Icom iC-706MKTMG manual Optional AT-180 Automatic Antenna Tuner operation, Tuner Operation

4 RECEIVE AND TRANSMIT

DOptional AT-180 AUTOMATIC ANTENNA TUNER operation

The AT-180 automatic antenna tuner matches the IC- 706MKIIG to the connected antenna automatically. Once the tuner matches an antenna, the variable capacitor angles are memorized as a preset point for each frequency range (100 kHz steps). Therefore, when you change the frequency range, the variable capacitors are automatically preset to the memorized point.

CAUTION: NEVER transmit with the tuner ON when no antenna is connected. This will damage both the transceiver and the antenna tuner.

Note:

•The AT-180 cannot be used for the 144/430 MHz band.

•When operating on the 144/430 MHz band, pushing the tuner switch selects the call channel (p. 39).

•The AT-180 can match both HF and 50 MHz bands. However, operation is different for the HF and 50 MHz bands.

TUNER OPERATION

• For the HF band:

Push [TUNER] to turn the tuner ON. The antenna is tuned automatically during transmission when the antenna SWR is higher than 1.5:1.

•When the tuner is OFF, the [TUNER] light goes out. [TUNER/CALL]

MANUAL TUNING

During SSB operation on HF bands at low voice lev- els, the AT-180 may not be tuned correctly. In such cases, manual tuning is helpful.

Push and hold [TUNER] for 1 sec. to start manual tuning.

•CW mode is selected, a side tone is emitted, and the [TUNER] light flashes; then, the previous mode is select- ed.

[TUNER/CALL]

Push and hold for 1 sec. to start manual tuning.

If the tuner cannot reduce the SWR to less than 1.5:1 after 20 sec. of tuning, the [TUNER] light goes out. In this case, check the following:

•the antenna connection and feedline

•the antenna SWR (p. 26; meter function)

Through inhibit (HF bands only)

The AT-180 has a through inhibit condition. When selecting this condition, the tuner can be used at poor SWR’s. In this case, automatic tuning in the HF bands activates only when exceeding SWR 3:1. Therefore, manual tuning is necessary each time you change the frequency. Although termed “through inhibit,” the tuner will be “through” if the SWR is high- er than 3:1 after tuning.

Lights to indicate the AT-180 is turned ON.

• For the 50 MHz band:

Push and hold [TUNER] to tune the antenna. If the [TUNER] light flashes slowly while transmitting, push and hold [TUNER] again to re-tune the antenna.

[TUNER/CALL]

CONVENIENT

• Tuner sensitive condition (HF bands only)

If you require critical tuning at any time during trans- mission, select the tuner sensitive condition. See p. 55 for selection.

• Automatic tuner start (HF bands only)

If you want to turn OFF the tuner under conditions of VSWR 1.5:1 or less, use “automatic tuner on” and turn the tuner OFF. See p. 54 for turning the function ON and OFF.

Flashes to indicate re-tuning is necessary.

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