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Re: [TowerTalk] weird coax

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Subject: Re: [TowerTalk] weird coax
From: "Jim Hargrave" <w5ifp@gvtc.com>
Date: Mon, 12 Dec 2011 08:35:01 -0600
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
Sounds like it would make long lasting ground radials..

    73s de Jim
       W5IFP
 

  > -----Original Message-----
  > From: towertalk-bounces@contesting.com
  > [mailto:towertalk-bounces@contesting.com]On Behalf Of David Robbins
  > Sent: Monday, December 12, 2011 6:30 AM
  > To: towertalk@contesting.com
  > Subject: Re: [TowerTalk] weird coax
  > 
  > 
  > 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, ai.egrps@gmail.com 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
  > lossy.
  > 
  > Can anyone explain it to me?
  > 
  > If you measured the Zo, that might be a step in the right direction to
  > identify this coax.
  > 
  > Andy
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