Figure 5-1 Gtx (All Models) Transponder Troubleshooting - Garmin GTX 330D Maintenance Manual

Transponder will not turn
on
Corrective
Action
Ensure the XPDR
circuit breaker is
closed
Verify connections
for power and ground
Ensure transponder
is fully seated and
mated to the
connectors in the
mounting rack
190-00734-11
Rev. 6
Poor transponder
performance. Weak or Loss of, or incorrect altitude
intermittent radar contact reporting by the transponder
reported by ATC
Corrective Corrective
Action Action
Check the altitude
Check for proper source configuration
electrical bonding/ on the GTX. Verify
grounding of the primary and secondary
antenna installation sources are configured
properly.
Check and verify
integrity of the
antenna installation,
ground planes, and
coaxial cable
Check and verify the
Test coaxial cables for
integrity of the
insertion loss and VSWR.
transponder-altitude
VSWR should be checked
encoder interface,
with an in-line type VSWR/
including wiring and
wattmeter inserted in the
altitude encoder
coaxial transmission line
operation
between the transponder and
the antenna. The VSWR
should be 1.5:1 at 1090 MHz
or less. Insertion loss should
be less than 1.5 dB at 1090
MHz

Figure 5-1 GTX (All Models) Transponder Troubleshooting

GTX Symptom
Transponder audio too quiet/
loud
Corrective
Action
Verify that the GTX
volume setting is at or
above the minimum
required setting
Verify the unswitched
audio input at the
audio panel setting is
at or above the
minimum required
setting
GTX 33X and GTX 3X5 ADS-B Maintenance Manual
Incorrect Mode S aircraft Transponder will not come
data transmitted out of standby
Corrective Corrective
Action Action
Verify the Flight ID and Verify transponder
ICAO address are select switch position,
configured properly (#1 or #2) if installed
Check the
Verify the Tail number
configuration mode
and ICAO address are
settings and reset if
properly configured
necessary
If fault still exists,
contact Garmin.
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