RCA 9T246 linearity

[dtvmcdonald]

I can do tube tests with our shop's (transconductance) tube tester. I've got to
remember to bring the tubes in. However, the fact that three tubes with nominally
the same curves gave identical results suggests that all three have to be the same
quality. All three give DC measurements that are spot on what they are supposed to be.
The 6L6 and 6V6 gave different DC values.