[TenTec] Model 238C Tuner Questions
jruing at ameritech.net
Tue Oct 16 07:19:42 EDT 2012
Greetings TenTec Tuner Mavens --
I have a new Model 238C tuner. It is a different design from my two
Palstar tuners, one a manual tuner, the other an auto tuner.
I have a couple of questions which relate to my getting used to this
different sort of tuner...
1) It is normal and expected that it has a VERY narrow effective tuning
range? It is extremely fussy, and while I understand an L type tuner
has only one match point, I am finding it very difficult to find that
point, as it is a very narrow, sharply defined range.
2) I am trying to match an OCF dipole - which presents SWR of around
4:1 on a couple of bands, and as low as 1.2:1 on others. It seems to
work best on the first Low-Z (1) and I only need to turn the inductor
two rotations, and the capacitor works best below the zero (0) mark.
That is where the capacitor has gone entirely around and is over lapping
on the far side of the range. Sound OK?
3) Does anybody have a simple description of the procedure one should
use to quickly find the sweet spot? Here is what I am doing, but not
sure if anyone has a better approach:
I turn the Capacitor to Zero (0), and the Inductor
all the way to its Zero (0) mark, to start with.
Then I transmit with the handy "Tune" button
on my Omni VII, which puts out a bit less than
20 watts tone.
I turn the Inductor knob clockwise until I see a
substantial dip in reflected power. Then I
rotate the Capacitor knob clockwise until
reflected power dips sharply to a low point.
At this point it is typically only as good as
1.5:1 SWR - so I again slowly rotate the
Inductor clockwise until reflected power dips
again, and, finally, rotate the capacitor clockwise
until a really low match of 1.1:1 SWR or
1.1:1 SWR is achieved.
But this is a really sharp, narrow point on the
capacitor dial - very slight movement of the
capacitor dial shifts SWR dramatically.
Does this sound normal?
Note: I tried it on a couple of different Low-Z and High-Z settings,
and it seems to work best on the first (1st) Low-Z setting.
3) I wonder if there is a simple way to use my RigExperts AA-230
antenna analyzer to determine if the antenna has high or low impedance
so it would be easier to determine, in advance, which High-z or Low-z
setting to start out with or to confirm my selection and best guess as
to which works best ?
ANY HELP WOULD BE APPRECIATED.
(I hoping this makes sense... it seems hard to put all this into words,
-------------------- K8JHR -----------------------------
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