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12Turn on the SPKR ON button. The meter should read –38 dBu or less. Turn off the SPKR ON
button.
NOTE
Noise measurements in the following steps were made using a 400 Hz to 30 kHz bandpass
filter with +40 dB of gain.
13Turn on the MIC ON switch. Measure noise at U1 pin 1 (mic preamp out). The voltmeter
should read –26 dBu or less.
14Turn on the PANEL MIC button. The meter should read –37 dBu or less.
15Turn all buttons off.
16Measure noise at U12 pin 7 (program A preamp out). The voltmeter should read –51 dBu or
less.
17Measure noise at U12 pin 1 (program B preamp out). The voltmeter should read –51 dBu or
less.
18Measure noise across intercom channels 1 through 4. All should measure –50 dBu or less.