User's Manual Part 2

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CAS / Part No. 9000000

SYSTEM DESCRIPTION AND INSTALLATION MANUAL

34-43-20

15 Feb 2003

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4--20

Table 4--1. TT--950/951/952 T

CAS Computer Unit Interface Description (cont)

Connector Pin

Designation

Functional Description

CAS Computer Unit Left Top Plug (LTP)

LTP --1 Top Antenna 0 Degree Port

J1 on the antenna is color--coded yellow. This antenna port (Note 2) is called the 0

degree port because it produces a transmission pattern in the forward quadrant of the

aircraft. J1 is physically located toward the rear of the antenna and to the rear of the

aircraft when antenna is properly installed. The T

CAS computer unit checks the built--in

dc to ground resistance of this antenna port. It must detect approximately 1000 Ohms or

TCAS fails its antenna test.

LTP --2 Top Antenna 270 Degree Port

J2 on the antenna is color--coded black. This antenna port (Note 2) is called the 270

degree port because it produces a transmission pattern in the left wing quadrant of the

aircraft. J2 is physically located toward the right wing of the aircraft when antenna is

properly installed. The TCAS function checks the built--in dc to ground resistance of this

antenna port. It must detect approximately 8000 Ohms or it reports antenna test failure.

LTP --3 Top Antenna 180 Degree Port

J3 on the antenna is color--coded blue. This antenna port (Note 2) is called the 180

degree port because it produces a transmission pattern in the rear quadrant of the

aircraft. J3 is physically located toward the front of the antenna and to the front of the

aircraft when antenna is installed properly. The T

CAS computer unit checks the built--in

dc to ground resistance of this antenna port. It must detect approximately 4000 Ohms or

it reports antenna test failure.

LTP --4 Top Antenna 90 Degree Port

J4 on the antenna is color--coded red. This antenna port (Note 2) is called the 90 degree

port because it produces a transmission pattern in the right wing quadrant of the aircraft.

J4 is physically located toward the left wing of the aircraft when antenna is properly

installed. The TCAS function checks the built--in dc to ground resistance of this antenna

port. It must detect approximately 2000 Ohms or it reports antenna test failure.

CAS Computer Unit Left Middle Plug (LMP)

LMP --1 Bottom Antenna 0 Degree Port

J1 on the antenna is color--coded yellow. Same as top antenna 0 degree port (LTP--1).

In addition, this port (Note 2) is used as the omnidirectional antenna connection. The

TCAS function determines that a bottom omnidirectional antenna is installed if it detects

less than 500 Ohms (50 Ohms typical) to ground on this pin and an open circuit (>13k

Ohms) at LMP-- 2, --3, and --4 or a dc short (<500 Ohms) if unused ports are terminated

at back of mounting tray.

LMP --2 Bottom Antenna 90 Degree Port

J2 on the antenna is color--coded black. This antenna port (Note 2) is called the 90

degree port because it produces a transmission pattern in the right wing quadrant of the

aircraft. J2 is physically located toward the left wing of the aircraft when antenna is

properly installed. The TCAS function checks the built in dc to ground resistance of this

antenna port. It must detect approximately 8000 Ohms or it reports antenna test failure.