[Jayce]

It can be amazing how you sometimes find faulty tubes in groups. Usually that doesn't happen, so it can throw one off when it occurs and it can be easy to blame the tube checker. One reason why my friend always said to keep a couple testers around. I have had a similar issue with type 47 tubes lately. I've managed to get three radios with push-pull 47s now and in all three cases one 47 in each radio was burnt out or would burn out as I was testing it. Tapping the tubes lightly would cause an arc inside them, but nothing else. I actually watched one burn the filament out on my tester when I tested the tubes in my Philco 90X.