Garmin VHF 725 Owner's Manual And Reference Manual page 12

Keys &
Function
Displays
Squelch Key - This key breaks the squelch
(unmutes the audio) when pressed and held. It is
Squelch Key
also used to set the squelch threshold (the level
at which only strong signals can be received).
The squelch threshold is set by pressing and
holding the squelch key while using the UP/
DOWN keys to adjust the squelch level from 0
to 9. At level 0 (L0), all signals can be heard,
while at level 9 (L9), only the strongest signals
can be heard. Adjusting the squelch level
eliminates weak, unwanted signals, as explained
on page 17.
H/L (High/Low) Power Key - This key toggles
the transmitter power level from High (5 watts)
to Low (1 watt) when pressed and released. It
H/L Power Key
also locks the keypad when pressed and held for
more than one second. The Power key, PTT key,
backlighting key and the Squelch key still
function in the Lock mode. Locking the keypad
prevents inadvertent changing of channel
settings and feature modes.