Since I am getting more and more repair jobs for tube amps, I designed (well most is nicked from others) and built my own diy simple tube tester. Of course ´simple´ is relative since during design I wanted more and more functionality. However, I am quite happy with the result. Faulty tubes will show and gm and mu measurements are possible. Best of all: I did not get an electrical shock (yet).
I did not put much effort in the webdesign or the photo.....
Questions? Drop me a note
http://checkout-systems.com/tubetester/