[Elecraft] Question about suspending a delta loop...

[Geoffrey Mackenzie-Kennedy]

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