Nortel Networks RTU-292 operation manual Hybrid Balance Test Set-Up Main Hybrid Test Procedure

RTU-292 Operations Manual

Figure 6-1 Hybrid Balance Test Set-Up

6.5.2.1 Main Hybrid Test Procedure

1.Disconnect the RTU-292 from all other equipment and connect the test equipment as shown in Figure 6.1.

2.Set the PSTN levels for -9 dBm using Option SW2-1, -2, and -3.

3.Start with the following pushbuttons OFF: TEL LINE/PHONE, TEL LINE/RADIO, and TEL VOX. The positions of the other buttons are unimportant. Place the RTU-292 in set-up mode by setting SW2-7 ON and then turning on the power. (See paragraph 2.10.1 for further details about set-up mode.)

4.Adjust the TX Level Adjust, R133, so that the audio voltmeter reads -6dBm (0.387V rms). This sets the transmit signal output path in the RTU-292 for unity gain if the input level is correctly set.

5.Adjust the RX Level Adjust, R116, so that the PEAK LED flashes rapidly and is on about 50% of the time. (This is different from the instructions in paragraph 2.10.3, which set the RX Level Adjust for voice)

6.Remove the unit from Set-up Mode by turning the RTU-292 Main Power OFF, setting SW2-

7OFF, and then turning the main power back ON.

7.Push the TEL LINE/RADIO button to start the adaptation cycle.

8.When the initial adaptation cycle is complete, the noise output can be read on the audio voltmeter. The voltage should be less than -37dBm (10.9 mV). The trans-hybrid loss is the difference between this reading and the approximate -7 dBm noise level.

6-21 JPS Communications, Inc.