On Apr 30, 2006, at 5:28 AM, <radio_k4rv@peoplepc.com>
<radio_k4rv@peoplepc.com> wrote:
> Is Andrew 1/2 inch superflex continuously flexible enough to be
> suitable for
> use as a rotor loop?
No. Use coax with a braided shield and stranded center conductor
instead. It will flex fine for a while, but eventually the
corrugated copper outer conductor and/or the solid center conductor
will fail.
About 30 years ago I was working on an application for feeding an
antenna on a gimballed platform at Hughes Aircraft and we were
concerned about the effects of flexing the coax. We did a life test
where we continuously flexed the cable and measured return loss,
looking for changes. We first tried RG-142B, which had a copperweld
center conductor. After several hours it failed and the autopsy
showed that the copperweld had broken into several small pieces in
the region being flexed. We tested again with RG-400, which is
similar except that it has a stranded copper center conductor and
that was still going fine after several hundred hours of flexing.
73,
Bob Nielsen, N7XY
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