Headset Carbon-Mic Level
1. Insert a -25dBm signal (1 KHz at 50 ohms) into the
carbon mic input of the HEADSET connector
(reference Table 4 for pin-out).
☞
A +12 vdc bias voltage is supplied at pin 3 (carbon
mic + input) of the HEADSET connector. The signal
generator should be isolated from this dc bias
voltage.
2. Activate the HDST key on the front of the keypanel.
3. Monitor the signal level at the MIC PRE OUT
connector. It should be +8 dBu. If not, adjust the
CARBON HDST trimmer (RV407) to achieve an
output reading of +8 dBu.
4. Remove the signal from the carbon mic input.
Compressor/AGC Setup
1. Insert a -60 dBm signal (1 KHz at 150 ohms) into the
front panel microphone connector. Or use the EXT
MIC IN connector (with the front panel microphone
removed).
2. Adjust the COMPR trimmer (RV405) to measure
+13dBu at the audio output of the FRAME
connector, P10.
3. Reduce the input signal level to -80 dBm.
4. Adjust RV409 (internal) for a +4 dBu audio output
level at the FRAME connector.
5. Perform this procedure several times to optimize the
compression ratio accuracy. This will test
compression at a 2:1 ratio (0.5dBu). Confirm correct
operation of the compression circuit by increasing
and reducing input levels and measuring output ratio
accordingly.
3.2.3 SPEAKER/HEADSET AMPLIFIER
ADJUSTMENTS
Matrix-to-Speaker Gain
1. Disconnect the loudspeaker (either internal or
external) from the + AMP OUT and - AMP OUT
terminals on the back of the keypanel.
2. Terminate the + AMP OUT and - AMP OUT
terminals with an 8-ohm, 10-watt resistive load.
Connect an audio analyzer across the load.
3. Remove the keypanel audio connection from the
intercom matrix.
4. Insert a +8dBu (1 KHz) signal into the audio input +
and - pins of the FRAME connector, P10 (Table
2,
page 10).
5. Turn the front panel HDST switch off.
6. Turn the front panel intercom audio level control
(outer knob) fully clockwise (maximum volume).
7. Adjust the SPKR trimmer (RV207) to measure
4.9VRMS (3 watts) at the audio analyzer. There
should be no clipping of the output signal.
8. Turn the front panel intercom audio level control
fully counterclockwise (minimum volume). Adjust
the MIN I/C trimmer (RV202) to measure -30 dB
below the 4.9VAC reference level.
9. Readjust the front panel intercom audio level control
to again measure 4.9VAC at the audio analyzer.
10. Insert a 1 KHz common mode signal into the audio
input + and - pins of the FRAME connector.
11. Adjust RV201 (internal) for a minimum common
mode signal.
12. Remove the signal from the FRAME connector.
Line Input-to-Speaker Gain Adjustment
1. Install a shorting plug across J201, pins 2 and 3.
2. Insert a +8dBu (1 KHz) signal into the EXT LINE IN
connector (reference Table
5, page 12, for pin-out).
3. The HDST switch should be off.
4. Turn the line input level control (inner knob on the
front panel) fully counterclockwise.
5. Adjust the MIN EXT trimmer (RV205) to measure
-30 dB below a reference level of 4.9VAC level at
the audio analyzer connected to the amplifier output.
6. Readjust the line input level control to measure
4.9VAC output at the audio analyzer.
7. Insert a 1KHz common mode signal into the EXT
LINE IN connector.
16 Installation Instructions, KP95-0 Keypanel
(31 Seiten)
(22 Seiten)
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