Ericsson MGM 450, Руководство по обслуживанию

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Modulation Deviation Adjustment
1. Connect an RF deviation meter to the radio through a power attenuator.
2. Set the CHANNEL selector to a transmit channel which has a DCS code pre-programmed (should be a
mid-frequency channel).
3. Press the PTT switch.
4. Adjust RV3 for proper deviation, typically 750Hz. Release the PTT switch.
5. Set the CHANNEL selector to a transmit channel which has a low-frequency CTCSS tone (67.0Hz)
pre-programmed.
6. Press the PTT switch and verify that the deviation is between 500Hz and 1000Hz. Release the PTT switch.
7. Set the CHANNEL selector to a transmit channel which has a high-frequency CTCSS tone (250.3Hz)
pre-programmed.
8. Press the PTT switch and verify that the deviation is between 500Hz and 1000Hz. Release the PTT switch.
a. If deviation level is not that obtained in Step 6 adjust RV 401 to same level.
9. Connect an audio frequency generator to the MIC input (connected to the white wire in the microphone
cable) of the radio. Set the audio output level for 30 mV. the audio frequency should be 1 kHz.
10. Press the PTT switch.
11. Adjust RV4 (maximum deviation adjustment) for the 4.2 kHz deviation if no CTCSS tones are present, and
4.9 kHz deviation if CTCSS tones are present.
RECEIVER ALIGNMENT
1. Connect an RF signal generator or communications service monitor to the antenna receptacle.
2. Connect a SINAD meter and an audio distortion analyzer across the speaker terminals. If an audio
distortion analyzer is not available, connect an oscilloscope across the speaker terminals.
3. Turn the SQUELCH control fully counter-clockwise.
4. Adjust the VOLUME control to the proper level for the SINAD meter and audio distortion analyzer.
5. Set the CHANNEL selector to a mid-frequency receive channel.
6. Tune the RF signal generator to the channel frequency. the RF output level should be set for -47 dBm. The
modulation should be set for
±
3 kHz FM deviation of a 1 kHz tone.
7. Adjust T10 for maximum audio output. Readjust the VOLUME control if necessary to avoid clipping on
the output audio wave form. (This adjustment is typically not required.)
8. Decrease the RF generator output and adjust T1 through T9 for maximum sensitivity.
9. Check the sensitivity at the lowest and highest receive frequencies. If necessary, repeat steps (8) and (9)
above at the lowest middle and highest frequencies for the best overall sensitivity.
MONOGRAM SERIES LBI-38865
ALIGNMENT PROCEDURE
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Nov. 94