ICOM IC-706MKIIG User Manual

27

4

RECEIVE AND TRANSMIT

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.

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.

• 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.

• 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.

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.

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.

• 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.

D Optional AT-180 

[TUNER/CALL]

Lights to indicate the AT-180
is turned ON.

[TUNER/CALL]

Flashes to indicate re-tuning
is necessary.

NEVER transmit with the tuner ON

when no antenna is connected. This will damage
both the transceiver and the antenna tuner.

[TUNER/CALL]

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