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6.1.3 The 'EXT' or External Position
The CMX25 serves as the voltage comparator and variable gain stage. It will enable the
maintaining of a constant RF voltage vs. frequency at the input to an imperfect load or a virtually
constant E-Field at a measurement point in space.
The front panel, ALC control, switches direct level control from the front panel Level Control
potentiometer to the output of a linear comparator. The comparator output level is dependent on
the reference input from the front panel Level Control and the input from the aforementioned
detected voltage or E-Field. The total gain of the leveling loop serves to maintain the output of
the comparator virtually constant and thus maintain the desired test level at the remote detector
or remote E-Field sensor.
The 'EXT' position enables the amplifier to automatically control an operator determined power
level by means of an external 0.0 to 5.0 VDC reference source connected to the External Source
connector. An example of an 0.0 to 5.0 VDC external input would be the output of a LDI or an
EFS. Refer to Paragraph 6.3 for procedures on leveling with an external voltage level.
