6802800U74-AN
Chapter 7: Radio Frequency Distribution System
7.3.2.1.2
Reinstalling the MTS 4 Preselector
Procedure:
1 Fasten the Preselector onto the bracket.
2 Slide the Preselector into the cabinet.
3 Tighten the two fastening screws at the front.
4 Screw on the antenna cable and connect the RX cables to the back of the Preselector.
5 Slide on the top rear and front panels and fasten these with screws.
6 Put the front panel back on and screw this into place.
7 Put the door of the cabinet back on.
7.3.3
MTS 4 Duplexer
The Duplexer is a Preselector with an integrated receiver multicoupler (RMC) and a Post Filter with a
digital power monitor (DPM) combined into one unit. These form the two bandpass filters that make up
the Duplexer; one is a receive filter and the other a transmit filter. See the block schematic of the MTS
4 Duplexer in Figure 154: Schematic Diagram of MTS 4 Duplexer on page 278
For 400 MHz, the duplex spacing between a transmitter frequency and the corresponding receive
frequency is 10 MHz, with the transmitter frequency highest. This leaves a 5 MHz spacing between the
lowest possible transmit frequency and the highest possible receive frequency.
For 260 MHz, the duplex spacing between a transmit frequency and the corresponding receive
frequency is 9 MHz, and leaves a 3 MHz spacing between the lowest possible transmit frequency and
the highest possible receive frequency.
For 800 MHz, the duplex spacing between a transmit frequency and the corresponding receive
frequency is 45 MHz, and leaves a 19 MHz spacing between the lowest possible transmit frequency
and the highest possible receive frequency.
The MTS 4 Duplexer has 4 RX outputs and one expansion output. It can handle a maximum power
180 Watts.
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