I suspect I might know about this under another name, but I want to make sure that I haven't missed something important. Just what is the "R91 mod"? My K3 is #444. Thanks, Tony, KM0O -- View this message in context: http://www.nabble.com/What-is-the-%22R91-mod%22--tp18316001p18316001.html Sent from the Elecraft mailing list archive at Nabble.com.