Garmin GNC 420(A) Pilot's Manual & Reference

Also see for GNC 420: Instructions Pilot's guide addendum Pilot's guide addendum Pilot's guide addendum Quick reference

Contents

Garmin GNC 420(A) Pilot's Manual & Reference Manual pdf 29 page image

GNC 420(A) Pilot’s Guide and Reference 2-1SECTION 2COM190-00140-20 Rev. KSECTION 2: COM2.1 COMMUNICATING USING THE GNC 420The GNC 420 features a digitally-tuned VHF COM radiothat provides a seamless transition from communicationto navigation, bringing the two most important functionsin flying together in one panel-mounted unit. The GNC420’s COM radio operates in the aviation voice band, from118.000 to 136.975 MHz, in 25 kHz steps (default). ForEuropean operations, a COM radio configuration to allowfor 8.33 kHz steps is also provided (Section 9.5, Setup 2Page: COM Configuration).VolumeCOM radio volume is adjusted using the COM Power/Volume Knob. Turn the COM Power/Volume Knobclockwise to increase volume, or counterclockwise todecrease volume.SquelchThe COM radio features an automatic squelch,providing maximum sensitivity to weaker signals whilerejecting many localized noise sources. The pilot maywish to override this automatic squelch function whenlistening to a distant station or when setting the desiredvolume level. The COM Power/Volume Knob allows thepilot to disable the automatic squelch and keep the COMaudio open continuously.Overriding the automatic squelch:1) Press the COM Power/Volume Knobmomentarily.2) Press the COM Power/Volume Knob againto return to automatic squelch operation.COM Window and TuningCommunication frequencies are selected with thetuning cursor in the standby COM frequency field (Figure2-1), using the small and large left knobs to tune thedesired frequency. The standby frequency always appearsbelow the active frequency. The active frequency isthe frequency currently in use for transmit and receiveoperations.Figure 2-1 ‘RX’ Receive Indication‘RX’ Receive IndicationStandby COM Frequency FieldA frequency may also be quickly selected from thedatabase by simply highlighting the desired frequency onany of the main pages and pressing the ENT Key. Thisprocess is referred to as auto-tuning. Once a frequency isselected in the standby field, it may be transferred to theactive frequency by pressing the COM Flip-flop Key.