Instruction manual

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1. To the left channel only, apply a 500Hz test tone from the console

at a level 2.5dB above normal reference level. This is simply a

console VU meter indication of +2.5VU.

2. Adjust the left channel (L) INPUT GAIN control so that both the 0dB

and the –5dB AGC GAIN indicators light to equal brilliance.

Remember that the AGC circuit responds slowly to level changes, so

have patience in performing this step of the procedure.

3. Turn off the +2.5VU test signal to the left channel and apply

+2.5VU to the right channel only.

4. Adjust the right channel (R) INPUT GAIN control so that both the

0dB and the –5dB AGC GAIN indicators light to equal brightness.

This completes INPUT GAIN adjustment. The DAVID-II may now be

fed normal stereo program material from the console. If this

procedure has been performed properly, and the operator pays

reasonable attention to console metering, the AGC GAIN indicators will

always remain the green-LED “safe operating” zone between –5dB and

+5dB.

Output Level

Adjustment

Perform this part of the procedure “on-air” under normal operating

conditions, and using typical program material. You also must have

access to the station’s Modulation Monitor. An RDS or SCA subcarrier

should not be connected until Step #6. Be sure that the COMPOSITE

PROCESSING control is OUT; that is, fully counterclockwise.

PLEASE be certain that you understand operation of the Mod-

Monitor, and that it is properly calibrated and connected to the correct

transmitter/exciter RF sample point.

1. Put the Mod-Monitor in its “Total Peak Modulation” measurement

mode with peak flasher(s) set to 100%.

2. Turn the AVERAGE COMPRESSION control fully clockwise (10dB).

With normal program fed to the DAVID-II (at the level which

maintains AGC GAIN in the center of its range), adjust the OUTPUT

LEVEL control for a Mod-Monitor indication of frequent 100%-

modulation peaks.

3. Back-down the OUTPUT LEVEL control slightly, so that the 100%

peak flasher(s) light only occasionally.

4. Switch the Modulation Monitor to display the injection level of the

19kHz stereo pilot.

5. Adjust the PILOT INJ. control for a 9% Mod-Monitor reading of pilot

injection.

6. (OPTIONAL) If an RDS or an SCA subcarrier is to be broadcast,

connect it to the DAVID-II (or other combining point) at this time.

Using the Mod-Monitor, or other means of reading the auxiliary

subcarrier injection level, adjust the SUB INJ. level control (or other

subcarrier level control) for the proper injection. This is normally