Early production runs of the IC-M700 suffered from slight frequency drift when the radio warmed up. Clarifier (RIT) Installation
The M700 has a spot on the main board for an optional mechanical or crystal filter (often a Murata CFJ455K or equivalent). Many surplus units have an empty slot.
Out of the factory, the IC-M700 restricts transmitting to specific marine bands. Opening up the radio for general coverage transmit allows you to use it on the amateur radio bands.
In this article, we'll delve into the world of Icom M700 mods, exploring the various upgrades and modifications available, their benefits, and how to install them. Whether you're a seasoned boater or a DIY enthusiast, this comprehensive guide will help you unlock the full potential of your Icom M700.
The original marine transceiver, featuring receive coverage from 1.6 MHz to 23.9999 MHz and transmit restricted to the marine HF bands. It typically has the fewest rear-panel I/O ports and is a prime candidate for the modifications discussed below.
If you enjoy the smell of rosin flux and the satisfaction of pulling a weak signal out of the noise using a rig you hot-rodded yourself, buy an M700. Open it up. Perform these mods. And join the nets with a piece of radio history that now performs like a modern classic.
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.
: Locate the Main Unit or local oscillator board. Increasing the voltage swing across the tuning pot by altering the series resistors gives you much finer control over incoming, drifted signals. 3. Adding an External VFO Control
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.
If the 10-key numeric buttons are unresponsive, there is often a small toggle switch, , on the Matrix board that can be used to reactivate them. Audio and Interface Upgrades
Eli wasn't a spy. He wasn’t a prepper or a pirate. He was a late-night AM DXer, a hunter of ghosts in the static. He’d bought the M700 at a maritime flea market in Rotterdam for two hundred euros, its grey paint chipped, the "CH" button worn smooth. The seller, a grizzled tugboat captain, had called it "indestructible, and just as deaf."
Let’s break down the top three modifications that will change your M700 experience.
: 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.
This helps the radio recover faster after receiving strong signals. Microphone Audio EQ
Disclaimer: Modifying radio equipment requires technical knowledge and soldering skills. Altering transmitting capabilities may violate local regulations if operated outside authorized frequencies. Proceed at your own risk. 1. General Coverage Transmit Mod (Ham / MARS / CAP)