2 BASIC OPERATION

2.1Power On

Turn the GNC 255 on by either turning the Power/Com Volume/ Squelch knob clockwise to turn the power on or, if installed, turning on the master switch that powers the radios.

2.2Com Radio

2.2.1Selecting a Com Frequency

New frequencies are first selected as a Standby frequency and then toggled to the Active side with the FLIP/FLOP key. While viewing the Standby frequency display, use the LARGE and SMALL knobs on the right side of the GNC 255 to select the desired frequency.

1.Press C/N, if necessary, to reach the Com radio function. The COM annunciator on the top line of the display will show.

2.Turn the LARGE knob to change the values in one MHz increments. The MHz selection range is between 118 and 136 in one MHz steps.

3.Turn the SMALL knob to change the values in 25 kHz or 8.33 kHz increments. The kHz selection range is between 000 and 975 kHz in 25 kHz steps or 000 and 990 kHz in 8.33 kHz steps.

4.Turn the LARGE and SMALL knobs clockwise to increase and counterclockwise to decrease the frequency values. Standby frequency selection is not inhibited during transmit.

5.When connected to a position source, nearby station identifiers will be shown for the selected frequency. Frequencies with multiple types will have an asterisk next to the identifier.

Identifier and Type Shown For

The Selected Frequency

Asterisk Indicates Multiple Types Exist For The Selected Frequency

Figure 2-1 Com Frequency Selection

6.Press and release the FLIP/FLOP key to toggle the Standby frequency to the Active frequency.

190-01182-01 Rev. A

Garmin GNC 255A/255B Pilot’s Guide

2-1

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Garmin 255A manual Power On, Com Radio, Selecting a Com Frequency