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4.3 PROTECTION CIRCUITS
The SMX100 is designed with a variety of protection circuits to provide safeguards for the amplifier
should any adverse electrical conditions occur or if the amplifier accidentally experiences operator
deviation of the design application. Listed below are the safeguards built into the SMX100.
4.3.1 Over Heat Protection
The SMX100 critical components are mounted to heat sinks, which are, in turn, air cooled by four
fans. Should an over heating condition occur, either through component failure or by a restricted
airflow, the SMX100 contains heat sensors that will shut down the system. As a result, the air inlet
and outlet openings should be free of obstructions for proper cooling of the amplifier. Operation is
restored automatically when the amplifier cools to normal temperature levels.
4.3.2 Input Protection
The SMX100 is designed to operate with less than a 0 dBm ( 1.0 mW ) input signal however, to
prevent overdriving the amplifier, the Input Protection circuit will activate if the input signal exceeds
3 dBm ( 2.0 mW ) and will automatically compensate for the increased input signal by reducing the
gain of the preamplifier. Even though the amplifier has an Input Protection Circuit, overdriving the
amplifier is not recommended; refer to paragraph 5.1.2 for more details.
4.3.3 Output Protection
The SMX100 incorporates a microprocessor controlled Output Protection Circuit which monitors the
Forward Power Meter indication and limits the output power. This feature protects the amplifier
from being over driven and causing damage to the power transistors.
It is important to note that this feature only operates when the Forward and Reverse Sample Ports on
the amplifier have 50 Ohm Terminations installed.
IMPORTANT NOTE:
The SMX100 Sample RF Output connector must be terminated with the supplied 50 Ohm
load if the output is not being used. Should the SMX100 be operated without a termination
on the Sample RF Output connection will jeopardize the accuracy of the metering and output
protection; which are based on the Forward Power Readings, which may result in damaging
the amplifier and voiding the unit’s warranty.
