The current web sdr receivers tune up to 30 mhz. The older receivers didn't work that way. They used a ham it up- up converter and fed the signal to an rtlsdr (or split the signal to multiple rtlsdrs). The standard rtlsd r really doesn't work to well below 24 mhz, regardless of what you hear. The ham it up steps the signal up to the 125 mh z region. They usually attached one rtlsd r ,as well, just to receive standard vhf/uhf signals. As you know, if no restriction is put on receive freq. , the rtlsd r will go up to about 1700 mh z ( give or take). It would be nice to get something like 136 mh z satellite weather signals. That's if there are no bandwidth issues.