The tube tester I use is a Jackson Dynamic Tube Tester, make sure it's a "Dynamic Tube Tester" so you can check the plate current. Some tube testers do not give accurate good/bad tube under dynamic conditions. Any tube tester you would get I suppose will test most tubes you'll need to test. Since there are very few numbers still manufactured like the 6L6, and the beam power tubes. Don't forget your tester will need a cap to connect to the anode for testing the high power tubes.
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