E8257D/67D, E8663D PSG Signal Generators Service Guide 133TroubleshootingTroubleshooting Option UNR/UNX/UNY and Instruments with Serial Prefixes ≥US4805/MY4805 Phase NoiseTroubleshooting Option UNR/UNX/UNY and Instruments with SerialPrefixes ≥ US4805/MY4805 Phase NoisePoor grounds or shielding problems in either the test environment or themeasurement system can cause the phase noise measurement to fail. Physicalvibration is another common cause of phase noise. Before performing a phasenose measurement make sure all covers are installed, the work surface is freeof physical vibrations, and the phase noise system is working properly.Phase noise failures at specific offsets are fairly predictable. After making surethe measurement accurately reflects a failure, use Table 1-27 to troubleshootphase noise problems. The troubleshooting procedure consists of assemblysubstitution.Table 1-27 Phase Noise FailuresFrequency Offset Most Likely Assembly0 to 100 Hz A32 High Stability Time Base100 Hz to 10 kHz A7 Reference<5 kHz to 10 kHz A6 Frac–N; A45 Frac-N (Option UNY)10 kHz to 100 kHz A5 Sampler; A46 Offset (Option UNY)>100 kHz to 1 MHz A28 YIG Oscillator or A9 YIG DriverFrequencies <3.2 GHz A8 OutputFrequencies >3.2 GHz A29 20 GHz Doubler or A30 Modulation FilterFrequencies >20 GHz A27 40 GHz DoublerIn non–Option UNR/UNX and instruments with serial prefixes ≥ US4805/MY4805,the most likely assemblies and frequency offset are the same except for <100 Hz.In non–Option UNR/UNX and instruments with serial prefixes ≥ US4805/MY4805,the most likely assembly for <100 Hz offset is the A7 Reference.
