Rtl-sdr blog v3 has a direct sampling mode that will get you into the single-digit mhz.
I assume that the v4 does as well. The earlier versions apparently also have this mode but it requires opening the devices up and a bit of soldering here and there.
I assume that the v4 does as well. The earlier versions apparently also have this mode but it requires opening the devices up and a bit of soldering here and there.