Icom AH-4 Instructions

1-1-32 Kamiminami, Hirano-ku, Osaka 547-0003 Japan

A-8295H-1EX-w  Printed in Japan

© 1997–2012 Icom Inc.

Tuning is required for each frequency. 

Be sure to retune 

the antenna before transmitting when you change the fre-

quency— even slightly.

(eg. IC-7000)

Set the desired frequency in an amateur band.

q

 •The AH-4 will not operate on frequencies outside of ham

bands.

Hold down [TUNER/CALL] for 1 seconds.

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 •“

 ” indicator appears while tuning.

Hold down [TUNER/CALL] for 1 second.

“

e

 ” indicator stays ON when tuning is complete.

 •Whentheantennacannotbetuned,“

 ” indicator blinks, 

and the AH-4 is bypassed and the antenna is directly connected 

to the antenna connector on the transceiver.

To manually bypass the AH-4, push [TUNER/CALL].

r

OPERATION

Specifications

D

•Frequencyrange

:3.5–54MHz(withanantennalonger

than 7 m; 23 ft) 

7–54MHz(withtheAH-2b)

•Maximuminputpower

:120W

•Inputimpedance

:50

Ω

•Tuningpowerrequired

:5to15watts

•Ratedvoltage 

:13.8VDC±15% 

(current less than 1 A)

•Usabletemperaturerange :–10°Cto+60°C(+14°Fto+140°F)

•VSWR

:2.0:1orless(exceptantennasa

one half wave or multiple of a one 

half wave in length)

•Weight(approximately)

:1.2kg(2.65lb)

•Dimensions

:172(W)

×69.5(H)×230(D)mm 

(projectionsnotincluded)

 ;6.8(W)

× 2.7(H) ×9.1(D)inches

All specifications are subject to change without notice or obligation.

Options

D

•

OPC-420 

shielded

control

cable

ShieldedcontrolcablehelpsprotectthetransceiverfromRFfeed-

backandextendsseparationbetweentunerandtransceiverupto

10 m. (cable length 10 m; 32.8 ft)

•

AH-2b 

antenna

element

A2.5mlongantennaelementformobileoperationwithAH-4.Fre-

quencycoverage:7–54MHzwiththeAH-4.

SPECIFICATIONS AND OPTIONS

U-bolts

q

  ………………………………………………………2

U-bolt brackets

w

  ……………………………………………2

Flatwashers(M6large)

e

 ……………………………………8

Flatwashers(M6small)

r

 ……………………………………4

Springwashers(M6)

t

  ………………………………………8

Nuts(M6)

y

 ……………………………………………………8

Hexheadbolts(M6

u

× 50) …………………………………4

Self-tappingscrews(A06

i

× 30)  …………………………4

PL-259 connectors

o

 …………………………………………2

!0

Weatherproofcap  …………………………………………1

!1

Rubbervulcanizingtape  …………………………………1

Controlcable*(5m;16.4ft)  …………………………………1

Coaxialcable*(5D-2V:5m;16.4ft) …………………………1

*Not shown in the illustration to the left.

INSTRUCTIONS

HF+50MHzAUTOMATICANTENNATUNER

AH-4

Thank you for purchasing the 

AH-4 HF + 50 MHz AU-

TOMATIC ANTENNA TUNER. The AH-4 matches your 

transceiver to an antenna more than 7 m/23 ft long (3.5–

54MHz),ortheoptionalAH-2b(7–54MHz).

Please read these instructions thoroughly before installing 

and operating the AH-4.

RNEVER operate this tuner without a solid ground. Always 

connect the ground wire to the ground terminal. 

DO NOT use 

the mounting plate as a ground terminal.

NEVERtransmitortunewithoutanantennaconnected.Fail-

ure to use an antenna will damage the tuner.

RHIGH VOLTAGE! NEVER touch the antenna while trans-

mitting or tuning. Place the antenna in a position where you 

are sure it will not be touched.

DANGER!

WIDE TUNING RANGE

❍

 TheAH-4providesreliablematchingfrom3.5MHzto54MHz

whenusingatleasta7m(23ft)antenna;or7MHzto54MHz

when using the AH-2b 

antenna

element

.

AUTOMATIC DIGITAL CONTROL TUNING

❍

 Thebuilt-in8-bitmicroprocessorchoosesthelowestSWRusing

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 auto-

maticallymemorized.Onceafrequencyismemorized,theAH-4

tunes on that frequency in less than 1 second. Note that the AH-4 

doesnotmemorizeafrequencywhichisnormallytunedwithin2.5

seconds.Memoriesareretainedonlywhenthepowerison.

WEATHERPROOF DESIGN

❍

   The AH-4’s tightly sealed plastic case allows convenient mount-

ing virtually anywhere. The AH-4 can be mounted outdoors under 

your antenna.

0.3 W RADIATED POWER

❍

 Radiatedpowerduringtuningislessthan0.3W,minimizinginter-

ference to other stations.

✍

  NOTE: 

 TheAH-4canbeusedwithmostofIcomHFtransceiver,

whichcoversHFthrough50MHzbands.

 However,theIC-706andIC-736canonlybetunedinthe

3.5–30MHzrange.

FEATURES

SUPPLIED ACCESSORIES

Ground terminal

Mounting plate

q

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e

r

t

y

u

i

o

!0

!1

CALCULATION OF UNDESIRABLE ANTENNA LENGTHS

Length of 

half wave

(½ 

λ)

=

300

×

1

Operatingfrequency(MHz)

2

[EXAMPLE]Antenna lengths to avoid when operating at 29.00

MHz

Multiple

of ½ 

λ

=

300 × 1 × (1, 2, 3…) = 5.2, 10.3, 15.5 m

29

2

Fig.6 MOUNTING EXAMPLES

AH-2b+longwire

AH-2b

antenna

element

kit

 (op-

tional)

Long wire

Long wire