The Icom IC-M700, originally a 150-watt marine HF SSB radiotelephone from the 1980s

Many users modify the radio to work with Pactor modems for data services like Sailmail. This often involves installing a dedicated lead with a DIN plug that intercepts PTT, Line In, and Line Out signals inside the unit. Performance & Usability Improvements Split Mode Toggle:

• Procedure: Locate the ALC trimmer pot (VR1 on the PA unit). Transmit into a dummy load with a low drive level. Monitor output power on a wattmeter. Adjust VR1 until the radio limits at 100W maximum. This extends the life of your tuner and finals.

• Open the radio casing.
• Locate the "D" (Diode) matrix on the control board.
• Typically, cutting or adding a specific diode opens the transmitter to "General Coverage" (TX 1.6–30 MHz).
• Note: This varies heavily by the specific revision of the logic board. Consult the specific service manual for your serial number prefix.

• Role: Fixed-mount marine VHF transceiver used on commercial vessels and large pleasure craft; supports DSC, NMEA connectivity, and multiple functions for bridge communications.
• Key features affecting mods: front-panel controls, microphone connector, speaker, power supply points, NMEA/RS-232 or NMEA 2000 interface (depending on options), and antenna connector.

Most M700s are software or hardware limited to marine bands. Here’s how to open them.

Programming Unlocking: If memory banks A and B are locked out from user programming, remove jumper W33 (W1033) on the Logic Board.

, has become a popular project for amateur radio enthusiasts due to its robust build and low cost on the second-hand market. While powerful, its original firmware and hardware are strictly tailored for marine use, necessitating several modifications to make it a versatile amateur station. Frequency Expansion and Control