I just learned a lesson: don't use 18AWG wire on antennas under tension:
THE WIRE STRETCHES!
A few days ago, I decided to string my 250' two-wire (W1WCR-style)
Beverage, and grabbed two new 500' rolls of Essex 18AWG TFFN (insulated,
stranded) wire, and laid them out across my lawn. Mounted with three 10-foot
T-poles, with 60' slopes at the ends.
The wires were tightened-up as I always do, tight enough to keep them
parallel, straight and to keep the poles erect and in place. We're not
talking guitar-string tight: just pulled tight and anchored to the pegs at
the termination/feed points.
Today, I came home and looked out the window at the closest point thereto,
and saw two sagging wires, and immediatly thought that a pole or two had
fallen down out on the lawn. When I checked, all was in place, and the
wires were still connected to each end! Some of the outer coating was
"flaking", like they do after being in the sun for 6 months or more, but
no indications of breaks.
Each of the two wires had stretched 4.5 feet in just three or four days!
CONCLUSIONS:
1) Use larger wire, #14 or #12;
2) "Walk the wire" regularly: check for all sorts of problems.
73,
Jeff Maass (jmaass@freenet.columbus.oh.us) Amateur Radio K8ND
USPSA/IPSC # L-1192 NROI/CRO NW of Columbus Ohio
25000 Members in 2000!
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