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: The suppression degree of transmission carrier cannot be adjusted/ no
transmission occurs
The two faults have highly coincident inspection parts, so they are explained together.
Maintenance methods:
Fault cause 1: Carrier suppression caused by transmission
channel fault cannot be adjusted.
Check whether the transmitting baseband amplifier, transmitting mixer
and small transmitting transformer have welding problems such as
false welding and short circuit.
Fault cause 2: The transmission channel fault causes no
transmitting small signal , and the suppression degree of the
transmission carrier cannot be adjusted.
The cause of this fault is the same as the maintenance process without
transmitting power, and the maintenance method is as follows:
Instrument settings:
Switch the test switch to "transmission state", set the radio station to
USB mode, set the power to: 20W, and unplug the TX small signal
cable.
Name
Setting Parameters
Parameter 1
Parameter
2
Parameter 3
Oscilloscope
Time base: 50ns
Y-axis:
100mV
X10 gear
Press the hand microphone PTT button, and the inspection sequence
and operation level of each checkpoint shall be as follows:
Checkpoint
Frequency
MHz
Amplitude
mVpp
Name
A20
14.27
140
Transm
A21
14.27
140
Transmitting -
A22
14.27
70
Transmitting small signal
A25
14.27
500
Amplified transmitting
small signal
Checkpoint
Voltage V
Name
A23
2.4
Switching voltage of transmitting
small signal into BRF
A24
5.2
Operating voltage of transmitting
small signal amplifier
Before performing the above inspection, it is necessary to
confirm that the local oscillator unit should work normally, or that
the receiving function is normal and the TX/RX voltage switching
is normal.
Transmitting Mixer
TX
B
as
eb
an
d
A
m
p
lif
ier
TX Small
Transformer
