[TowerTalk] Strange coax failure

[Patrick Greenlee]

While true, Mark, I isolated the problem to the bad jumper in a couple 
minutes, as fast or maybe faster than getting out the boat anchor HP to 
do the TDR bit.  I did waste some time comparing good to bad etc mostly 
due to my amazement having never experienced such a problem in over 50 
years of coax use.  I spent a minute cutting the coax to see the 
problem.  I admit I was lucky that the defective inch or two of coax was 
exposed on the first cut but that is reality.  I also took some time 
putting a connector on the cut ends and testing to see if there were 
other anomalous sections but there weren't.  I will tag the short 
jumpers salvaged after removing the bad spot so if anything "funny" 
happens I will suspect them right off.

Lucky trumps good.

Patrick    NJ5G



On 12/15/2014 1:27 PM, Mark Stennett wrote:
> A time domain reflectometer would eliminate the guess work and show you where the defect was on the line.
>
> 73 de na6m
>
>
>> On Dec 15, 2014, at 13:19, Ray Benny <rayn6vr at cableone.net> 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...
>>
>> Ray,
>> N6VR
>>
>>> On Mon, Dec 15, 2014 at 11:09 AM, Tom Osborne <w7why at frontier.com> wrote:
>>>
>>> Hi Patrick
>>>
>>> Don't think I'd cut them in half.
>>>
>>> I'd just cut the plugs off and replace them and check the cable again.
>>> Might be something in the plugs that are bad and you would be wasting a
>>> bunch of cable.
>>>
>>> If still bed, then start cutting them.  73
>>> Tom W7WHY
>>>
>>>
>>>> On 12/15/2014 8:09 AM, Patrick Greenlee wrote:
>>>>
>>>> I'm going to cut the bad jumper in half and test the halves and then cut
>>>> the bad piece in half and test those pieces.  Whichever is bad will then be
>>>> dissected carefully to see, if possible, what was physically wrong with the
>>>> coax.  This is a real head scratcher for me.  The good news is I'm back on
>>>> the air with a pan adapter full of signals again and loving it.
>>>>
>>>> Patrick     NJ5G
>>>>
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