The most common modification for marine transceivers is enabling transmit capabilities across the entire HF band.
If you are performing these yourself, it is highly recommended to reference the Kenwood TKM-707 Service Manual for exact board layouts and component locations. Kenwood Tkm-707 Mods
While the TKM-707 is already a high-power unit, some operators explore the technical characteristics of the low-power settings or the efficiency of the high-power output on amateur frequencies. The most common modification for marine transceivers is