SB 220 Rebuild # 8 Testing Used 3 500z Tubes

A simple and safe method of testing used Triode transmitting tubes like 3-500Z's or 572-B's, using an ohm meter, and a linear amplifier. We test for Shorts, Gas, and Idle plate current...both at cut off and with operating bias. The final test - not shown here..is to test tubes one at a time with increasing RF drive. If you tabulate the results, you can compare and match tubes. If you test a New tube..you can compare the results with your used tubes. If you are impatient and skip steps...don't blame me.
This also happened to allow us to test the bias circuits of our recently rebuilt SB-220. However, you cannot use an amplifier in unknown or questionable condition to test tubes which are also in an unknown or questionable condition! it's like testing bad soup with a dirty spoon..what's the point?
73 Larry W6WUH