10 Maintenance Manual
Measurements: Measure the voltage on the voltmeter and set the dB relative to
show 0dB at the 100mA/M setting. Reduce the output level on the 8000 to the
56.2mA/M setting and note that the meter reading goes down 5 dB (+/- .5 dB) plus
the tolerance of the voltmeter. Repeat this for the 31.6, 17.8, 10, 5.62, 3.16, 1.78 and
1mA/M settings.
3.4 Source Output Amplitude Accuracy
Instrument Required: Precision sound level meter with ½ inch condenser micro-
phone, response set to flat frequency response.
Setup: Enter the Coupler Multicurve screen. In the menu, set the noise reduction
(tone) to “off” and the static tone to “single.” In the test screen, set the 8000 ampli-
tude to 90dB. Place the coupler microphone at the reference point in the sound
chamber. Close the chamber lid. Level the 8000. Replace the coupler microphone
with sound level meter’s microphone at the reference point in the sound chamber.
Close the chamber lid.
Measurement: Starting at 200Hz, measure the RMS levels, at the reference point,
with the sound level meter, for each puretone frequency. It should read 90 dBSPL
within 1 dB from 300 to 5000 Hz and within 3 dB at other frequencies, plus the tol-
erance of the sound level meter.
3.5 Telecoil Drive Current Accuracy
Instrument required: Precision A.C. current meter that is accurate to 1 kHz.
Setup: Enter the Coupler Multicurve screen. In the local menu, set static tone to
“single” and transducer to “telewand.” Connect the current meter to the telewand
jack on the 8050 or 8120 sound chamber. In the test screen, adjust the amplitude
of the telecoil amplitude. The measured electrical output on the meter should cor-
respond to the displayed telecoil field strength within 2 dB plus the tolerance of the
current meter in the following chart:
Electrical output Field Strength
0.044 mA 1 mA/M
0.079 mA 1.78 mA/M
0.140 mA 3.16 mA/M
0.250 mA 5.62 mA/M
To Next Page
Loading...