ADX-MINI QRP Antenna Tuner

All credit for this design goes to Scott Baker. The ADX Mini is a Pi-network antenna tuner built specifically for portable QRP operation. It features two hex switch arrays that act as a variable capacitor, plus four inductors with binary values of 1, 2, 4, and 8 microhenries. Switches across each inductor allow you to combine them for a total inductance ranging from 1 to 15 microhenries in precise 1-microhenry steps. The board also includes a built-in SWR indicator circuit with an LED, so you can tune your antenna correctly and detect high SWR instantly without needing any external meter.

Why was it made? For POTA contests and other portable operations, this tuner is exceptionally small and lightweight. It gets the job done without requiring bulky gear that weighs down your pack or slows down your setup in the field.

What makes it special? This QRP antenna tuner is a versatile gadget that lets you easily tune any vertical or horizontal antenna. Whether you are running a random wire, a dipole, an end-fed, or a vertical, the ADX Mini provides the matching range you need. The Pi-network design offers wider matching capability than simple L-networks, while the binary inductor switching makes tuning repeatable, predictable, and fast. The onboard SWR LED means you can tune with confidence even when you have left your external meter at home.

Perfect for POTA, SOTA, field day, emergency comms kits, or any QRP operator who values portability without sacrificing performance. Just connect your transceiver, attach your antenna, dial in a match, and get on the air.