Frequency Accuracy Test - Keysight N5224A Service Manual

Tests and Adjustments
Performance Tests

Frequency Accuracy Test

Function of the Test: To verify the frequency accuracy and range of the analyzer's source output.
Specification Tested: Test Port Output–CW Accuracy
Equipment Used:
• Frequency counter
• Test cable
• Adapters
Description of the Test:
This test is performed over the full frequency range of the source synthesizer board, not the full frequency
range of the analyzer. To generate the higher frequencies, the analyzer passes the synthesizer signal through
a series of frequency doublers. These doublers exactly double the source frequency, so the deviation from a
perfectly accurate frequency is exactly doubled. The frequency accuracy is specified as the ratio parts per
million (ppm), so this ratio is unaffected by the signal doubling. Therefore, only the frequency accuracy of
the synthesizer board needs to be tested.
1. The analyzer is Preset.
2. The analyzer is set up for a CW measurement on Port 1.
3. A test cable is connected between Port 1 and a frequency counter with any necessary adapters.
4. The signal frequency is measured and compared with the analyzer source frequency setting. The
difference must be less than the source frequency divided by 1
specification.
5. This test is repeated at several frequencies across the range of the source synthesizer board.
If the Analyzer Fails this Test:
• Verify the accuracy of the 10 MHz OCXO by using a frequency counter to measure the rear-panel 10 MHz
REF OUT. If the 10 MHz reference is off by more than 10 Hz, perform the
Adjustment" on page 3-40
3-32
and then repeat this test.
PNA Series Microwave Network Analyzers
N5224A and N5225A
6
for a 1 part per million (ppm)
"10 MHz Frequency Reference
Service Guide N5225-90001