on a calibrated TV-7D/U tube tester on which 40 is the minimum
***On some tubes the minimum being 65% of the typical new score is not a workable formula on the TV7-D/U. So a % score is not meaningful and only an actual meter reading is given. These are
5Y3GT - 12BH7 - 6X4
Test results may differ between various testers for many reasons such as technical design, aging components, etc. So while test results are a good indication of quality there can be some difference between the many differently designed & maintained testers.