[Elecraft] how much to stretch copper wire

[Charlie T, K3ICH]

Or, you could simply use copperweld and forget
about stretching.
RF Connection sells a fairly flexible stranded and
insulated (black poly-ethelyne) wire that, if I
remember correctly is 13 gauge.

I built a four band dipole * a few years ago using
those aluminum swaged wire clamps.  It's still up
and to my knowledge, has not stretched or
de-tuned.

73, Charlie k3ICH

* Two wires from each center balun connector.  The
upper wires have 75 M traps for 75/160M and the
lower wires have 40 M traps for 40/60 M bands.



-----Original Message-----
From: Elecraft
[mailto:elecraft-bounces at mailman.qth.net] On
Behalf Of Jim Hoge
Sent: Thursday, February 11, 2016 5:58 PM
To: Elecraft Reflector <elecraft at mailman.qth.net>
Subject: [Elecraft] how much to stretch copper
wire

I drew the wire for my first antenna about 40
years ago. That was for a quad utilizing solid
copper. Since then,I have made numerous dipoles,
all using stranded THHN or THWN 12g wire. My
method has always been to anchor one end to a tree
or a bumper hitch and hold the free end with a
pair of Vise grip pliers. The advantage of the
armstrong method is you can feel the draw and
sense when it nears its limit. The force require
to continue drawing the wire escalates and then
failure occurs. In practice, I lay out a tape
measure on the ground beneath the wire to be
drawn. Once I have my rough length of wire, I will
draw it about 10% more in length. (Example:
1/4wave for 7.010 mHz is 33.3' so I will draw to
about 36.7'.)This has been enough to prevent
additional stretching once the antenna is up in
the air. The thermoplastic insulation degrades
well before the wire fails and my oldest antenna
up at the moment is my 40m dipole, it's about 12
years old.
73,Jim W5QM