Impressive noise performance of an R&S SMHU signal generator

Today in the lab, I measured the phase-noise performance of a Rohde & Schwarz SMHU RF signal generator.

The reference used was a very low phase-noise Wenzel OCXO.

As a comparison, the phase-noise of an Agilent 8664A was also measured, in standard mode and with the low-noise option 004 enabled.

The results are interesting. Seeing that the SMHU can be picked up used at really good prices it may be of interest for members looking for a good signal generator.

There shouldn't be such difference between 2 generators.The difference approx. 40-45dB @ 1kHz offset.
It does not seem to be natural..
Even Chinese made cheap signal generators cannot have such bad characteristics.

The results seem to agree with Agilent's own specifications on this series..
http://literature.cdn.keysight.com/l...73549:epsg:dow

8664 is not supposed to be a low phase noise signal generator!

BTW, it would help if you told us the OUTPUT FREQUENCY of the test. it makes a big difference

With the option 004 fitted, Agilent marketed it as a high performance, low phase noise generator at the time. All the tests were performed at 10 MHz as tabulated in the plots.

The SMHU was considered to be a direct competitor for the 8664 back then.

Maybe is a software cheat as VW did with their diesel cars...Something like measuring carbon dioxide emissions in dBc/Hz

The point I was trying to make is if you had a choice between a used Agilent 8664A unit or the SMHU, you would have better phase-noise performance with the SMHU. If you look at used prices of the two models, the Agilent units are usually much more expensive than the R&S model.