DP990/DP995service manual
25
Co-channel interference
suppression
[email protected], 8dB@25kHz
Spurious response rejection
TIA603C: 75dB, ETSI: 70dB
Conducted spurious
emission
-57dBm@< 1GHz, -47dBm@>1GHz
Blocking
90dB
Rated audio power
1W
Rated audio distortion
3% (typical)
Hum and Noise
[email protected], -45dB@25kHz
Audio response
+1dB, -3dB
8. Repairing and Testing Devices
Device
Specification
Standard signal
generator
Frequency range: 350MHz~400MHz
Modulation: Frequency modulation and external modulation
Output: -127dBm/0.1uV ~ > -47dBm/1mV
Power meter
Input impedance: 50Ω
Operating frequency: 350MHz~400MHz
Measurement range: About 10W
Frequency deviation
meter
Frequency range: 350MHz~400MHz
Digital voltmeter
Measurement range: DC 10mV~10V
Input impedance: High input impedance of minimum circuit load
Oscilloscope
Max 30MHz DC bandwidth
High-sensitivity
frequency counter
Frequency range: 50Hz~10KHz
Frequency stability: 0.2ppm or lower
Ammeter
20A
Audio voltmeter
Frequency range: 50Hz~10KHz
Voltage range: 1mV~10V
Audio sweep
generator
Frequency range: 50Hz~5KHz or higher
Output: 0V~1V
Distortion tester
Capability: 3% or lower at 1KHz
Input level: 50mV~10Vms
Spectrum analyzer
Measurement range: Max 1GHz DC or higher
Trajectory generator
Center frequency: 50kHz~600MHz
Dummy load
About 16Ω, 3W
Adjustable power
supply
3V~10V, about 5A
9. Troubleshooting
NO
Problem Description
Reasons and Solutions
1
Power-on
A. The remaining battery capacity may be low. Charge or replace the battery.
B. The power switch is broken. Replace it.
C. The power management chip U1 is broken. Replace it.
D. Zener diode D1 is broken. Replace it.
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