407738 Datasheet, PDF (7/8 Pages) Extech Instruments Corporation. – Digital Sound Level Meter

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
the 3.5mm stereo phono plug diagram for wiring).
AC Output
DC Output
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’).
• Output voltage: 0.707Vrms at full scale of the selected range.
• Output impedance: 5KΩ approx.
DC analog output specifications
The DC output is level-converted and generated by rms detection and logarithmic
compression. The signal reflects the frequency weighting selected (‘A’ or ‘C’).
• Output voltage: 10mV (±1mV) per displayed dB.
• Output impedance: 5KΩ 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
2. Put the meter in the ‘A’ weighting mode
3. Put the meter in the ‘SLOW’ response mode
4. Place the 407738 microphone into the calibrator.
5. Turn the calibrator ON.
6. Put the meter in the 70 to 130dB range
7. Adjust the meter’s CAL potentiometer so that the meter’s display matches the
output of the calibrator.
Safety
Read the following safety information carefully before attempting to operate or
service the meter. Use the meter only as specified in this manual; otherwise, the
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.
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Model 407738 Version 2.2 September 2005