Icom IC-756 - Manual (Page 43)

• AH-3 HF AUTOMATIC ANTENNA TUNER
The AH-3 matches the IC-756 to a long wire antenna
more than 3 m/10 ft long (3.5 MHz and above) or
more than 12 m/40 ft long (1.8 MHz and above).
• See p. 18 for the transceiver and AH-3 connection.
• See the AH-3 instruction manual for AH-3 installation and
antenna connection details.
AH-3 setting example:
R WARNING: HIGH VOLTAGE!
NEVER touch the antenna element while tuning or
transmitting.
NEVER operate the AH-3 without an antenna wire.
The tuner and transceiver will be damaged.
NEVER operate the AH-3 when it is ungrounded.
Transmitting before tuning may damage the trans-
ceiver. Note that the AH-3 cannot tune when using a
1 ⁄
2
λ
long wire or multiple of the operating frequency.
NOTE: When connecting the AH-3, the antenna
connector assignments are [ANT2] for the internal
tuner and [ANT1] for the AH-3. The antenna indi-
cator in the LCD displays “ANT1(EXT)” when the
AH-3 is connected and selected.
NOTE: The AH-3 can be used for HF bands only. It
cannot be used for the 50 MHz band.
• AH-3 operation
Tuning is required for each frequency. Be sure to
re-tune the antenna before transmitting when you
change the frequency—even slightly.
q Set the desired frequency in an HF band.
- The AH-3 will not operate on frequencies outside of
ham bands.
w Push [TUNER] for 2 sec.
- The [TUNER] light blinks while tuning.
e The [TUNER] light lights constantly when tuning is
complete.
- When the connected wire cannot be tuned, the
[TUNER] light goes out, the AH-3 is bypassed and the
antenna wire is connected to the antenna connector on
the transceiver directly.
r To bypass the AH-3 manually, push [TUNER].
40
4
RECEIVE AND TRANSMIT
When using an external antenna tuner such as the
IC-4KL’s tuner or IC-AT500 with a linear amplifier, tune
with the external antenna tuner, while the internal
tuner is turned OFF. After tuning is completed, turn
the internal tuner ON. Otherwise, both tuners tune si-
multaneously and correct tuning may not be obtained. See the instruction manual included with each an-
tenna tuner for their respective operations.
■ Optional external tuner operation
For mobile operation
For outdoor operation
Long wire
Optional AH-2b
antenna element
• ANTENNA TUNER OF THE IC-4KL or IC-2KL/IC-AT500
[TUNER] switch