Rick, Is your delta loop suspended with its apex up or down, or is it a horizontal loop? If the apex is down or up it is better to use only one counterweight, otherwise the antenna will "walk" if the trees sway in the wind. A supporting catenary will also "walk" if a counterweight is used at each end.
At my last QTH in GM all of my HF wire antennas were supported by tall pines and exposed to very high winds. So I might be able to offer some suggestions if you could please tell me about the configuration of your loop. 73, Geoff LX2AO On September 16, 2012 at 4:37 AM, Rick McClelland, AA5S wrote: >I have a 240' delta loop suspended at three points about my QTH. I've been > pondering adding another 47' but this is quite a challenge given the > dimensions of my suburban lot. One thing I'm considering is to make good > use of two trees located in a common area outside my property lines. > Easily > said, but I would not want to hang a 5 kg line ballast at either of these > points because I can imagine a couple of neighborhood youths scaling a > tree > with one of them cutting a line causing the 5kg weight to crash down upon > the tender skull of the other youth. > > Legal matters notwithstanding, my question is whether I'm inviting certain > mechanical failure if I fix the two endpoints outside my property lines > and > make use of only a single 5 kg ballast on the tree located within my > property lines. The advantage of doing this is obvious, if any of the > supporting lines outside my property are cut, the antenna falls onto my > property and there is no possibility of injury to the purpetrators of the > dastardly deed. > > As a possibly relevant aside, I don't use a typical insulator at each of > the three suspension points. I use a 4" flat acrylic insulator with two 6" > acrylic insulators attached to the end of the 4" insulator such that the > resulting insulating apparatus appears to be a rather large 8" tuning rod. > In my non-mechanical-engineering mind, I imagine that having the insulator > arranged in such a fashion reduces the peak tension at each apex of the > triangle and also allows the wire to move more freely through the > insulator > without binding at that point. I realize that this matter isn't related > to > any Elecraft product but there are so many sage OMs here that I feel that > an answer will be quickly forthcoming and without controversy. > > -- > Rick McClelland, AA5S > Fort Collins, CO ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
