My K2 is s/n 0157 completely updated. Bought the K2 already built, but I'm now building a KPA100 with KAT100 in an EC2. Very pleased with Elecraft in every respect. Recently, when I put the K2 in CW mode, the CW annunciator alternates "CW" and "F." I'm a bit perplexed by this. Any idea what it's trying to tell me? Thanks, John KB1NO