Kenwood TS-850S - Manual (Page 36)

If the transceiver is operated into an antenna with a
high SWR, the final stage SWR protection circuit
may
operate (when SWR is greater than
approximately 2 : 1). Use of the Automatic Antenna
Tuner will help you to match the antenna to the
transceiver. The AT unit is capable of matching a 20
- 150 ohm load, or approximately a 2.5 : 1 SWR. If
the antenna and feed line exceed this range the
tuner may not be able to find the correct match. If
the tuner cannot match after two attempts, check
your antenna and feed lines.
Output power of the transceiver will automatically be
reduced to approximately 10 watts during the tuning
process to protect the finals against damage.______
Note
The carrier control should be adjusted for normal
CW output (at least 10 watts).
4-9. AUTO ANTENNA TUNER
OPERATION
While the automatic antenna tuner is capable of
reducing the apparent SWR of the antenna system,
it is important to remember that maximum power
output will only occur when the antenna has been
adjusted for the lowest possible SWR.
The antenna tuner has the following three modes;
® Preset mode
This transceiver has a Preset Memory function
capable of storing tuning conditions of each amateur
radio band. The transceiver stores the tuning
conditions after tuning of an amateur radio band is
completed, and automatically provides the stored
tuning conditions when switched backed to that
amateur radio band from other amateur radio bands,
reducing the time for tuning. When you switch to an
amateur radio band, the AT TUNE indicator lights
briefly to indicate that the Preset function is
operating.
1. Set the THRU/AUTO switch to AUTO.
The AT TUNE indicator will light and the
transceiver will adjust to it’s preset condition.
2. When preset is completed, the AT TUNE indicator
turns off.
Note
If you change BANDS and then return to the
previously tuned BAND, after tuning is complete,
the SWR may have changed.
If the SWR has changed, set the AT TUNE switch
to ON so the unit will retune.
(2) Auto Tune mode
In this mode, tuning signals are transmitted to tune
the antenna and transceiver automatically.
Note
If switch SW 1 on the rear is set to EXT, the built-
in antenna tuner does not work.
1. Set the THRU/AUTO switch to AUTO.
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2. Set the AT TUNE switch to ON.
The transceiver switches to the CW mode, the AT
TUNE indicator lights, and the unit starts tuning.
Note
This switch will not function when the CAR
control is turned fully counterclockwise.
3. When tuning is completed and the AT TUNE
indicator goes out, the frequency display returns
automatically.
4. A warning beep tone is sounded if tuning is not
completed within 20 seconds. If this occurs turn
the AT TUNE switch OFF, and then repeat steps
1 - 3.
@ Manual Tune mode
Manual adjustment of the tuner is possible with the
tuning knob and M.CH/VFO CH control if auto-tuning
is not possible.
1. Press and hold the LSB/USB key while you turn
on the POWER switch.
2. Select the number 20 by rotating the M.CH/VFO
CH control.
Use the UP/DOWN switch to select OFF.
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3. Press the CLR key, or press the POWER switch
OFF and then back ON.
4. Place the THRU/AUTO switch to AUTO.
5. Turn the AT TUNE switch ON. While reading the
SWR meter, alternately turn and adjust the
TUNING knob and M.CH/VFO CH control for the
lowest SWR. When tuning is completed, the AT
TUNE indicator will go out. Once it goes out,
further tuning will not be possible even if you turn
the controls.
6. The current setting is stored in memory as the
preset data for the amateur band when the AT
TUNE indicator turns off or you stop tuning by
pressing the AT TUNE switch.
If manual tuning is done in one band, then again
in another only, the tuning data for the first band
is memorized. So, if the first band is reselected,
the memorized tuning data is recalled,
reestablishing the original tuning.
7. To cancel the manual tuning mode, perform step
1, select ON in step 2, and then step 3._________
Note
If manual adjustment fails to lower the SWR and
complete the tuning, adjust the SWR of the
antenna.