7.2.6 NR Mode A
7.2.6.1 Threshold Check
1. Set input signal equal to lk H za t +26dBu.
2. Set NR MODE switch to A.
3. Set NR THRESHOLD to +30.
4. Place an osilloscope probe on D409’s anode.
5. Observe waveform and adjust the threshold so the voltage goes negative. This
should occur near the +30 end of the pot.
6. Set input signal to -40dBu.
7. Adjust NR THRESHOLD to -40.
8. Adjust the NR Threshold know until the voltage goes negative. This should oc
cur near the -40 end of the range.
7.2.6.2 Ratio Check
1. Set input signal to 5KHz at + lOdBu.
2. Set SOLO to "ON".
3. Set TUNE to 700 Hz.
4. Set PEAKING to 12 o ’clock position.
5. Set NULL FILL to minimum.
6. Set NR THRESHOLD to -40.
7. Set MIX for +10 output.
8. Set NR THRESHOLD 0.5dB past the verge of attenuation.
9. Drop the input to OdBu.
10. The output should drop to -4dBu.
7.2.7 NR Mode B
1. Set input signal to 5 kHz at OdBu.
2. Set NR MODE Switch toB .
3. Set SOLO to "ON".
4. Set MIX to maximum.
5. Set NR THRESHOLD to -40.
6. Verify output level equals +8dBu.
7. Set NR THRESHOLD for output null.
8. Yellow indicator light should be "ON".
9. Set NR THRESHOLD to +30.
10. Verify output level equals -3dBu.
7 - 4 Test and Nulling Procedure
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