Sailor RE2100 Technical Manual page 61

3 SERVICE
17. To check the stopband attenuation, change the modulation frequency of the generator to 6 kHz and
control the AC voltage at testpoint TP2-1 to decrease more than 40 dB relative to the value
measured in point 15.
3.6.1.8 CHECK OF EARPIECE AMPLIFIER
The purpose of this test is to control the earpiece amplifier, which is built-up around the integrated circuit
U07. If the earpiece output level is outside the specified range, it is necessary to re-adjust the trimming
resistor R52-1, which is located at the receiver unit. If it is not possible to adjust the output level to be within
the specified range, it is necessary to control the detector output level before any conclusion can be made.
1. Connect the generator to the aerial socket at the front end unit (module 2).
2. Connect the voltmeter and the distortion meter to earpiece output at testpoint TP2-1.
3. Turn the RE2100 on and turn the RF gain control fully clockwise.
4. Choose generator frequency f
point 7.
5. Measure the earpiece output level at testpoint TP2-1 and control the result to be within the range
0.7V - 0.9V
RMS RMS
6. Measure the earpiece output distortion at testpoint TP2-1 and control the result to be less than
1.5%.
7.
3.6.1.9 CHECK OF SQUELCH CIRCUIT
The squelch circuit in the RE2100 is voice activated and it works in principle by detecting deviations in
the frequency of the received signal. This relative complex squelch function is implemented by means of
four separate blocks, which are:
1. Limiting amplifier
2. Frequency to Voltage Converter
3. Voltage Change Detector
4. Hold Circuit
The output voltage from the Hold Circuit is sensed by the microprocessor and this unit is then controlling
the analog switch, which is used to mute the audio frequency output.
In the check procedure given below only the analog part of the squelch is controlled and if this is
performing as expected, a failure may be caused by the microprocessor or the connection cabling.
1. Connect the generator to the aerial socket at the front end unit.
2. Connect a handset or loudspeaker to the testbox or directly to the RE2100.
3. Turn the RE2100 on and turn the RF gain control fully clockwise.
4. Choose generator frequency f
in point 15.
, generator output level V
G
.
; generator output level V
G
, and receiver frequency f
G
, and receiver frequency f
G
RE2100
according to
RX
as specified
RX
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