190-00734-11
GTX 33X and GTX 3X5 ADS-B Maintenance Manual
Rev. 6
Page 3-2
3.1 GTX 330/330D
Figure 3-1 GTX 330/330D Front Panel
Function Selection Keys
The function selection keys are:
OFF
Powers off the GTX 330.
STBY
Selects the standby mode. Pressing the
STBY
key when the GTX 330 is powered off
automatically powers the unit on in standby mode. When in standby mode, the transponder
does not reply to interrogations. If using software v8.02 or later, GND mode is
automatically determined using either a squat switch or calculated data from various system
inputs including GPS data from an approved control/display unit such as a GTN 6XX/7XX,
GNS 400W/500W Series, or GNS 480.
ON
Selects Mode A and Mode S. Pressing the
ON
key when the GTX 330 is powered off
automatically powers on the unit in Mode A and will transmit a squawk code when
interrogated.The transponder replies to Mode A and Mode S interrogations, as indicated by
the reply symbol (®). The replies do not include altitude information.
NOTE
If the transponder is in the ON or ALT operating mode, the transponder becomes an active
part of the Air Traffic Control Radar Beacon System (ATCRBS). The transponder
responds to interrogations from TCAS equipped aircraft.
ALT
Selects Mode A, Mode C, and Mode S. Pressing the
ALT
key when the GTX 330 is
powered off automatically powers on the unit in altitude reporting mode.The transponder
replies to identification, altitude and Mode S interrogations as indicated by the reply symbol
(®). Replies to altitude interrogations include the standard pressure altitude received from
an external altitude source, which is not adjusted for barometric pressure.
IDENT
Pressing the
IDENT
key activates the Special Position Identification (SPI) Pulse for 18
seconds, identifying the transponder return from others on an air traffic controller’s screen.
During the IDENT period, the word “IDENT” appears in the upper left corner of the display.
VFR
Sets the transponder code to the pre-programmed VFR code selected in Configuration mode
(Set to 1200 at the factory). Pressing the
VFR
key again restores the previous identification
code.
NOTE
The
VFR
key is on (functional) by default, but can be disabled in configuration mode.
FUNC
Changes the page shown on the right side of the display. Display data includes pressure
altitude, flight time, altitude monitor, count up, and count down timers. In the
Configuration mode, steps through the function pages.
