This depends upon whether you just want to test the tubes, or whether you want to match them. If you just want to test them, then something like the Jackson 648 series will do a good job--and it is very easy to use. For this tester you will need the additional "Special Tube data", as the 2A3 is not on the roll (at least not on mine). If you want to match the tubes, you will need a mutual conductance tester. These are more complicated and more expensive. I am sure there are good alternatives to the 648. I just suggest this model because I have one, it is very easy to use, and it does a nice job. In addition, they are not usually too expensive.
