Keysight Technologies N5247B, Service Manual

Page: 64 / 566

3-34 Keysight N5247B Service Guide
Tests and Adjustments
Performance Tests
3-
6. The analyzer’s output power is increased until a “Source Unleveled” error
is detected. The output power is then decreased in increments of 0.01 dB
until the error goes away. if the output power r18 dBm without
any error, the power is left at this level.
7. The power level at this point is measured and compared to the maximum
output power specification.
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 4-35 .
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.