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The original HM-28 microphone is no longer manufactured. Icom has a technical bulletin for replacing it with an HM-114. This modification involves replacing the internal mic connector (J3) and, if needed, cutting the mic cord restraint on the new HM-114. For a straightforward upgrade, the HM-180 is a popular replacement microphone.
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.
Since the M700 uses a non-standard microphone connector (often 7 or 8-pin), users frequently build interface boxes. These boxes bridge the radio’s Mic/PTT and Speaker outputs to a Pactor modem or a computer sound card for digital modes like FT8 or JS8Call.
Once any internal component is changed, it is vital to test the radio on a dummy load before connecting it to an antenna.
These capacitors form high-pass filters in the receive audio chain. By increasing their capacitance, you lower the cutoff frequency to approximately 80-100 Hz, allowing natural voice fundamentals and low-end richness to pass through. icom m700 mods
Unlocking the radio allows continuous transmission across the entire HF spectrum (typically 1.6 MHz to 23.999 MHz), giving you full access to all amateur radio bands (such as 80m, 40m, 20m, 15m, and 10m). The Diode Matrix Modification
: Use the rear terminal connections to fetch fixed-level receive audio (detector output) and to inject transmit audio directly into the modulator stage.
is a legendary HF Marine SSB transceiver, known for its rugged construction, high power output, and simple operation. While built for marine use, the M700's robust design has made it a popular choice among amateur radio operators, preppers, and enthusiasts looking for a reliable, older, and affordable HF rig.
: Locate the lithium memory backup battery or the hardware reset trace. Briefly shorting the reset pads or disconnecting power completely for a few minutes forces the CPU to re-read the diode matrix upon startup. The original HM-28 microphone is no longer manufactured
| Question | Answer | | :--- | :--- | | Can I use the IC-M700 on the 10m ham band? | Some versions, like the base M700, only tune up to about 22–23 MHz and are not capable of reaching the 28 MHz 10m band due to PLL limitations. | | Do I need to modify the IC-M700PRO for ham bands? | Likely not. Many IC-M700PRO units, particularly version 02, will transmit and receive on ham bands without any modifications. | | Can I add a continuous VFO tuning knob to the M700? | No. The M700 series is primarily a channelized marine radio, designed for fixed-frequency channels rather than continuous VFO-style operation. | | What is the maximum safe power output for data modes? | For continuous high-duty-cycle modes like FT8, it's wise to keep the output power moderate. The M700 is only capable of about 50 watts continuous output, so reducing power from the maximum is highly recommended. | | Which sideband (LSB or USB) should I use? | It depends on the amateur band. On 160m, 80m, and 40m, LSB is the standard convention. On 20m, 17m, 15m, 12m, and 10m, USB is standard. |
: The original IC-M700 relies on older crystal-controlled master oscillators. While incredibly stable for marine environments, it may drift slightly during the first 15 minutes of operation. For tight-bandwidth digital modes like FT8, allow the radio to thoroughly warm up.
The Icom M700 is a popular marine radio used by sailors and boaters worldwide. While it's a reliable and feature-rich device, some users may want to explore modifications to enhance its performance, functionality, or compatibility with specific accessories. In this article, we'll discuss some common Icom M700 mods, their benefits, and provide a step-by-step guide on how to perform them.
The second method uses the rear panel ACC (accessory) connector. By connecting an external circuit to this port, continuous power adjustment can be achieved through external control. This approach is particularly valuable for operators who frequently switch between power levels for different operating scenarios. For a straightforward upgrade, the HM-180 is a
The IC-M700 has a rudimentary noise blanker that works poorly on most impulse noise (ignition, power lines). It effectively mutes the receiver rather than clipping the noise pulses.
Marine microphones focus heavily on mid-range frequencies to punch through engine noise. This can sound harsh on SSB ham nets. Open the hand microphone casing.
The frequency restriction is controlled by a set of diode matrices on the main logic board (PLL Unit). By adding or removing specific diodes, you can unlock full continuous TX coverage from 1.6 MHz to 29.999 MHz.
Older analog components may experience frequency drift over time. Regular calibration is recommended to ensure the radio stays within its intended operating window and does not cause interference with neighboring frequencies. Conclusion
