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Appendix H: Viavi CX300 Tests
MAINTENANCE GUIDE | MT-4E ANALOG & P25 DIGITAL RADIO SYSTEMS
Audio Level:
The audio level adjustment is not required when connecting the receiver in a repeater configuration using LVDS
Serial Data. The audio level adjustment can be done on both the Rx Balanced Audio Output and the Auxiliary
Balanced Output (1 and 2). The Auxiliary Balanced Output is only available on the AC-3E Control Card or CI-
BC-4E Base Control Card�
To adjust the receiver balanced audio output, ensure that the AC-3E Control Card or CI-BC-4E Base Control
Card is NOT plugged into the subrack, and inject -70 dBm RF carrier level into the receiver (no external load is
required as the internal 600 ohm load of the CX300 is used).
In the Audio Levels area of the Service section on the RSS, adjust the Rx Balanced Audio Output level
adjustment as shown in Figure H-6 until -8.0 dBm audio level (0.308 Vrms @ 600 ohms) is measured on the AF
Level meter of the CX300 as shown in Figure H-4.
Figure H-6: RSS Receiver Audio Level Adjustment
To adjust the auxiliary balanced audio output, plug the AC-3E Control Card or CI-BC-4E Base Control Card into
the subrack using an extender card and connect the Auxiliary Balanced audio output to the AF INPUT 1 on the
CX300 (no external load is required as the internal 600 ohm load of the CX300 is used). Auxiliary 1 audio output
is available on pins B11 and A11, and Auxiliary 2 audio output is available on pins C1 and C3 for the AC-3E
Control Card and pins C2 and C4 for the CI-BC-4E Base Control Card. Ensure that NO external devices (eg.
tone remote adapter or IP router) are connected to the auxiliary audio output. Adjust the Auxiliary Balanced
Audio Output level adjustment (R13 for Aux Out 1, R56 for Aux Out 2) for 0.0 dBm audio level (0.775 Vrms @ 600
ohms).
Enter the Balanced Audio Output Level and Auxiliary Audio Output Level (if used) readings on the MT-4E Test
Sheet.
There are no specific measurements to check Receive CTCSS, just verify that the receiver CTCSS is operating.
