Greg from Electronicsnerd will be building some RF projects over the next few days. Today he presents an AM Broadcast Band Rejection Filter for Shortwave Reception which is based on the work of Joseph J. Carr. You can find the circuit in this article (PDF). With only 7 components it’s a simple circuit that could be built in a short time.

“With an eye toward proper RF construction techniques, I kept lead lengths short and the components in a line from input to output. The SparkFun board I used doesn’t have huge traces (which at RF tend to perform like little antennas) and I’m happy with the clean build. The best way to construct this would have been on a nice copper ground plane, but I wanted to pop this together in an hour and see if it worked. Next I’ll put the filter in a nice metal box with overlapping edges. The finished product will sit between a long-wire antenna and the G3′s external antenna input.”