Communication (Com) Transceivers - Cirrus DESIGN SR20 Information Manual

Cirrus Design Section 7
SR20 Airplane Description

Communication (COM) Transceivers

Two VHF communications (COM) transceivers are installed to provide
VHF communication. The transceivers and integrated controls are
mounted in the Garmin GNS 430 and GNC 250XL units. The
transceivers receive all narrow- and wide-band VHF communication
transmissions transmitted within range of the selected frequency. The
antennas pick up the signals and route the communication signals to
the transceivers, which digitize the audible communication signal. The
digitized audio is then routed to the audio control unit for distribution to
the speakers or headphones.
COM 1 - The Garmin GNS 430 (upper unit) is designated COM 1. The
Garmin GNS 430 control panel provides COM 1 transceiver active and
standby frequency indication, frequency memory storage, and knob-
operated frequency selection. The COM 1 transceiver provides either
720-channel (25 kHz spacing) or 2280-channel (8.33 kHz spacing)
operation in a frequency range from 118.000 to 136.975 MHz. The
COM 1 antenna is located above the cabin on the airplane centerline.
28 VDC for COM 1 transceiver operation is controlled through the
Avionics Master Switch on the bolster switch panel and supplied
through the 7.5-amp COM 1 circuit breaker on the Essential Avionics
Bus.
COM 2 - The Garmin GNC 250XL (lower unit) is designated COM 2.
The Garmin GNC 250XL control panel provides COM 2 transceiver
active and standby frequency indication, frequency memory storage,
and knob-operated frequency selection. The COM 2 transceiver
provides 760-channel (25 kHz spacing) operation in a frequency range
from 118.000 to 136.975 MHz. The COM 2 antenna is located on the
underside of the cabin on the airplane centerline. 14 VDC for COM 2
transceiver operation is controlled through the Avionics Master Switch
on the bolster switch panel and supplied through the 28 to 14 VDC
voltage converter from the 7.5-amp COM 2 circuit breaker on the Non-
Essential Avionics Bus.
P/N 13999-002 Info Manual 7-73
September 2011