The humble SA612 mixer chip , long a cornerstone of QRP and RockMite transceiver designs, has officially gone end-of-life. Announced by Bill Meara on Soldersmoke, the news marks the close of an era in home-built HF radios. KO6BTY and I have relied on this little chip throughout Project TouCans, and while it’s never failed us in the field, its retirement feels like losing a trusted bandmate.