[TenTec] Repeatability of Tuner Settings

[K & H Darwin]

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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