[TowerTalk] I called Belden

[Tom Rauch]

I called Belden OEM support. They kept transferring me through 
people as I asked more and more questions. I eventually reached 
someone named "Dana".
 
This is how it went:
 
Q. What makes a coaxial cable braid discolor and turn black?

A. Water.

note: Everyone I spoke to gave that answer! The next question is 
always what got me transferred.

Q. Anything else do that?

A. Not that I can think of, unless some sort of mild corrosive gets 
into the cable.

Q. What is non-contaminating PVC?

A. Did you ever pick up two vinyl notebooks that stick together? 
That's because the plasticizers migrate. Non-contaminating PVC 
reduces plasticizer migration.

Q. Does that affect loss in the cable?

A. Not really. 

Q. Does plasticizer migration discolor the braid?

A. No, but non-contaminating PVC jackets retain flexibility over a 
longer period of time. That improves life in some situations.

Q. Does it always make the cable have a longer life before 
attenuation goes up?

A. I wouldn't exactly say that.

note: I should have probed that response a little more.

Q. Will too much current discolor the braid?

A. It can melt the cable, but it normally doesn't discolor the braid 
unless the current nearly reaches the fusing current of the 
conductor. Maybe your customer is using the cable around large 
storage batteries. That could explain the blackened braid and his 
concern about current.


73, Tom W8JI
w8ji@contesting.com

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