Casella CEL CEL-278 - Manual (Page 24)

Warning
Remove batteries from both Filter Set and Sound Level Meter if they are to
be powered by an external supply.
Alternatively, connect the instruments for external power using the CEL-
3732/2 Power Supply and C4461/2 Cable as shown in Figures 8.
8.
Check the condition of the batteries in the sound level meter and
recording instrument according to the relevant handbooks.
9.
Move the RANGE switch on the Filter Set to "Hi" to switch the Filter
Set ON.
It takes approximately ten seconds for the CEL-278/2 to reach the
specified stability and measuring accuracy.
10.
If the "LOW BAT" message is displayed on the Filter Set, change the
batteries.
11.
Calibrate the Instrumentation arrangement according to the
instructions given In the Sound Level Meter handbook.
Normally, the Filter Set RANGE switch will be set to "Hi", but If the
instrument is being used with a CEL-493/2 or /2N which has a 100dB
dynamic range, set the switch to "Lo" if required.
Note: On all these measuring instruments, except CEL-493, CEL-275, and
CEL-383 series sound level meters. a different calibration level will exist
between the sound level meter alone on A-weighted or Linear and the sound
level meter PLUS Filter Set on the same setting.
Usually it will be possible to adjust the CAL control on the meter to
compensate for the condition, however a "k factor" may be required in some
cases.
The equipment is now ready for operation.
Page 24 CEL-278/2 Handbook CEL Instruments Ltd