Furuno FM-2710 Operator's Manual page 20

3-1-1. Controls
VOLUME
1) Volume Control(Power on/off)
Turns the radio on /off and adjusts volume of the speaker.
OFF
CH
2) Channel Selector
Selects channels.
3) Squelch Control
SQUELCH
Adjusts the squelch. Rotate the control counterclockwise until noise is heard,
then rotate it clockwise slowly until noise just fades out.
4) [16] Key
16
Immediately selects CH16. Next pressing returns control to previously
selected channel.
16