2TAKEOFF TOUR190-00356-00 Rev Bf The small left knob (COM/VLOC)(420W/430W only) is used to tune the kilo-hertz (kHz) value (to the right of the decimalpoint) of the standby frequency for the com-munications transceiver (COM) or the VLOCreceiver, whichever is currently selected by thetuning cursor. Press this knob momentarilyto toggle the tuning cursor between the COMand VLOC frequency fields.W The COM flip-flop key (420W/430W only)is used to swap the active and standby COMfrequencies. Press and hold to select emer-gency channel (121.500 MHz).V The VLOC flip-flop key (430W only) isused to swap the active and standby VLOCfrequencies (i.e., make the selected standbyfrequency active).Key and Knob FunctionsKey and Knob FunctionsThe 400W-series unit is designed to make operationas simple as possible. The key and knob descriptions onthe next three pages provide a general overview of theprimary function(s) for each key and knob. This TakeoffTour section is intended to provide a brief overview ofthe primary functions of your 400W-series unit. Experi-ment with the unit and refer to the Reference sectionsfor more information.Left-hand Keys and KnobsLeft-hand Keys and KnobsGPS 400W GNC 420W/AW GNS 430W/AWk The COM power/volume knob (420W/430Wonly) controls unit power and communicationsradio volume. Press momentarily to disableautomatic squelch control. In the GPS 400W,this control is used only for power.j The VLOC volume knob (430W only)controls audio volume for the selected VOR/Localizer frequency. Press momentarily toenable/disable the ident tone.h The large left knob (COM/VLOC)(420W/430W only) is used to tune the mega-hertz (MHz) value (to the left of the decimalpoint) of the standby frequency for the com-munications transceiver (COM) or the VLOCreceiver, whichever is currently selected bythe tuning cursor.
