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User's Guide 

 
 
 
 
Digital Sound Level Meter 
 
Model 407750

 

 

 

Summary of Contents for 407750

Page 1: ...User s Guide Digital Sound Level Meter Model 407750 ...

Page 2: ...d 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 Introduction Congratulations on your purchase of the Extech 407750 This device measures sound level in dB and the measurement range can be set automatically or manually The 407750 offers selectable frequency weighting A and C and Time Response Fa...

Page 3: ...ct key 7 BA Background Absorber key 8 F S Fast Slow Response select key 9 DOWN 10 Backlit LCD backlighting key 11 UPPER 12 AC adaptor jack 13 Calibration screw adjust 14 AC analog output jack 15 DC analog output jack 16 RS 232 output jack Note The Battery Compartment and the Threaded Tripod mount access are located on the back of the instrument not pictured ...

Page 4: ...OW 1 second response measurements by pressing the F S key The LCD will reflect the currently selected mode Selection of Fast or Slow is determined by the application and any directives or standards related to that application For example most hearing conservation or OSHA related testing is done using SLOW and A weighting MAX HOLD The meter is capable of taking continuous measurements and only upda...

Page 5: ...ally finds the correct range in order to produce the best accuracy However if it is desired to set the range manually follow these steps 1 Power the meter 2 Notice the two 2 digit number to the immediate left of the analog bargraph This number is the low end of the presently selected range see the specifications for the ranges 3 To change the range press the UP key to raise the range or press the ...

Page 6: ...AC output is 0 707V rms full scale and the DC output is 10mV per dB The labeled 3 5mm output mini plugs are located on the bottom of the instrument RS 232 Output The meter includes an RS 232 PC interface jack This PC interface allows the meter to store and display readings on a PC as they are recorded The interface cable and software for data acquisition are sold separately Detailed instructions a...

Page 7: ...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 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 Whi...

Page 8: ... includes a Calibration adjustment on the bottom of the meter A sound level calibrator must be used to complete a calibration Extech can supply a calibrator for this purpose Once the Calibrator is affixed on the microphone adjust the calibration screw so that the LCD sound level display matches the calibrator s output signal Extech offers repair and calibration services for the products we sell Ex...

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