Icom IC-T81 SM free download

File name IC-T81_SM.pdf

SERVICE MANUAL MULTIBAND FM TRANSCEIVER INTRODUCTION This service manual describes the latest service information for the IC-T81A/E at the time of publication. MODEL VERSION SYMBOL U.S.A. USA-1 IC-T81A Australia AUS S.E.Asia SEA Europe EUR IC-T81E U.K. UK Italy ITA To upgrade quality, all electrical or mechanical parts and internal circuits are subject to change without notice or obligation. DANGER NEVER connect the transceiver to an AC outlet or to a DC power supply that uses more than 16 V. Such a connection could cause a fire hazard and/or electric. DO NOT expose the transceiver to rain, snow or any liquids. DO NOT reverse the polarities of the power supply when connecting the transceiver. DO NOT apply an RF signal of more than 20 dBm (100mW) to the antenna connector. This could damage the trans- ceiver's front end. ORDERING PARTS Be sure to include the following four points when ordering replacement parts: 1. 10-digit order numbers 2. Component part number and name 3. Equipment model name and unit name 4. Quantity required 1130009370 S.IC TB31242FN IC-T81A/E RF UNIT 1 pieces 8810008990 Screw PH BT M2x10 ZK IC-T81A/E Chassis 10 pieces Addresses are provided on the inside back cover for your convenience. REPAIR NOTES 1. Make sure a problem is internal before disassembling the transceiver. 2. DO NOT open the transceiver until the transceiver is disconnected from its power source. 3. DO NOT force any of the variable components. Turn them slowly and smoothly. 4. DO NOT short any circuits or electronic parts. An insulated turning tool MUST be used for all adjustments. 5. DO NOT keep power ON for a long time when the transceiver is defective. 6. DO NOT transmit power into a signal generator or a sweep generator. 7. ALWAYS connect a 40 dB to 50 dB attenuator between the transceiver and a deviation meter or spectrum analyzer when using such test equipment. 8. READ the instructions of test equipment thoroughly before connecting equipment to the transceiver. TABLE OF CONTENTS SECTION 1 SPECIFICATIONS SECTION 2 INSIDE VIEWS SECTION 3 DISASSEMBLY INSTRUCTIONS SECTION 4 CIRCUIT DESCRIPTION 4-1 RECEIVER CIRCUITS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-1 4-2 TRANSMITTER CIRCUITS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-3 4-3 PLL CIRCUITS . . . . . . . . . . . . . . . . . . . . . . . . . .