I don't have a Kx3 so I can't answer to whether this will work for that unit. But I do get (Elpac Power Systems FW5012 Adapter 12V) for other 12V radios. Its a linear regulated supply. No observable noise on receivers I power with it. Rated at 1.45 Amps Coaxial barrel connector, positive on inside. N1BBR -- Bw_dw at fastmail.net