VOX feature will not work without the Vox Headset Microphone. The built in mic of uh073sx is temporarily disabled, however accidental pressing of PTT will cause the unit to transmit briefly.
To activate VOX
1. Press and hold vox for 1.5 secs. "VOX" icon blinks.
2.Press either 
or 
within 10 secs. to select the desired VOX sensitivity level (9 with the lowest sensitivity to 1 with the highest sensitivity).
3.Press vox to save the selected level. "VOX" icon stops blinking.
4.Install VOX Headset (not supplied) to uh073sx.
To De-activate VOX
1. Remove VOX Headset from uh073sx.
2. Press and hold vox for 1.5 secs. until "VOX" blinks.
3. Press 
repeatedly and until "oF" is displayed.
4. Press vox to save the setting. "VOX" icon disappears.
Changing the VOX sensitivity setting to "oF" without removing the microphone will cause the unit to transmit continuously.
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