I bought one from Amazon w/ the suggested pwr supply/plug. In many cases it boosted my signal on short wave but on the AM broadcast band it had an absolutely terrible hum for which there was simply no remedy, even tho it helped the signal in many cases. Unfortunately, the louder the signal, the louder the hum. I tried distancing it from the receiver & it was still there. My receiver is an Icom R8600, & my antennas for HF & VHF/UHF are good so I was in good shape to begin with & this was just icing on the cake. So for me, I'd say it had very unsatisfactory performance on AM broadcast.
