User's Manual

SYSTEM DESCRIPTION AND INSTALLATION MANUAL
TCAS 3000 Traffic Alert and Collision Avoidance System
34−43−23
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Page 2−4
15 Dec 2005
F. Transponder Provisions
This paragraph contains the mechanical installation data for the ACSS Mode S Data Link
Transponder, Part No. 7517800−XXYYY and ACSS Diversity Mode S Transponder, Part
No. 7510700−850/−951. It also contains provisions for installing the ATC transponder
antennas.
(1) Mode S Data Link Transponder Provisions
Mechanical installation data for the ACSS Mode S Data Link Transponder, Part No.
7517800−XXYYY is shown in Figure 2−13. The transponder can be mounted in any
convenient location in the aircraft; however, it should be mounted within 30 feet of the
antennas unless low loss coaxial cable is used to maintain a worst case loss of 3dB
per ARINC 718−A. Top and bottom antenna coaxial run length differences can be
compensated for by use of the antenna delay program pins on the transponder. The
unit can utilize external cooling air in accordance with ARINC 600 or ARINC 404 or
operate in convection−cooled environments. The transponder is mounted in an
ARINC 600 4−MCU tray assembly.
(2) Diversity Mode S Transponder Provisions
Mechanical installation data for the ACSS RCZ−852 Diversity Mode S Transponder,
Part No. 7510700−850/−951 is shown in Figure 2−14. The transponder can be
mounted in any convenient location in the aircraft that allows the unit to be upright
during normal flight. The exact location should allow the cabling between the unit,
control panel, and antennas to be as short as possible. The location of the mounting
tray (part of installation kit, Part No. 7510707−968) should allow adequate space for
installation of the transponder, provide reasonable accessibility for servicing, and
allow space on top, sides, and rear of unit for adequate ventilation. The location
must also provide a solid mechanical mount to prevent vibration amplification. The
mounting tray should be electrically bonded to the aircraft frame by a low resistance
path of less than 2.5 milliohms.
(3) ATC Transponder Antenna Provisions
When installing transponder antennas, a TSO’d antenna should be selected. The
antenna must be vertically polarized and operate in the frequency range of 960 to
1220 MHz. Antenna impedance must be 50 ohms. Voltage standing wave ratio
(VSWR) shall not exceed 1.5:1. Selection of a grounded or lightning protected type
antenna is required to pass the transponder bite continuity detection circuitry, if
enabled.
In dual transponder antenna installations it is important to provide adequate isolation
from each other to prevent receiver front−end damage. A 20−inch minimum
separation of Mode S antennas from other L−Band antennas, including TCAS
antennas, must be maintained. The maximum cable length for RG−214/U is 30 feet
(9.144 meters). Allow adequate cable length so bends in cable have a minimum
3−inch (76 mm) radius. Selection of coax cable assemblies with moisture barrier
protection is highly recommended to minimize the effects of humidity and corrosion.