User's 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.
NNoottee::
• 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.
TTUUNNEERR OOPPEERRAATTIIOONN
•
FFoorr tthhee HHFF bbaanndd::
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.
•
FFoorr tthhee 5500 MMHHzz bbaanndd::
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.
MMAANNUUAALL TTUUNNIINNGG
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.
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)
TThhrroouugghh iinnhhiibbiitt
(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.
•
TTuunneerr sseennssiittiivvee ccoonnddiittiioonn
(HF bands only)
If you require critical tuning at any time during trans-
mission, select the tuner sensitive condition. See
p. 55 for selection.
•
AAuuttoommaattiicc ttuunneerr ssttaarrtt
(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
OOppttiioonnaall AATT--118800
AAUUTTOOMMAATTIICC AANNTTEENNNNAA TTUUNNEERR
ooppeerraattiioonn
[TUNER/CALL]
Lights to indicate the AT-180
is turned ON.
[TUNER/CALL]
Flashes to indicate re-tuning
is necessary.
CCAAUUTTIIOONN::
NNEEVVEERR
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.
CONVENIENT
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