This service manual contains information relative to the theoretical, physical, mechanical and electrical characteristics of the IC-4GA GAT/ GE UHF FM Transceiver ECTION 1 SPECIFICATIONS... 1-1 SECTION 2 OUTSIDE AND INSIDE VIEWS ... 2-1-4 2-1 FRONT AND SIDE PANELS ... 2-1 2-2 TOP PANEL ... 2-2 2-3 FUNCTION DISPLAY... 2-2 2-4 MAIN UNIT... 2-3 2-5 RF UNIT ... 2-4 2-6 SPEAKER AND DTMF UNITS... 2-4 SECTION 3 BLOCK DIAGRAM... 3-1 SECTION 4 CIRCUIT DESCRIPTION... 4-1-7 4-1 Receiver CIRCUITS ... 4-1 4-2 Transmitter CIRCUITS... 4-2 4-3 PLL CIRCUITS ... 4-3 4-4 Power Supply CIRCUITS ... 4-4 4-5 OTHER CIRCUITS ... 4-4 4-6 CPU (IC501) PORTALLOCATION ... 4-6 4-7 MATRICES ... 4-7 SECTION 5 MECHANICAL PARTS AND DISASSEMBLY ... 5-1-2 SECTION 6 ADJUSTMENT PROCEDURES... 6-1-4 6-1 PLL ADJUSTMENT... 6-1 6-2 Receiver ADJUSTMENT... 6-2 6-3 Transmitter ADJUSTMENT... 6-3 SECTION 7 BOARD LAYOUTS ... 7-1-9 7-1 INTERCONNECTION ... 7-1 7-2 LOGIC-A UNIT ... 7-2 7-3 LOGIC-B UNIT... 7-3 7-4 RF UNIT ... 7-4 7-5 MAIN UNIT... 7-6 7-6 OTHER UNITS... 7-8 SECTION 8 VOLTAGE DIAGRAM... 8-1-3 8-1 LOGIC UNIT ... 8-1 8-2 RF UNIT ... 8-2 8-3 MAIN UNIT... 8-3 SECTION 9 PARTS LIST... 9-1-5