Icom M700 Mods Now
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The Icom M-700 series (specifically the M-700Pro and its descendants like the M-710) occupies a legendary status in the world of maritime communication. It is the "Toyota Land Cruiser" of marine HF/SSB radios: over-engineered, built like a tank, and capable of far more than its stock configuration suggests.
While modern maritime gear is often "black box" architecture—sealed, software-locked, and disposable—the M-700 is a relic of the golden age of radio. It uses discrete components, robust filters, and an architecture that invites modification.
Here is a deep dive into the culture, technical reality, and specific modifications surrounding the Icom M-700.
The M700 uses a Phase-Locked Loop (PLL) with programmable dividers. Jumpers on the main PLL board (often labeled the "PLL Unit" or "Frequency Unit") set the frequency limits. By changing diode or jumper configurations, you override the marine band limits.
Note: This guide focuses on legitimate, safety-first, and legal modifications for the Icom IC-M700 (marine VHF fixed station) to improve usability, reliability, and integration. Do not perform modifications that violate local radio laws, FCC/ITU regulations, or that alter the unit’s certified transmission characteristics (e.g., increasing transmit power beyond spec, changing frequencies, or bypassing required emission limits). Always consult a certified radio technician or Icom for repairs that impact RF circuits or safety. Use this guide only for permitted hardware, ergonomic, and software/firmware tweaks that do not change certified RF parameters.
Contents
Quick checklist for a safe mod/install
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The Icom IC-M700 is a classic marine HF transceiver that has become a popular project for amateur radio enthusiasts due to its robust build and low second-hand cost. While originally locked to marine bands, several modifications can unlock its full potential for ham radio use. Core Functionality Modifications
These "jumpers" on the internal logic board control the radio's primary operating restrictions.
MARS/CAP (Transmit Unlock): To enable transmission on all covered frequencies (roughly 1.6 MHz to 23.9 MHz), ensure that jumper W37 (W1037) on the Logic Board is installed. If it has been cut, resoldering it restores full coverage.
Memory Bank Unlock: To allow programming of banks A and B (which are sometimes locked out), jumper W33 (W1033) must be removed. icom m700 mods
Keypad Activation: If the front-panel 10-key buttons are unresponsive, toggle the small switch S1228 located on the Matrix board. Advanced Amateur Radio Mods
For those looking to go beyond basic frequency unlocks, advanced hobbyists have documented more complex upgrades:
SRAM Expansion: The standard 48-channel memory can be expanded to 480 channels via an SRAM expansion mod, making it more practical for storing numerous amateur bands and nets. Mode & Audio Upgrades:
Speech Processor: Adding a speech compressor improves talk power during SSB operation.
LSB Addition: While most marine operations are USB, some regional versions (like those in Australia) may have LSB removed; it can often be restored with internal switch and wiring adjustments.
Digital Interface: By constructing a custom interface box for the microphone socket, users can connect the M700 to a PC for digital modes like FT8, SSTV, or Pactor. Microphone Compatibility
The original HM-28 microphone is often missing or damaged. Because it is no longer manufactured, a common mod involves adapting the radio to accept the newer HM-114 microphone.
Replace the internal connector J3 on the MIC-C-UNIT with a compatible 8-pin connector (#936-05432).
Route the HM-114 cord through the existing side hole and solder it to the new connector.
Note: The up/down buttons on the HM-114 will not function after this mod. Operating Tips for Modified Units IC-M700 Mods - Elliott Liggett - GitLab
No deep piece on the M-700 mods is complete without mentioning the AT-130 automatic antenna tuner.
The M-700 is almost always paired with an Icom AT-130 or AT-140. While not a modification to the radio chassis itself, the "mod" here is often in the installation.
The Icom IC-M700 is a classic marine HF transceiver that can be modified into a highly capable ham radio rig The Icom M-700 series (specifically the M-700Pro and
. Below is a summary of the most common and effective modifications for this unit. Core Frequency & Programming Mods
These modifications unlock the radio's full potential by allowing it to operate outside restricted marine bands. Transmit Frequency Expansion (MARS/CAP):
To enable transmit on all covered frequencies (approx. 1.6 MHz to 23.9 MHz), check the Logic Board for jumper
). If this wire is cut, solder it back together to restore full range. Enable Memory Programming:
If banks A and B are locked out from programming, ensure jumper ) on the Logic Board is not installed Enable Keypad Entry: If the front-panel 10-key buttons aren't working, check the Matrix board for a small toggle switch, Performance & User Experience Upgrades
Advanced mods can modernize the radio for contemporary amateur use. Memory Expansion: You can upgrade the standard 48 memory channels to 480 channels
by performing an SRAM expansion. Detailed schematics for this ramboard mod are available via community repositories. Audio & Digital Modes: External Audio Interface:
Constructing an interface box allows you to connect the radio to a PC for digital modes like Modern Microphone Adapters:
You can modify the mic socket to accept newer microphones or high-quality dynamic mics with XLR outputs. Speech Processor:
Adding an internal speech compressor can significantly improve your signal punch during SSB operations. Operational Tips for Ham Use
The radio's "AM" mode is actually upper sideband with a 40-watt carrier (A3H), which provides a loud, fully modulated sound compatible with most AM receivers. Split Mode:
Some users install a dedicated toggle switch to disable "split" behavior, making standard simplex programming faster. Filter Limitations:
While the radio works well on amateur bands, it lacks the narrow filtering found in dedicated ham rigs, which may make it sensitive to nearby interference during contests. The M700 uses a Phase-Locked Loop (PLL) with
For deep technical dives and step-by-step guides, refer to the IC-M700 Mods repository on GitLab or the extensive archive at Do you have a specific version
of the M700 (like the M700TY or PRO) that you're working on? IC-M700 Mods - Elliott Liggett - GitLab
Modifying the Icom M700: A Guide to Enhancements and Upgrades
The Icom M700 is a popular marine VHF radio known for its reliability, durability, and feature-rich design. First introduced in the late 1990s, it has become a staple on many boats and ships worldwide. While the M700 remains a capable and effective communication device, some users may want to explore modifications (mods) to enhance its performance, add new features, or improve its user interface. In this blog post, we'll explore some common Icom M700 mods, their benefits, and what you need to consider before making any changes.
Common Icom M700 Mods
Benefits of Icom M700 Mods
Modifying the Icom M700 can bring several benefits, including:
Considerations Before Modifying Your Icom M700
Before attempting any mods, consider the following:
Conclusion
The Icom M700 remains a reliable and effective marine VHF radio, and modifying it can enhance its performance, functionality, and user experience. However, it's essential to carefully consider the benefits and risks of any mod, ensuring that you're making informed decisions about your radio and onboard systems. If you're unsure about any aspect of the modification process, consult with a qualified technician or Icom support specialist to ensure a successful outcome.
ICOM M-700 Modification Report
The Icom IC-M700 (and its variant the IC-M700TY) is a legacy HF marine transceiver. While robust, it is an older analog radio. Most modifications performed today fall into two categories: restoration (bringing the radio back to spec) and expansion (enabling HAM band usage or replacing obsolete components).
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