FWIW, I had a 350' run to my towers in Illinois. I had over 60 control
wires in a PVC pipe and also various runs of hardline, including 1 5/8. I
only used Polyphasers at the house enterence. My taller tower was hit by
lightning numerous times, sometimes severe enough to burn up the Polyphaser
protectors. I never sustained any control wire or coax damage.
From: "Dick Green WC1M"
Date: Wed, 27 Sep 2006 12:36:48 -0400
Several people have responded saying I don't need suppressors at both ends.
I agree that the critical place to put them is at the shack end. My
reasoning for putting another set at the tower is that the cable runs are
long (220') and they'll be direct-buried (no conduit.) If a cable gets
damaged it will be a lot of work to replace it.
Gary points out that a surge could arc through the cable to a metal conduit.
Although there won't be any metal conduit in my installation, each cable
bundle will contain ground wires and most of them have grounded shields as
well. Also, there will be two runs of 1-5/8" heliax buried beside the
control cables. The outer conductor of the heliax is nearly 2" in diameter
and is essentially solid copper. That's got to be a low impedance path to
ground -- probably lower than metal conduit. Seems to me there's a
possibiliy that a surge could arc from a control line to a ground line in
the same cable, to the cable shield, or even to the heliax outer conductor.
I would think the center conductor of the heliax would be particularly
vulnerable, so I'm going to use coaxial suppressors at both ends to protect
the expensive and hard-to-come by heliax.
Flame suit on.
73, Dick WC1M
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