Comtech EF Data MBT-4000B - Manual (Page 82)

MBT-4000B Multi-Band Transceiver System Revision 1
Appendix B MN/MBT4000B.IOM
B–4
B.4 External Fault Monitoring
Each MBT-4000B base includes a logic input on the “J9 | AUX COMM” connector that may be
connected to contact closure fault indications of external equipment (usually an SSPA or TWTA).
Thus, external equipment failure may participate in overall fault indication and redundant
switchover operation according to the following rules:
1. An open connection (or 2.7 V min) indicates a fault condition exists.
2. A closed connection (or 0.7 V max) indicates no fault condition exists.
3. Maximum voltage range on fault logic inputs is –12V to +12V.
4. The fault input of “J9 | AUX COM” corresponds to the BUC installed as “BUC1”.
5. To enable fault input checking, the EAM=1m remote command is used (where m=0 for
disabled, or 1 for enabled).
B.5 LNB Power Supply Current Monitoring
The bias tee in the MBT-4000B base is used to supply power and the 10 MHz reference to the
LNB.
This power supply features current monitoring with programmable failure limits. Overcurrent
and undercurrent failures can participate in overall fault indication and redundant switchover
criteria.
The following remote commands and rules configure operation of this feature:
1. The power supply provides +18V with a 450 mA current limit.
2. The Bias Tee supply is enabled by issuing the LCS=2m remote command (where m=0
(OFF) or 1 (ON)).
3. In case of excessive current (more than 450 mA), the supply will be disabled and a fault
will be posted. The LCS=2m remote command must be re-sent to re-enable the supply.
4. To enable programmable current monitoring, the following steps are taken:
a. The desired output is enabled as outlined above.
b. The nominal current is calibrated using the CLC=2 remote command.
c. The programmable current window is specified using the LCW=2xx remote
command. (Note that xx=the allowable percentage of variance from nominal (set by