Operation; Manual Tuning; Tuner Sensitive Condition; Automatic Tuner Start - Icom AT-180 Operating Instructions And Service Information

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RECEIVE AND TRANSMIT

D O O p p t t i i o o n n a a l l A A T T - - 1 1 8 8 0 0
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.
C C A A U U T T I I O O N N : :
N N E E V V E E R R transmit with the tuner ON
when no antenna is connected. This will damage
both the transceiver and the antenna tuner.
N N o o t t e e : :
• The AT-180 cannot be used for the 144/430 MHz
band.
• When operating on the 144/430 MHz band, push-
ing 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.
T T U U N N E E R R O O P P E E R R A A T T I I O O N N
• F F o o r r t t h h e e H H F F b b a a n n d d : :
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]
Lights to indicate the AT-180
is turned ON.
• F F o o r r t t h h e e 5 5 0 0 M M H H z z b b a a n n d d : :
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]
Flashes to indicate re-tuning
is necessary.
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A A U U T T O O M M A A T T I I C C A A N N T T E E N N N N A A T T U U N N E E R R
o o p p e e r r a a t t i i o o n n
M M A A N N U U A A L L T T U U N N I I N N G G
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 tun-
ing.
• 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)
T T h h r r o o u u g g h h i i n n h h i i b b i i t t (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.
CONVENIENT
• T T u u n n e e r r s s e e n n s s i i t t i i v v e e c c o o n n d d i i t t i i o o n n (HF bands only)
If you require critical tuning at any time during trans-
mission, select the tuner sensitive condition. See
p. 55 for selection.
• A A u u t t o o m m a a t t i i c c t t u u n n e e r r s s t t a a r r t t (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.