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 coupler group permits several transmitters to operate simultaneously into a single, associated, broadband antenna, thus reducing the total number of antennas required in the limited space aboard ship.

These antenna coupler groups provide a coupling path of prescribed efficiency between each transmitter and the associated antenna. They also provide isolation between transmitters, tunable bandpass filters to suppress harmonic and spurious transmitter outputs, and matching networks to reduce antenna impedances.

The three antenna coupler groups (AN/SRA-56, -57, -58) are similar in appearance and function, but they differ in frequency ranges. Antenna coupler group AN/SRA-56 operates in the 2- to 6-MHz frequency range. The AN/SRA-57 operates from 4 to 12 MHz, and the AN/SRA-33 operates from 10 to 30 MHz. When more than one coupler is used in the same frequency range, a 15 percent frequency separation must be maintained to avoid any interference.

Antenna Coupler Group AN/SRA-33

Antenna coupler group AN/SRA-33 operates in the uhf (225-400 MHZ) frequency range. It provides isolation between as many as four transmitter and receiver combinations operating simultaneously into a common uhf antenna without degrading operation. The AN/SRA-33 is designed for operation with shipboard radio set AN/WSC-3. The AN/SRA-33 consists of four antenna couplers (CU-1131/SRA-33 through CU-1134/SRA-33), a control power supply C-4586/SRA-33, an electronic equipment cabinet CY-3852/SRA-33, and a set of special-purpose cables.

OA-9123/SRC

The OA-9123/SRC multicoupler enables up to four uhf transceivers, transmitters, or receivers to operate on a common antenna. The multicoupler provides low insertion loss and highly selective filtering in each of the four ports. The unit is interface compatible with the channel select control signals from radio sets AN/WSC-3(V) (except (V)1). The unit is self- contained and is configured to fit into a standard 19-inch open equipment rack.

The OA-9123/SRC consists of a cabinet assembly, control power supply assembly, and four identical filter assemblies. This multicoupler is a state-of-the-art replacement for the AN/SRA-33 and only requires about half of the space.

RECEIVING ANTENNA DISTRIBUTION SYSTEMS

Receiving antenna distribution systems operate at low power levels and are designed to prevent multiple signals from being received. The basic distribution system has several antenna transmission lines and several receivers, as shown in figure 2-39. The system includes two basic patch panels, one that terminates the antenna transmission lines, and the other that terminates the lines leading to the receivers. Thus, any antenna can be patched to any receiver via patch cords.

Figure 2-39.—Receive signal distribution system. 2-23