[gregb]

I actually use three different testers on a regular basis depending on a number of factors.

The warm up time of a tube depends on the tube, a directly heated cathode should be up to full temp within a few seconds of power on. An indirectly heated cathode could take up to a minute or more depending on the tube design. Some tubes had controlled warm up times.

A lot of what I say is 30 years of testing tubes and just my experience with doing it and using my testers. If you really have an interest in doing this then there will some experimentation for you to carry out. You will need new tubes as reference and have some bad ones to see how they react in your testers and your equipment.

The other thing is just because a tester says a tube is good really means nothing until it works in the set. I have a 47 tube that I broke the seal on its box and tested and it was 100% as I would have hoped and installed it in a radio and had zero output. I did some trouble shooting and it appeared the tube was bad so swapped it with another known good tube and the radio played great.
I retested the original tube and it still tests 100% but will not work in a radio.

Have fun and don't be to quick to judge your tester, it might be doing what it was designed to do and some do it better than others for sure.

Gregb