I own two.
My advice is to buy one that is already working and calibrated. Also, make sure that it can test the kinds of tubes that you want to test. Because not all testers are equivalently capable. This will mean that you'll pay quite a bit for a good tester.
My advice is to buy one that is already working and calibrated. Also, make sure that it can test the kinds of tubes that you want to test. Because not all testers are equivalently capable. This will mean that you'll pay quite a bit for a good tester.