Keysight Technologies N5221A, Руководство по обслуживанию

Страница: 65 / 368

Keysight N5221A/22A Service Guide 3-37
Tests and Adjustments
Performance Tests
— If the analyzer still fails this test, replace the A23 mixer brick for a Port 1 or
Port 2 failure or the A24 mixer brick for a Port 3 or Port 4 failure, then repeat
this test. Refer to “Removing and Replacing the A23 and A24 Mixer Bricks”
on page 7-37 .
Noise Floor Test
Function of the Test: To measure the absolute power level of the noise floor for
the analyzer’s receivers.
Specification Tested: Test Port Input–Test Port Noise Floor
Equipment Used:
— Power meter
— Power sensors
— Test cable
— Calibration kit
Description of the Test:
This test uses the source signal out of one analyzer test port as part of the
noise floor measurement on another test port. Port 2 is the source port when
measuring the noise floor of Port 1. Port 1 is the source port when measuring
the noise floor of Ports 2, 3, and 4.
1. The analyzer is Preset.
2. The analyzer is set up for a CW transmission measurement between the
source port and the test port to be measured. The analyzer is set to an IF
bandwidth of 1 kHz and 801 points per sweep.
3. A test cable is connected to the source port.
4. A power sensor is connected to the end of the test cable with any
necessary adapters.
5. For hundreds of frequencies across the analyzer’s full range, a source
power calibration is performed to ensure a flat power response at the end
of the cable at the Preset power level.
6. The power sensor is disconnected and the cable is connected to the port
to be tested.
7. A CW linear measurement sweep is measured for each test point. The
receiver reference power level, Pref, in dBm is calculated for each point
from the mean of each sweep.
8. The test cable is removed and loads are connected to both ports.
9. A CW linear measurement sweep is measured for each test point. The
receiver test power level, Ptest, in dBm is calculated for each point from
the mean of each sweep.