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QHB Article

Rainbow Tuner for 2023 ...
is the popular N2CX-designed resistive-type SWR bridge that displays the relative SWR by illuminating combinations of colorful LEDs. It handles up to 5W RF power and includes a tunable parallel resonant circuit ("ATU") using a tapped inductor that readily tunes an end-fed half wave antenna to cover 7.0-10.16 MHz. When assembled, pc board mounts nicely in an Altoids mint tin, included in the kit!

... designed in 2007 by the late, great Joe Everhart, N2CX

Photo Gallery:

Overview:

The Rainbow Tuner doesn’t really tune rainbows, but it does use a rainbow of sorts to show the SWR of the antenna system connected to it. The "Rainbow" embodies the Spartan design philosophy exemplified by the 40-9er, the Pixie, the Fireball 40, the MRX-40, and many other simple QRP radios that have been available over the years. It combines a very special antenna tuner with a simple-to-use and accurate SWR meter. Intended to fit in popular mint tins, it can be built for under $25. The heart of the Rainbow Tuner is a user-friendly SWR indicator that can be used by itself or in other homebrew projects.