Icom IC-A24 User manual

S-14115HZ-C1-q
July. 2007
VHF AIR BAND TRANSCEVER
iC-a24
iC-a24e
iC-a6
iC-a6e

This service manual describes the latest service information
for the IC-A24/E and IC-A6/A6E VHF AIR BAND
TRANSCEIVER at the time of publication.
NEVER connect the transceiver to an AC outlet or to a DC
power supply that uses more than specified. This will ruin
the transceiver.
DO NOT expose the transceiver to rain, snow or any liquids.
DO NOT reverse the polarities of the power supply when
connecting the transceiver.
DO NOT apply an RF signal of more than 20 dBm (100 mW) to
the antenna connector. This could damage the transceiver’s
front-end.
To upgrade quality, any electrical or mechanical parts and
internal circuits are subject to change without notice or
obligation.
MODEL VERSION WX RX VOR
IC-A24
[USA]
Yes
Yes
[USA-1]
[USA-2]
[GEN]
[CHN] Yes
IC-A24E [EUR] No
[UK] No
IC-A6
[USA]
Yes
No
[USA-1]
[USA-2]
[GEN]
[AUS] No
IC-A6E [EUR] No
[UK]
Be sure to include the following four points when ordering
replacement parts:
1. 10-digit Icom parts numbers
2. Component name
3. Equipment model name and unit name
4. Quantity required
<ORDER EXAMPLE>
1110003491 S.IC TA31136FNG IC-A24 RF UNIT 5 pieces
8820001210 Screw 2438 screw IC-A24 Top cover 10 pieces
Addresses are provided on the inside back cover for your
convenience.
Icom, Icom Inc. and logo are registered trademarks of Icom Incorporated (Japan) in the United States, the United
Kingdom, Germany, France, Spain, Russia and/or other countries.
ORDERING PARTS
1. Make sure the problem is internal before disassembling
the transceiver.
2. DO NOT open the transceiver until the transceiver 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
transceiver is defective.
6. DO NOT transmit power into a Standard Signal
Generator or a Sweep Generator.
7. ALWAYS connect a 50 dB to 60 dB attenuator between
the transceiver and a Deviation Meter or Spectrum
Analyzer when using such test equipment.
8. READ the instructions of test equipment throughly
before connecting a test equipment to the transceiver.
REPAIR NOTES
INTRODUCTION
CAUTION

TABLE OF CONTENTS
SECTION 1 SPECIFICATIONS
SECTION 2 INSIDE VIEWS
SECTION 4 CIRCUIT DESCRIPTION
4 - 1 RECEIVER CIRCUITS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 - 1
4 - 2 TRANSMITTER CIRCUITS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 - 2
4 - 3 PLL CIRCUIT. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 - 3
4 - 4 POWER SUPPLY CIRCUITS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 - 4
4 - 5 CPU PORT ALLOCATIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 - 5
SECTION 5 ADJUSTMENT PROCEDURES
5 - 1 PREPARIOTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5 - 1
5 - 2 SOFT WEAR ADJUSTMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5 - 3
SECTION 6 PARTS LIST
SECTION 7 MECHANICAL PARTS AND DISASSEMBLY
SECTION 8 SEMI-CONDUCTOR INFORMATION
SECTION 9 BOARD LAYOUTS
9 - 1 LOGIC UNIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9 - 1
9 - 2 RF UNIT. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9 - 3
SECTION 10 BLOCK DIAGRAM
SECTION 11 VOLTAGE DIAGRAMS
11 - 1 LOGIC UNIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11 - 1
11 - 2 RF UNIT. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11 - 2

1 - 1
SECTION 1 SPECIFICATIONS
▄GENERAL
• Frequency coverage :TX 118.000–136.975 MHz
RX 108.000–136.975 MHz [IC-A24/E]
118.000–136.975 MHz [IC-A6/E]
WX 161.650–163.275 MHz [USA] only
• Type of emission : 6K00A3E, 16K0G3E (Weather channel;[USA] only)
• Channel spacing : 25 kHz
• Number of memory channels : 20 channels ×10 banks
• Power supply requirement :
Specified ICOM's battery packs (BP-208N, BP-209N, BP-210N, BP-211N)
• External power supply requirement : 11.0 V DC
• Current drain (at 7.2 V DC) :Transmit 1.5 A typical
Receive 300 mA typical (AF max.)
70 mA typical (Stand-by)
• Operating temperature range : –10°C to +60°C; +14°F to +140°F [GEN], [USA], [CHN]
–20°C to +55°C [EUR]
–10°C to +50°C [AUS]
• Frequency stability : ±5 ppm
• Antenna connector : BNC type (50 Ωnominal)
• Dimensions (projections not included) : 129.3(W) × 54(H) ×35.5(D) mm;53⁄32(W) × 21⁄8(H) ×113⁄32(D) in
• Weight (antenna, battery pack not included) : 180 g; 611⁄32 oz (Approx.)
▄TRANSMITTER
• RF output power (at 7.2V DC) : 5.0 W (PEP) typical, 1.5 W (CW) typical [GEN], [USA], [CHN]
3.6 W (PEP) typical, 1.0 W (CW) typical [EUR], [AUS]
• Modulation system : Low level modulation
• Modulation limiting : 70–100% [GEN], [USA], [CHN]
• Modulation depth : 85% [EUR]
85% to 95% [AUS]
• Audio harmonic distortion : Less than 10% (at 60% modulation) [GEN], [USA], [CHN]
Less than 10% (at 85%±3 dB modulation) [EUR]
• Hum and noise ratio : More than 35 dB [GEN], [USA], [CHN]
• Spurious emissions : More than 46 dB [GEN], [USA], [CHN]
(except operating frequency ±62.5 kHz range)
• Harmonic spurious emissions : Less than –36 dBm [EUR]
(except operating frequency ±1 MHz range) Less than –26 dBm [AUS]
• Microphone connector impedance : More than 100 kΩ (3-conductor 2.5(d) mm (1⁄10"))
▄RECEIVER
• Receive system : Double conversion superheterodyne
• Intermediate frequencies : 1st 30.05 MHz
2nd 450 kHz
• Sensitivity :
VOR (AM 6 dB S/N) 0.71 µV typical [IC-A24/E]
COM (AM 6 dB S/N) 0.5 µV typical [GEN], [USA], [CHN]
COM (AM 12 dB SINAD with CCITT filter) 0.71 µV typical [EUR], [AUS]
WX (FM 12 dB SINAD) 0.22 µV typical [USA]
• Threshold squelch sensitivity : Less than 1 µV (AM)
Less than 0.45 µV (FM for WX channel) [USA]
• Selectivity : More than 7.5 kHz/6 dB, Less than 25 kHz/60 dB
except [AUS]
More than 60dB [AUS]
• Spurious response rejection ratio : More than 60 dB (AM), More than 30 dB (FM)
[GEN], [USA], [CHN]
More than 70 dB (AM) [EUR]
More than 60 dB (AM) [AUS]
• Audio output power (at 7.2V DC) :500 mW typical
(at 10% distortion with an 8 Ωload, 30% modulation)
• Hum and noise : More than 40 dB at 30% modulation [GEN], [USA], [CHN]
More than 40 dB at 90% modulation [EUR]
More than 30 dB [AUS]
• External speaker connecter : 3-conductor 3.5(d) mm (1⁄8")/ 8 Ω
Specifications are measured in accordance with FCC Part87 ([USA]], [GEN], [CHN]), EN300 676 ([EUR], [UK]) or AS/NZS 4583:1999 ([AUS])
All stated specifications are subject to change without notice or obligation.

9 - 1
SECTION 9 BOARD LAYOUTS
• LOGIC UNIT (TOP VIEW)
PWR F CLR ANL 121.5
3
2
1
6
5
4
9
8
7
MR
0
ENT
SQL
DS2DS3
DS5
DS6 DS7
DS8
DS9
DS10
MC1
H0H5H10H15H20H25H30H35H40H45H50H55H60H65H70H75
H80H85H90
V0 V5 V10 V15 V20 V25 V30 V35 V40 V45

1-1-32, Kamiminami, Hirano-ku, Osaka 547-0003, Japan S-14115HZ-C1-q
© 2004–2007 Icom Inc.

SERVICE
MANUAL

INTRODUCTION
This service manual describes the latest service information
for the IC-A24/E/IC-A6/E VHF AIR BAND TRANSCEIVER
at the time of publication.
DANGER
NEVER connect the transceiver to an AC outlet or to a DC
power supply that uses more than 11.5 V. This will ruin the
transceiver.
DO NOT expose the transceiver to rain, snow or any liquids.
DO NOT reverse the polarities of the power supply when
connecting the transceiver.
DO NOT apply an RF signal of more than 20 dBm (100
mW) to the antenna connector. This could damage the
transceiver’s front end.
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>
1110003490 S.IC TA31136FN IC-A24 RF UNIT 5 pieces
8810009560 Screw PH BT M2×6 ZK IC-A24 CHASSIS 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 transceiver.
2. DO NOT open the transceiver until the transceiver 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 transceiver is defective.
6. DO NOT transmit power into a signal generator or a sweep generator.
7. ALWAYS connect a 50 dB to 60 dB attenuator between the transceiver and a deviation meter or spectrum analyzer when
using such test equipment.
8. READ the instructions of test equipment thoroughly before connecting equipment to the transceiver.
To upgrade quality, any electrical or mechanical parts and
internal circuits are subject to change without notice or
obligation.
MODEL VERSION SYMBOL
IC-A24
U.S.A. USA
General GEN
U.S.A.-1 USA-1
U.S.A.-2 USA-2
IC-A24E Europe EUR
IC-A6
U.S.A. USA
General GEN
U.S.A.-1 USA-1
U.S.A.-2 USA-2
IC-A6E Europe EUR
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.
IC-A24 IC-A6

TABLE OF CONTENTS
SECTION 1 SPECIFICATIONS
SECTION 2 INSIDE VIEWS
SECTION 4 CIRCUIT DESCRIPTION
4 - 1 RECEIVER CIRCUITS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 - 1
4 - 2 TRANSMITTER CIRCUITS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 - 2
4 - 3 PLL CIRCUIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 - 3
4 - 4 POWER SUPPLY CIRCUITS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 - 4
4 - 5 CPU PORT ALLOCATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 - 5
SECTION 5 ADJUSTMENT PROCEDURES
5 - 1 PREPARIOTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5 - 1
5 - 2 SOFT WEAR ADJUSTMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5 - 3
SECTION 6 PARTS LIST
SECTION 7 MECHANICAL PARTS AND DISASSEMBLY
SECTION 8 SEMI-CONDUCTOR INFORMATION
SECTION 9 BOARD LAYOUTS
9 - 1 LOGIC UNIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9 - 1
9 - 2 RF UNIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9 - 3
SECTION 10 BLOCK DIAGRAM
SECTION 11 VOLTAGE DIAGRAMS
11 - 1 LOGIC UNIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11 - 1
11 - 2 RF UNIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11 - 2

SECTION 1 SPECIFICATIONS
1 - 1
▄GENERAL
• Frequency coverage :TX 118.000–136.975 MHz
RX 108.000–136.975 MHz*1
WX 161.650–163.275 MHz*2
*1: IC-A24/E only. IC-A6/E: 118.000–136.975 MHz
*2: [USA] only
• Type of emission : 6K00A3E, 16K0G3E (Weather channel;[USA] only)
• Channel spacing : 25 kHz
• Number of memory channels : 20 channels ×10 banks
• Power supply requirement : Specified ICOM's battery pack BP-209N, BP-210N, BP-211N
• External power supply requirement : 11.0 V DC
• Current drain (at 7.2 V DC) :Transmit 1.5 A typical
Receive 300 mA typical (AF max.)
70 mA typical (Stand-by)
• Operating temperature range : –10°C to +60°C; +14°F to +140°F [GEN], [USA]
–20°C to +55°C [EUR]
• Frequency stability : ±5 ppm
• Antenna connection : BNC type (50 Ωnominal)
• Dimensions (projections not included) : 129.3(W) × 54(H) ×35.5(D) mm; 53⁄32(W) × 21⁄8(H) ×113⁄32(D) in
• Weight (without antenna, battery pack) : 180 g; 611⁄32 oz (Approx.)
▄TRANSMITTER
• RF output power (at 7.2V DC) : 5.0 W (PEP) typical, 1.5 W (CW) typical [GEN], [USA]
3.6 W (PEP) typical, 1.0W (CW) typical [EUR]
• Modulation system : Low level modulation
• Modulation limiting : 70–100% [GEN], [USA]
• Modulation depth : 85% [EUR]
• Audio harmonic distortion : Less than 10% (at 60% modulation) [GEN], [USA]
Less than 10% (at 85%±3 dB modulation) [EUR]
• Hum and noise ratio : More than 35 dB [GEN], [USA]
• Spurious emissions : More than 46 dB [GEN], [USA]
(except operating frequency ±62.5 kHz range)
• Harmonic spurious emissions : Less than –36 dBm [EUR]
(except operating frequency ±1 MHz range)
• Microphone connector : 3-conductor 2.5(d) mm (1⁄10")/more than 100 kΩ
▄RECEIVER
• Receive system : Double conversion superheterodyne system
• Intermediate frequencies : 1st 30.05 MHz
2nd 450 kHz
• Sensitivity :
VOR (AM 6 dB S/N) 0.71 µV typical [IC-A24/E]
COM (AM 6 dB S/N) 0.5 µV typical [GEN], [USA]
COM (AM 12 dB SINAD with CCITT filter) 0.71 µV typical [EUR]
WX (FM 12 dB SINAD) 0.22 µV typical [USA]
• Threshold squelch sensitivity : Less than 1 µV (AM)
Less than 0.45 µV (FM for weather channel)
• Selectivity : More than 7.5 kHz/–6 dB
Less than 25 kHz/–60 dB
• Spurious response rejection ratio : More than 60 dB (AM), More than 30 dB (FM) [GEN], [USA]
More than 70 dB (AM) [EUR]
• Audio power output (at 7.2V DC) :500 mW typical
(at 10% distortion with an 8 Ωload, 30% modulation)
• Hum and noise : More than 40 dB at 30% modulation [GEN], [USA]
More than 40 dB at 90% modulation [EUR]
• Ext. speaker connection : 3-conductor 3.5(d) mm (1⁄8")/ 8 Ω
Specifications are measured in accordance with FCC Part87 / EN300 676.
All stated specifications are subject to change without notice or obligation.

1-1-32, Kamiminami, Hirano-ku, Osaka 547-0003, Japan S-14115HZ-C1
C 2004 Icom Inc.

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