I think that you are lucky that it lasted two years! I set up a temporary
tower/rotator when I moved to this QTH and in less than a week the rotator
and control cables were chewed so bad that it did not work. For the coax I
used old Heliax and that was not chewed, although at my previous home in
IL something would occasional chew the smaller Heliax near the tower base,
but not enough to make it unusable. So I repaired the rotator cable and
temporarily elevated it on lawn chairs, etc which stopped the chewing.
So you have several options, bury the cable, elevate it, cover it inside
something or use Andrew Heliax. I believe even burying it a little would
resolve the issue and this should not be difficult using a trencher.
John KK9A
To: <topband@contesting.com>
Subject: Topband: Why do rodents eat coax?
From: "Dave Olean" <k1whs@metrocast.net>
Date: Mon, 9 Nov 2015 19:38:32 -0000
I was transmitting on 160 last week, and after calling a CQ I noted that the
background noise from one of my beverages dropped to almost nothing.
Something
obviously broke right then. All checks pointed to something external to the
shack. I finally got out in the woods and checked the antenna system. All
looked great. I used my new SARK-110 vector network analyzer and saw very
believable results when connected to my 1100 ft long Europe beverage:
about 75
ohms impedance and a VSWR that fluctuated between 1.5 and maybe 1.8:1 across
the freq range. I double checked the entire beverage run for shorts or
anomalies, and even took apart the termination box to make sure all was
OK. The
last thing left was the 1000 ft run of flooded RG-6 coax. I had run the cable
on the ground back to the house about 2 years ago. It was mostly invisible
now,
being covered with leaves and moss etc etc. A TDR check showed gross "bad"
things and a VOM test across the center pin to ground showed a resista
nce of 35 ohms while the far end was terminated in a 75 ohm load. Obviously
the cable was compromised. I made a quick inspection and found a few spots
where small animals had chewed on the coax enough to break through the outer
plastic covering and into the braid and aluminum foil shield. Water and gunk
have caused a low resistance between center pin and the shield.
What are my options now? I don't want to spend another $150 for another
roll of coax just so a squirrel can feast on the PVC. Should I route the coax
in the air and away from small mouths? That is one option. It seems that
digging a 1000 ft trench thru the woods and burying it would work, but it
would
be an awful big chore for a 70 year old doofus. I doubt that I could manage
that. If I run the coax above ground, I run the risk of picking up noise
etc. I
also worry about falling limbs and old dead trees falling on it. With a few
beverages in the woods, I can't afford to spend $150 each time an animal
feasts
on it. I need to do something different!
Incidentally, the beverage still has great directivity, but signals are
very weak with the bad cable. It is barely useable now as a result.
73
Dave K1WHS
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