Featured image: Prototypes of the TinyFilter
At our November meeting, SPARC welcomed Mike Seiffert, K6STR and Ara Kourchians, N6ARA to discuss the development and marketing of their product, the TinyFilter, a compact band-pass filter for 2-meter handheld radios.
Mike loves adventure, portable radio, and building things. That includes hiking, mountain biking, and Summits on the Air. He enjoys building his own gear and writes about his activities at his new blog, Solder to Summit.
Ara is an electrical engineer with a background in circuit design, embedded systems, visual effects, robotics, and space systems. His first ham radio passion was building and flying custom APRS trackers on high-altitude balloons. Today he runs a small business building and selling amateur radio gear at n6ara.com.
What is a band-pass filter, and why would you want one?
A band-pass filter attenuates unwanted radio signals so your receiver only hears frequencies in the range you want. Handhelds already contain band-pass filters, but they can be ineffective, especially in low cost radios. If out-of-band signals are strong enough, your radio may not receive anything you actually want to hear.
SOTA operators encounter this issue whenever they try to make simplex contacts from summits that also host communications sites. Mike pointed to Mt. Wilson as an extreme example. Most L.A.-area FM and TV stations transmit from there, and he estimated the total signal output at ten megawatts. Ironically, attaching a better antenna to your handheld only makes matters worse, because it picks up more of everything. Adding the TinyFilter between an inexpensive HT and its antenna can make the difference between hearing nothing and completing a distant simplex contact.
From prototype to product
Mike designed the initial circuit of the TinyFilter in early 2026, and he brought it to Ara to start building prototypes. They learned from broken units and adjusted their design accordingly. Once the design and the production process were finalized, the finishing touch was to wrap the TinyFilter in a bright label whose color they refer to as “never-lose orange.”
SPARC thanks Mike and Ara for an informative and entertaining talk. You can find the TinyFilter at n6ara.com. A video of their presentation and the accompanying slides are embedded below.