On 5/2/2013 9:27 PM, Marvin Shelton wrote:
I don't know if I've ever seen anyone here make mention of the fact that you should NOT
attach ANY coax cable to the stand-off arms of a crank up tower regardless of how
"flexible" it is. I just learned this the hard way. I read about someone
somewhere saying that they had attached the coax coming thru the standoffs to the
standoffs themselves so that the coax would not lie on the ground when the tower was
cranked down. While this helps keep the coax off the ground, it can cause flexible coax,
in my case Belden 9913F7 (recommended by Texas Tower) to take too sharp of a bend, when
the weight of the coax above the standoff comes into play.
It took me awhile to figure out what was wrong so I thought I'd pass the word
along here, as many on this reflector have helped me in the past.
So my suggestion is to get a tub or some type of container on the ground to
receive the coax as you crank your tower down and let the coax slide thru the
standoffs. The fewer bends you put into coax the better.
Finally, I thought I saw somewhere in QST or elsewhere, a description of what
coax brands use soft foam center dielectrics. I think this is the case with the
Belden 9913F7 and I want to know what other cables could be subject to this
problem so that I stay away from them.
The tower now has a run of RG-213 and one of LMR-400 both without problems.
LMR 400 is not recommended for repeated bending. It has a Copper plated
solid Aluminum center conductor. OTOH LMR-400UF is very flexible but
does not normally stand up well to out door use. The jacket is a rubber
like material that is easily abraded, catches on most any thing and has
a short advertised life of 10 years. Best I've gotten out of using it
in normal situations has been around 6 years. It works very well, but
not for long.
73
Roger (K8RI)
73's from Marv
wa2bfw@att.net
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