[Hallicrafters] 12at7

[Jack Schrader]

Lately I seem to have found a bunch of 12AT7 that test bad or just marginal on my B&K 700 tube tester but I also have many that test ok. I have not tried to switch them in and out of a good operating receiver but 'am wondering if this tube
is prone to failure or is it maybe the B&K tester or even the operator.

Would appreciate any thoughts you might have.

73   Jack