This post is mostly a shout out to Ronald Dekker, the inventor and seller of a very neat tube tester kit called the uTracer. I did quite a bit of web searching before buying this kit in 2014. It was at that time, and still appears to be, the best device of its kind, especially when you compare to the (high) prices of old tube testers or (you better be sitting down) a Tektronix 570 curve tracer.
I had a large stash of tubes I wanted to sell on eBay. I found that I got much better prices for tested tubes, and in the case of audio power tubes, EVEN BETTER prices if I matched characteristic curves. The uTracer device seems to be, far and away, the best most cost effective device to measure detailed tube data. Buyer’s were very happy when I shipped a curve-trace plot with each tube.
The uTracer is an extremely well thought out design. It is a perfect blend of old and new in that it measured tubes but interfaces to a PC, which provides control and displays the data plots. I won’t go into more detail here, because all is thoroughly explained on the uTracer web site: https://www.dos4ever.com/uTracer3/uTracer3_pag0.html
There are some incredibly slick uTracer builds on the above the site. Mine is pretty bare bones by comparison, but still did it’s job very well.