Kenwood TS-870S Automatic Antenna Tuner, Presetting Internal Tuner Only, Operating Aids

7 OPERATING AIDS

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

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.

1Press [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.

AT TUNE

•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.

Band	Range
No.	(MHz)

10.030 ~ 1.85

2 1.85 ~ 2.01

3 2.01 ~ 3.525

4 3.525 ~ 3.575

5 3.575 ~ 3.725

6 3.725 ~ 4.49

7 4.49 ~ 7.03

8 7.03 ~ 7.1

9 7.1 ~ 7.49

Band	Range
No.	(MHz)

107.49 ~ 10.49

1110.49 ~ 14.1

1214.1 ~ 14.49

1314.49 ~ 20.99

1420.99 ~ 21.15

1521.15 ~ 21.99

1621.99 ~ 25.49

1725.49 ~ 29

1829 ~ 30

• 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: 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).

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 [AT TUNE] after changing bands to ensure the tuner has tuned for minimum SWR.

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