I see a lot of posts where Amateurs are complaining about distorted sound. I have been through that with everyone of our ubitx radios. Once the frequency display has been calibrated I have seen bfos over 12,000,000 hz. Many times I can hear points that seem to work at 11,80x,xxx but not clear and many times there is a tone along with the audio.
My oldest unit build date, about feb 2018 now has a bfo of 11,996,635.
The second unit was built in mid Feb 2018 has a raduino clone card in it and has a bfo of 11,996,455. The third unit, the newest A more recent v4 build has a bfo setting of 11,996,515hz.
Before you calibrate the bfo, zero beat your radio on to a commercial AM station. I have tried wwv and found the tones that they play makes using it more confusing than anything else. I figure that a commercial station has way better frequency measuring capability than I have. The v4 unit has much less audio output than the older ones.
I believe that the ubitx board has been tested by the factory before it has shipped.
_Dave_ AD0B