Casella CEL CEL-393 User Manual
Page 83
should indicate the level generated by the calibrator as indicated in its
handbook for this configuration.
Caution
Do not adjust the calibration using the screwdriver
supplied with the instrument, this is for opening the
battery compartment and is NOT suitable for cali-
bration adjustments.
If the instrument calibration has changed, it may be brought back to the
correct level (114.0dB) by adjusting the sensitivity control with the trim
tool provided. This control is accessible through the aperture in the front
of the nose cone, marked CAL, and should be rotated counter-clockwise
to increase the reading and vice versa. The span of the single turn control
is approximately 10dB. It is a conventional 300
o
rotation control and must
only be adjusted with the trim tool provided.
Other calibrators such as the older CEL-177 electroacoustic type, or a
pistonphone may be used to calibrate the instrument. The procedure
below is offered as a guide to the methods to be used.
8.3
Pistonphone Calibration
When the CEL-393 is to be used at the extremes of its temperature
range, it is recommended that the sound level meter be calibrated using
this electro-mechanical device, as it has superior temperature stability
relative to conventional electro-acoustic devices.
393 Handbook
/79.