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400 SERIES MAINTENANCE MANUAL Page 1-5
P/N 190-00140-05 Rev. C
1.5.2 Com Board
The Com Board contains the VHF COM Transceiver that provides voice communication in the
118.000 to 136.992 MHz general aviation band. The transceiver consists of a 10 or 16 watt (“A”
versions) amplitude modulated transmitter (see the unit matrix tables on page 1-1), and a single
conversion superhetrodyne AM receiver. The 10 watt transmitters are Class 4 and 6 devices as
described in RTCA DO-186A, indicating that they have channel spacing modes of 25 kHz and
8.33 kHz, and are intended for a communications range of 100 nautical miles. The 16 watt
transmitters are class 3 and 5 devices as described in RTCA DO-186A, indicating that they have
channel spacing modes of 25 kHz and 8.33 kHz and are intended for a communications range of
200 nautical miles.
The receiver is a Class C and E device as described in RTCA DO-186A, indicating that it has
channel spacing modes of 8.33 kHz and 25 kHz, with offset carrier capability in 25 kHz mode.
The Com Board contains connectors J2 and J26. J4 is the Com BNC antenna connector.
1.5.3 Nav Board
The Nav Board contains the processor controlled navigation receiver for VOR and Localizer
signals from 108.00 MHz to 117.95 MHz in 50 kHz increments providing 200 channels.
Functionally, the Nav Board performs the following:
1. Tunes a VOR or localizer frequency as commanded by the Main Board.
2. Communicates VOR/LOC receiver sub-system status to the Main Board.
3. Communicates VOR radial or localizer deviation, TO/FROM flag state and
navigation flag state to the Main Board.
4. Drives horizontal deviation, flag and TO/FROM electrical outputs.
5. Receives glideslope data from the Main Board to be sent out in ARINC 429 format.
6. Toggles the VOR/LOC identifier filter as commanded by the Main Board.
7. Communicates to the Main Board the detection of a remote frequency transfer key
press.
8. Drives electrical outputs for OBI.
9. Channels a remote DME if connected to the VOR/LOC Receiver Board.
10. Transmits ARINC 429 labels.
11. Receives ARINC 429 labels.
12. Provides signal pass-through for G/S flags and drivers to NAV Board Connectors.
1.5.4 GPS Module
The GPS Module contains a twelve channel parallel receiver that is capable of tracking and using
up to twelve visible satellites for position, velocity, and time calculations. The GPS Receiver is
designed to operate with the GARMIN GA 56 antenna (P/N 011-00134-00). The GPS Module
interfaces with the Main Board via connector J101.