[TowerTalk] 7-16 DIN Males for RG-213/214

[Jeff DePolo]

> FSJ4 has a black polyethylene jacket. This material used in 
> other Heliax
> products and it is perfectly suited for outdoor use. The 
> jacket is thinner
> than LDF4 however it is still pretty though.
> 
> John KK9A

I think you meant to write the jacket is tough, not that it's pretty.
Anyway, the composition of the jacket isn't the issue.

If you get even the slightest nick in the jacket of Superflex, due the
helical ("spiral") corrugation, you will eventually have a flooded lower
connector as moisture is able to "spiral down" the cable between the jacket
and shield.  The problem is most prevalent at colder latitudes, where all it
takes is a few freeze-thaw cycles and what started out as a little nick in
the jacket turns into a gaping wound.

I can't tell you how many problems we've had over the years with Superflex
used as an antenna jumper.  The failures are always the same - a flooded
lower connector.  

Between the thicker jacket and annular ("ring") corrugation of regular
Heliax, it is less likely to suffer this kind of failure as compared to
Superflex.  But it still can and does happen.  If you slice open a piece of
Heliax or cut off the bottom connector of a run of Heliax and the outside of
the shield has turned green or black, that's a tell-tell sign that you have,
or had, water between the jacket and shield.

If you want additional reports of the undesirability of Superflex outdoors,
pose the question on one of the mailing lists oriented toward the wireless
industry and see what kind of response you get from the veterans.  Cell
carriers and others quit using Superflex outdoors for antenna jumpers a long
time ago due to these problems; standard 1/2" Heliax is the preferred jumper
between the main feedline and antenna (or TMA or RRH or whatever).  Even
some of the equipment manufacturers' literature states that Superflex should
not be used outdoors, and I believe it was even stated in Andrew print
catalogs back in the day, I can check.

					--- Jeff WN3A


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