Comtech EF Data MBT-4000B Installation And Operation Manual page 35

Multi-Band Transceiver System
Redundant Configuration
Step
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Procedure
Enable external fault monitoring by sending an EAM=11 command to both base
units.
Fault the online SSPA by removing its power and confirm LED one of the
associate MBT is red(indicates fault detected" and blinking(indicates the switch
has thrown and is now offline). Restore the system and repeat for the second
amplifier.
If the online/offline control line(Pin G of the Aux comm. connector) is being used,
proper operation can be established by querying the amplifiers mute status. The
line must be enabled as an output using the "EOM-1O" command. If the logic
levels are opposite of what is required, the "IOM=1X" command can be used.
Setting the BUC attenuators independently performs gain balancing. If the
BUC/amplifier chain associated with MBT A has 1 dB more gain then the chain
associated with MBT B, add one dB of attenuation to the desired setting of the
BUC on MBT A.
Downlink Test
Ensure redundancy is enabled and set to AUTO mode as outlined above
Connect the LNBs
Enable the LNB voltage by sending "LCS=21" to both base units.
Verify the LNBs are drawing appropriate current by polling the with an "RMS?"
query. Reported current for "LNA2" should be in the 200 to 400 mA range.
Calibrate the normal operating point of the LNB by sending "CLC=2" to both base
units. This records the operating current of the LNB and the MBT will monitor this
current.
Set the desired current window(outside of which a fault will be declared) using the
"LCW=2XX" command. Note the "XX" is the percentage of the nominal current
allowed before a fault is declared. 30%(LCW=230) is a typical setting.
Disconnect the online LNB(indicated by the solid unit two LED). The LED should
now turn red and blink and the LNB switch should throw. The unit 2 LED on the
other MBT should stop blinking
Restore the first LNB and fault the second. The same change in LEDs and switch
position should be observed.
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MN/MBT4000B.IOM