Codan MT-4E, Maintenance Manual

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MT-4E ANALOG & P25 DIGITAL RADIO SYSTEMS | MAINTENANCE GUIDE
Chapter 5: Codan Radio System Testing Page 41
In the Deviation Levels area of the Service section on the RSS, click on the “Key Tx” button and adjust
the Tx Balanced Audio Input level adjustment as shown in Figure 5-27 until a deviation of +/- 1.5 KHz
(narrowband) or +/-3.0 KHz (wideband) is measured on the IFR 2975. The high and low alarms are set
at +/-1.4 KHz to +/- 1.6 KHz deviation.
Figure 5-27: RSS Transmitter Audio Level Adjustment
Enter the Transmitter Deviation Level reading on the MT-4E Test Sheet.
Confi gure FGEN1 to inject a 300 Hz tone at +10.0 dBm (2.500 Vrms) into the Tx Balanced audio input
and adjust the audio frequency from 300 Hz to 3400 Hz in increments of 100 Hz and check that the
transmitter deviation does not rise above +/- 2.5 KHz (narrowband) or +/-5.0 KHz (wideband). The MT-
4E Transmitter will transmit a maximum deviation at an audio frequency of approximately 1300 Hz.
Enter the Transmitter Maximum Deviation Level reading on the MT-4E Test Sheet.
To adjust the auxiliary balanced audio input, plug the AC-3E Control Card or CI-BC-4E Base Control
Card into the subrack using an extender card, disconnect the Tx Balanced audio input and connect the
Auxiliary Balanced audio input to the Audio Out 1 on the IFR 2975 (audio box). Auxiliary 1 audio input
is available on pins C19 and C20, and Auxiliary 2 audio input is available on pins B14 and A14. Ensure
that NO external devices (eg. tone remote adapter or IP router) are connected to the auxiliary audio
input. Confi gure FGEN1 to inject a 1.0 KHz tone at 0.0 dBm (0.775 Vrms) into the Auxiliary Balanced
audio input. Adjust the Auxiliary Balanced Audio Input level adjustment (R120 for Aux In 1, R123 for
Aux In 2) for deviation of +/- 1.5 KHz (narrowband) or +/-3.0 KHz (wideband). The high and low alarms
are set at +/-1.4 KHz to +/- 1.6 KHz deviation.
Enter the Auxiliary Deviation Level (if used) reading on the MT-4E Test Sheet.