I would mark them as questionable. A tube can test
weak & still work fine. Also if you are subbing it to
a dead tube it makes a good test. We had a B&K
checker at the shop. We never used it, it was for
the customers. Made more money on that than new TV
sales back in the 70's & we sold a lot of new TV's.
Bottom line a tube checker can find some bad tubes
like open filaments or dead shorts. Whether it will
oscillate or handle 500V spikes NOT. A checker, even the best
is just a helper & not the final word.
73 Zeno
