Yeah, sorry if I confused things with my various questions -- I'm only interested in HF right now. My mid-term goal is ultimately to make a QRP digital mode transceiver from scratch. For me, at least, it's not enough to just go copy the PA from some other project and move forward. For example, I've assembled a QCX, which has a ~4W output with 3 BS170s, but I can't say I really understand what design process went into making it. I just assembled it, according to instructions. I'd like to build a thing, and be able to pop the lid open and tell my kids what every part does and why it's there . I've been most inspired by EMRFD and a couple of individuals' project sites because they describe their design process and at least enough theory that I feel like I'm learning things. I have a working receiver chain that I've studied, built, tested, and measured (not that I won't learn some more and improve it, but hey, one thing at a time!). So now I need to make baby steps on the transmit side. I've narrowed down which kind of super-basic class AB amplifier I'd like to build, but the part listed in the article seems unobtainable. Hence, this post . If that BFU590G would work in a braindead-simple amplifier circuit for HF, then I'm good to go, and can build one up and play with it.