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9
ANTENNA TUNER OPERATION
2001 NEW
■ Optional external tuner operation
DD
AH-4 HF/50 MHz AUTOMATIC ANTENNA TUNER
The AH-4 matches the IC-7400 to a long wire antenna
more than 7 m/23 ft long (3.5 MHz and above).
•See the AH-4 instruction manual for AH-4 installation and
antenna connection details.
NEVER operate the AH-4 without an antenna wire.
The tuner and transceiver will be damaged.
NEVER operate the AH-4 when it is not grounded.
Transmitting before tuning may damage the trans-
ceiver. Note that the AH-4 cannot tune when using a
1
⁄2 λ long wire or multiple of the operating frequency.
When connecting the AH-4, the antenna connector
assignments are [ANT2] for the internal tuner and
[ANT1] for the AH-4. The antenna indicator in the
LCD displays “EXT” when the AH-4 is connected
and selected.
DD
AH-4 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 or 50 MHz
band.
•The AH-4 may not operate on frequencies outside of
ham bands.
w Push [TUNER] for 1 sec.
•“TUNER” blinks while tuning.
e “TUNE” appears constantly when tuning is com-
plete.
•When the connected wire cannot be tuned, the “TUNE”
indicator goes out, and the AH-4 is bypassed. At that
point the antenna wire connection root is to the trans-
ceiver directly, and not via AH-4 antenna tuner.
r
To bypass the AH-4 manually, push [TUNER].
AH-4 setting example:
R WARNING: HIGH VOLTAGE!
NEVER touch the antenna element while tuning or
transmitting.
For mobile operation
For outdoor operation
Long wire
Optional AH-2b
antenna element
Coaxial cable (from AH-4)
ANT1
Transceiver
Ground
AH-4
Control cable
Long wire or optional AH-2b
• Connecting the AH-4
IC-7400.qxd 02.4.2 11:35 Page 76
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