Don Brown said: "As I understand it the mods can be retrofitted to the Rev A radios by installing on the bottom of the boards. So your present K2 is not obsolete it can just be upgraded to the 'B' level with a little work and a few parts." Don Sorry, you lost me there. Which mods are you referring to that are 'installed on the bottom of the boards' that would bring earlier K2's to the latest Rev B? 73, Mike - K5PU