[time-nuts] Safely getting the electrical length of a connected antenna feedline

Didier Juges shalimr9 at gmail.com
Fri Aug 12 06:22:07 EDT 2016

Good point! It is only an issue when you try to calibrate/correlate to the physical length.

On August 11, 2016 1:56:09 PM CDT, Bob Stewart <bob at evoria.net> wrote:
>Why is velocity factor an issue?  Aren't we only interested in the
>electrical time from one end of the coax to the other?
> -----------------------------------------------------------------
>GFS GPSDO list:
>      From: Didier Juges <shalimr9 at gmail.com>
>To: Bob Albert <bob91343 at yahoo.com>; Discussion of precise time and
>frequency measurement <time-nuts at febo.com> 
> Sent: Thursday, August 11, 2016 1:20 PM
>Subject: Re: [time-nuts] Safely getting the electrical length of a
>connected antenna feedline
>I used the PPS from a Thunderbolt (fast rise lime, low rep frequency,
>was handy) and a digital storage scope and a couple of resistors to
>make a reflectometer based on this experiment:
>You can very clearly see a 50 ohm/75 ohm mismatch.
>The biggest variable will be the velocity factor.
>Didier KO4BB
>time-nuts mailing list -- time-nuts at febo.com
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Sent from my Moto-X wireless tracker while I do other things.

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