I'm not sure the lack of repeatability in tuner settings is the fault of
the tuner. Let me explain.
My antenna is a 32' ground mounted vertical. 30 Feet of RG-8 coax run from
the base to my garage. Just inside the garage, I have an MFJ tuner. From
there I run another 40 feet of RG-8x to my rig in the basement. I use the
tuner on 80/75, 30 & 17 to get an impedence match.
Since the tuner is in the garage, I use the presets. I ran some tests with
my rig in the garage to get the initial settings, the moved the rig into
the basement. For over a month I was able to cruise into the garage, dial
in the settings and have a perfect match for the radio. Then, as the
weather here in VT began to change, some of my settings quit working. When
I rechecked them the MFJ Ant analizer, they had shifted quite a bit. I saw
these problems on 80 where the settings are very touchy as well as on 30
where they are not. I expected this on 80 but on 30 I sure didn't. During
this whole time the SWR on 40 remained largely unchanged. I set the tuner
to bypass for 40 m operation.
My conclusion is that the antenna system itself changed enough to throw the
settings off. I've also checked impedence of my 20 M dipole and have seen
it shift around a bit as weather conditions change.
Keith Darwin
KD1E
Ferrisburg, VT
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