Comtech EF Data SMS-758 - Manual (Page 37)

SMS-758 Modem Protection Switch Installation
MN/SMS758 Rev. 3 2–9
2.4.7 Back-up Demods (J11, J16)
J11 and J16 provide the outputs from the downlink switching matrix. J11 is the backup
demod 1 output, and J16 is the backup demod 2 output. They connect to the backup
modem’s RX IF inputs.
Any of the 4 downlinks can be directed internally to J11 and J16. The default setting is
downlink 1.
The input frequency range is 50 to 180 MHz, with an input impedance of 75
Ω
.
Terminate any back-up demod port into 75
Ω
when not being used.
2.4.8 Prime Mod Inputs (J18 through J25)
J18 through J25 are the prime modulator IF input connections to the Modulator IF
switching matrix. They connect to the prime modem IF outputs.
The input frequency range is 50 to 180 MHz, with an input impedance of 75
Ω
.
Prime mod inputs that are not being used must be terminated into 75
Ω
.
2.4.9 Back-up Mod Inputs (J26, J36)
J26 and J36 are the backup modulator IF input connectors. They connect to the backup
modem IF outputs.
The input frequency range is 50 to 180 MHz, with an input impedance of 75
Ω
.
2.4.10 Offline IF Outputs (J17, J27)
The offline IF output connectors, J17 and J27 are used as a monitor and test point:
•
The outputs of the backup modulators are routed here when not in use.
•
When backups are online, the offline primes are routed here.