I've heard of these before; they are very cool. The only problem, as far as I've seen, is a smaller frequency range and lower gain compared to tubes or transist

I've heard of these before; they are very cool. The only problem, as far as I've seen, is a smaller frequency range and lower gain compared to tubes or transistors. Not crazy smaller or lower, but don't expect a single magnetic ham radio amplifier to get you from 160m to 10m at 1.5kW legal limit.