Comtech EF Data CRS-311 - Manual (Page 86)

CRS-311 1:1 Redundancy Switch Revision 7
Cables and Connections MN/CRS311.IOM
3–38
3.3.8 IF Connections – User to CRS-281x to Modems
The CRS‐281x modules connect the online modulator's Tx IF signal to your RF Up Converter. It
also passively splits the receive IF signal to provide both demodulators with the same IF signal
coming from the LNB, thus reducing switching time.
• Referring to Figure 3‐23, the SLM‐5650/5650A uses the CRS‐281 IF Switch Module
with 50Ω TNC connectors for 70/140MHz IF switching.
• Referring to Figure 3‐24, the SLM‐5650/5650A uses the CRS‐281L IF Switch Module for
L‐Band with Type‐N connectors.
• Referring to Figure 3‐23 and Figure 3‐24, connect and secure the IF cable pairs
(CA/3005‐3 TNC or CA/RF10453‐4 Type‐N) between your Up/Down Converters, CRS‐311,
and SLM‐5650/5650A modems as follows:
Traffic Modem Connections:
• From the SLM‐5650/5650A “J3 Rx” (70/140 MHz) or “J4 Rx” (L‐Band) connector, to the
CRS‐281x Switch Module connector labeled “J1 Rx”, and
• From the SLM‐5650/5650A “J1 Tx” (70/140 MHz) or “J2 Tx” (L‐Band) connector, to the
CRS‐281x Switch Module connector labeled “J2 Tx”.
User Connections:
• From your Down Converter to the CRS‐281x Switch Module connector labeled “J3 Rx”,
and
• From your Up Converter to the CRS‐281x Switch Module connector labeled “J4 Tx”.
Redundant Modem Connections:
• From the SLM‐5650/5650A “J3 Rx” (70/140 MHz) or “J4 Rx” (L‐Band) connector, to the
CRS‐281x Switch Module connector labeled “J5 Rx”, and
• From the SLM‐5650/5650A “J1 Tx” (70/140 MHz) or “J2 Tx” (L‐Band) connector, to the
CRS‐281x Switch Module connector labeled “J6 Tx”.
Mixed IF Bands for Tx/Rx:
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
3‐25 and Figure 3‐26 for these mixed‐use configuration examples.