Name: Icom IC-271A
Brand: Icom
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Table of Contents2
Specifications3
General3
IC-271 Versions Available4
Control Functions5
Front Panel5
Rear Panel Connections (IC-271 A/E)8
Accessory Socket Connections8
Outside View8
Rear Panel Connections (IC-271 H)9
Controls under the Access Cover10
Inside Views11
Top View (IC-271 A/E)11
Bottom View (IC-271 A/E)12
PLL (HPL) Unit (Located under the Logic Unit)12
Top View (IC-271 H)13
Bottom View (IC-271 H)14
Block Diagrams15
IC-271 A/E15
IC-271 A/H17
Circuit Description19
Receiver19
RF Circuit (RF-YGR Unit)19
Intermediate Frequency Circuit (Main Unit)19
BFO Circuit (Main Unit)20
Noise Blanker Circuit (Main Unit)20
Audio and Squelch Circuits (Main Unit)20
S-RF Meter Circuit (Main Unit)20
Transmitter21
Audio Amplifier and Limiter Circuits (Main Unit)21
Buffer Amplifier Circuit (Main Unit)21
Vox Control and CW Break-In Circuits (Main Unit)21
Automatic Level Control (ALC) Circuit (Main Unit)22
Transmitter Mixer and Buffer Amplifier (RF-YGR Unit)22
Power Amplifier22
ALC and Power Limiter (IC-271 H)22
Power Amplifier Cooling System (IC-271 H)23
PLL (HPL) Unit23
Reference Oscillator and lo Circuits23
HPL Unit Block Diagram23
Mixer Amplifier Circuit24
Prescaler Circuit24
Loop Filter24
Sub-Loop Circuit24
Mode and Frequency Step Circuits25
CPU Port Allocations25
CPU Memory Map25
Auto Tuning Rate(Ts), Program Scan (Ps), MIC Up/Down Circuits26
Input/Output Control IC Port Allocations26
Matrix Circuit27
Display and PLL Strobe28
Display Data29
Mode, Memo, VFO, Scan and Rit Displays29
Scan Circuit30
MIC Up/Down Circuit30
N Data31
Tone Generator31
Filter Unit (IC-271 H)31
RF Meter Detector, SWR Detector, Protector Circuits32
CSS and DC-DC Units32
CSS (Center Scanning Stop) Circuit32
Display Unit32
Display Unit Circuit33
Power Supply Switching Circuit (Main Unit)33
Transmit/Receive Switching Circuit (RF-YGR Unit)33
Terminal Circuit Board (IC-271 H)33
Mechanical Parts and Disassembly34
Frame Disassembly (IC-271 A/E)34
Frame Disassembly (IC-271 H)36
Front Panel Disassembly38
Front Sub-Chassis Connector Assembly40
Main Board Connector Assembly (IC-271 A/E)41
Logic/Pll Board Connector Assemblies (IC-271 A/E)42
Logic/Pll Board Connector Assemblies (IC-271 H)43
Rear Panel Connector Assembly (IC-271 A/E)44
Rear Panel Connector Assembly (IC-271 H)45
Rear Panel Parts Disassembly (IC-271 A/E)46
Rear Panel Parts Disassembly (IC-271 H)47
Maintenance and Adjustment49
Preparation before Servicing49
PLL Adjustment50
Main Unit51
HPL Unit52
Transmitter Adjustment53
Tone Unit55
RF YGR Unit58
PA Unit (IC-271 H)59
Logic Unit60
Receiver Adjustment61
CSS Unit62
RF-YGR Unit64
VR Unit64
Circuit Diagrams/Voltage Charts65
EF Unit65
Terminal Unit (IC-271 H)81
Tone Unit (#02, 05)82
Transistor Voltage Chart83
IC Voltage Chart84
Board Layouts (IC-271 H)85
IC Specifications94
Parts List107
IC-271 A/E Schematic Diagram128
IC-271 H Schematic Diagram138

Brand	Icom
Model	IC-271A
Category	Transceiver
Language	English

Icom IC-271A Service Manual

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Icom IC-271A Specifications

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