Introduction
This service manual provides detailed technical information for the Icom IC-M604 VHF Marine Transceiver. It covers specifications, internal component views, disassembly procedures, circuit descriptions, and parts lists, essential for maintenance and repair.
Key Features and Specifications
The IC-M604 is a VHF marine transceiver designed for reliable communication at sea. Key specifications include:
- Frequency Coverage: 156.025-157.425 MHz (TX), 156.050-163.275 MHz (RX)
- Modes: 16K0G3E (FM) / 16K0G2B (DSC)
- Power Supply: 13.8 V DC ±15%
- Output Power: 25 W (High), 1 W (Low)
- Dimensions: 220(W) x 110(H) x 109.4(D) mm
- Weight: 1400 g
Service Information
The manual details the internal structure of the IC-M604, including the Main Unit, Logic Unit, and optional accessories like the HM-157 microphone. It provides step-by-step instructions for disassembling various components, such as the front unit, rear panel, logic unit, main unit, and AF unit.
Circuitry Explained
In-depth explanations are provided for the transceiver's circuitry, including:
- Receiver Circuits: Antenna switching, RF amplification, 1st mixer and IF stages, 2nd IF and demodulator circuits, AF amplifier, and squelch circuits.
- Transmitter Circuits: Microphone amplifier, modulation, pre-drive and YGR amplifiers, power amplifier, and APC (Automatic Power Controller) circuits.
- PLL Circuits: Details on how the Phase-Locked Loop system ensures stable transmit and receive frequencies.
For detailed schematics and component identification, refer to the respective sections within the full manual.
