I would not trust the VOP of any coax cable of a non-precision types. Generally, if you need that kind of precision, you use air line or hard line and measure it with a TDR.
-John ============= > If I understand you correctly, then I did not have things setup > symetrically. Now I have a tee on each of the A and B inputs. The > unused port on the B tee has a 50 Ohm terminator. Is this what you > mean? > > With the above setup, using the shortest cable I have gives me 1.5 ns. > Adding the longer cable to the shorter, using a F-F BNC coupler gives > me 21 ns, for a difference of 19.5 ns. The readings are bouncing > around a bit, so these numbers aren't exact. Using the 19.5 ns figure > and a 66% VOP, I get 3.86 M, which is much closer to the measured > length. > > If I use the calculated length vs the measured length, I get a VOP = > 65%. Pretty close to the specified 66%. > > Thanks to everyone for the help. Any more hints or discussion are > always appreciated. > > Joe Gray > W5JG > > On Sat, Apr 2, 2011 at 8:55 PM, Hal Murray <[email protected]> > wrote: >> >> You want the difference in path lengths. Is there an asymmetry in the >> setup? >> If so, count the BNC connectors that don't have a match on the other >> path. >> >> If you have input-Tee-coax-Tee-terminator, then the difference is the >> coax >> plus half of each Tee. That is you want to measure the length from >> center of >> Tee to center of Tee. > > _______________________________________________ > 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.
