User's Manual

Table Of Contents
SYSTEM DESCRIPTION AND INSTALLATION MANUAL
T
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CAS/Part No.9005000
(5) If an open circuit, short circuit, or unacceptable resistance measurement is
detected on the directional antenna path, a failure has occurred in the connector,
coax cable, or directional antenna.
(6) Locate the directional antenna that has a suspected failure. Remove the coax
cable from the antenna port that is suspected to have failed. Isolate which
section of the antenna system is at fault by a process of elimination. The
resistance values of the antenna ports should be as specified in Table 6-12.
(7) Remove and replace the appropriate failed component in accordance with
approved AMM procedures.
Table 6-13: Antenna Wiring Resistance
Antenna
Connector
Section
Pin dc Resistance
Top Directional Antenna
LTP
1
2
3
4
1,000 ±100 ohms
8,060 ±800 ohms
4,020 ±400 ohms
2,000 ±200 ohms
Bottom Directional Antenna
LMP
1
2
3
4
1,000 ±100 ohms
8,060 ±800 ohms
4,020 ±400 ohms
2,000 ±200 ohms
Optional Bottom
Omnidirectional Antenna
for part numbers 9005000-
11203, -11801 and -55801.
LMP
1
2
3
4
0 to 50 ohms (50 ohms maximum)
Infinite (>50k ohms)
Infinite (>50k ohms)
Infinite (>50k ohms)
NOTE:
The procedures that follow are recommended for intermittent antenna system
failures or if the continuity tests have not identified a failed component in the
antenna system or if the flight crew detects an unacceptable visual discrepancy
between an intruder aircraft and its displayed location.
(8) If the displayed location of an intruder aircraft is believed to be in error,
appropriate ramp test equipment can be used to simulate intruder aircraft to
check the suspected discrepancy while on the ground.
(9) Remove the suspected TCAS directional antenna and terminate the antenna side
of the cable with a 50-ohm termination (Omni-Spectra Part Number 3102-6100-
00 or equivalent TNC jack with VSWR 1.15 : 1).
(10) Perform a thorough inspection for moisture or contamination of all coax cable
assemblies.
(11) Remove the T
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CAS LRU and do a VSWR check on the coax cable from the
T
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CAS computer tray side. Use approved VSWR test equipment and operating
procedures. The measured VSWR should be less than 2.0 : 1.
(12) If the VSWR test fails, isolate failed antenna coax section. Remove/repair
appropriate cable and/or connector.
Pub. No. 8600200-001, Revision 004
34-45-29
6-57
04 Nov2014
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