FIGURE 2-1. Rack Mounting.

TM 11-5820-917-13

2-10. AIRCRAFT INSTALLATION. The Aircraft Installation kit (part number

9125-1907) is primarily designed to assist installation of a RCS-4B Receiver in an E3A

AWACS aircraft and is typical for other installations. The kit consists of an

RF power divider, a 25W 10-dB attenuator (pad), a 30-MHz low pass filter, and

cables. Figure 2-2 is the block diagram of a typical installation. The power divider

must be connected as close as possible to an aircraft receive-only antenna. No active

or passive filter elements should be between the antenna and the power divider. The

antenna input coax should be disconnected from the existing receive system and

attached to Port A of the power divider. Connector adapters are provided. The air-

craft receive system should be connected to Port C; the Chirp sounder receiver to

Port D. A 50-ohm termination is provided for Port B.

2-11. A 25-watt 10-dB attenuator is provided to reduce the possible effects of any

RF energy picked up from an aircraft transmit antenna. This attenuator and the

power divider should be secured to the aircraft structure. A long (approximately

50- foot) coax cable links the power divider and attenuator to a low pass filter which

can be secured anywhere near the RCS-4B receiver. The filter, with a 30 MHz upper

frequency limit, attenuates RF above the VHF band.

2-2