The Icom AH-4 is an Automatic Antenna Tuner designed for HF + 50 MHz operation. This device offers automatic tuning capabilities, allowing for efficient impedance matching across a wide range of 3.2 to 320 ohms, with typical tuning times of 2-5 seconds. It features an SO-239 antenna connection and a terminal for ground connection, requiring an antenna length of 7 meters or longer. Operating on 13.8 V DC internal power, it consumes approximately 1.5 A during tuning and about 10 mA in standby. The tuner is built for reliability and ease of use in various environmental conditions, with an operating temperature range of -10°C to +60°C and a humidity rating of 95% RH.

This Service Repair Manual provides comprehensive guidance for the Icom AH-4 Automatic Antenna Tuner. It covers essential information including detailed specifications, internal views, circuit descriptions, and adjustment procedures. The manual also includes a parts list, mechanical disassembly instructions, semiconductor information, board layouts, and block and voltage diagrams. Its purpose is to assist owners, technicians, and mechanics in understanding, maintaining, and repairing the device, ensuring optimal performance and longevity. All content is presented in English for clarity and accessibility.