A local dealer has an Orange as well as a couple of TV7’s. The Orange is much easier to use because you don’t have to set various tube parameters (about as easy as the Amplitrex I own). I don’t know what it is testing; I hope it is transconductance if it is only testing one thing. What I do know is that, for many tube types, it will show a poor reading where the TV7 indicates that the tube is strong. It appears to be a tough grader. The Orange might indicate a tube is weak when it is not so because it often does not fully warm up the tube before testing. What you have to do is re-test the tube immediately after completing a test to see if the tube improves enough to be good. Aside from this quirk, it seemed to be a decent device for testing most common tubes. It is not an Amplitrex, but it costs a lot less.
