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HPOD
Customer Commands
However, the Mute command only turns off the first few low power stages of the
amplifier, the high power stages remain on. By allowing the higher power transistors to
stay on, the amplifier remains in more thermally stable state should the mute condition be
removed. If the user desires to completely turn off the bias to the entire amplifier
(perhaps to conserve energy in a redundant system), both the MUT=1 and AMP=0
commands should be executed.
For normal transmit operation, MUT=0 and AMP=1 are required.
4.5 F
AULTS
The M&C system monitors certain key functions of the SSPA for proper operation.
Should any of these parameters exceed predetermined limits, the M&C system will
declare a fault. The conditions that trigger a fault are:
• Any power supply more than ± 10% outside its nominal value
• Either fan less than 25% of maximum speed
• I2C internal bus communications fault
• Thermal Shutdown - A temperature fault is indicated if the unit is ≥ +95°C. This
creates a summary fault and will cause the unit to mute itself and switch to the
back-up unit (if in a redundant system). However, the 10V supply to the FET
transistors will remain on until the unit reaches the thermal shutdown temperature
of ≥ 100°C. For protection reasons, the unit will shut down the 10V supply to the
power transistors at temperatures ≥ 100°C.
4.6 P
D
OWER
A power detector is provided to monitor the output power. It has a useful range of over
20 dB, referenced to the unit's rated P1dB point, and its value can be read by exercising
the "RMS" command. The test data supplied with each unit gives an indication of the
excellent accuracy and flatness of the power monitor over the frequency band of
operation.
ETECTOR
4–2
Revision 1
MN/HPOD.IOM
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