Composite Output; Using A Modulation Monitor; 19Khz Level; 19Khz Phase - Crown FM600 User Manual

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5.2.2 Composite Output

You can make adjustments to the composite output in the following manner:

1. Set the Stereo-Mono switch to Mono.

2. Check that the setting of the Modulation compensation control (see illustration 2–9) on

the RF Exciter circuit , falls within the range specified for the frequency of operation.

(See section 2.3.1.)

3. Feed a sine wave signal of about 2.5 kHz into the left channel at a level sufficient to put

the wideband gain-reduction indicator somewhere in the middle of its range.

4. Set the Composite level control to produce 90% modulation as indicated on an FM

monitor.

5. Apply pink noise or program material to the audio inputs and confirm, on both Mono and

Stereo, that modulation peaks are between 95% and 100%.

5.2.3 19–kHz Level

Adjust the 19–kHz pilot for 9% modulation as indicated on an FM modulation monitor.

(The composite output should be set first, since it follows the 19–kHz Level control.)

5.2.4 19–kHz Phase

1. Apply a 400–Hz audio signal to the left channel for at least 70% modulation.

2. Look at the composite stereo signal at TP301 on the RF Exciter circuit board with an

oscilloscope, expanding the display to view the 19–kHz component on the horizontal

centerline.

3. Switch the audio to the right-channel input. When the 19–kHz Phase is properly ad-

justed, the amplitude of the 19–kHz will remain constant when switching between left

and right.

4. Recheck the separation adjustment as described in section 5.2.1.

Refer to section 2.3.

Adjustments and Tests

5-3

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