The BA5SBA direct sampling kit is a kitset PCB that combines with a standard (included) RTL-SDR dongle in order to enable the direct sampling mod. The direct sampling mod is a hardware modification that can be applied to any RTL-SDR dongle in order to enable HF reception capabilities. The BA5SBA kit improves upon some of the problems with the direct sampling mod by adding additional features such as a low pass filter to block broadcast FM interference, a matching transformer to better match the RTL2832U’s input impedance, extra power supply filtering, SMA connectors for HF and VHF/UHF (UV), an aluminium case and a bias tee.
The BA5SBA direct sampling RTL-SDR can be bought as a kit that requires hand assembly for about $30 USD or as a fully assembled product for about $50 USD. It is usually listed on Amazon and eBay as a “100KHz-1.7GHz full band UV HF RTL-SDR USB Tuner Receiver/ R820T+8232 Ham Radio”
Recently, RTL-SDR.com reader Simon (MW0SGD) bought one of these kits and discovered that the English instructions were very rare and hard to come by. We’ve decided to post these English instructions here for any future buyers who may search for them as this post should show up on Google. Simon also notes that “most of the instructions on the internet wind the inductors on a 5mm former. This says to use a 3mm one, which I did and it works ok.”