Comtech EF Data CRS-311, Installation And Operation Manual

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CRS-311 1:1 Redundancy Switch Revision 7
Introduction MN/CRS311.IOM
1–4
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CRS ‐ 281 (70/140 MHz IF) with Type ‘BNC’ (75 Ω ) connectors
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CRS ‐ 281L (L ‐ Band IF) with Type ‘N’ (50 Ω ) connectors
Two CRS ‐ 281x switch modules are compatible for use with the SLM ‐ 5650/5650A modem:
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CRS ‐ 281 (70/140 MHz IF) with Type ‘TNC’ (50 Ω ) connectors.
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CRS ‐ 281L (L ‐ Band IF) with Type ‘N’ (50 Ω ) connectors.
The SLM ‐ 5650/5650A modem permits simultaneous operation of the Tx IF and Rx IF
bands at 70/140 MHz and L ‐ Band frequencies, independent of one another. If you
want the Tx and Rx to be of different IF bands, the CRS ‐ 281x module must be
selected based on the Tx IF band. An external splitter is then used for the Rx IF band
when that side differs from the Tx IF band – see Figure 3 ‐ 19 and Figure 3 ‐ 20 in Sect.
3.3.6 IF Connections – User to CRS ‐ 281x to Modems for configuration examples.
See Sect. 1.3.6 CRS ‐ 281x IF Switch Modules and Sect. 1.4.2 CRS ‐ 281x IF Switch Module
Specifications for more information on these switch modules and their specifications.
CRS ‐ 351 Option: Where protection of the overhead signals (backward alarms, audio ESC, data
ESC, etc.) is desired, the CRS ‐ 351 Overhead Module may be added.