Icom AT-140, AT-130E, AT-130 Service Manual

HF AUTOMATIC ANTENNA TUNER

AT-130
AT-130E
AT-140

SERVICE
MANUAL

MODEL

AT-130

AT-130E

AT-140

SYMBOL

USA
USA-1
USA-2

EUR
EUR-1
USA-3

VERSION

U.S.A.
U.S.A.-1
U.S.A.-2

Europe

Europe-1

U.S.A.-3

INTRODUCTION

This service manual describes the latest service information
for the

AT-130/AT-130E/AT-140 HF AUTOMATIC ANTENNA

TUNER at the time of publication.

DANGER

NEVER connect the antenna tuner to an AC outlet or to a DC

power supply that uses more than 16 V. This will ruin the
antenna tuner.

DO NOT expose the antenna tuner to rain, snow or any liq­uids.

DO NOT reverse the polarities of the power supply when
connecting the antenna tuner.

ORDERING PARTS

Be sure to include the following four points when ordering
replacement parts:

1. 10-digit order numbers

2. Component part number and name

3. Equipment model name and unit name

4. Quantity required

<SAMPLE ORDER>

1140003000 IC

µPD78212CW

AT-130 TUNER UNIT 5 pieces

8810000660 Screw PH M4

×12 SUS AT-130 Top case 10 pieces

Addresses are provided on the inside back cover for your
convenience.

REPAIR NOTES

1. Make sure a problem is internal before disassembling the
antenna tuner.

2.

DO NOT open the antenna tuner until the antenna tuner
is disconnected from its power source.

3. DO NOT force any of the variable components. Turn
them slowly and smoothly.

4.

DO NOT short any circuits or electronic parts. An insu­lated tuning tool MUST be used for all adjustments.

5. DO NOT keep power ON for a long time when the anten­na tuner is defective.

6.

READ the instructions of test equipment thoroughly
before connecting equipment to the antenna tuner.

To upgrade quality, any electrical or mechanical parts and
internal circuits are subject to change without notice or
obligation.

Icom, Icom Inc. and are registered trademarks of Icom Incorporated (Japan) in the United States, the United Kingdom,
Germany, France, Spain, Russia and/or other countries.

TABLE OF CONTENTS

SECTION 1 SPECIFICATIONS

SECTION 2 INSIDE VIEW

SECTION 3 CIRCUIT DESCRIPTION

SECTION 4 ADJUSTMENT PROCEDURES

SECTION 5 PARTS LIST

SECTION 6 MECHANICAL PARTS

SECTION 7 SEMI-CONDUCTOR INFORMATION

SECTION 8 BOARD LAYOUTS

8 - 1 TUNER UNIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 - 1

8 - 2 MANUAL UNIT (AT-130E ONLY) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 - 2

SECTION 9 BLOCK DIAGRAM

SECTION 10 VOLTAGE DIAGRAM

1 - 1

SECTION 1 SPECIFICATIONS

‘‘

GENERAL

• Number of memory channels : 45

• Frequency range : 1.6 MHz to 30 MHz with a 7 m (23 ft) or longer antenna element

• Maximum input power : 150 W PEP
100 W continuous

• Input impedance : 50 Ω

• Minimum operating input power : 5 to 15 W

• Automatic tuning time :

(General) Approx. 2 to 3 sec. (max. 15 sec.)
(Returning to a memorized frequency) Approx. 1 sec.

• Tuning accuracy (VSWR) : Less than 2.0 : 1
(after tuning; except for multiples of

1

⁄2 λ)

• Antenna required : Marconi-type with suitable RF ground

(More than 7 m (23 ft) is suggested)

• Power supply required : DC 13.6 V ± 15 % (supplied from HF transceiver)

• Current drain : Less than 2 A

• Usable temperature range : –30˚C to +60˚C; –22˚F to +140˚F

• Dimensions

(projections not included) : 230(W) × 80(H) × 340(D) mm

9

3

⁄32(W) × 33⁄32(H) × 1313⁄32(D) in

• Case construction : Weatherproof

• Weight :

(AT-130/AT-140) Approx. 2.5 kg; 5 lb 8 oz
(AT-130E) Approx. 2.7 kg; 6 lb

• Control cable : OPC-420 (For [IC-77/78])
OPC-566 (For [IC-M700PRO], [IC-M710/RT])
OPC-1147 (For [IC-M802])
OPC-1186 (For [IC-F7000])

All stated specifications are subject to change without notice or obligation.

2 - 1

SECTION 2 INSIDE VIEW

+5V regulator
(IC8: TA7805S)

Comparator
(IC10: TA75393S)

Mounting plate

Antenna cable receptacle

Dip switch
(SW3: SSGM18049A)

Dip switch
(SW4: SSGM17012A)

Dip switch
(SW5: SSGM18049A)

LED's
(DS1-DS23: EL204HD)

Antenna terminal

Mode switch
(SW1: MS621C)

Control cable
receptacle

CPU
(IC1: mPD78212CW-613)

Ground terminal

Water drain screw

+5V regulator
(IC8: TA7805S)

Comparator
(IC10: TA75393S)

Mounting plate

Antenna cable receptacle

Dip switch
(SW3: SSGM18049A)

Dip switch
(SW4: SSGM17012A)

Dip switch
(SW5: SSGM18049A)

LED's
(DS1-DS23: EL204HD)

Antenna terminal

Mode switch
(SW1: MS621C)

Control cable
receptacle

CPU
(IC1: µPD78212CW-613)

Ground terminal

Water drain screw

Photo: AT-140

3 - 1

SECTION 3 CIRCUIT DESCRIPTION

3-1 GENERAL

An 8-bit microprocessor controls the AT-130/AT-130E/AT-

140. The tuner matches the antenna system to the trans­ceiver by using four kinds of detector circuits. These circuits
are:

(1) FORWARD POWER DETECTOR
(2) SWR DETECTOR
(3) PHASE DETECTOR
(4) IMPEDANCE DETECTOR

Detailed descriptions of each circuit as follows.

• GENERAL

3-2 FORWARD (FWD) POWER DETECTOR

CIRCUIT

This circuit ensures the input power from the transceiver is
low enough to be handled by the attenuator within the tuner.

In the TUNER UNIT, L1 and D1 detects the RF input current.
C2 and C3 divide the detected voltage and feed it to IC10a.

3-3 SWR DETECTOR CIRCUIT

The reflected power from the antenna system provides a
detection voltage.

The voltage doubler, consisting of D13 and D14, rectifies
this voltage and passes through the voltage divider formed
by R36 and R37.

These SWR data from voltage divider feed into IC1, The
CPU. The CPU controls the setting of the coils and capaci­tors in the matching network.

• FORWARD POWER DETECTOR CIRCUIT • SWR DETECTOR CIRCUIT

3 - 2

3-4 PHASE DETECTOR CIRCUIT

This circuit consists of L2, L3 and IC9. The phase detector’s
purpose is to detect reactance components and provide a
pure resistance.

The output of IC9 is a reference voltage of approximately
4 V when the load of L3 is a pure resistance with no reac­tance. An inductive load produces an output voltage from
IC9 which is lower than the reference voltage, whereas, a
capacitive load produces an output voltage higher than the
reference voltage. IC10a amplifies the output voltage and
passes it to comparator IC10a.

3-5 IMPEDANCE DETECTOR CIRCUIT

The tuner uses an attenuator to reduce the transmit power
to a very low level. The low power minimizes the risk of inter­ference to other stations while matching an antenna to the
transmitter.

The VSWR at the input terminal is usually close to 1:1 even
with a large change of impedance at the attenuator output
due to the 16 dB of isolation between the input and the
matching network.

The circuit uses the constant voltage at D7 and D8 on The
TUNER unit as a reference. If the impedance of the attenu­ator output is higher than 50 Ω, the detected voltage by D11
and D12 is HIGH. If the impedance is lower than 50 Ω, the
voltage is LOW. Both the reference and detected voltages
feed to comparator IC10b.

3-6 LOGIC CIRCUIT

IC1, The CPU, controls the antenna matching network. The
CPU receives +5V through IC8 when DC power is applied to
the tuner. This voltage initializes the CPU. The stored pro­gram in the Read Only Memory (ROM) IC12 sets each relay
to the initial condition.

The tuning program begins only if the START line is at LOW
level. RL1 and RL2 activate when RF power at the input
antenna connector from the transceiver is present at an
appropriate level (See Section 6-2).

The data from the previously described detectors (input RF
power, reflected RF power, phase difference, impedance dif­ference) feed into the CPU. The coil data then passes to
IC4, the capacitor data to IC3 and the control data to IC2
according to the tuning program.

3-8 ANTENNA CURRENT DETECTOR CIRCUIT

(MANUAL UNIT — Europe version only)

On the MANUAL UNIT, L319 detects the antenna current.
D305 rectifies the detected voltage and feed it to J301
through low-pass filter comprising R305, C305 and C306.

• PHASE DETECTOR CIRCUIT

• IMPEDANCE DETECTOR CIRCUIT

• ANTENNA CURRENT DETECTOR CIRCUIT