[TowerTalk] Double Coax Runs to Reduce Loss?

[Jim Thomson]

Date: Wed, 21 Dec 2016 14:41:54 -0500
From: Michael Clarson <wv2zow at gmail.com>
To: Jim Thomson <jim.thom at telus.net>
Cc: "TowerTalk at contesting.com" <towertalk at contesting.com>
Subject: Re: [TowerTalk] Double Coax Runs to Reduce Loss?

Perfectly clear. However, would the same math apply if the pair of cables
were treated as a shielded balanced line? I could see some applications for
that. --Mike, WV2ZOW

##  a buddy did just that..to feed a 100 ohm Z quad loop.  100 ohms between
the 2 x center conductors.  Braids bonded at each end.   =  shielded balanced line.

##  dunno what the total system loss would be in that config.   He used no balun at the
feedpoint.  Forget what he did at the shack end.  

##  75 ohm, kw rated twinlead would have been a lot lighter. 

##  He could have used a quarter wave of 75 ohm coax, as a matching section, to get from 100 ohms down to 50 ohms. 
You would still require a CM choke at the feedpoint though. 

##  an L network would easily transform the 100 ohms down to 50. 

Jim  VE7RF