Hi George, You should not need a keying buffer, as the PW1 keying line is low-level. The negative-going ALC fix must be installed in your K3, and the ALC adjusted to level the PW1 output at 1 kW per the PW1 user manual. Do not attempt to operate the PW1 without ALC, as otherwise severe damage to the PW1 could result. Cheers for now, 73, Adam VA7OJ/AB4OJ