Page 6-40 GTN 625/635/650 TSO Installation ManualRev. C 190-01004-026.11.4 VHF NAV Checkout (GTN 650 Only)While on the Map Page, touch the CDI key on the display to select VLOC mode, which is indicated by agreen ‗VLOC‘ annunciation on the bottom center of the display. Check the VOR reception with groundequipment, operating VOT or VOR, and verify audio and Morse code ID functions (if possible). Tune aLocalizer frequency and verify the CDI needle and NAV flag, and VDI needle and GS flag operation.6.11.5 VHF COM Checkout (GTN 650 Only)6.11.5.1 Antenna CheckIf desired, the antenna VSWR can be checked using an inline wattmeter in the antenna coax usingfrequencies near both ends of the band. The VSWR should be < 2:1. A VSWR of 2:1 will cause a drop inoutput power of approximately 12%.6.11.5.2 Receiver/Transmitter OperationTune the unit to a local VHF frequency and verify the receiver output produces a clear andunderstandable audio output. Verify the transmitter functions properly by contacting another station andgetting a report of reliable communications.6.11.6 TAWS System Check (For Units with TAWS Only)While on the ground, turn on the GTN following normal power-up procedures. Also turn on the audiopanel.NOTEA 3D GPS position fix is required to conduct this check.1. Touch the ‗Terrain‘ key.2. On the Terrain page, touch the ‗Menu‘ key and select ‗Test TAWS‘.3. Wait until the TAWS self-test completes (10-15 seconds) to hear the TAWS system status auralmessage.The aural message ―TAWS System Test OK‖ will be annunciated if the TAWS system isfunctioning properly.The aural message ―TAWS System Failure‖ will be annunciated if the TAWS system isNOT functioning properly.If no audio message is heard, then a fault exists within the audio system and the TAWS capability mustbe considered non-functional.
