Geoffrey, I did leave out that important point. My delta loop is oriented horizontally, all three support points are at the same height (about 40') in three different trees.
On Sun, Sep 16, 2012 at 9:23 AM, Geoffrey Mackenzie-Kennedy <lx...@pt.lu>wrote: > 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 >> > > -- 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
