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Re: [TowerTalk] Open wire measurments

To: <towertalk@contesting.com>
Subject: Re: [TowerTalk] Open wire measurments
From: "Paul Christensen" <w9ac@arrl.net>
Date: Tue, 3 Sep 2019 16:30:59 -0400
List-post: <mailto:towertalk@contesting.com>
Wes,

"As has been suggested elsewhere in this thread, you might be tempted to try 
connecting the balanced line to the unbalanced test port of the analyzer, in 
the belief that since it is a "floating" device it's also "balanced".  This has 
not worked for me."... "So the line radiates; it's part transmission line and 
part antenna."

No argument there, but that doesn’t mean the CIA cannot report back a valid 
impedance measurement.  I have yet to find an instance where it hasn’t worked 
with a complex Z on a balanced line.   I routinely reverse the balanced 
termination on the unbalanced reflection port and achieve the same result.  
Moreover, I obtain the same (or nearly the same) result when using a 1:1 
Mini-Circuits RF transformer, then OSL calibrate after the transformer.  By 
contrast, I often cannot obtain identical results when changing line polarity 
when: (1) using a "bench" type VNA device where powering comes from electrical 
mains; and (2) a transformer isn’t used.  

Paul, W9AC 

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