In article ,
Lumpy wrote:

I'm a little stumped.
I'm sure I'm missing something obvious
but I just can't see it.

Silly question - have you calibrated your MFJ meter against a
known-good load recently?

The fact that you get the same impedance reading when you add 50 feet
of coax (which is pretty close to a quarter-wavelength) is a red flag.
Since the added cable is roughly 1/4 wavelength, you'd expect to see a
*big* impedance transformation - a load of 6 ohms at one end, would be
transformed up to around 450 ohms at the other end.

Since you're getting the same reading with, and without the
quarter-wavelength cable extension, I'd be very prone to suspect that
your measurement tool (the MFJ meter) is frotzed.

The MFJ-259 and -269 meters use "zero bias" Schottky diodes as part of
their power-measurement circuitry. These diodes are relatively
delicate, and can be damaged if the meter inputs are exposed to more
than a relatively small amount of RF. Even keying up a transmitter on
one antenna, while having the meter hooked to another (nearby) antenna
at the same time, can hit the diodes with a high enough voltage to pop
'em. Reportedly, the -269 meter can also be damaged if you turn the
UHF feature on or off at the wrong time or with the controls in the
wrong settings.

Check your meter with several loads - a 50-ohm dummy load, 25- and
100-ohm test loads, open circuit, and short circuit. See whether it
reads close to the correct value or not.


--
Dave Platt AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
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