Keysight Technologies N5247B, Service Manual

Page: 78 / 566

3-48 Keysight N5247B Service Guide
Tests and Adjustments
Performance Tests
3-
2. Within the dynamic accuracy test set, the source signal is routed through
a small amplifier and a 10 dB step attenuator, A1, to a power splitter. One
side of the power splitter is connected to the power sensor port. The
signal from the other side of the splitter is routed through a 110 dB step
attenuator, A2, to the receiver port.
3. The PNA-X is set to make a relative noise power measurement with the
noise gain set to 0 dB.
4. With the amplifier active and A1 set to 0 dB, the signal generator power is
adjusted to achieve exactly
- 10.0 dBm at the power sensor. This is the power meter reference
reading, Pmr.
5. A2 is set to 50, 60, or 70 dB, depending on the gain stage being tested,
and the analyzer’s noise receiver power level is measured. This is the
analyzer reference reading, Par.
6. A1 is changed to 2, 4, 6, 8 and 10 dB. At each point, delta power levels are
read on the power meter, Pmd and the analyzer, Pad.
7. The power linearity error at each point is calculated as Pe = (Pmr – Pmd) –
(Par – Pad).
8. A2 is incremented 10 dB, A1 is set to 0 dB, and the signal generator’s
source power is adjusted until the receiver power level is exactly the same
as it was before the attenuators were switched.
9. New power meter and analyzer receiver reference readings are recorded.
The process is repeated until the total attenuation reaches the minimum
test level.
10. The process is reset to the reference levels from step 4, and it is run in
reverse until the total attenuation reaches the maximum test level.
11. This test is repeated for the 15 and 30 dB noise gain settings.
If the Analyzer Fails this Test:
A failure of this test indicates a fault in the noise receiver chain. This can
indicate a faulty assembly or a loose cable.
— Check for proper torquing of all semi-rigid cables in the receiver chain, and
then repeat this test.
— If the analyzer still fails this test, replace the A7 Noise Receiver board and
repeat this test. Refer to “Removing and Replacing the A4–A17 Boards” on
page 7-18 .
Noise Receiver Compression Test
Function of the Test: To measure the PNA-X noise receiver compression at the
receiver’s specified maximum input power level.
Specification Tested: Test Port Input: Option 029 – Noise Receiver Input Range