Towertalk
[Top] [All Lists]

[TowerTalk] hardline sweep - strange result

To: towertalk@contesting.com
Subject: [TowerTalk] hardline sweep - strange result
From: "John Keating" <john.keating@outlook.com>
Reply-to: John Keating <john.keating@outlook.com>
Date: Thu, 18 Sep 2025 21:06:16 +0000
List-post: <mailto:towertalk@contesting.com>
I have two roughly 50m lengths of unterminated hardline that I swept in TDR mode using a RigExpert AA-600. Each has an N-connector on one end. The first length is Commscope CR-540PE (smoothwall 1/2" heliax) and it shows a good result with no discontinuities in impulse response or step response until the end of the cable, with the step response reflection coefficient at zero the entire run. The other length is Andrew FJS4-50B (corrugated 1/2" heliax). The impulse response is ok but the step response reflection coefficient drifts negative over the length of the run, ending at about -0.5 at the terminal end.

Why does the FSJ4 show that result? Note that when terminating that run into 50 ohms, the step response reflection coefficient is zero across the run.

John K7LY
_______________________________________________



_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk

<Prev in Thread] Current Thread [Next in Thread>