NCH 321A Distress Message Controller for JRC MF HF Radio JSS 2150 2250 2500 Attractive: The NCH 321A is a distress message controller for the JRC MF HF radio systems (JSS 2150, 2250, 2500), designed to help transmit distress signals in emergency situations. This system plays a crucial role in ensuring that vessels can communicate distress alerts in the event of an emergency. Regular maintenance and service are necessary to keep the controller functioning properly, ensuring that distress messages are sent without delay.