Actually, the internal tuner can effect the readeings. If you want an
accurate reading, be sure the tuner is off. The tuner makes the radio see
50 ohms, but the impedence of the line and load on the output, the
antenna, and the load back toward the radio, the tuner, can be far from 50
ohms. The meter is designed to run in a 50 ohm circuit, which it isn't
any more. I fought this battle a while back trying to tune up a six meter
antenna on the 2000, and got all kinds of strange readings until I
remembered to turn off the tuner. The tuner does effect things, because
it can present a high impedence to the meter on that end. Also, you'll
find that sometimes just changing the length of the cable between the rig
and the meter can change readings. I had a regincy 2 meter rig once and I
was just a beginner in all this stuff. I had run another radio on my 2
meter beam and knew the beam was working great. The regincy worked great
on my mobile, but when I hooked it up to the beam, no output. As they
came from regincy, they were very sensative to a "high s w r", and would
shut down. I thought o.k., I'll check the swr. Put the meter in the
line, and radio worked fine. Took the meter out, and no output. I
finally found that by either adding 6 inches or cutting six inches off of
the line made the thing work. It was dependant on exactly where in this
run of 70 feet of coax the radio was.
This is why if you are checking the s w r on a 72 ohm line, you have to
change some resisters in the meter so it matches the line.
73s
Butch Bussen
wa0vjr
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