Model 407740 version 1.6 8/05
4
Battery Replacement
The low battery indication (BAT) appears on the LCD when the 9V battery is nearing
depletion. Reliable readings can be obtained for several hours after the first appearance of
the low battery indication. To replace the battery, slide the battery compartment cover off
the rear of the instrument and replace the 9V battery. Secure the cover before use.
Reference Information
Frequency Weighting Characteristics
Frequency (Hz)
A Weighting
C Weighting
Tolerance
(IEC 651 Type 2
)
31.5 -39.4dB
-3dB
±3dB
63 -26.2dB
-0.8dB
±2dB
125 -16.1dB
-0.2dB
±1.5dB
250 -8.6dB
0dB
±1.5dB
500 -3.2dB
0dB
±1.5dB
1 k
0dB
0dB
±1.5dB
2 k
+1.2dB
-0.2dB
±2dB
4 k
+1dB
-0.8dB
±3dB
8 k
-1.1dB
-3dB
±5dB
Typical A-Weighted Sound Levels
Calibration and Repair Services
Extech offers repair and calibration services for the products we sell. Extech also provides
NIST certification for most products. Call the Customer Service Department for information
on calibration services available for this product. Extech recommends that annual
calibrations be performed to verify meter performance and accuracy.
Copyright
©
2003 Extech Instruments Corporation
All rights reserved including the right of reproduction in whole or in part in any form.
50HP Siren (100')
130
120
110
100
90
80
70
60
50
40
30
20
10
140
0
Jet takeoff (200')
dB
Riveting machine
Chain saw
Subway (20')
Boiler room
Pneumatic drill (50')
Freight train (100')
Vacuum cleaner (10')
Speech (1')
Large store
Large Office
Small office
Residence
Night residential area
Whisper (5'0)
Sound studio
Threshold of hearing
