9. Turn the 216 switch to OPF when you hllve finished.
NoTE
Under celff,ldll (dretllllStIlllceS it i_ possilfle to oveHoad the
ill[0rllal _lnllllirit!r add eiltlSO ;i sJil_ht error ill some roadillgs. A
snudl alter (in most eases IleglJgihle) can I)e developed olIly
when the overall linear rospOllSe noise level exceeds 126 dB
RMS, alld you are tryklg to read octave ll;tll/I levels on the 70
dB range position or lower. Noise above 12(] dB will I)e
clipppd at that level when you use tile 70 dB range position
or lower. This clipping action causes sgltaring of the wave
i)ell]_.';and introduces small amollnts of ]lllFtllonit: freqLleDck*s
which aetllally illily Dot be prose/it. The ltnlOtlllt Of error lit
worst c_,se is less than 1% of the overall noise, and tllllS for
IllO._t applications is not it CO/learn. 111it similar milliner over
all noise almve 136 dB will be clipped when reading octave
bands on tile 80 dB r_mgo or lower.
OPERATIONAL CHECK
'rile 215 meter should be calibrated alone using the Quest
CA-12 Calibrator at outlhled on Page 10, With the 215 calibrated,
eOnlleCt it to tile O11-,15, and lock them together with the thunlb
screw provided, The 216 meter w_ designed so that tile calihration
screw is not accessible when tile meter is attached to the OB-d5; the
motor therefore can not be adjusted when it it attached to the OB-,t5.
The OB-,15 has a fixed input to output voltage ratio o1'one and there-
fore lea no external adjustments. Cheek the operation of the 215-,15
Analyzer as follows:
1. Set the 215 meter to the 100 dli range position, and the
OB-d5 frequency band to 1000 llz (1K).
2, Using tile CA-12 Calibrator (110 dB at 1000 IIz) insert the
microphone into tile Calibrator and turll both units ON. With tim
meter set aL A, B, C or LIN position, It filll scale deflection (+10)
should be obtained.
3. Move the WEIGHTING selector to EXT to engtlge tile
OB-d5* The metPr reading shotdd still he almost +10 but rally be its
nltl_h llS D,5 all lower t]lilll full sellle I)eelltlse or tile contour of the
filter in the bandpass zone (see Figure 11).
d. Next mow, the FgEQUENCY selector to 2 Kllz and then to
500 llz. In both positions filt_ meter reading should drop 18 to 19
dB (see Figure ill
5, Renlove tile calibrator, lllld the mlalyzer is ready to lisa.
18
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