Because Velocity Factor determines the time it takes a EM wave to traverse the cable it ALSO shortens the wavelength by the same amount relative to free space this is why coaxial cables can be used as delay lines and why when cutting resonant sections of coaxial cable the Velocity Factor must be known
Content by Scott Typos by Siri > On Aug 11, 2016, at 2:56 PM, Bob Stewart <[email protected]> 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? > Bob > ----------------------------------------------------------------- > AE6RV.com > > GFS GPSDO list: > groups.yahoo.com/neo/groups/GFS-GPSDOs/info > > From: Didier Juges <[email protected]> > To: Bob Albert <[email protected]>; Discussion of precise time and frequency > measurement <[email protected]> > 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: > > www.ko4bb.com/getsimple/index.php?I'd=coax-cable-impedance-matching > > 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 -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
