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Old October 31st 03, 12:39 PM
Jason Dugas
 
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"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