Tube tester?

Good advice from oddiofyl about warming up the tube sufficiently in the tester.  I recommended the Orange tester as a reasonably-priced modern alternative, but, someone who uses it at a dealership told me that it does not operate at high power and may give a poor rating to certain types of output tubes (e.g., KT88) unless the test is run several times in quick succession so the tube has warmed up sufficiently.  

If you are not really experienced with tubes, a tube testers can be a good thing and a bad thing, sure you can weed out shorted tubes that aren’t any good, but you may also be throwing out tubes that are gassy and are not bad. My advice would be to get on the diy tube audio forum and do some research about tubes, tube life, and what are the pros and cons of tube testers.

Schematic, BoM, CAD dwg w dimensions and build photos for

available @ ieLogical Valve Tester