I have a fully functional TV-7 and have recently acquired a Triplett
3444. After replacing the metallic rectifiers, the things work very
well. I noticed a post, here, a few days ago regarding the conversion
of the scale factors on the TV-7 meter to GM. I noted the GM ranges and
decided to compare the TV-7 with the 3444. Before even turning on the
equipment, I selected a new 6DC6 tube. Using the test criteria in the
TV-7 book, I calculated the expected minimum GM for the TV-7. I then
looked at the direct reading minimum GM value on the 3444 rollchart.
They are nowhere near each other. I then checked the new tube in both
tube testers to see if there was any correlation.. there was none. I
did find that both testers agree a tube is good and conversely showed a
known bad tube to be bad, when it was.

May I therefore assume that the parameters each manufacturer (Triplett
and Hickok, in this case) selected for a given test may be differing,
but in each test scenario if that manufacturer's respective minimum
value is obtained, the tube can be assumed to be "good"? The above
would dispose of a notion that are (were) published tube test parameters
that the manufacturers would implement in their designs. The big RCA
manual does allude to test standards but maybe they were for them
(RCA). Any insights would be helpful. I've been testing tubes since
the 50's but never had the opportunity to do this type of comparison.
Regards de K3HVG