Source Power Linearity Test - Keysight N5224B Series Service Manual

Tests and Adjustments
Performance Tests
8. This process is repeated at hundreds of frequencies across the analyzer's
full range in every specified path configuration.
If the Analyzer Fails this Test:
Troubleshoot the source section of the analyzer and then repeat this test. Refer
to "Checking the Source Group" on page

Source Power Linearity Test

Function of the Test: To verify that the power level is linear over the analyzer's
frequency range and to check the linearity of the automatic leveling control
(ALC).
Specification Tested: Power Sweep Range and Power Level Linearity
Equipment Used:
— Test cable
— 20 dB attenuator if the analyzer does not have an internal step attenuator
Description of the Test:
Ports 1 and 2 are tested as a pair. The Port 2 receiver is used to test the
linearity of the source power out of Port 1, and vice versa. Ports 3 and 4 are
similarly tested as a pair on 4-Port analyzers. The receiver linearity is the
standard against which the source linearity is checked.
1. The analyzer is Preset.
2. The analyzer is set up for a CW transmission measurement on the test port
pair to be measured.
3. A test cable is connected between the port pair to be tested with 20 dB of
attenuation in series with the cable. This is done with an internal source
step attenuator or an external 20 dB attenuator. This attenuation ensures
that the receiver remains in its linear range.
4. The receiver measurement is normalized at this Preset power level.
5. The source setting is then stepped from the minimum to the maximum
ALC power setting range in 1 dB steps, and the receiver power is
measured at each setting.
6. The non-linearity in dB at each frequency point is calculated as the
difference between the change in the source power setting away from
Preset and the change in the receiver power reading.
7. This power linearity measurement is repeated at several CW frequencies
across the full frequency range of the analyzer.
If the Analyzer Fails this Test:
— Perform the
Keysight N5224B/25B Service Guide
"Source Adjustment" on page 3-46
4-37.
and repeat this test.
3-33