Icom IC-718 - Manual (Page 30)

The AT-180 automatic antenna tuner matches the
IC-718 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.
TUNER OPERATION
• Tuner type setting (p.46)
q
Push [PWR] for 1 sec. to turn power OFF.
w While pushing and holding [SET], push [PWR] to
turn power ON.
e Push [UP Y] or [Z DN] one or more times to
select [TUNER].
r Rotate the main dial to select “18”.
• AT-180 AUTOMATIC ANTENNA TUNER is selected.
NOTE: NEVER select “4” (AH-4 AUTOMATIC
ANTENNA TUNER ), otherwise the transceiver
transmits automatically when turning the power ON.
Push [TUNER] to cancel unexpected tramsmission.
Then, re-select the tuner type correctly.
y Push [PWR] for 1 sec. to turn power OFF.
u Push [PWR] to turn power ON again.
• AUTO TUNE:
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, “ ” goes out.
• MANUAL TUNING
During SSB operation on HF bands at low voice
levels, 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 “
” blinks; then, the previous mode is selected.
If the tuner cannot reduce the SWR to less than
1.5:1 after 20 sec. of tuning,
“ ” goes out. In this
case, check the following:
• the antenna connection and feedline
• the antenna SWR (p. 26; meter function)
• Through inhibit
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
higher than 3:1 after tuning.
CONVENIENT
• Tuner sensitive condition
If you require critical tuning at any time during
transmission, select the tuner sensitive condition.
See p. 51 for selection.
• Automatic tuner start
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. 46 for turning the function
ON and OFF.
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5
RECEIVE AND TRANSMIT
CAUTION: NEVER transmit with the tuner ON
when no antenna is connected. This will be damage
both the transceiver and the antenna tuner.
DO NOT! connect the AT-180 and AH-4 at
the same time. Both turners will not be function
correctly.
Y Y
[TUNER]
Y Y
[TUNER]
Tuning indicator;
Blinks: Tuning now
Appears: Tune is completed
Disappears: Tune is not completed
Push and hold 1 sec. to start manual
tuning.
ï Optional AT-180
AUTOMATIC ANTENNA TUNER
operation