Make sure the input channel is activated and a microphone is assigned. Press to enter the calibration menu, select the input channel and tap to enter the calibration mode. A special calibration display with a spectrum part and a calibration history for the actual transducer is shown. If the level is OK you can select to exit the calibration menu now, otherwise we recommend that you do "Manual check" procedure.
Use right and left cursor buttons to select a frequency (e.g. 1 kHz for a standard calibrator) or a network (C usually works fine). The spectrum of the calibration tone will be displayed. Tap the selection. The sensitivity can now be adjusted up and down. Use the orange and buttons at the bottom of the screen until the expected dB level is obtained. The step size is dependant on the number of decimals selected for the dB numbers (0 - 3, See Setup Instrument Menu). A line diagram is also shown giving the historical calibration values for this transducer. There may be a red line in this diagram indicating calibration results obtained in a calibration laboratory, while the blue line represents all the field checks or calibrations that are performed by the operator.
Please be aware that something may be wrong either with the transducer or with its settings if it is a need to change the sensitivity with more than a few tenths of a dB.