I'm looking for a kit for an HF band-pass filter that can be put in front of an RTL-SDR running in direct-sampling mode. The filter would pass only HF bands to the receiver. Ideally, it would pass 160m through 10m, although that might be unrealistic for a single filter, so I am also interested in BPFs that can cover 80m through 10m filters, or LPFs that pass frequencies below 30MHz. Since this is only a receiver filter, the power handling of the components need not be large, as with a transmit filter. I found several kits for BPFs that cover only one band, but I was hoping to find a single filter that could do some amount of preselection when the RTL-SDR is running on the HF bands. I'm happy to build a kit, or from a schematic. My first thought was to use a few stages of RC filter, in LPF/HPF pairs. But if there is a better design floating around, I would like to try that first. Thanks & 73!