271 - COM190-00356-00 Rev B420W / 430W Onlywhen finshed.4. Turn the large right knob to hghlght thedesred frequency.5. Press ENT to place the hghlghted frequencyn the standby COM wndow field.Emergency ChannelThe 420W/430W emergency channel select pro-vides a quick method of selecting 121.500 MHz as theactive frequency in the event of an in-flight emergency.The emergency channel select is available wheneverthe unit is on, regardless of GPS or cursor status, orloss of the display.To quickly tune and activate 121.500, press andhold the COM flip-flop key for approximately twoseconds.Press and hold the COM flip-flop key fortwo seconds to activate the 121.500 MHzemergency frequency.Note: Under some circumstances if the com sys-tem loses communication with the main system,the radio will automatically tune to 121.500MHz for transmit and receive regardless of thedisplayed frequency.Stuck MicrophoneWhenever the 420W/430W is transmitting, a ‘TX’indication will appear in the COM window. If themicrophone is stuck or accidentally left in the keyedposition, or continues to transmit after the key isreleased, the COM transmitter will automatically timeout (or cease transmitting) after 35 seconds of continu-ous broadcasting. You’ll also receive a “COM push-to-talk key stuck” message as long as the stuck conditionexists.A “COM push-to-talk key stuck” messageappears to warn you of a stuck microphone.Transmitting is disabled after 35 seconds ofcontinuous broadcasting.Emergency Channel
