Made a minor error on how I tune the 238C. The capacitor has to be set at
mid range before checking the SWR by turning the switch first to Low Z and
then to High Z and selecting whichever one shows the lower reading. Then
proceed as I said. Position 1 on the switch just switches in the variable
Capacitor. Positions 2, 3, 4 and 5 switches in fixed capacitance in
paralles to the variable capacitor.
Dave WN5V
-----Original Message-----
From: TenTec [mailto:tentec-bounces@contesting.com] On Behalf Of David W
LeJeune, Sr
Sent: Tuesday, October 16, 2012 11:11 AM
To: 'Discussion of Ten-Tec Equipment'
Subject: Re: [TenTec] Model 238C Tuner Questions
I usually put the capacitor to 0, the inductor to 0, and the switch to
bypass. Set the SWR switch to SWR, sensitivity to max. Then put enought
carrier through the tuner to register close to full scale on the SWR meter.
I then turn the switch to low z, check the meter reading, then turn the
switch to high z and note the meter reading. Whichever is lowest is the one
that I leave the switch turned to. I then set the capacitor to mid range,
and tune the inductor until the meter starts dipping. once you have a dip,
rock the capacitor to lower the dip. I then just start switching from
inductor to capacitor until I get the lowest SWR.
Works every time for me. (I do note the readings so I can reset it in the
future whenever I switch bands).
Dave WN5V
-----Original Message-----
From: TenTec [mailto:tentec-bounces@contesting.com] On Behalf Of Richards
Sent: Tuesday, October 16, 2012 6:20 AM
To: Discussion of Ten-Tec Equipment
Subject: [TenTec] Model 238C Tuner Questions
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,
after all...)
-------------------- K8JHR -----------------------------
_______________________________________________
TenTec mailing list
TenTec@contesting.com
http://lists.contesting.com/mailman/listinfo/tentec
_______________________________________________
TenTec mailing list
TenTec@contesting.com
http://lists.contesting.com/mailman/listinfo/tentec
_______________________________________________
TenTec mailing list
TenTec@contesting.com
http://lists.contesting.com/mailman/listinfo/tentec
|