I needed to build a bandstop filter against local FM broadcast band to make my RTL-SDR have fewer imaging issues. It took 6 tries before I got a decent one. I followed the one from LNA4ALL here. The next step is to build it into a box for better sturdiness -- currently attempt 6 likes to fall apart and need resoldered.
Attempt 6 The extra wire coming out of the SMA connector is to feed my RTL-SDR for HF frequencies.