Page 5-30 400W Series Installation ManualRev. E 190-00356-025.5.4 VHF NAV Checkout (GNS 430W)Press the CDI key to select VLOC mode (indicated by a white VLOC in the lower left corner of thedisplay). Check the VOR reception with ground equipment, operating VOT or VOR, and verify audioand Morse code ID functions (if possible). Tune a Localizer frequency and verify the CDI needle andNAV flag, and VDI needle and GS flag operation.5.5.5 VHF COM Checkout (GNC 420W/GNS 430W)5.5.5.1 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, and is not to exceed 3:1. A VSWRof 2:1 will cause a drop in output power of approximately 12%, and 3:1 causes approximately a 26%drop.5.5.5.2 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.5.5.6 Interface CheckoutThis section describes checks that must be carried out to verify that systems interfacing to the GNS400W Series unit are communicating properly. Only those interfaces that are connected to the GNS400W Series unit must be verified.5.5.6.1 Honeywell (Bendix/King) EFS40/50 Interface CheckIf a Honeywell EFS40/50 has been connected to GNS 400W Series unit the interface should be verifiedas described in this section.1. Cycle power to the first GNS 400W Series unit and acknowledge the prompts until it gets to theself test page (see Section 5.5.1).2. Ensure that GPS1 data is displayed by pressing the “1-2” key on the EFS40/50 control panel.3. While the GNS 400W Series unit is displaying the self test page, verify that the EFS40/50 isdisplaying data from the GPS source. Note that vertical deviation will not be displayed.• Course Deviation: Half-scale left deviation, TO indication, flag pulled• Active Waypoint: GARMN• Vertical Deviation: Half-scale up deviation (Only if installation is set up to display GPSvertical deviation)4. On the GNS 400W Series unit verify that an OBS value is displayed (and not dashed out).5. Using a VOR test set verify that the CDI deviation on the EFS40/50 is displayed correctly.6. Cycle power to the second GNS 400W Series unit and acknowledge the prompts until it gets tothe self test page (see Section 5.5.1).7. Switch to GPS2 data by pressing the “1-2” key on the EFS40/50 control panel and repeat steps 3through 5 with the second GNS 400W Series unit.5.5.6.2 Sandel SN3308 Interface CheckIf a Sandel SN3308 EHSI has been connected to the GNS 400W Series unit, the interface should beverified as described in one of the following sections, as appropriate for the installation.
