Model 407764 Version 1.4 December 2004
5
Operation
1.
Power the meter and select the desired Response Time (Fast or Slow) and Frequency
Weighting (A or C).
2.
Select the desired range.
3.
Hold the instrument comfortably in hand or position on tripod. Point the microphone
toward the noise source, the sound pressure level will be displayed on the meter’s LCD
display.
4.
When MAX (maximum hold) mode is selected by pressing the MAX key, the instrument
captures and holds the maximum noise level reading on the display. Press the MAX key
again to clear the MAX reading.
Calibration
Note that a Sound Level Calibrator is required. Set up the meter as listed in Step 1 below.
To calibrate the meter;
1. Display:
SPL
(dBA)
Response Time: FAST
Disable the MAX function
Range: 70 to 120dB.
2.
Insert the microphone carefully into the sound
level calibrator.
3.
Power the calibrator and adjust the Sound Level Meter’s
CAL potentiometer (as shown in figure at right) to match
the Calibrator’s output.
4.
Typically, a Sound Level Calibrator will supply 94dB
or 114dB at 1KHz. Adjust the Sound Level Meter’s CAL
potentiometer for a 94dB or 114dB LCD display
(Figure-3)
Analog output
The 407764 has two analog output jacks located on its right side; one for AC and one for DC.
For DC, the meter transmits 10mv / dB. For AC the full scale value is 0.707V. The output
impedance is 600
Ω
for AC and 100
Ω
for DC.
The supplied 3.5mm stereo mini-plug can be used to assemble a cable to connect to either of
the meter’s analog output jacks. When using a stereo plug, like the one supplied, short the Tip
and the Ring (see diagram below). Ground (negative) connects to the Sleeve while the positive
signal is taken from the Tip/Ring. For mono plugs, ground connects to the Sleeve while the
positive signal is taken from the Tip. The meter output can then be transmitted to a chart
recorder, datalogger, or other data storage device.
(Figure 4)
Tip
Sleeve
Mono
Tip
Ring
Sleeve
Stereo
