Technical data

13773-001
23-10
Page 1
SPEECH COMMUNICATIONS
1. DESCRIPTION
This section covers the systems which utilize the voice to transmit and/or receive messages from air-to-air
or air-to-ground. For additional maintenance practice information refer to the appropriate Garmin Installa-
tion Manual indexed in the front of this manual.
The speech communications system consists of two digitally-tuned integrated VHF communications
(COM) transceiver. The transceiver receives all narrow- and wide-band VHF communication transmissions
transmitted within a frequency range of 118.000 MHz to 136.975 MHz in 25.0 kHz steps (720 channels).
For European operations, the COM can be operator configured for 8.33 kHz channel spacing (2280 chan-
nels). The tuning controls are collocated with the NAV at the left side of the transceiver front panel. Fre-
quency tuning is accomplished by rotating the large and small concentric knobs to select a standby
frequency and then transferring the frequency to the active window. The COM frequency display window is
at the upper left corner of the transceiver display. Auto-tuning can be accomplished by entering a fre-
quency from a menu. The COM 1 antenna is located above the cabin on the airplane centerline. The COM
2 antenna is located below the cabin on the airplane centerline. 28 VDC for transceiver operating is con-
trolled through the Avionics Master Switch and supplied through the 7.5-amp COM1 and COM2 circuit
breaker on the Avionics Essential Bus.
2. MAINTENANCE PRACTICES
A. Garmin GNS 430 GPS/COM
/NAV
The GNS 430 is an IFR certified VHF communications transceiver and Navigation Management Sys-
tem (NMS). The NMS includes GPS sensor, VOR/Localizer and Glideslope receivers. The GNS 430
includes two removable data cards, one with a Jeppesen data base, and second being a custom data
card. GPS signals are received by an internally mounted antennas. NAV/LOC/GS signals are received
by the VOR antenna. For installation and removal procedures refer to Position Determining. (Refer to
34-40)
30 Nov 2000