it took a while to add the matching volume control into my digikey orders. I simply forgot to add it multiple times. Now it has arrived and I put it into the unit and it works.
But to correct some misleading statements:
From the issues I had with my board, I do not state that the whole thing is a bad idea or at general bad manufactured. And I know the difference between this hobbyists self build unit and a four digit cash unit from any major brand.
So the question, if someone has some reference values for my measurements was meant neutrally with respect to quality or expectations. As there was at least one defect, I needed that values for getting an idea if there may ne another cold joint or broken part.
As it shows, there had been several bad solder joints on my version of the v6 and after fixing them I get a stable -119dBm @ 10dB SINAD. So we are on a good way, I guess.
May be I modify the unit by exchanging the oscillator board with something less noisy and replace the AVR by an STM32L4 for having more options on the display. As you wrote, this unit is for being played with.
The YL is a HAM for many many years, but she likes to buy all sorts of radios, every radio that is new and sometimes a radio that is old or rare or just a curiosity.