Since I want to do some experiment to homebrew GHz spectrum analyzer and GPS recievers, which model do you suggest? I can live with poor phase noise performace under 10MHz range .
They are both very good signal generators and assuming they are both healthy then I don't think there's a right one or a wrong one. So it may come down to simple human factors as below:
I had the pleasure of using the 2GHz R&S SMH throughout the 1990s as a general purpose sig gen. This generator was too expensive for the company to buy but it was donated to us by the customer on a research task. It is a really nice instrument to use, the whirly wheel has a high quality feel as do the buttons and it even sounds nice when the attenuators click etc. The display is pretty basic but it still looks good.
It hasn't been totally reliable since then (been back more than once for repairs) but we still have it and I think we first got it way back in the early 90s.
The phase noise is pretty good (but not spectacular). I have a library of phase noise plots for lots of our works generators here and here is the SMH at 1500MHz. The noise profile at 1500MHz shows a fairly high pedestal of noise out to 200kHz and you can see this isn't as good as the 8665A.
It's quite good down at lower frequencies although I didn't measure it below 10MHz. But there's a plot of it at 10MHz below.
Hope this is useful.
I would definitely find room for an SMH here, partly through nostalgia and partly because it is such a nice generator to use. However, I didn't ever use any of its modulation modes back then. It was just used as a low phase noise signal source in the tasks I used it for.
For me, the human factors of the 8665A make it a non starter. It is huge and it weighs about 35kg and unless I 'needed' the performance of the YIG + FLL mode up at UHF then I can't see why I would want to have this monster taking up space on my workbench. However, it is an amazing piece of technology and I don't want to appear disrespectful to HP with these views.
However, I just noticed that the 4GHz SMHU is bigger than I thought. The 2GHz SMH we have at work is only about the same size as a Marconi 2019 but the 4GHz SMHU looks to be very big and is going to be very heavy too.