@Zack -
welcome to the forum and great finding! This should actually wipe away all my (our?) concerns regarding differences between DG800 and DG900 series, the hardware is identical and hence the performace should be the same after the upgrade. I'm curious if there's a calibration guide available on the chinese site already?
During my tests of the "DG811+++" I found a few peculiarities:
It's good to see that parameter changes (frequency) of sine output takes place without any glitches. Square and Pulse waveforms provide (almost) glitch-free parameter changes (frequency, symmetry/pulse width, slope) up to frequencies of 1MHz, above that, the signal pauses for a few milliseconds at half the signal level (i.e.[Vmax+Vmin]/2).
The "almost" mentioned above means that once in a while I was able to catch a strange high frequency glitch of several superimposed frequencies when changing the frequency setting, see attached screenshots.
Ramp and Arb waveforms always pause for a few milliseconds upon parameter changes.
Amplitude changes only cause glitches if the internal attenuators switch ranges. Yet, this happens rather often. I found such switching events (50 Ohms output impedance selected, for high-impedance, double the specified figures) to take place at 2.5mV, 6.4mV, 16mV, 40mV, 100mV, 256mV, 640mV*, 1.6V and 4V. It's quite peculiar that the 640mV switching event takes place without an audible relay click. If a glitch-free level sweep is required, the output signal can be amplitude modulated by an internal ramp.
I also did the "PAL raster frequency test" (outputting two ramps of 50Hz and 15625Hz and observing the relative phase) that my SDG6000X failed at and found the "DG811+++" to fail as well. The phase should stay constant, i.e. the frequencies should stay locked against each other, but I find them to walk through at very slow pace in an incremental manner, see the third and fourth screen shot. They can be brought back to the original relation by pressing the "Align" button.
Considering the price of the "unimproved" instrument
, these small problems may be tolerable, especially since they are really of minor importance for the average user.
Btw, the very nice touch screen is extremely well integrated into the UI concept, it's obvious that the whole UI had been designed with the touch panel in mind instead of other manufactures' approaches where it's plain to see that a touch panel had been added to an existing firmware package and it more or less only duplicates functions that can be accessed via the key pad as well.
Cheers,
Tom
P.S. Just for fun I aded a fifth screen shot where I compared the rise times of the edges in Pulse mode between the "DG811+++" and my "SDG6000X-I" ("I" = improved...must be chosing the equipment upon the possibility to hack...
) Hint: The measured rise time of the SDG is rather limited by the scope used than by the generator!