K9DP 100w BCI Filter

Now available on Amazon here.

Kit versions coming soon!

The K9DP 100w broadcast interference (BCI) filter allows amateur radio operators to reduce or eliminate unwanted broadcast interference in their signals. Primary designed to help HF transceivers and receivers that struggle with front-end overload from AM broadcast stations.

This lightweight and portable kit is ideal for use in field operations such as Parks on the Air (POTA), Summits on the Air (SOTA), and Field Day. It has been tested at power levels up to 100 watts with SSB, CW, and digital modes. Measures only 4 inches (102mm) in length and weighing just 78 grams. SO-239 UHF connectors on both ends for compatibility with amateur radio stations.

The kit includes all of the components needed to build the filter, including SO-239 connectors, capacitors, enameled wire, toroids, printed circuit board and 3D printed case. The high quality online instructions provided with the kit will guide you through the process of soldering the components onto the board and assembling the filter, step by step. Once the filter is built and tested, it can be easily attached inline with your radio equipment using PL259 connectors.

These filters have a 50Ω impedance and are symmetrical, so it's not important which end is the input or output.

Caution: High SWR can damage the filter. The filter should be inserted inline between the transceiver and tuner, rather than between the tuner and antenna. If your radio has an internal tuner, be sure to use a resonant antenna or an antenna with a matching circuit, such as an EFHW (end fed half wave), in combination with the filter.