I think it works. The LED light comes on when I turn the power on. I can hear a tone and static on my radio at about the same frequency as what’s indicated by the dial. The SWR meter moves when I change the frequency selector dial.
I’m not sure I’d use it for actually quantifying the SWR performance of an antenna. Maybe useful for quick checks of an antenna. I’ll need to find someone with a good working antenna analyzer that I could use to compare to this one.