I used the K2 at 5W with either the built-in battery or the Radio Shack Power-Up system. Conditions weren't that great, but most people could hear me OK. I made QSO's on 80, 40, 20, 15, and a few on 10. It's nice having all bands in one little box. Tnx to all who strained their ears to copy me. 72, John W2XS