Garmin GTX 330 User Manual

GTX 330/330D Installation Manual 190-00207-02
Page 4-6 Rev. U
4.4.4 Altimeter Selection Priority
The installer must be aware of the GTX 330 priority for selecting encoded altimeter interconnections. The
GTX 330 searches in this sequence for altitude, and stops when it finds a valid pressure altitude input.
Only approved devices may provide altitude to the GTX 330 in accordance with 14 CFR 91.217. In
addition, all altitude reporting devices installed in the aircraft must meet certification requirements of
14 CFR 91.413. The installer must select an altitude reporting device that is a certified altitude source for
the particular aircraft.
NOTE
Devices which convert Gillham (gray) coded altitude data to serial data are not
authorized.
Altitude reporting equipment order of precedence:
1) ARINC 429 Air Data Computer (label 203, if configured W/ALT) (25’)
2) ARINC 429 EFIS (label 203, if configured W/ALT) (25’)
3) RS-232 data from GNS 480 (CNX80) or GTN 6XX/7XX
4) RS-232 Fuel/Air Data Computer (if configured W/ALT.) (25’)
5) Shadin Altitude Serializer/Encoder (if configured for 25’)
6) Icarus Altitude Serializer/Encoder (if configured for 25’)
7) Parallel wire Gray Code input (100’)
8) Shadin Altitude Serializer/Encoder (if configured for 100’)
9) Icarus Altitude Serializer/Encoder (if configured for 100’)
It is the installing agency’s responsibility to determine that the installed encoder is compatible with the
selected altitude reporting criteria, either 100’ or 25’. Refer to
Section 5.2.9 and Section 5.2.10 for the
altitude data reporting configuration.
Refer to the GNS 480 (CNX80) Installation Manual or the appropriate GTN 6XX/7XX Installation Manual
for altitude data reporting configuration when connecting a GTX 330 to these units.
4.5 Discrete Functions
4.5.1 Discrete Outputs
External suppression should be connected if a DME is installed in the aircraft avionics system. The
GTX 330 suppression I/O pulses may not be compatible with all models of DME. Known incompatible
units include the Bendix/King KN 62, KN 64 and KNS 80. These models have an output-only suppression
port and can be damaged by the GTX 330 mutual suppression output. In this case, leave the suppression
pin open.
Table 4-6 Discrete Outputs Pin Assignments
Pin Name Pin Number I/O
ALTITUDE ALERT ANNUNCIATE* 19 Out
EXTERNAL SUPPRESSION I/O 31 In/Out
*This output is considered active if either the voltage to ground is < 1.9 V or the resistance to ground is
< 375 . This output is considered inactive if the voltage to ground is 11-33 Vdc.

Garmin GTX 330 Specifications

General

Reply Frequencies	1090 MHz
Frequency Range	1090 MHz (reply)
Power Output	200 Watts peak
Dimensions	5.7 x 1.6 x 7.5 inches (145 x 41 x 191 mm)
Temperature Range	-20°C to +55°C
Operating Voltage	11-33 VDC