I've received such great help from this forum, so thanks in advance! I'd like to learn about amplifiers. I have built a few class A amplifiers on a breadboard using the ubiquitous small signal choices (2n2222, etc.). But I understand these are not ideal. I'd like to put together a BJT-based class AB amplifier to experiment with, where I can change parameters and measure things. A lot of the textbooks, guides, or circuits I find specify transistors that are no longer made, have to be obtained from specialty shops, were harvested from a dead CB radio, or the author says are less than ideal, etc. I saw that digikey has a category for RF transistors, which seems like a good place to start, but a lot of them seem to be intended for UHF and beyond. So, what's better? Try to hunt down these obsolete or unusual transistors other people use Try to find a non-RF transistor with the parameters I think I need Use these UHF transistors for my little HF experiments I find #1 pretty frustrating, and I honestly don't know if people just use those parts because they have them, or if they really are ideal somehow. For #2, I don't know what parameters really matter (I know gain bandwidth product... but are there other showstoppers?). For #3, I just don't know if it's bad to use something with a transition frequency of 8GHz for a 10MHz project. Or, maybe put another way, what in-production transistor should I buy from digikey that will not shoot me in the foot trying to build a 0.5-1W amplifier to learn from?