Larryi, I'm most interested in testing small octals so it may work for me. You are right--it's not clear what it does test exactly. I wish someone had one who could review it.
Tube Tester Option
https://www.ebay.com/itm/233953776139?chn=ps&mkevt=1&mkcid=28
With all the money I "gamble" on audio, maybe I should just buy this and try it.
With all the money I "gamble" on audio, maybe I should just buy this and try it.