what is the lowest output db value out of theses ![Huh? ???](https://www.eevblog.com/forum/Smileys/default/huh.gif)
I tried the one in the photo, and the few discrete values that can be set in the touch-screen interface do not actually match what is output. The screenshot shows the actual result at the four configurable output levels, at a spot frequency (the chosen spot frequencies are slightly different each time just to display it like that, no other reason).
When set to the max level, the output is reasonably flat (to within about 1 dB) from LF to approx 4 GHz, and then tails off a bit (maybe a couple of dB). I didn't test the other output levels across the spectrum, because I figured I'd just use it at the max output and attach an external attenuator if required.
I think the device is OK for the price (by OK I mean kind of average : ), but could be better. They are not getting the best output from the chip. Also, there are some bugs (e.g. sweep is temperamental). But not bad if you need a single frequency generated for a purpose. Harmonics are as expected, they will need to be dealt with if it matters to whatever use-case the device is needed for, and spurs are quite low, especially up to VHF or so, then a bit higher.