Agilent Technologies N5241A, Service Manual

Page: 66 / 354

3-32 Service Guide N5242-90001
Tests and Adjustments PNA Series Microwave Network Analyzers
Performance Tests N5241A/42A
Receiver Compression Test
Function of the Test: To measure the compression at the analyzer’s specified maximum
power level for the receivers.
Specification Tested: Test Port Input–Maximum Test Port Input Level
Equipment Used: The compression test set (Z5623A Option K01), a power meter, power
sensors, two test cables, and a calibration kit. (And 10-dB and 20-dB pads if the analyzer
does not have an internal step attenuator.)
Description of the Test:
1. All measurements are made with a 1 kHz IF bandwidth and 201 points per sweep.
2. The measurements are made separately on each port.
3. The analyzer is set to various CW frequencies across the range of the analyzer.
4. A power sensor is connected to the “signal source point” to be used to test the port. The
“signal source point” may be either the port connector itself, when a short is used, or
the end of the test cable, when the compression test set is used to source the test signal.
5. The analyzer source output level is adjusted to create the maximum power level
specified for the receiver.
6. The power sensor is disconnected and the “signal source point” is connected to the port
to be tested.
7. The absolute log magnitude value (dBm) for the reference receiver is read.
8. The log magnitude ratioed measurement using the receiver under test is read: (P
a
).
9. The source output level is adjusted to decrease the output by 15 dB.
10. The log magnitude ratioed measurement using the receiver under test is read: ( P
b
).
11. Attenuation of 20 dB is introduced between the source and receiver. This can be done
with an internal step attenuator, an external 10 dB pad (if a short is being used to
reflect the signal back into the port), or an external 20 dB pad (if the signal source is
the compression test set).
12. The log magnitude ratioed measurement using the receiver under test is read: ( P
c
).
13. The source output level is adjusted to produce a reading of Pref (within
±
0.03 dBm) for
the reference receiver on the source port.
14. The log magnitude ratioed measurement using the receiver under test is read: ( P
d
).
15. The compression in dB
=
(P
a
−
P
b
)
−
(P
d
−
P
c
) .
If the Analyzer Fails this Test:
• Repeat this test. There are no adjustments that can be made.
• 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 7-34 .