Hytera MD78X - Frequency Generation Unit (FGU)

UHF5 (806MHz
–
941MHz)
Troubleshooting Flow Chart
33
[1] During sensitivity test, use a communication test set to demodulate the audio signal at TP4012 and
TP4016. If the signal is demodulated normally, it is concluded that the front panel is defective.
[2] Use the communication test set to apply a 73.35 MHz IF signal at the mixer, and sensitivity is about
-110 dBm.
[3] There is a second LO signal (71.1MHz) at TP704.
[4] The sensitivity at C6207 is about -110 dBm.
[5] The received LO signal at TP9003 is about 18 dBm. Make sure that the LO amplification circuit is
disconnected from the mixer during test.
[6] The sensitivity at R6105 is about -120 dBm.
6.5 Frequency Generation Unit (FGU)