At 09:42 PM 4/2/2011, Joseph Gray wrote...
I'm reading 18.9 ns. The coax specs give a VOP of 66%. This should calculate out to a length of 3.74 M. When I measure the coax, I get 3.8 M.
Your calculation is incorrect. If the velocity factor only has 2 significant digits, the result of the calculation can only have 2 significant digits. And, I doubt the coax manufacturer will guarantee the VF to 1 part in 66.
VF is the reciprocal of the square root of the dielectric constant of the coax insulator. 66% implies you're using a cable which uses solid polyethylene. A quick google for the dielectric constant of polyethylene shows a range (2.2-2.4 depending on the source). That would be a VF range of .67-.65.
Working your numbers, I get a length of 3.7-3.8 m. _______________________________________________ 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.
