At the time I got mine, he advertised them as being swept with an analyzer and useable down to 100mhz. For $10, it was worth a chance. Comparing side by side with an Icom R8500, the signal quality was virtually the same. Scrounged around an got a couple Minicircuits amplifiers. Finally settled on this one; Mini Circuits ZFL 1000 Amplifier 0 1 to 1000MHz Gain 18nu ll Po9D BM15V | eBay
These can be had for half this if you look around. I think I paid all of $15 for mine.