[TowerTalk] Hardline Fault

[Jim W7RY]

If you have access to such a device.....

All you have to do is run a distance to fault measurement with a precision 
load on the far end. Using a wide frequency range (100 to 1000 MHz or the 
maximum frequency range that will allow you to "see" 500 feet with your 
particular cable) you can see all of the imperfections along the cable.

73
Jim W7RY




-----Original Message----- 
From: Roger Parsons
Sent: Tuesday, August 21, 2012 4:12 PM
To: towertalk at contesting.com
Subject: [TowerTalk] Hardline Fault

For about 15 years I have been using CATV type flooded hardline lying
on the ground to feed my receiving antennas. It has worked very well,
and until now I have had no failures caused by biting animals. However,
I recently found that I had a short on one ~500' section. Easy, I thought
- to cause a short there must be a pretty big bite that has crushed the
outer into the inner - just follow the cable along until I find it. So I did 
just
that. Of course the cable had got buried under the forest floor most of the
way so I had to disturb it in order to check it. I found lots of small bite
marks, but no big ones.


The problem is that when I got the far end and measured the resistance,
the short had disappeared - my moving the cable presumably moved
the outer a few microns away from the inner.


If I had been sensible and used a TDR to find the approximate location
of the short I would only have a small section of cable to check carefully.
I do not believe that a TDR would now find what can only be a very small
discontinuity somewhere along the length.

Now, I have no idea whatsoever how to find where the fault was, and

can think of no way of avoiding it recurring just when the P5 finally gets
onto 160m other than replacing the whole length.

Anybody got any bright ideas?

73 Roger
VE3ZI
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