair share of storms here too and rather than go the route of counter weights since I had to kinda skirt the side of a big cedar I opted for a rope method.
I ended up tying two ropes together at the center point of the dipole. Then ran the rope up into the trees. The rope bears all the force (and it can take some HEAVY beating). Then the antenna is simply hung from the rope using crossed zipties around the spreaders (its a fanned dipole). This has lived through some pretty hair situations. I did lose a few feet of elevation one year but that was because the tree lost a limb and I fell down to the next branch! hihi. ~Brett (KC7OTG) On Sun, 2008-07-27 at 22:16 -0700, Jim Brown wrote: > On Sun, 27 Jul 2008 11:47:54 -0700, Ron D'Eau Claire wrote: > > >The counterweights need to be heavy enough to hold the antenna, but not > >heavier than needed for that. When trees whip in the winds, the inertia > >of the counterweights can produce shock loads many, many times greater > >than the weights themselves for a brief moment until the weights begin > >to move. The heavier the counterweight, the greater its inertia and the > >shock load > > Yes. I have a half dozen dipoles suspended in redwoods, a Douglas Fir, and a > Madrone at roughly 100 ft. I'm at 2,000 ft, about 5 miles from the Pacific, > about 250 ft below the top of the ridge on the ocean side. Without weights, > every antenna I installed was on the ground after the first real storm. Since > I've installed counterweights, all have weathered 75 MPH winds for a couple > of days. > > These antennas are heavy -- typically 150-250 ft spans, #10 copper, most with > parallel #12 fan elements (to cover additional bands), and fed with RG8 or > RG11. My weights are roughly 90-95#, and are made by simply filling 6.5gal > water jugs with dry sand (roughly 1.5x heavier than water). Others have had > good success by recycling the counterweights from vintage wood frame windows. > I chose the tension by experimentally determining what it took to achieve the > acceptable degree of droop. > > Counterweighting, of course, is only part of the story. When an antenna must > withstand these kinds of forces, every element of their construction becomes > critical. For this reason, I find nearly all of the commonly available center > insulators for dipoles to be seriously lacking. The absolute worst was the > RadioWavz unit. I bought two and used them to build 6M dipoles. Both fell > apart when I pulled on the LM240 that attached to them! > > 73, > > Jim K9YC > > > _______________________________________________ > Elecraft mailing list > Post to: [email protected] > You must be a subscriber to post to the list. > Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > > Help: http://mailman.qth.net/subscribers.htm > Elecraft web page: http://www.elecraft.com _______________________________________________ Elecraft mailing list Post to: [email protected] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
