Telex MCE325 manual Frequency Response and Level Check, Mic to Line, Four-Channel, Two-Wire Mode

2Set the MIC ON button to on. Set all other front panel buttons to off.

3Check for 13 VDC minimum at the key 1 output.

4Turn CH 1 TALK on and check for less than 2 VDC at the key 1 output.

5Repeat steps 3 and 4 for the other channels:

CH2 TALK: key 2 out (J22 pin 19)

CH3 TALK: key 3 out (J22 pin 7)

CH4 TALK: key 4 out (J22 pin 20)

6Remove the 47 kohm pull-up resistors when finished.

USMB (Un-Switched Microphone Balanced) Frequency Response and Level Check

1Set all front panel buttons to off.

2Connect a signal generator to the DYN MIC HEADSET jack mic input (J2 pins 1 & 2).

3Connect a 600 ohm resistor across the USMB output (J22, pins 1 and 14).

4Connect an AC voltmeter across the 600 ohm resistor.

5Verify the output levels for the input frequencies and levels in Table 4.2.

6Remove the 600 ohm resistor across the USMB output.

Frequency Response and Level Check, Mic to Line

Four-Channel, Two-Wire Mode

1Activate the MIC ON button. (All other front panel buttons should be off.)

2Connect an AC voltmeter across the channel 1 output. The signal generator should still be connected to the dynamic mic input.

3Activate the CH 1 TALK button.

4Verify the output levels for the input frequencies and levels in Table 4.3.

5Repeat for channels 2 through 4 by connecting the AC voltmeter across the appropriate output, activating the appropriate TALK button, and measuring the output level:

Table 4.1 Talk button vs. output.

TALK BUTTON	OUTPUT
CH 2	J8, pins 1 and 3
CH 3	J10, pins 1 and 2
CH 4	J10, pins 1 and 3

Table 4.2 USMB frequency response and level check.

INPUT
FREQUENCY	INPUT LEVEL	OUTPUT LEVEL
1 kHz	-55 dBu (1.4 mV)	-1 ±3 dBu (0.49 – 0.98 VAC)
	–45 dBu (4.35 mV)	2.5 ±2 dBu (0.83	– 1.32 VAC)
	–25 dBu (43.5 mV)	2 ±2 dBu (0.75 – 1.2 VAC)
100 Hz	-55 dBu (1.4 mV)	-0.5 ±3 dBu (0.51 – 1.03 VAC)
	–45 dBu (4.35 mV)	4.2 ±2 dBu (0.98 – 1.55 VAC)
	–25 dBu (43.5 mV)	4.2 ±2 dBu (0.98 – 1.55 VAC)

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