HP 8559A Operation And Service Manual page 278

MODEL 8559A
DPM Accuracy
The following is a guide to troubleshooting poor DPM accuracy. Further information is included following the
circuit descriptions of the indicated assemblies.
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Check
Perform and verify Frequency Display Adjustment (Paragraph 5-30).
Verify Tuning Accuracy (Paragraph 4-12).
Check Marker Board Assembly A8.
Check frequency accuracy of first and second local oscillators.
First LO: DPM inaccuracies become worse as the higher bands are selected (i.e., increases in harmonic
mixing mode).
Second LO: DPM inaccuracies are constant in all bands.
SERVICE