Icom IC-735 - Circuit Description; Main Unit; Attenuator (ATT), Reception Band-Pass Filter (BPF), and Band-Signal DC Amplifier; NB Circuit

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Table of Contents3
Specifications5
Installation and Connections6
Antenna6
Microphone6
CW Key6
Power Supply7
For AC Operation with the PS-557
For AC Operation with Other Manufacturers AC Power Supply7
Ground7
System Interconnections8
Linear Amplifier8
Using the IC-2KL Linear Amplifier8
Antenna Tuner8
Using the AT-1509
Using the IC-AT100/5009
RTTY Terminal Unit9
Using MIC/Phone Jacks9
Using ACC (1) Connector10
RTTY Operation10
Frequency Readout10
Receive Antenna10
Rear Panel Connections11
Accessory Socket Connections12
Acc (1, 2)12
Band Control Voltage Chart12
Option Installations13
IC-EX243 Electronic Keyer Unit13
Installing Optional Electronic Keyer Unit13
Fl-32, FL-63 CW Narrow Filters13
UT-30 Tone Encoder Unit14
Subaudible Tone Encoder Programming Chart14
Assembly Procedure14
Circuit Description15
Main Unit15
Attenuator (ATT), Reception Band-Pass Filter (BPF), and Band-Signal DC Amplifier15
NB Circuit15
9 Mhz Band if Amplifier and Notch Filter16
455 Khz if Amplifier16
Configuration of the PBT16
PBT Operation of this Unit16
SSB and CW Detection Circuit17
FM, am Detection Circuit17
AGC Circuit17
All-Mode Squelch Circuit17
AF Amplifier18
CW Key Circuit Side Tone18
Vox Break-In Circuit18
RF and SWR Circuit18
Power Supply Circuit19
Timing Diagram of CW Operation19
PLL Unit20
PLL Section20
Frequencies of the PLL Section am Mode20
PLL Block Diagram20
Reference Oscillation Circuit21
Main Loop21
Ics for the PLL21
Vco21
LO in the Loop22
PLL Reference Frequency and Marker Circuit22
Sub Loop (LPL)22
2Nd lo Output23
Determining the N-Data23
MIC Amplifier Circuit23
Logic Section23
CPU Port Allocations24
Reset Circuit25
CPU Reset Circuit25
Sensor and MIC Up/Down Circuit26
Sensor Circuit27
MIC Up/Down Circuit27
4 Times Speed27
Truth Tables27
PLL and Display Data28
Frequency Ranges28
BPF, LPF, VCO, and LDA Classifications29
Shift in PLL Data According to Mode29
Displayed Frequency: Constant29
LCD Display29
Front Unit30
Rit Circuit30
Send Circuit30
Dimmer Circuit31
PA Unit31
Protection Circuit31
Filter Unit31
Die-Cast Heat Sink32
Theory of Matrix Function33
Front Panel Operation (Matrix Input)34
Xmit34
Description of Additional Matrix Input37
Voltage/Circuit Diagrams38
Front Unit and Wiring Diagram38
Main Unit Diagram40
PL Unit42
PA Unit (Power Amplifier)44
PA Unit (Filter)45
Front Unit Dimmer Circuit46
Sensor Unit46
Maintenance and Adjustment47
Preparation before Servicing47
General Adjustment48
PLL Adjustment50
Transmitter Adjustment54
Rear Panel59
Receiver Adjustment61
Adjustment Locations63
Main Unit Side63
Bottom View63
Side View64
PL Unit Side64
Top View64
Lithium Battery Replacement65
Fuse Replacement65
How to Remove PA Cover65
Troubleshooting66
Inside Views68
PA Unit (Power Amplifier and Filter)70
Disassembly and Assembly Diagrams72
Front Panel Disassembly72
Top Cover, Bottom Cover, PA Disassembly74
Front Sub-Chassis Connector Assembly75
Main Unit Connector Assembly76
PL Unit Connector Assembly77
PA Unit Connector Assembly78
Board Layouts79
Block Diagram87
IC Ratings88
Pd4066Bc89
Maximum Ratings89
Pin Connection89
PD7225G (LCD Controller/Driver)89
Nd487C1-3R90
Ba61890
PC577H (FM-IF Amplifier)91
PC1037 (Double Balanced Modulator)91
NJM4558D (Dual Low Noise Amp)92
Njm072082D92
HD10551 (Pre-Scaler for Digital Tuning System)93
PC1181H (Audio Power Amplifier)93
M5218L (Dual Audio Amplifier)94
A78M0894
BA222 (Monolithic Timer)95
Pd4001Bc95
Logic Diagram95
Pd4069Ubc96
Equivalent Circuit Diagram96
Hd63A01V196
Pd4510Bc97
Pd4021Bc97
Pd82C43C98
DAN401 (High-Speed Switching Diode Array)98
PD2834C (PLL Frequency Synthesizer)99
Pb555C99
SN76514 (Circuit Type Balanced Mixer)100
A78M05C100
PC1037H (Double Balanced Modulator)101
SN4LS90N (Decode Counter)101
Optional Units102
Other Options Available102
Parts List103
ICOM CI-V Communication Interface System126
Features126
Theory of Operation126
CPU I/O Port and Input Matrix126
Terminal Descriptions127
Serial Data127
Typical Command Message128
Csma/CD128
Control Code128
Collision Detection131
Operation with the IC-735131
Control Code Operation131
IC-735 Baud Rates132
Control Code [00] (Set Frequency-Transceive)132
Control Code [01] (Set Mode-Transceive)133
Control Code [02] (Tuning Range Request)134
Control Code [03] (Frequency Request)134
Control Code [04] (Mode Request)135
Control Code [05] (Set Frequency)135
Control Code [06] (Set Mode)137
Control Code [07]138
Control Code [08] (Set Memory Channel)139
Control Code [09] (Memory Write)140
Control Code [0A]141
IC-735 Schematic Diagram142

Icom IC-735 - Circuit Description; Main Unit; Attenuator (ATT), Reception Band-Pass Filter (BPF), and Band-Signal DC Amplifier; NB Circuit

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