[klondike98]

I did get to test the tubes in the 552N and had a puzzling test result. The 50L6GT showed a short. If I understand things right it would be between the cathode and the filament. I tested two other 50L6GT tubes that I had and one tested fine, no shorts, and the other seemed to indicate a possible short between the cathode and filament depending on where I set the leakage resistance on the tester. I have a Jackson 648R tube tester.

I figured that the tube testing with the strong short signal should be able to be checked with a multimeter but when I did that I did not detect any short.