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HARRIS
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WARNING: Disconnect and lockout AC primary power prior to servicing
147
In a similar manner, the output reflected power, (VIS_RFLD_PWR), is compared to a
digitally controlled voltage and generated a reflected fault.
The three reject loads are compared with a voltage that is calculated to be 75% of the
load rating. Above this point, a warning only is generated and a fault will shut down
two cabinets if the load rating is exceeded.
5.5.1.15 Dual Tran Interface (Sheet 16)
This is interfacing for the Dual Tran interfacing, detailed information is included in the
Dual Tran documentation.
5.5.1.16 Remote Commands Input (Sheet 17)
The parallel control command inputs are opto-coupler and are inputs to an eight bit
parallel-input/serial output shift register. The /RMT_I/O_CS line is used to inhibit
remote control commands when remote is DISABLED.
Jumper JP2 allows powering the opto-coupler from the internal 5 volts or a voltage
furnished by the remote control system. The furnished voltage shall not exceed 12 volts.
This voltage has a 15 volt zener clamp diode, CR2 and a 0.2 A current limiting resistor
R31.
The +5V_ISOL, 5 volts, is furnished from U3, a 5 volt DC to DC supply rated at 150
mA maximum.
5.5.1.17 Remote Status Output Drivers (Sheets 18 and 19)
The 74AHCT594 devices contain an 8-bit serial-in, parallel-out shift register that feeds
an 8-bit D-type storage register. Separate clocks and direct overriding clear (SRCLR,
RCLR) inputs are provided on both the shift and storage registers. U46 is used to change
the serial status information into stored status information that is opto-coupled and then
drives the gate of the 2N7002 FETs. When the fault is valid, the FET pulls the line low,
indicating to the remote control that the fault is active.
U47, sheet 19 drives 8 more status lines. The bottom two status lines are direct from the
CPLD, isolated and are part of the RF coax switch control system.
5.5.1.18 Optional Remote Status Output Drivers (Sheet 20)
J31 pins 1-3 are used to output the status of the exciter switcher, the status lines come
direct from the CPLD. The status lines at pins four and five are status lines from an
analog transmitter system with redundant drive paths.
5.5.1.19 Remote Analog Outputs (Sheet 21)
The microprocessor digital values are sequenced to the input of U61, a multiple output
digital to analog converter. The digital values are converted to an analog voltages at the
outputs of U61. These voltages are buffered by sections of U69 through U72, and are
available for remote metering at J33.