I thought the K1 was the commercial version of the Sierra. Didn't the Sierra predate Elecraft? BTW, the K1 is about the neatest QRP radio I own, even above my K2. I've built boards for every band 80M-10M, especially enjoy working from the patio @ 1W into an EFHW on 20M. It's my "go to" rig for QRP contests. 73, Curt KB5JO