Today I tested another unit, and this one tested good, even 2dB or so better than your screenshot.
Its made in Malaysia. You might have pointed us in the right direction... I will check if this issue is consistent with the DAC revision, or if the previously tested units are just bad.
https://edadocs.software.keysight.com/kkbopen/does-my-e4406a-vsa-series-analyzer-have-a-14-bit-digital-if-or-a-12-bit-digital-if-589306038.htmlAnother question occured.
https://www.keysight.com/de/de/assets/9018-03347/technical-specifications/9018-03347.pdf (p.13)
The technical specification specifies the noise sidebands at 673.6 MHz, 960 MHz and 1990 MHz with offsets of
0.1 kHz,1,10,100,600,1.2 MHz, 6.0 MHz and 10 MHz (Offsets <1 MHz measured with RF Input ≥ −2 dBm; Offsets ≥ 1 MHz measured with RF Input > +12 dBm).
The Instrument Messages and Functional Tests Guide ...
https://www.keysight.com/de/de/assets/9018-01461/user-manuals/9018-01461.pdf?success=true (p.59)
...uses different test frequencies and only two offsets, 10 and 30 kHz.
There is no test limit for offsets over 30kHz. And there is no spec for 30kHz (only 10 and 100 kHz).
At 960 MHz, the spec with 10 kHz is -96dBc/Hz with "something over -2dBm input" and the test limit at 900 MHz is -80dBc/Hz with 7dBm input and 10dB input att switched (while no att setting is written in the spec for -2 and +12dBm).
Is there a third document to make sense out of this or should I just take it as it is, and test for both?
Next issue, the messages and functional tests guide is inconsistent at the procedure. In the text, it says to set Mode to Basic, but the table says Mode is Service. I think It does not work in Basic mode, because I can not set ADC Range to -6, only 0, +6dBm etc.
Heres the short version for those who do not want to download the pdf to look at the test procedure:
Step 1: Align All 2: Prest Step 3: Set UUT to measure the carrier: Mode:Basic, Marker:Trace:A+Spectrum Avg, Freq:600 MHz, Span:800Hz, InputAtt:10dB, ADC-Dither:On, ADC-Range:Manual:-6dB, Pre-ADC BPF:Off, AVG-Number:5, Avg Type:Pwr Avg(RMS), TraceDisp:Avg.
Step 4: Preset the source to 600 MHz 7dBm. %. connect. 6. Adjust amplitude until UUT shows 7dBm.
Step 7: Reset the UUT to measure noise: ResBW 5Hz, ADC Range:Auto, Pre-ADC BPF:On, MarkerFct:Noise.
Then the offset Frequencies 600.01 and 600.03 (and 900.01 MHz etc) are measured with an 800Hz span at 5Hz bandwith.
When doing this, there's a spurious response at -92dBm right next to the center, but looking at the spurious response spec this seems OK.
The test manual btw only tests residual response, with nothing at the input.
The specification says, with input CW between 700 and 1678.6 MHz the spurious signals are below -59dBc.