The specs are the target, not a must. A lot of suggestions here are very good, thank you, guys.
Nothing beats own experience - this is why I don't want to go purely by datasheets.
I have measured PN of my three ESG-AD sig gens and two of them were within 1-2dB from Agilent datasheet but the third is about 10dB worse. I am tempted to trace and fix the reason but it's a distraction from what is already a distraction.
Commercial cross-correlation PN kit is outside of my money budget and designing one blows the time budget so for now I am staying with classic measurement methods.
Leo
P.S. A lot of my needs are specific to PN testing so they relax overall sig gen criteria.
What
I don't need or care too much:
Don't need accurate small step attenuator.
No need for anything below +0dBm
No need for reverse power protection
Amplitude noise is not critical as long as it is not awful.
Modulation is not necessary as long as it outputs CW and can be gently steered with external DC input
Dwell time, sweep speed or range, I/Q modulation, AWG, multi-tone output are not important
Can live with high harmonics levels
Don't care about lower range below 10MHz
Your requirements are very high and with price restrictions in my opinion it's difficult to meet.
Here are my rough criteria:
10MHz..1GHz range. More is better
+7..+15dBm output
External frequency control (FM with DC coupling) or internal reference tuning input. 10Hz BW and few ppm is enough
10MHz carrier phase noise: 10dB better than attached chart
1GHz carrier phase noise:–90dBc/Hz at 10Hz, –120dBc/Hz at 1kHz offset, –150dBc/Hz at 100kHz offset
Higher carrier frequencies are OK to follow 20dB/decade degradation rule.
Not more than £2k from eBay in fully working shape (to be able to use two for cross-check tests)