Hi,

Looks like the tubes in my acom2000a have died. I have a bunch of gu74b tubes but now I need to figure out the following when selecting tubes from my stash:

1) what is a good way to check that a given tube is good? I don't have any special testers or the like  but I imagine that I can check for shorts or disconnect between some of the pins?
2) once I have found good candidates then I need to find a matched pair. Is there a good (simple) way of doing this?

The actual tube replacement I know how to do.

Jussi (aa6kj)