Table Of Contents - Icom IC-271A Maintenance Manual

Table of Contents

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