3-34 Service Guide E8364-90038
Tests and Adjustments PNA Series Microwave Network Analyzers
Performance Tests (Agilent N7840A Software Package) E8362C, E8363C, E836C
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: A power meter, power sensor, a calibration kit, and a test cable.
Description of the Test:
1. The analyzer is set to various CW frequencies across its frequency range at an IF bandwidth of 1 kHz
and 801 points per sweep.
2. A test cable is connected to the driving port for the measurement and a power sensor is connected to
the other end of the cable.
3. The power level at the end of the cable is set to -5.00 dBm.
4. The power sensor is disconnected and the cable is connected to the port to be tested.
5. The absolute power level in dBm (log magnitude) is read: (P
log
).
6. The test cable is removed and loads are connected to both ports.
7. The analyzer’s trace is set to represent the absolute power level (linear magnitude) for the receiver
under test and a sweep is taken.
8. The mean of the points on the trace, in watts, is read: (P
lin
).
9. Average power in dBm is calculated: P
dBm
=10*Log10(P
lin
*1000).
10. Corrected noise floor in dBm for a 10 Hz IF bandwidth = P
dBm
-19.96 dB-(5.00-P
log
).
If the Analyzer Fails this Test:
• A failure of this test indicates a failure of one or more of the following assemblies.
•A31 channel A receiver
• A34 channel B receiver
•A6 SPAM board
• Since all four receivers are identical, the channel A and channel B receivers can be swapped with the
channel R1 and channel R2 receivers to determine if they are the cause of the failure. Refer to “Removing
and Replacing the A31, A32, A33, and A34 Receiver Modules and A49 IF Multiplexer Board” on
page 7-54. After swapping the receivers, repeat this test.
• If the analyzer still fails this test, replace the A6 SPAM board and repeat this test. Refer to “Removing
and Replacing the A6, A8, A9, and A10 Boards” on page 7-18.
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