Extech 407764 Operating Manual

User's Manual

Datalogging Sound Level Meter

Model 407764

Range: 30dB to 130dB

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4-digit LCD Display with 0.1dB resolution

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A and C Frequency Weighting

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RS-232 PC Interface with

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128,000 point datalogger an d Date / Time Stamp

Auto-Ranging

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Introduction

Congratulations on your purchase of Extech’s Datalogging Sound Level Meter. The meter is capable of performing all your noise measurements needs in addition to it’s capabilities for data acquisition (direct data storage to a PC) or datalogging (data storage to internal memory for later download). Data storage enables the user to save data, analyze data and generate reports. This professional meter, with proper care, will provide years of safe reliable service.

Specifications

Applicable Standards IEC651 Type 2, ANSI S1.4 Type 2 Accuracy ±1.5dB (under reference conditions) Frequency range 31.5Hz - 8KHz Measuring level 30 - 130dB Frequency weighting A and C Microphone 0.5” Electret condenser microphone Display 4-digit LCD

Resolution: 0.1dB Display period: 0.5 sec.

Bargraph 50dB scale (1dB steps). Display period: 50mS; Auto-ranging:

100dB scale, 2dB steps

Sampling rate 50mS Memory size 128,000 records / 255 sets (non-volatile memory) Datalogging sample rate 1 to 86,400 seconds per record Time weighting FAST: 125mS, SLOW: 1 sec. MAX Maximum reading held Level ranges 30-80dB, 40-90dB, 50-100dB, 60-110 dB, 70-120dB, 80-130dB

(Total of 6 ranges)

Auto range 30 to 130dB Linearity range 50dB Alarm function OVER indicator for readings higher than high limit.

UNDER indicator for readings lower than low limit. AC output 0.707 Vrms at Full Scale Output impedance approx. 600Ω DC output 10mV / dB Output impedance approx. 100Ω

Power supply Four 1.5V ‘AA’ batteries Battery life Approx. 30 hrs continuous operation AC adap ter Voltage: 6VDC

Voltage Ripple: < 100mVpp Supply Current: > 100mADC Socket: Pin Ground Casing: Positive External Diameter: 3.5mm

Operating temperature 32 to 104 Operating humidity 10 to 80%RH Storage temperature 14 to 140

F (0 to 40oC)

F (-10 to 60oC)

Storage humidity 10 to 80%RH Memory size 128,000 data records with Date and Time Stamping RS-232 Interface Baud rate: 9600bps Dimensions 10.4 x 2.8 x 1.4” (265 × 72 × 35mm Weight Approx. 11.5 oz. (358g) including battery Accessories Batteries, carrying case, screwdriver, windscreen, 3.5mm plug, RS-232

cable , Windows

compatible software.

Safety symbols

Meter is protected throughout by double insulation or reinforced insulation.

CE Complies with EMC

Model 407764 Version 2.1 9/07

Meter Description

1. Microphone

2. Display

3. Power switch

4. Level range control switch

5. MAX hold switch

6. Frequency weighting switch

7. Response time select switch

8. AC output terminal

9. DC output terminal

10. CAL (calibration) pot.

11. External DC 6V power

12. RS-232 interface connector

13. Battery cover

14. Tripod mounting screw

15. Wind-screen

(Figure 1)

Display Description

1. Range selection

2. Date information

3. SPL: Instantaneous sound pressure level

4. Low-Battery

5. MAX: Maximum SPL value is held

6. Data recording

7. Measurement value

8. Memory full

9. Units

10. Frequency weighting (A/C)

11. TIME function

12. 50dB level (Bargraph)

13. Over range

14. SLOW time response

15. FAST time response

16. Under range

(Figure 2)

Model 407764 Version 2.1 9/07

Measurement Preparation

Read the following safety information before attempting to operate the meter

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Use the meter only as specified or the meter's built-in protection may be impaired.

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Maintenance & Cleaning

Service not covered in this manual should be performed by qualified personnel

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Periodically wipe the case with a dry cloth. Do not use abrasives or solvents.

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Battery Replacement

When the battery voltage drops to a critical level, the

symbol appears on the LCD. Replace batteries as soon as possible after the battery symbol appears. The batteries (4 AA) are located in the rear battery compartment. Remove the single Philips head screw (center rear) for access to the batteries.

Measurements

Default Configuration

1. The meter's default configuration is as follows: 40 to 90dB, 'A' Frequency Weighting, and

'FAST' Response Time

2. The LCD will reflect the meter's configuration.

Measurement Considerations

1. Use a windscreen to cover the microphone in windy conditions.

2. Calibrate the meter often, especially if the meter has not been used for a long time.

3. Do not store/operate the meter in high temperature/humidity for long periods of time.

4. Keep the meter and the microphone dry.

5. Avoid severe vibration when using the meter.

6. Remove the battery when the meter will be stored for long periods of time.

Frequency Weighting

Change the Frequency Weighting by pressing the 'A/C' button. The 'A' or 'C' icon will display on the right-hand area of the LCD.

Note: With ‘A’ weighting selected, the meter responds like the human ear (boosting and cutting the noise amplitude over the frequency spectrum - see Appendix). ‘A’ weighting is used for environmental measurements, OSHA regulatory testing, law enforcement, and workplace design. Select ‘C’ weighting for flat response measurements (no boost or cut). ‘C’ weighting is suitable for the sound level analysis of machines, engines, etc. Most OSHA related testing is performed using 'A' Weighting and SLOW Response Time settings.

Response Time

Change the Response Time by pressing the 'FAST/SLOW' button. The 'FAST' or 'SLOW' icon will display on the upper area of the LCD.

Note: Select FAST to capture noise peaks and noises that occur very quickly. In FAST mode, the meter responds in 200ms. Select the SLOW Mode (meter responds in 500ms) to monitor a sound source that has a reasonably consistent noise level or to average quickly changing levels. Selection of Fast or Slow is determined by the application and any directives or standards related to that application.

Auto/Manual Range

Press the LEVEL button up arrow to scroll through the following ranges: 30-80dB, 40-90, 50-100dB, 60-110, 70-120, 80-130 and 30-130dB (auto). The displa y will reflect the range for each button press.

Use Auto Range when the noise source is relatively steady. Use one of the Manual

Notes: ranges may be required if the dB levels are changing over a wide range.

Model 407764 Version 2.1 9/07

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