There was no "spot" switch on the DX-100B. The "spot" switch and "improved keying" were a modification kit that was available from Heath for both transmitters. Glen, K9STH Website: http://k9sth.com --- On Sat, 6/4/11, lee <pulsarxp at embarqmail.com> wrote: Different cabinet, spot switch, and loading output capaicitor is variable> and not fixed with step switch.