[Bradley Rush]

Just starting you would want at least a Emission's testing Tube Tester. You can down load most manual's at http://bama.edebris.com/manuals/ to verify what they are.

You'll find most of these on e-bay will cost more. I started with a SENCOR that just did short checks.

This will help you look at the different types here: http://en.wikipedia.org/wiki/Tube_tester
This is a pdf online that talks about testing a 12AU7 on different tube testers: TESTING THE 12AU7 ON VARIOUS TUBE TESTERS
Also look at Gm vs mu by Mike McCarty pdf file online let me know if you can not find them.

I myself have bounced around thru different testers. After doing so I have a 600 Hickok and a TV-7 Military both Calibrated. You can get a module Hickok CA-4 for a Hickok 6000 that will allow you to do the modern tubes. I have used it with my 600 it checked the tube out it did ok for the tube I had. After looking at them with both Calibrated and unCal tester's the best test if it is not short are open is putting them into the RADIO or Amp to check it out completely. I have not used any curve tracers but I am looking at making one just to see if it can show me performance that is equal to what it does in the RADIO. Curve tracer's would be the best if you are trying to match tubes for G Amps.