Icom M700 Mods

: Modifying the transceiver to transmit outside the marine bands means the radio should only be used on amateur frequencies by a licensed amateur radio operator. It technically voids type-acceptance for commercial marine use under many jurisdictions.

: The stock 455 kHz IF ceramic filter has a relatively wide bandwidth meant for robust marine voice. Swapping this out for a tighter Murata or mechanical filter (around

Marine microphones are designed for high-noise environments and can sound "thin" on amateur bands.

That night, with the final modification complete, Eli sat in his basement shack. The M700, now a hybrid beast of 80s muscle and 21st-century wits, hummed softly. He spun the main dial, a satisfying flywheel inertia behind it. The new filter sliced through a pileup on 40 meters. The modified receiver coaxed a faint whisper from a research station in Antarctica, their signal a thin silver thread across the darkness. icom m700 mods

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:

Tap into the AF Out pin on the rear external speaker jack or accessory plug for clean receive audio. Tap into the Mic Input pin for transmit audio.

What is your comfort level with ? Share public link : Modifying the transceiver to transmit outside the

: You can install a physical switch to disable "Split Mode" behavior. This makes programming much faster for simplex operation by removing the need to enter transmit and receive frequencies separately. Audio & Interface Improvements

While the mod is electrically simple, it comes with risks. The output filtering network on the M-700 is optimized for marine bands. Transmitting on, say, the 80-meter amateur band (3.5 MHz) with an M-700 can result in high SWR (Standing Wave Ratio) internal to the radio, potentially stressing the final transistors (MOSFETs) if an external tuner isn't perfectly matched.

: Modern operators frequently wire a digital Direct Digital Synthesis (DDS) VFO chip (like the AD9850 or AD9851) directly into the first local oscillator (LO) injection port. Swapping this out for a tighter Murata or

Which do you have (e.g., original M700 with dial wheels, M700PRO, or M700TY)?

Here are brief guides for each mod: