I Optional External Tuner Operation - Icom IC-7400 Instruction Manual

I Optional external tuner operation

D D 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
λ long wire or multiple of the operating frequency.
1
⁄
2
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.
D D
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].
• Connecting the AH-4
Coaxial cable (from AH-4)
ANT1
Transceiver
Control cable
AH-4 setting example:
For mobile operation
For outdoor operation
R WARNING: HIGH VOLTAGE!
NEVER
transmitting.
[TUNER]
AH-4
Ground
ANTENNA TUNER OPERATION
Optional AH-2b
antenna element
Long wire
touch the antenna element while tuning or
Long wire or optional AH-2b
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