Page 1
q U-bolts .................................................................. 2
w U-bolt plates ......................................................... 2
e Flat washers (M6 large) ........................................ 8
r Flat washers (M6 small) ....................................... 4
t Spring washers (M6) ............................................ 8
y Nuts (M6) .............................................................. 8
u Hex head bolts (M6 × 50) ..................................... 4
i Self-tapping screws (A0 6 × 30) ........................... 4
o PL-259 connectors ............................................... 2
!0 Weatherproof cap ................................................. 1
!1 Control cable (OPC-136; 5 m)............................... 1
!2 Coaxial cable (5D-2V × 5 m) ................................. 1
INSTRUCTIONS
HF + 50 MHz AUTOMATIC ANTENNA TUNER
AH-4
Thank you for purchasing the AH-4 AUTOMATIC
ANTENNA TUNER. The AH-4 matches your trans-
ceiver to an antenna more than 7 m/23 ft long (3.5
MHz and above).
Please read these instructions thoroughly before installing and operating the AH-4.
RNEVER use this tuner when it is ungrounded. Always
ground the tuner through the ground terminal before
operating. DO NOT use the mounting plates for
grounding.
NEVER transmit or tune without an antenna. Failure to
use an antenna will damage the tuner.
RHIGH VOLTAGE! NEVER touch the antenna while
transmitting or tuning. Place the antenna in a position
where you are sure it will not be touched.
DANGERµ
❍ WIDE TUNING RANGE
The AH-4 provides reliable matching of frequencies
from 3.5 MHz to 54 MHz when using at least a 7 m
(23 ft) antenna; or 7 MHz to 54 MHz when using the
AH-2b
ANTENNA ELEMENT
.
❍ AUTOMATIC DIGITAL CONTROL TUNING
The built-in 8-bit microprocessor chooses the lowest
SWR condition from more than 1,040,000 different
LC (coil/capacitor) combinations.
❍ 45 FREQUENCY MEMORIES FOR FAST TUNING
The LC combinations of 45 previously-used frequencies are automatically memorized in the AH-4. Once
a frequency is memorized, the AH-4 tunes on that
frequency in less than 1 sec. Note that the AH-4
does not memorize a frequency which is normally
tuned within 2.5 sec. Memories are retained only
when the power is on.
❍ WEATHERPROOF DESIGN
The AH-4’s tightly sealed plastic case allows convenient mounting virtually anywhere. The AH-4 can be
mounted outdoors under your antenna.
❍ 0.3 W RADIATED POWER
Radiated power during tuning is less than 0.3 W,
minimizing interference to other stations.
✍ NOTE: 50 MHz tuning is possible with the IC-729*,
IC-706MKII, IC-746 and IC-756; the IC-706 and IC736 can only be tuned 3.5–30 MHz.
* Connect a 50 MHz antenna connector for 50 MHz
operation.
FEATURES
SUPPLIED ACCESSORIES
Ground terminal
Mounting plate
u
q
w
i
e
r
t
y
o!0
Page 2
Fig. 2 CABLE CONNECTIONS (ex. IC-706MKII)
Coaxial cable
IC-706MKII rear panel
Control cable
Bottom cover
GND
Top cover
PL-259
connector
Antenna element
AH-2b (optional)
J8
J2
black (GND)
red (DC13V)
white (START)
green (KEY)
GND
✍ NOTE: After inserting the coaxial cable into the AH-
4 top cover, solder the PL-259 connector to the
coaxial cable.
➀ Remove the top cover (Fig. 1).
➁ Install the control cable and coaxial cable (Fig. 1).
➂ Connect and solder the PL-259 connector to the
coaxial cable (Fig. 4).
➃ Connect the control cable to the AH-4 (Fig. 2).
➄ Connect the GND cable to the AH-4 (Fig. 3).
➅ Replace the top cover.
➆ Mount the AH-4 in the desired location; on an an-
tenna pole, in your vehicle’s trunk, etc. (Fig. 5).
➇ Connect an antenna to the AH-4 (Fig. 6).
➈ Connect the control cable and the coaxial cable to
the transceiver.
INSTALLATION
Fig. 1 COVER REMOVAL AND CABLE
INSTALLATION
➀ Remove 8 screws from the top cover and remove
the cover.
➁ Loosen the screws on both cable clamps. If de-
sired, install a strain relief insert (supplied) corresponding to the diameter of the cable.
➂ Install the coaxial cable through the top cover
cable clamp.
➃ Install the control cable through the bottom cover
cable clamp.
➄ After connecting the coaxial cable and control ca-
bles, tighten the cable clamp screws.
✍ NOTE: For the IC-756
and IC-746, connect
to ANT 1.
Fig. 3 GROUND CONNECTIONS
The transceiver and antenna tuner must have an adequate ground connection. Otherwise, the overall effency of the transceiver and antenna tuner installation
will be reduced. Interference, RF feed back and electrical shocks from other equipment could also occur.
For best results, use the heaviest gauge wire or strap
available and make the connection as short as possible. (see right)
• A long wire connected to the GND terminal as a counterpoise is also acceptable.
• Ground example
Strain relief
insert
Coaxial
cable
Control
cable
Cable
clamp
Copper pipe Metal object Copper screen
To AH-4 GND terminal
Page 3
Fig. 5 MOUNTING THE AH-4
• Mounting on an antenna pole
• Mounting on a flat location
Fig. 6 MOUNTING EXAMPLES
Fig. 4 PL-259 CONNECTOR SOLDERING
➀ Slide the coupling ring over the coaxial cable. Strip
the cable jacket and pull it down to reveal 10 mm
(0.4 in) of braid.
• Soft solder the exposed braid and then pull the jacket
back in place.
➁ Strip the cable as shown at left. Tin the center con-
ductor the entire length of the exposed braid.
➂ Slide the connector body over the cable and sol-
der as shown at left.
➃ Screw the coupling ring onto to the connector
body.
AH-2b + long wire
AH-2b
ANTENNA ELEMENT
KIT (optional)
Nut
AH-4
Spring
washer
Flat
washer
Hex head
bolt
Drill a hole here
(diameter: 6.6–7 mm)
Weatherproof cap
Using the supplied U-bolts
Using self-tapping screws
Using nuts and bolts
30 mm
➀
Coupling ring
➁
➂
➃
(10 mm ≈ 3⁄8 in)
10 mm (soft solder)
Soft
10 mm
solder
1–2 mm
solder solder
Page 4
The AH-4 complies with essential requirements of the
89/336/EEC directive for Electromagnetic Compatibility.
This compliance is based on conformity with the ETSI
specification ETS300 684 (EMC product standard for
Commercially Available Amateur Radio Equipment).
• Frequency range : 3.5–54 MHz (with an antenna longer than 7 m; 23 ft)
7–54 MHz (with the AH-2b)
• Maximum input power : 120 W
• Input impedance : 50 Ω
• Tuning power required : 10 W (5–15 W)
• Rated voltage : 13.8 V DC ±15% (current drain less than 1 A)
• Usable temperature range : –10°C to +60°C (+14°F to +140°F)
• VSWR : 2.0 : 1 or less
(except antennas a half wave or multiple of a half wave in length)
• Weight : 1.2 kg (2.65 lb)
• Dimensions : 172(W) × 69.5(H) × 230(D) mm; 625⁄32(W) × 63⁄4(H) × 91⁄16(D) in
All specifications are subject to change without notice or obligation.
6-9-16 Kamihigashi, Hirano-ku, Osaka 547-0002 Japan
Count on us!
A-8295G-1EX Printed in Japan
Copyright 1997 by Icom Inc.
To ensure the correct impedance match, tune the antenna with the AH-4 each time the operating frequency
is changed.
➀ Set the desired amateur band and frequency of the
transceiver.
➁ Push and hold [TUNER] for 2 sec.
• The [TUNER] light flashes and “CW” appears while tuning.
➂ The [TUNER] light lights constantly when tuning is
complete.
• When the connected wire cannot be tuned, the [TUNER]
light goes out, the AH-4 is bypassed and the antenna
wire is connected to the antenna connector on the transceiver directly.
➃ To bypass the AH-4 manually, push [TUNER].
OPERATION
SPECIFICATIONS
CALCULATION OF UNDESIRABLE ANTENNA
LENGTHS
Length of 300
×
1
(1/2 λ) =
half wave operating frequency (MHz) 2
[EXAMPLE] Antenna lengths to avoid when operat-
ing at 29.00 MHz
Multiple 300 ×1
× (1, 2, 3…) = 5.2, 10.3, 15.5 m=
of 1/2 λ 29 2
• OPC-420 SHIELDED CONTROL CABLE
(cable length 10 m)
Shielded control cable helps protect the transceiver from RF feedback and extends separation between tuner and
transceiver up to 10 m.
• AH-2b
ANTENNA ELEMENT
A 2.5 m long antenna element for mobile operation with AH-4. Frequency coverage: 7–54 MHz with the AH-4.
OPTIONS
USB
Push [TUNER] for 2 sec.
CW
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