MODULATOR SWITCH

• BACKGROUND
• SIGNAL SOURCE
• SIGNAL DESTINATION
• LIMITS AND FAULTS

 

 
 
 
 
 

BACKGROUND


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The Stack Monitor A12A9 (see figure 11-5 sheet 5) monitor the RBDT switch assembly A12A1 fault status, and sends modulator voltage and current samples to Control and Monitoring.  The Voltage Equalization board A12A8 (see figure 11-5 sheet 4) sends RBDT voltage samples to Stack Monitor.  The RBDT voltage samples are applied to a stack of 10 comparators.  Each comparator in the summing amplifier logic examines the voltage across one element of the RBDT stack.  The comparator output are the equivalent of a go/no-go indication for each element.  All 10 outputs are summed together into a voltage summary signal (SUMVLT).  The SUMVLT signal is compared to two thresholds.  If one or two elements fail, SUMVLT drops below the first threshold, and a stack maintenance signal (MNT) is generated.  If three or more elements fail, SUMVLT drops below the second threshold and a stack fault signal (FLT) is generated and the MNT signal is cleared.
 

SIGNAL SOURCE


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The signal MODSWMNT originate on the Stack Monitor Board A12A9 and enter Control and Monitoring at J 26-10 & 30 (see 11-7 sheet 10) of the Control Card Rack A3.  And enter the RMS Interface A3A3 for further action.
 

SIGNAL DESTINATION


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After entering Control and Monitoring, MODSWMNT is forwarded to the Fault Bus at Port06EN- as Transmitter Data (TDATA).  It also leaves on bubble 1010-1 as MODSWMNT- for the Fault Display Panel.  There at bubble 1010 MODSWMNT- (see 11-7 sheet 1) goes out to light the lamp for Maintenance Required Modulation Switch.  This fault will not disable the transmitter.
 

LIMITS AND FAULTS


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If one or two RBDTs  fail, SUMVLT drops below the first threshold, and a stack maintenance signal (MNT) is generated.
 

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