Always a pleasure Terry.
Alan can explain some complex concepts quite simply. I found his videos when trying to learn how oscilloscopes can be used by amateurs.
What I like is that he will take a topic such as Bias-T's and draw it out on paper, explaining the why, then show one in use and measure the results. Want to know about Smith charts, then there is a video for that as well...
If you want to soak up even more hours, have a look at The Signal Path youtube channel. I don't understand a lot of what
Shahriar is saying (though I constantly pick up little bits of info for later use) but I like the thorough analysis and therefore approach to a repair on what is typically a really complex piece of kit such as a spectrum analyser.
Have a look at TSP #26 video...where he explains the various connectors used for microwave and mm-wave systems and the various sub variants of some of these along with the Production, Instrument and Metrology grades of the same. Connectors ain't just connectors (unless all you use is PL-259 which does not get a look in anyway).
So many people to learn from and the good part is that you can watch them again and again until it makes sense.
Hours of fun...
Regards
Bernard