I have a 1956 Heathkit emission tester shipped from Benton Harbor the day I was born. I use it most, because the bottom line is whether the cathode is doing it's job or not...........If I still get squirrelly results w/ a "good" tube, I fire up the Hickok and see if there's anything going on there before getting out the soldering iron. 73 DE JIM K6FWT