Hal,
As I said, it’s been a long time since and I don’t think I have even held a CATV box for many years, so things could be quite a bit different now.
Anyway, my point was though, regardless of the source, there was a distinct voltage or difference in potential that existed on the line only when a CATV box was installed. True, this in no way verifies that signal is present, but it can be used to locate a cable end.
I don’t think the OP was really interested so much in actually testing for the presence or quality of signal as he was in just identifying the line-in and getting the correct cable connections at the splitter in the attic to avoid having to make several trips up there.
