XIEGU G90, Руководство по обслуживанию

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XIEGU Product Maintenance Manual G90/G90S Portable Short-Wave Transceiver
XIEGU All Rights Reserved Version No.: 1.0 2022-07 Page
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Fault phenomenon: no PRE function (after turning on PRE, the amplitude-frequency curve of
network analysis does not rise)
Maintenance methods:
The fault phenomena are as follows:
During the network analysis test, turn on/ off the PRE function, and the
amplitude of the amplitude-frequency curve will not change (or
become low)
Maintenance methods:
The instrument settings are as follows:
Name
Setting Parameters
Parameter 1 Parameter 2
Parameter
3
Signal Source
Frequency:
14.271MHz
Amplitude:
-20dBm
/
Oscilloscope Time base: 50ns
Y-axis:
100mV
X10 gear
After PRE is turned on, the measured data at each checkpoint shall be
as follows:
Checkpoint
Frequency
MHz
Amplitude
mVpp
Name
A12 14.271 50 Amplifier input
A14 14.271 680
Amplifier
output
If there is a great difference between the measured signal amplitude
and the standard data in the table, the following measurements are
required:
Checkpoint Voltage
Voltage difference between base (B)
and emitter (E) of amplifier triode
About 0.55 ~ 0.7V
A13 4.5
～
5V

At the same time, check whether the PRE control signal
"#PRE_EN" and AS179 controlled voltage turn normally.
PRE circuit unit