Item 8: Afms And Harmonic Distortion - Ericsson EF738 Service Instructions Manual

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Service Instructions

Item 8: AFMS and Harmonic Distortion

Purpose:

Checking and, if necessary, calibrating the deviation of the receiver

Test method:

Radio test set in RX mode

Input signal:

Apply a -50dBm 935.0125MHz RF signal modulated with a 1kHz tone, ±2.3kHz

deviation to the antenna input

Measurement point:

At the AFMS output from the system connector measured with an AC volt meter

Limit:

25mV ±1.5dB (21.035 - 29.710 mV)

Procedure:

1. Enable the compandor (TP-29:1)

2. Apply a -50dBm 935.0125MHz RF signal modulated with a 1kHz tone, ±2.3kHz

3. Monitor the AFMS output with a 100kΩ load

4. If AFMS is outside the limits; adjust the AFMS level

5. Enter TP-10

6. Start the trimming by pressing M + #

7. Trim the AFMS level by pressing # and * to increase/decrease

8. Press M + S to store the value

9. Measure the receiver harmonic distortion

10.Should be less than 4.5% at AFMS using a CCITT filter

deviation to the antenna input

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