WindowsG Electronics

It probably ventures way too far into the "exactly wtf is happening" territory, but Mr. Carlson's Lab covers tons of tube electronics, mostly radios and amplifiers, but occasionally other equipment like oscilloscopes and function generators, etc.

Again, very in depth, but still really cool to see all the old equipment and some of the clever solutions the original engineers found to make it all work.

Some other channels I like which probably aren't all exactly in line with your stated interest (e.g. vacuum tube computers), but I believe produce good content in the retro computer (and adjacent) arena:

8 bit show and tell (mostly commodore stuff) Ben Eater CuriousMarc Tech Time Traveler

I've left out some that I like (Cathode Ray Dude comes to mind) which are just too far afield of what I think you are asking for, but are still, in my opinion, good retro computer channels (more or less). Of the ones I mentioned I'm thinking maybe CuriousMarc probably fits best with exactly the kind of thing you are looking for.