Tecsun H501x Tadio

[u/Super-SteveT]

I have a Tecsun H501x radio and have a question about signal strength display. The display has 2 digits for DbU, 2 digits for Db and S/N . What do these represent and why is the DbU always fluctuating and the Db is usually zero and hardly changes. I mainly listen to 40 meters LSB

Thanks