[TowerTalk] Strange coax failure

[Jim Lux]

On 12/15/14, 11:19 AM, Ray Benny wrote:
> Patrick,
>
> I had a case once of a shorted coax due to a manufacturing defect. The coax
> was a 100 ft piece. I had first cut off the connectors one at a time but
> found the coax still shorted. I cut the coax in half, one half open, the
> other shorted. I kept cutting the shorted section in half until I had about
> a 6 inch shorted piece remaining. I slid off the braid and found that
> during the manufacturing process the center conducted was bent outward and
> through the dielectric causing a direct contact with the braid. Don't know
> why the short was not caught in a QC check, but maybe only random
> pieces/rolls were checked.
>
> In the end, I still had 50ft of coax to use, plus a bunch of shorter
> pieces...
>


That's why a TDR or a VNA or equivalent that can tell you the position 
of the discontinuity is useful.  You'd know right away if the problem is 
in one connector or the other, or in the middle of the cable.

If you were real patient and had lots of time, you could do it with a 
SWR meter and tuning your rig around.