5.      COMPRESSION THRESHOLD
    
    Conditions:                             
	LIMIT				OFF
    	C0MPRESSION			ON
	BY-PASS				IN
	COMPRESSION THRESHOLD		0 dBm
	RECOVERY			200mS
	PPM SWITCH			CONTROL
	GAIN MAKE UP			0
    
    Monitor the signal input with the milivoltmeter, and set the
    level to 0dBm indicated. Then adjust 'SET THRESHOLD' until a just
    perceptible reading is seen on the PPM.
    
    Note: A just perceptible reading is defined as being halfway
    between the end stop and the first cardinal mark on the meter
    scale.
    
    The instrument is now set up for normal use.
    
    INTERNAL CONTROLS.
    
    There is only one internal pre-set control, which sets the standing
    collector current in the main line amplifier. This is set and
    sealed at the factory and requires no further adjustment.