Table 4.2 USMB frequency response and level check.
10 kHz | |||
| 2.2 | ±2 dBu (0.79 – 1.26 VAC) | |
| 2.5 | ±2dBu (0.83 – 1.32 VAC) | |
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Table 4.3 Mic to line response;
INPUT | INPUT |
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FREQUENCY | LEVEL | OUTPUT LEVEL |
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1 kHz | ||
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100 Hz | ||
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100 kHz | 0.8 ±2 dBu (0.56 – 0.89 VAC) | |
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Two-Channel, Four-Wire Mode
1Remove the 200 ohm terminations from intercom channels 1 through 4.
2Program the MCE325 to be in
3Connect 200 ohm termination resistors across the
NOTE Normally, the
4Set the MIC ON button to on. Set all other front panel buttons to off.
5Connect an AC voltmeter across the
6The signal generator should still be connected to the mic input. Set it to 1 kHz,
7Activate CH 1 TALK.
8The output level should read
9Connect the AC voltmeter across the
10Turn off CH 1 TALK and activate CH 2 TALK.
11The output level should read
12Remove the 200 ohm termination resistors.
Sidetone Null Test and Adjustment
NOTE This procedure verifies sidetone null operation and optimizes nulling for an ideal 200 ohm line termination. Since actual intercom line impedance may vary from the ideal, the MCE325 may have to be readjusted slightly during actual use.
1Reprogram the MCE325 to be in
2Reconnect 200 ohm termination resistors across each of the four intercom channels.
3Set the MIC ON button to on. Set all other front panel buttons to off.
4The signal generator should still be connected to the mic input. Set it to 1 kHz,
5Activate the CH 1 TALK button.
6Monitor the AC signal level at U5 pin 7.
7Adjust R57 (Sidetone 1 on front panel) for maximum null (minimum signal level) at U5 pin 7. The signal should be 0.025 VAC or less.