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Re: [TowerTalk] weird coax

Subject: Re: [TowerTalk] weird coax
From: David Robbins <>
Date: Mon, 12 Dec 2011 06:29:59 -0600 (CST)
List-post: <">>
I don't know if i can trust my meters with such a high loss, but i think it is 
around 150 ohm... but i'm sure that none of the methods i used take into 
account the high loss.  for instance, the minivna can't measure enough phase 
shift on reflections to get a lenght or velocity factor, and my mfj meter just 
reports constant 3db loss regardless of frequency.

I saw some vague references to uses as some kind of probe use, but nothing 
specific.  i could see that it would act as an attenuator for reflections so 
you could make measurements without adding distortion to a wave being sampled.  
Where i work they have made high voltage measurements on long transmission 
lines and measured traveling waves on transmission line towers, perhaps this 
was left over from a long forgotten experiment.

Dec 11, 2011 11:29:23 PM, wrote:

>  This  stuff is
> definitely intentionally lossy, the center conductor is very high resistance
> material like nichrome and only 26-28ga.

I am trying to understand why lossy wire would be wanted.

One use for coax delay lines, was oscilloscopes, so you could see the
part of the waveform it was triggering on. Lossy line would result in
frequency dependent losses, which I'd think would be undesirable.

I see how lossy might be a consequence of the very thin wire needed to
get an unusually high Zo, but not why someone would want to make it

Can anyone explain it to me?

If you measured the Zo, that might be a step in the right direction to
identify this coax.


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