Digital Sound Level Meter
Contents
1. Microphone Electret condenser Microphone collar unscrew to remove microphone LCD Display Push buttons Power button A C buttons Sets the frequency weighting FAST SLOW buttons Sets the response time MAX button Selects MAX MIN or current measurement also used to test the FAST SLOW characteristics Press and hold the MAX button for 5 seconds MAX will flash on the LCD press again to exit For specifics refer to relevant sections in this manual MEM button Press to store a data set in memory READ button Press to read the stored data sets Up and Down Arrow buttons Used to select measurement ranges also used to scroll through the stored data sets in the MEM memory mode CAL potentiometer For calibration Optional calibrator required External 9VDC power adaptor DC AC analog output Retransmission of sound level measurement for chart recorder or other datalogger Tripod Mount Battery compartment 365 csr 00 05 06 3 Model 407738 Version 2 2 September 2005 Display Description go ON Oa PF WO ND wo Sei See yok ac Sk a oe ee a LS od 8 47 16 8 mmu FAST SLOW g g 1 45 6 I QUIT Le FULL MIR Om a a aa Sound Level Range Bargraph indication Under range indicator for current reading Under range indicator for reading in memory Frequency weighting Over range indicator for2. User s Guide EXTECH INSTRUMENTS Digital Sound Level Meter Model 407738 EXTECH 407738 Sound Level Meter With Memory Introduction Congratulations on your purchase of the Extech 407738 Digital Sound Level Meter The 407738 measures and displays sound pressure levels in dB decibels from 26 to 130dB in six measurement ranges The microphone can be removed and remotely stationed for convenience In addition to the LCD numerical displays a bargraph is included for quick and easy viewing of sound level changes Features include selectable Frequency Weighting A and C selectable Response Time Fast and Slow Max Hold and a 99 reading storage utility Careful use of this meter will provide years of reliable service Specifications Applicable Standards Measurement Functions Primary Functions Total range Maximum level Accuracy Noise floor Calibration signal Range selections Frequency range Frequency weighting Time weighting Calibration Display update rate Data memory Microphone Display Display features Warning indicators Analog Outputs Power requirements Operating conditions Storage conditions Dimensions Weight Support line 781 890 7440 Technical support Extension 200 E mail support extech com Repair amp Returns Extension 210 E mail repair extech com Product specifications subject to change without notice For the latest version of this
3. User s Guide Software updates and other up to the minute product information visit our website www extech com IEC61672 1 2002 Class 2 IEC 60651 1979 Type 2 ANSI 1 4 1983 Type 2 Sound Pressure Level Maximum Sound Level Minimum S ound Level 26 to 130dB 32 to 130dB for C weighted measurements 130dB 1 5dB under reference conditions A weighting 26dB C weighting 32dB 94dB at 1kHz sinusoidal 26 to 80 30 to 90 40 to 100 50 to 110 60 to 120 70 to 130 31 5 to 8000 Hz A and C Fast 125ms and Slow 1 second Response Requires external calibrator not included Bargraph display 125ms Numerical indication 1 second 99 data sets max for sound level L maximum sound level Lmax and minimum sound level Lmin can be stored with elapsed timer 0 5 electret condensor 4 digit indication of sound level with 0 1dB resolution Bargraph indication of sound level with 1dB resolution Elapsed time 100 hours maximum Store and recall readings 99 data sets max Over range OV Under range Un AC 0 707Vrms full scale Output impedance 5KQ DC 10mV 1dB Output impedance 5KQ 9V Battery Battery life approx 50 hours 14 to 122 F 10 to 50 C 90 relative humidity max 14 to 132 F 10 to 60 C 90 relative humidity max 10 4 x 2 7 x 1 1 264 x 68 x 27mm 9 2 02 260g T 2 Model 407738 Version 2 2 September 2005 Meter Description PON
4. 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 2005 Extech Instruments Corporation All rights reserved including the right of reproduction in whole or in part in any form 8 Model 407738 Version 2 2 September 2005
5. g selected A or C e Output voltage 10mV 1mV per displayed dB e Output impedance 5KQ approx Calibration To calibrate the 407738 an external calibrator such as the Extech 407744 or the Extech 407766 is required in addition to a small screw driver 1 Turn the meter ON Put the meter in the A weighting mode Put the meter in the SLOW response mode Place the 407738 microphone into the calibrator Turn the calibrator ON Put the meter in the 70 to 130dB range Adjust the meter s CAL potentiometer so that the meter s display matches the output of the calibrator NOOR OL Safety service the meter Use the meter only as specified in this manual otherwise the f Read the following safety information carefully before attempting to operate or protection provided by the meter may be impaired Environmental Conditions Altitude up to 2000 meters Relative Humidity 90 max Maintenance and Cleaning Servicing not covered in this manual should be performed by qualified personnel Periodically wipe the case with a dry cloth Do not use abrasives or solvents 7 Model 407738 Version 2 2 September 2005 Typical A Weighted Sound Levels dBA 40 SOHP Siren 100 30 Jet takeoff 200 20 Riveting machine 19 00 Chain saw Subway 20 20 Boiler room Pneumatic drill 50 0 Freight train 100 Vacuum cleaner 10 70 Speech 1 Large store 60 Large Office Small office 0 Residence N
6. ight residential area 40 Whisper 5 0 0 Sound studio 10 Threshold of hearing 0 Warranty EXTECH INSTRUMENTS CORPORATION warrants this instrument to be free of defects in parts and workmanship for one yeer from date of shipment a six month limited warranty applies to sensors and cables If it should become necessary to return the instrument for service during or beyond the warranty period contact the Customer Service Department at 781 890 7440 ext 210 for authorization or visit our website www extech com for contact information A Return Authorization RA number must be issued before any product is returned to Extech The sender is responsible for shipping charges freight insurance and proper packaging to prevent damage in transit This warranty does not apply to defects resulting from action of the user such as misuse improper wiring operation outside of specification improper maintenance or repair or unauthorized modification Extech specifically disclaims any implied warranties or merchantability or fitness for a specific purpose and will not be liable for any direct indirect incidental or consequential damages Extech s total liability is limited to repair or replacement of the product The warranty set forth above is inclusive and no other warranty whether written or oral is expressed or implied Calibration and Repair Services Extech offers repair and calibration services for the products we sell Extech also provides NIST
7. on will appear on the LCD 2 Use the arrow keys to scroll through the stored reading list The memory location number displays for each stored reading 01 through 99 3 Use the MAX button to scroll through the MAX MIN and Elapsed Time data stored at the current location 4 Press the READ button again to exit the recall mode Clearing Stored readings 1 Turn the meter OFF 2 Press and hold the MEM button while turning the meter ON 3 When the CLr clear display icon appears release the MEM button 4 All of the readings that were stored in memory are now erased 6 Model 407738 Version 2 2 September 2005 Analog Outputs The Model 407738 is equipped with an analog output feature The analog output jack is located on the meter s right side see Description section of manual for location AC and DC analog signals are available from the provided jack refer to haere the 3 5mm stereo phono plug diagram for wiring pe cree be 1D Common AC analog output specifications The AC output is a retransmitted representation of the meter s measurement note that the output factors in the meter s frequency weighting selection A or C e Output voltage 0 707Vrms at full scale of the selected range e Output impedance 5KQ approx DC analog output specifications The DC output is level converted and generated by rms detection and logarithmic compression The signal reflects the frequency weightin
8. reading in memory Over range indicator for current reading Battery status indicator FAST response time setting SLOW response time setting Elapsed time indicator 100 hours max Memory FULL indicator Memory indicator READ memory indicator Address for stored reading Sound level unit of measure decibel Maximum sound level reading Minimum sound level reading Sound pressure level 4 Model 407738 Version 2 2 September 2005 Power Supply The meter can be powered by one 9V battery or by the specified optional AC power adaptor Before inserting or replacing the battery and before connecting the AC adaptor be sure to turn off the meter Battery Installation Remove the battery compartment cover lower back of the meter and install or replace the 9V battery Fully charged Battery Capacity Indicator The battery status indicator on the meter s display see diagram informs the user of the battery s condition The number of segments in Partially charged the display icon decreases as the battery weakens When all segments switch off and the icon flashes the meter is about to lose power AC Voltage Adaptor Replace batte Insert the AC adaptor into the DC 9V jack on the side of the meter Connect the other end of the adaptor to an AC source With a battery installed and the AC adaptor in use the AC adaptor has priority Measurements 1 Turn the meter ON by pressing the button The default settings are A frequenc
9. s the highest reading encountered since the meter was last reset Note that the elapsed timer display shows the time at which the MAX reading was recorded 2 Press the MAX button again The MIN icon will appear on the LCD and the reading shown represents the lowest reading encountered since the meter s memory was last reset The elapsed timer display shows the time at which the MIN reading was recorded 3 Press the MAX button again to exit the MAX MIN display mode the MAX and MIN display icons switch off when this mode is exited 4 To clear the MAX MIN memory simply press the up or down arrow to change range Note that the elapsed timer starts when the meter is switched ON and continues running until the meter is shut off or until 100 hours is reached 5 Model 407738 Version 2 2 September 2005 Measurement Considerations 1 Wind blowing across the microphone increases the noise measurement Use the supplied windscreen to cover the microphone when applicable 2 Calibrate the instrument before each use if possible Especially if the meter has not been used for a long period of time 3 Do not store or operate the instrument in areas of high temperature or humidity 4 Keep meter and microphone dry 5 Avoid severe vibration Protect the meter from impact Do not drop it Transport the meter in the supplied case 6 Remove the battery when the meter is to be stored for long periods of time Notes on A and C Frequenc
10. y response FAST response time and 70 to 130dB range 2 Select the frequency weighting A or C as desired using the A or the C buttons Typical sound level measurements use A weighting 3 Press the FAST or SLOW button to select the desired response time Normally the SLOW setting is used 4 Use the up and down buttons to select the appropriate range The range is shown at the top left corner low end of range and top right corner high end of range of the LCD Use a range that puts the sound level reading in the center of the bargraph If the OV over range or UN under range icons appear with dashes on the main display area select a new range Refer to the Specifications page for the list of available ranges 5 The numeric and bargraph displays indicate the sound level measurement The numerical reading updates every second while the bargraph updates every 125ms MAX MIN Operation The Model 407738 stores the highest MAX and lowest MIN readings in its memory The stored MAX and MIN values are continually updated as new MAX and MIN values are encountered The user can recall these stored readings using the MAX button as described in the steps below Before starting select an appropriate range as described previously otherwise the stored MIN MAX readings may indicate all dashes out of range 1 Press the MAX button and the MAX icon will appear on the LCD The reading shown i
11. y Weighting Use the A and C buttons to select A or C frequency weighting With A weighting selected the frequency response of the meter is similar to the response of the human ear A weighting is commonly used for environmental or hearing conservation programs such as OSHA regulatory testing and noise ordinance law enforcement C weighting is a much flatter response and is suitable for the sound level analysis of machines engines etc Most noise measurements are performed using A Weighting and SLOW Response Notes on FAST and SLOW Response Time Use the FAST and SLOW buttons to select a FAST 125 ms or a SLOW 1 second response time Select FAST to capture noise peaks and noises that occur very quickly Select the SLOW response to monitor a sound source that has a consistent noise level or to average quickly changing levels Select SLOW response for most applications Storing and Recalling Readings Storing readings Press the MEM button momentarily to store a reading The meter will store the current measurement the current MAX amp MIN values and the elapsed time The display icon W will appear briefly when the MEM button is pressed along with the storage location 01 through 99 The FULL display icon will appear when the meter s internal memory has reached capacity 99 readings Recalling readings 1 Press the READ button to enter the recall mode the R display ic
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