On their website you can download the schematic. They are a bit obscure on the mosfets, it seems they are four MS1307. As said they lack of any lowpass filters so as such they do not comply to the FCC rules.

Il 11/giu/2018 15:48, "Richie Chambless" <rchambless7@...> ha scritto:

I’ve thought about these amplifiers, also. Despite the negativity around them, I think the only thing that’s missing is the low pass filters (the ones biased for linear operation). I’m thinking they all use RF transistors, but I could be wrong.