Entel HT446 Owner's Manual page 14

With the exception of PTT each time a you press any of HT446 buttons
a single beep tone is emitted. This can be disabled should you wish.
To disable the beep tone press "FCN" button seven times.
As default this feature is set to ON. By pressing the UP or DOWN button
you can tun this feature ON or OFF. Press the enter key to store the setting.
SQUELCH LEVEL (SL)
A squelch circuit allows muting of undesired noise while receiving no
signal, and emits audio when receiving signal. If operating HT446
directly next to machinery or computer equipment you may get squelch
breakthrough. Either move away from the equipment, or change the
squelch level to a lower setting.
Note : If using CTCSS or DCS on your HT446 you will not get squelch breakthrough.
To change the squelch level press "FCN" eight times. As default the
squelch level is set to 5. It can be increased or decreaed by pressing
the UP or DOWN buttons.
Press the ENTER button to confirm your setting.
A key lock feature is available should you wish to lock the keypad.
Located under the PTT button there is a X button. Holding this button
for just over a second locks the front keypad. When locked the only
button that continues to operate is the PTT button. To release the lock
simply press the X button.
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