The Rikstone Tube Tester is based on a simple tester published
in a Polish radio amateur magazine in 50's. I have modified the original circuit  for the tubes I use mostly i.e. 12AX7 (ECC83), EL84 and EL34. For more information see the detailed description.

See also the Polish (Polish only) article.

Schematic (More advanced)
User's Guide (In Finnish only)