ICOM IC-703 用户手册
65
9
ANTENNA TUNER OPERATION
The AT-180 automatic antenna tuner matches the IC-
703 to the connected antenna automatically. Once the
tuner matches an antenna, the variable capacitor an-
gles are memorized as a preset point for each fre-
quency range (100 kHz steps). Therefore, when you
change the frequency range, the variable capacitors
are automatically preset to the memorized point.
703 to the connected antenna automatically. Once the
tuner matches an antenna, the variable capacitor an-
gles are memorized as a preset point for each fre-
quency 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
the transceiver. Be careful of the antenna selection.
the transceiver. Be careful of the antenna selection.
• The AT-180 can match both HF and 50 MHz bands.
However, operation is different for the HF and 50
MHz bands.
MHz bands.
TUNER OPERATION
• For the HF band:
Push [TUNER] to turn the tuner ON. The antenna is
tuned automatically during transmission when the an-
tenna SWR is higher than 1.5:1.
• For the HF band:
Push [TUNER] to turn the tuner ON. The antenna is
tuned automatically during transmission when the an-
tenna SWR is higher than 1.5:1.
• When the tuner is OFF, the [TUNER] light goes out.
• For the 50 MHz band:
Push [TUNER] for 1 sec. to tune the antenna. If the
[TUNER] light flashes slowly while transmitting, push
and hold [TUNER] for 1 sec. again to re-tune the an-
tenna.
Push [TUNER] for 1 sec. to tune the antenna. If the
[TUNER] light flashes slowly while transmitting, push
and hold [TUNER] for 1 sec. again to re-tune the an-
tenna.
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.
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 [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 selected.
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. 55; meter function)
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. 55; meter function)
Through inhibit (HF bands only)
The AT-180 has a through inhibit condition. When se-
lecting 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.
The AT-180 has a through inhibit condition. When se-
lecting 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.
• Tuner sensitive condition (HF bands only)
If you require critical tuning at any time during trans-
mission, select the tuner sensitive condition. See
p. 81 for selection.
If you require critical tuning at any time during trans-
mission, select the tuner sensitive condition. See
p. 81 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. 81 for turning the function
ON and OFF.
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. 81 for turning the function
ON and OFF.
CONVENIENT
[TUNER]
Push and hold for 1 sec. to start manual tuning.
[TUNER]
TUNER
Flashes to indicate
re-tuning is necessary.
re-tuning is necessary.
DOptional AT-180
AUTOMATIC ANTENNA TUNER
operation
DOptional external tuner operation
[TUNER]
TUNER
Lights to indicate AT-180
is turned ON.
is turned ON.
The IC-703 automatically detects and selects an optional
external tuner (AT-180/AH-4) when connected. In this
case, the internal tuner switches to the through function.
external tuner (AT-180/AH-4) when connected. In this
case, the internal tuner switches to the through function.
NOTE: When the connected power supply voltage
is lower than 11.0 V, the transceiver automatically
switches to the battery operating mode (power sav-
ing mode). In this case, the transceiver can not drive
an external antenna tuner.
is lower than 11.0 V, the transceiver automatically
switches to the battery operating mode (power sav-
ing mode). In this case, the transceiver can not drive
an external antenna tuner.
NOTE: When connecting the optional antenna tuner
AT-180, the IC-703’s output power must be set max-
imum (10 W) both in quick set mode and initial set
mode. Otherwise,
AT-180, the IC-703’s output power must be set max-
imum (10 W) both in quick set mode and initial set
mode. Otherwise,
the AT-180 may not be tuned cor-
rectly.
(AT-180’s minimum operating input power is 8 W.)