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7.
Press the CALIBRATE pushkey on the control panel of the 2116. The LED should
light, showing that the instrument is in CALIBRATE mode and the pen will move
down the left-hand margin of the paper
.
8.
Using a small screwdriver adjust the potentiometer to the right of the CALIBRATE
pushkey so that the pen lies 3 dB below any of the horizontal lines on the paper.
The 3 dB occurs because the output of the Calibrator is 10
ms-
2
peak i.e.
7,07 ms-2 RMS, 3 dB below 10
ms-
2 RMS. See Fig.4.3.
9.
Label the chosen line 10
ms-
2 and the rest of the scale as shown in Fig.4.3.
4.2.3. Direct Voltage Calibration using an External Signal Generator
This method may be used to calibrate for any transducer whose voltage sens1t1v1ty is
known e .g
.
microphones, accelerometers, hydrophones, force transducers etc. An exter-
nal source capable of supplying a known voltage within the 100Hz to 10kHz range of
the 211 6, such as the Type 1023 Sine Generator, is required. The procedure is as fol-
lows:
1.
Connect the Preamplifier Type 2642 to the output of the Signal Generator as in Sec-
tion 3.3.3.
2.
Set the frequency of the Sine Generator to within the frequency range of the 211 6
i .e. 100Hz to 1OkHz.
3.
Set the output to a suitable level e.g. a convenient round figure, say 10 mV rms.
4.
Press CALIBRATE on the 2116. The pen will move down the left-hand margin of the
paper and should be adjusted level with a convenient line by means of the CALI-
BRATE potentiometer.
DATE
_ _
__ _ _
O~ATOR
________________________
_
HEARING AID TYPE
-
-- - - - - - -
-- - - - -
-- - - - - - - - - - - - - - - _ _ _ _
REMARKS
____________________________________________
__
dB
dB
1,6
2,5
..--'-"--
140
90
-
I
I
r---
85
130
1----
-""'
j
80
I
I
1----
120
75
1----
I
I
Calibrate
70
INPUT SPL
11
0
1----
65
I
I
r--oo
100
-
94dB
r---
I
I
-10mV
~
~
MODE
90
Calibration
50
-
I
I
level
~
req
.
80
~
I
I
1V
100mV
10mV
HARMONIC
{
2nd
70
-
I
I
3rd
60
1mV
-
I
I
INTERMODULATION
{
2nd
50
-
3rd
I
I
I
40
10011V
0,125
0 ,250
0,5
8
kH
z
OP0009
0 0
Bruel
&
Kjmr Nm
rum,
Denmark
D O - +
790350
Fig.
4
.
4.
Direct voltage calibration of the 2116 using an external sig-
nal generator
19
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