For the first several months after I built my ATS-3B , I used a pair of mini-paddles with it. They were quite small, but slightly fragile. If I ever dropped them, it would effectively destroy them. I needed something more rugged, and hopefully, lighter. When running through some articles I'd saved from old QST magazines (July 2004, QST Magazine), I encountered the perfect device: The NUE key.
The NUE Key is a dual-paddle that uses capacitive sensing rather than motion to activate the output. It can consume incredibly low power making it ideal for field use, and if built with surface mount parts, can be made very small.
My version of these paddles is built into a 2" x 1.5" x .5" housing made of sheet aluminum. It has a base that extends 9" in front of it to allow you to rest your forearm to stabilize it (instead of weighting it down to prevent walking). It consumes less than 500uA from a single 3V button cell.
There is no power switch. To turn it on or off, you must open the case and flip the battery over. Using the battery holder I chose, mounting the battery backwards simply breaks the positive connection; it does not reverse the battery's polarity.