RTS KP95 Instrukcja Użytkownika Pobierz pdf (Strona 9)

2.2 AUDIO LEVEL ADJUSTMENTS

2.2.1 GENERAL

The following paragraphs describe the procedures to

calibrate the output level to the factory standard of +8

dBu. If a different level is required, substitute that level

for +8 dBu.

Most audio level trimpots are accessible through access

holes on the back of the keypanel. Each trimpot access

hole is labelled with its function. Some trimpots are

internal, and can only be accessed with the top cover

removed. Locations of trimpots are shown in Figure 2-1.

Audio levels may be adjusted with the panel disconnected

from the intercom system. However, proper operation

should be confirmed when the panel is re-connected. If

levels change after re-connection, check the intercom

system wiring for one-sided shorts to ground, wiring

errors, or unintended terminations.

The following procedures make use of the additional

connectors available on the KP95-0 Keypanel or the

KP-96-RC Rear Connector Plate option. Connector

pin-outs for these connectors were presented earlier in

this section. If the keypanel under adjustment does not

have these connectors, refer to drawing number

IKP-950/2-5 (in the KP95, KP96 and KP97 Keypanel

Drawings Manual). This drawing shows equivalent

locations where test equipment may be connected.

Required test equipment:

Audio Signal Generator with balanced output

Audio Signal Analyzer with balanced input

DC Millivoltmeter

Oscilloscope - any commercially available type

2.2.2 MICROPHONE PRE-AMPLIFIER

1. Set the HDST switch to off.

2. Remove the gooseneck microphone, and insert a -70

dBm signal (1KHz at 150 ohms) into the microphone

connector. Or use the EXT MIC IN connector with

the front panel microphone removed (ref Table 1-5

for pin-out).

3. Activate the microphone by setting a

Talk

key to the

latched-up position.

4. Check the level at the MIC PRE OUT connector (ref

Table 1-7 for pin-out). It should measure +8 dBu.

5. If the reading is not +8 dBu, but within a 3 dB range,

adjust the LEVEL TO MATRIX trimpot (RV406) for

+8 dBu.

6. If the reading is more than 3 dB from +8 dBu, or

another output level is used by your facility, proceed

to paragraph 2.2.2.1 to begin the mic preamp

calibration procedures.

7. Check the frequency response from 200 Hz to 15 KHz.

It should be within 1 dB.

8. Check the input noise. It should be at least -70 dB

below +8 dBu.

9. Check the Total Harmonic Distortion (THD) from

200 Hz to 15 KHz at +18 dBu output. It should be

less than or equal to 0.15 percent.

2.2.2.1 Balance Adjustment

1. Turn the COMPR trimpot (RV405) fully

counter-clockwise. This sets the compressor circuit to

minimum (compressor ratio of 1:1).

2. Measure and record the dc voltage at test point TP407.

3. Install a shorting plug across J402.

4. Measure the dc voltage at TP407, and adjust RV408

(internal) to match (within 5 mV) the previously

recorded voltage.

5. Remove the shorting plug at J402.

2.2.2.2 Tone Generator Level Adjustment

1. Activate the 400 Hz tone generator in the keypanel

(enter 0-8-7 on the keypad, or use CSedit).

2. Adjust the LEVEL TO MATRIX trimpot (RV406) for a

+8 dBu tone output level at the MIC PRE OUT

connector.

3. Turn off the tone generator (press CLR on the keypad,

or use CSedit). (If you turned the tone generator on

using CSedit, you must turn it off using CSedit.)

2.2.2.3 Panel Mic Level Adjustment

1. Configure the J404-J406 jumper blocks for a balanced

dynamic panel microphone: J404 short pins 2-3; J405

short pins 1-2; J406 short pins 1-2. (This is the

default microphone configuration.)

2. Insert a -70 dBm signal (1 KHz at 150 ohms) into the

gooseneck microphone connector. Or use the EXT

MIC IN connector (with the front panel microphone

removed).

3. Adjust the PNL trimpot (RV401) for +8 dBu at the

MIC PRE OUT connector.

4. Insert a common mode signal (120 Hz, -70 dBm) into

the gooseneck microphone connector, or into the

EXT MIC IN connector.

5. Adjust RV402 (internal) for a minimum common mode

signal at the MIC PRE OUT connector.

6. Re-insert a -70 dBm signal.

7. Remove the shorting plug across J401 (causes

continuous mic activation).

KP95/96/97 Keypanel Installation

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