Automatic Antenna Tuner; Presetting (Internal Tuner Only); Internal Tuner - Kenwood TS-870S Instruction Manual

AUTOMATIC ANTENNA TUNER

You have the choice of using the internal tuner, an
external AT-300 tuner, or both.
Note:
◆
The antenna tuners will not tune outside the authorized transmit
limits of Amateur bands.
◆ If an external AT-300 tuner is connected, the internal tuner is
bypassed when the ANT 1 connector is selected. The AT-300
cannot be used with the ANT 2 connector.
◆
When tuning in CW mode, the SWR meter may deflect upscale
momentarily. This is not a fault.
◆
If using Full Break-in CW, the internal antenna tuner can be
bypassed completely or can be in-line for both transmitting and
receiving. Even when OFF is selected via Menu No. 08 (RX AT),
received signals pass through the antenna tuner. To protect the
antenna tuner relay, the tuner cannot be used only for
transmitting.

PRESETTING (INTERNAL TUNER ONLY)

After each successful tuning session, the Preset
function stores the data for the position of the tuning
capacitors on each band. Then, if the frequency is
changed while the internal tuner is switched ON, this
function automatically positions the capacitors without
need for retuning. After changing bands, the Preset
function activates for the newly selected band.
A different set of data is stored for each of the
18 antenna tuner bands (see table) and for each
antenna connector (ANT 1 and ANT 2). Therefore,
enabling the other antenna connector by pressing the
[ANT] button may also cause the Preset function to
activate. If no Preset data exists for a particular band/
antenna combination, then the default data for 50 Ω is
stored.
Presetting does not activate while transmitting. For
split-band operation, even if Menu No. 08 (RX AT) is
ON, the antenna tuner is bypassed while receiving.
Also, at all times, presetting is only done for transmit
frequencies.
PRESET BANDS FOR INTERNAL TUNER
Range
Band
(MHz)
No.
0.030 ~ 1.85
1
1.85 ~ 2.01
2
2.01 ~ 3.525
3
3.525 ~ 3.575
4
3.575 ~ 3.725
5
6 3.725 ~ 4.49
4.49 ~ 7.03
7
7.03 ~ 7.1
8
7.1 ~ 7.49
9
Note: The lower limit is inside the band in each case; the higher
limit is inside the next higher band. For example, 14.1 MHz is in
Band 12 whereas 14.49 MHz is in Band 13 (exception: 30 MHz is in
Band 18).
Range
Band
(MHz)
No.
10
7.49 ~ 10.49
11
10.49 ~ 14.1
12
14.1 ~ 14.49
13
14.49 ~ 20.99
14
20.99 ~ 21.15
15
21.15 ~ 21.99
16 21.99 ~ 25.49
17
25.49 ~ 29
18
29 ~ 30

INTERNAL TUNER

Note: Setting Menu No. 33 (TUN.WIDE) to OFF to select an
SWR 1.2:1 reduces internal tuner losses. This setting is best.
≤
1 Press [THRU/AUTO].
• "– AT – TX" lights. If Menu No. 08 (RX AT) is ON,
then "– AT – TX RX" lights indicating that the
tuner is in-line while transmitting and receiving.
In this case, prior to tuning in Step 2, received
signals are attenuated and the receiver sensitivity
is lowered.
AGC AUTO
LSB
• If the tuner has not adjusted itself yet for the
selected frequency, then AT TUNE lights, and
Preset tuning begins. Signals pass through the
antenna tuner during this time. If Menu No. 08
(RX AT) is OFF, the antenna tuner is bypassed.
The AT TUNE light goes out when presetting is
completed. You cannot transmit while presetting
is in progress.
• If Preset data exists, the next step cannot be
done until the transceiver completes the Preset
tuning.
2 Press [AT TUNE].
• To cancel tuning for any reason, press
[THRU/AUTO] or [AT TUNE].
• If the Preset tuning is aborted by pressing
[AT TUNE], the new temporary data will be used,
but this new data does not update the stored
Preset data. Also, the new temporary data will be
lost if the operating band is changed. Return to
the stored Preset data by pressing
[THRU/AUTO] OFF and then ON again.
• AT TUNE lights and stays lit while the tuner
tunes. When the light goes out, the tuner has
successfully matched the transceiver to the
antenna system with an SWR less than the value
set in Menu No. 33 (TUN.WIDE). You can begin
operating.
• If tuning doesn't finish within about 20 sec, an
alarm sounds. You may stop the alarm and the
tuning by pressing [AT TUNE]. The alarm can be
either a triple beep or the Morse code "CHECK"
depending on the Menu No. 37 (WARN. BP)
setting.
• After each successful tuning, the Preset data is
updated.
Note:
◆
While receiving with Menu No. 08 (RX AT) ON on
frequencies outside the Amateur bands, sensitivity is
lowered.
◆
It's a good practice to press
to ensure the tuner has tuned for minimum SWR.
7 OPERATING AIDS
AT TUNE
[AT TUNE] after changing bands
49