http://www.engineeringtoolbox.com/cable-loads-d_1816.html
A wire supported at the ends and loaded uniformly only by its own weight will form a catenary, and mid-span sag is a function of mid-span tension. Zero sag = infinite tension. Unfortunately, center-fed dipoles are not uniformly loaded.
Just lay the wire out on the ground in a straight-ish line and measure it. I use a 50' steel tape. Lots of things will affect its ultimate electrical length when installed, you'll need to prune it some anyway. I just fold the ends back on the wire until I've got the right length and then cut it and belay it to the insulator(s).
73, Fred K6DGW - Northern California Contest Club - CU in the Cal QSO Party 1-2 Oct 2016 - www.cqp.org On 2/9/2016 12:22 PM, Bob McGraw K4TAX wrote:
The only challenge is to estimate the wire sag in measuring a long length of wire.
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