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Date: Fri, 26 Apr 2013 13:21:23 -0400
Message-ID: <CAMFjj72gqagv0cw7__THvXCXgAbAC=xb82SD4Sp-sGngx2V7qw@mail.gmail.com>
From: Warren Ziegler <wd2xgj@gmail.com>
To: rsgb_lf_group <rsgb_lf_group@blacksheep.org>
Subject: LF: Fire in the wire
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Just a quick report on a failure mode for LF TX antennas.
Last Fall my original TX loop made up of approximately 500 feet of RG-11
coax suspended from trees went open circuit (both center conductor and
shield), some time later part of the wire actually came down. I had thought
that abrasion from contact with the trees had eventually worn through it.

What I found was a little more interesting. Looking at the downed end, it
appeared that the insulation had melted for a considerable distance and
there were burn marks further up the cable. My hypothesis is that the outer
insulation was abraded away and the coax shield came into contact with the
tree limb causing the burning/melting.
Will try to get some pictures this weekend and put them up on my website.

Long term if one wants to operate at the kW level either better insulation
or a better way of supporting the antenna than trees would be required!

-- 
73 Warren K2ORS
                WD2XGJ
                WD2XSH/23
                WE2XEB/2
                WE2XGR/1

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<div dir=3D"ltr"><br clear=3D"all"><div><div>Just a quick report on a failu=
re mode for LF TX antennas.</div><div>Last Fall my original TX loop made up=
 of approximately 500 feet of RG-11 coax suspended from trees went open cir=
cuit (both center conductor and shield), some time later part of the wire a=
ctually came down. I had thought that abrasion from contact with the trees =
had eventually worn through it.</div>
<div><br></div><div>What I found was a little more interesting. Looking at =
the downed end, it appeared that the insulation had melted for a considerab=
le distance and there were burn marks further up the cable. My hypothesis i=
s that the outer insulation was abraded away and the coax shield came into =
contact with the tree limb causing the burning/melting.=A0</div>
<div>Will try to get some pictures this weekend and put them up on my websi=
te.</div><div><br></div><div>Long term if one wants to operate at the kW le=
vel either better insulation or a better way of supporting the antenna than=
 trees would be required!</div>
<div><br></div></div>-- <br>73 Warren K2ORS<br>=A0 =A0 =A0 =A0 =A0 =A0 =A0 =
=A0 WD2XGJ <br>=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 WD2XSH/23<br>=A0 =A0 =A0 =A0=
 =A0 =A0 =A0 =A0 WE2XEB/2<br>=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 WE2XGR/1<br><b=
r>=A0
</div>

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