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: receive failure (or no signal tone)
Maintenance methods:
1. First, check whether the local oscillator on the small signal board
works normally.
Instrument settings:
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
Note: The oscilloscope shall be set at X10 gear, and the test probe
shall also be set at X10 gear. Coupling mode: AC coupling.
2. First measure the working condition of local oscillator, and the test
data shall be roughly as follows:
Checkpoint
Frequency
MHz
Amplitude
Vpp
Name
A1
26.000
3.6
TXCO reference
clock
A2
14.27
5.9
Local oscillator
output
The upper end of the two resistors at A2 checkpoint is for the
quadrature output of the local oscillator signal, with the same
frequency and amplitude.
3. Connect the output signal of the signal source to the small signal
board, and measure the signal strength of checkpoints A3 and A4
respectively in turn. Normally, it shall be as follows:
Checkpoint
Frequency MHz
Amplitude mVpp
A3
14.271
80
A4
14.271
380
During the above test, PRE shall be turned on.
4. Measure the signal strength of checkpoint A5 as follows: (signal
source output: -40dBm)
Name
Setting Parameters
Parameter 1
Parameter 2
Parameter 3
Oscilloscope
Time base:
1ms
Y-axis:
100mV
X10 gear
