I'm interested in measuring the velocity factor of some coax I have (more of
an exercise than necessity). In order to do this, the MFJ-259 Operations
manual states that the "stub" to be measured should be attached with a
50-ohm noninductive resistor

Hi Jason, I just looked at the manual for the 259 and the 259B and it did not
mention a 50 ohm resistor in the velocity factor section. With both
instruments you measure the electrical length of the coax and compare to the
physical length to obtain velocity factor. It is a bit easier with a 259B
using the "distance to fault" function. The coax can be open or shorted (far
end) during measurement. No resistor needed as far as I can tell.
73 Gary N4AST

"JGBOYLES" wrote in message
...
I'm interested in measuring the velocity factor of some coax I have (more
of
an exercise than necessity). In order to do this, the MFJ-259 Operations
manual states that the "stub" to be measured should be attached with a
50-ohm noninductive resistor

Hi Jason, I just looked at the manual for the 259 and the 259B and it did
not
mention a 50 ohm resistor in the velocity factor section. With both
instruments you measure the electrical length of the coax and compare to
the
physical length to obtain velocity factor. It is a bit easier with a 259B
using the "distance to fault" function. The coax can be open or shorted
(far
end) during measurement. No resistor needed as far as I can tell.
73 Gary N4AST

Gary, the manual indicates to 'Set up the line to measure 1/4 wave stubs as
in the section on "Testing and Tuning Stubs"'... In that section, it
requires a 50-ohm resistor in series to the center conductor. Perhaps, the
resistor isn't needed to measure VF? This is really a poorly written
manual-- while it acknowledges possibilities, it really isn't clear in its
procedures :-/

Let me know what you think. Maybe you're right and the resistor isn't
needed for VF.

Thanks,

Jason

"JGBOYLES" wrote in message
...
I'm interested in measuring the velocity factor of some coax I have (more
of
an exercise than necessity). In order to do this, the MFJ-259 Operations
manual states that the "stub" to be measured should be attached with a
50-ohm noninductive resistor

Hi Jason, I just looked at the manual for the 259 and the 259B and it did
not
mention a 50 ohm resistor in the velocity factor section. With both
instruments you measure the electrical length of the coax and compare to
the
physical length to obtain velocity factor. It is a bit easier with a 259B
using the "distance to fault" function. The coax can be open or shorted
(far
end) during measurement. No resistor needed as far as I can tell.
73 Gary N4AST

Gary, the manual indicates to 'Set up the line to measure 1/4 wave stubs as
in the section on "Testing and Tuning Stubs"'... In that section, it
requires a 50-ohm resistor in series to the center conductor. Perhaps, the
resistor isn't needed to measure VF? This is really a poorly written
manual-- while it acknowledges possibilities, it really isn't clear in its
procedures :-/

Let me know what you think. Maybe you're right and the resistor isn't
needed for VF.

Thanks,

Jason