Model 407732 Version 1.4 June 2004

6

Calibration

To calibrate the 407732, an external calibrator such as the Extech 407744 or the Extech

407766 is required in addition to a small screw-driver.

1.

Open the battery compartment and locate the two

calibration potentiometers behind the 9V battery (see

diagram)

2.

Turn the meter ON

3.

Put the meter in the ‘A’ weighting mode

4.

Put the meter in the ‘SLOW’ response mode

5.

Place the 407732 microphone into the calibrator. Set

the calibrator to output a 1kHz sine wave @ 94dB

6.

Put the meter in the low range

7.

Adjust the ‘A (Lo)’ potentiometer for a display of 94.0

dB

8.

Put the meter in the high range

9.

Adjust the ‘A (HI)’ potentiometer for a display of 94.0

dB

Battery Replacement

When the low battery icon BAT appears on the LCD replace the 9V battery as soon as

possible. The battery compartment cover is located on the rear of the meter. Remove the

Phillips screw to loosen the cover. Slide the battery compartment cover off, change the

battery, and replace the compartment cover.

Typical A-Weighted Sound Levels

50HP Siren (100')

130

120

110

100

90

80

70

60

50

40

30

20

10

140

0

Jet takeoff (200')

dBA

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

Copyright © 2004 Extech Instruments Corporation

All rights reserved including the right of reproduction in whole or in part in any form.