ERRATA FOR THE FT-980 OPERATING MANUAL ... 2 SOLDERING AND DESOLDERING TECHNIQUE... 4 GENERAL PERFORMANCE IMPROVEMENT MODIFICATIONS... 7 CAT SYSTEM SERIAL I/O DATA MANUAL ...13 UNIT LOCATIONS ...18 SERVICE AND ALIGNMENT...20 COMPONENT APPLICATIONS...32 FREQUENCY RELATIONSHIPS ...49 SIGNAL PATHS...50 CPU BOARD BLOCK DIAGRAM...54 CONNECTION DIAGRAM ...55 PARTS LAYOUTS, SCHEMATICS, SIGNAL LEVELS AND VOLTAGE CHARTS RF UNIT ...56 IF UNIT ...60 AF UNIT...63 VFO UNIT...66 PLL AND VCO UNITS...69 CPU UNIT ...74 FSK UNIT ...77 LPF AND RELAY UNITS ...79 PROTECTOR UNIT...80 DIAL UNIT ...81 REG UNIT...83 CONTROL UNIT...85 KEY MATRIX UNIT...86 DISPLAY UNITS (A, B and C) ...87 MONITOR UNIT...90 100W PA UNIT...91 10W PA UNIT...92 I00W PS UNIT ...93 J 0W PS UNIT ...94 PI UNIT...95 MISCELLANEOUS UNITS ...96 FIF-80 INTERFACE UNIT...97 FRONT PANEL EXPLODED VIEW...98 REAR PANEL EXPLODED VIEWS...99 PARTS LIST...100 This manual is intended to serve as a technical supplement to the FT-980 Operating Manual. Detailed information regarding functions, installation, interconnections, operation, and installation of options has been provided in the Operating Manual, and is not reprinted herein. Therefore, this Technical Supplement is not intended to serve as an independent reference, but to be used in conjunction with the information provided in the Operating Manual. Because there are nearly eight hundred semiconductor devices in the FT-980 circuit description information is provided in the form of numerous block diagrams and a complete Component Applications list. It is our hope that this manner of providing functional information will prove to be more convenient for the owner and technician than would a lengthy verbal description. Those readers who are not familiar with the basic types of analog and digital circuits that serve as the building blocks of the FT-980 are encouraged to study instructional material, such as that contained in handbooks on amateur radio and digital circuit design, before attempting to understand the design of the FT-980 Each block in the block diagrams represents one such basic circuit, while the Component Applications list provides additional details for each semiconductor. Specific circuit details are provided in the schematic diagrams.