BRUEL & KJAER Mediator 2238 - Configuring Measurement Set-up

Chapter 2 — Checking Procedure
Checking Procedure
2238 Mediator Integrating Sound Level Meter
Service Manual
BI5043–13
15
play of Type 2238 reads 124.0dB. Repeat procedure to reset range for each of
the five remaining ranges.
● Change the generator output in steps of 10dB (use the 115011 Decade Attenuator,
if necessary) according to Table 2.5 below.
Note: This test may not be performed while the 2238 is set to Peak (LCPK).
Result:
● The display reading for the different ranges as given in Table 2.5 must be within
the tolerance relative to the reference value in the 50–30dB Range.
Table 2.5 Attenuator Linearity
2.3.6 Detectors–Amplitude Linearity of RMS and Peak Detectors
Action:
● Set the generator’s frequency to 1kHz and adjust the amplitude to read 94.0 dB
on the display of Type 2238 for the ‘SPL’ check, and 97.0dB for the ‘Peak’ check,
respectively.
● Check the Display Modes ‘LCFP’ and ‘LCPK’ according to Table 2.6.
Result:
● The display reading for the different input amplitudes versus RMS/Peak as given
in Table 2.6 must be within the tolerances relative to the reference value.
Note: This procedure must be repeated for Detector #2.
Range
dB
Input
dBµVRMS
Display
dBSPL
Actual
Reading
60 – 140 Ref.+10dB
134.0
± 0.3
50–130 Ref. 124.0
40–120 Ref. –10dB
114.0
± 0.3
30–110 Ref. –20dB
104.0
± 0.3
20–100 Ref. –30dB
94.0
± 0.3
10–90 Ref. –40dB
84.0
± 0.3