[TowerTalk] Coax choice for crank-up - looking for TT experience/recommendations
jd0 at broadsci.com
Mon Jul 10 17:55:21 EDT 2017
> Thanks for the input Mike.
> My experience with FSJ4-50B is not positive. I've nicknamed
> it the 'firehose' as a result of its ability to take on water
> and have it track down the coax.
> 73, David G3WGN M6O
Definately avoid Superflex outdoors. I could give many dozens of examples
of water ingress on commercial installations where Superflex was used
outdoors as the jumper between the vertical Heliax feedline and the antenna,
including a few lessons that I learned "the hard way" when Superflex first
came out. The jacket on Superflex is much thinner and seemingly less
durable than the jacket on non-Superflex Heliax. To make matters worse, the
corrugation on Superflex is helical (spiral), whereas with regular Heliax
the corrugation is annular (rings). As such, if you get a nick in the
jacket of a Superflex cable, water is able to "spiral down the cable"
between the jacket and shield, ultimately flooding the lower connector.
Yes, there is a gasket in the body of the connector which should prevent
this, but freeze/thaw cycles will ultimately lead to the barrier being
I'm not a big fan of using 9913F7 outdoors either.
If the bends are gentle enough, I would stick with LMR400-DB or other
flooded-braid cables and not be concerned about the center conductor being
solid. The minimum repeated bend radius of LMR400 vs LMR400-UF is the same
(4 inches). The repeated raising/lowering could result in an abraison or
nick along the cable, and the self-healing properties of a flooded cable
will extend the lifetime.
--- Jeff WN3A
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