I saw Bob's 2x 4CX800 tube conversion of a Titan II at Dayton, May 2004, and it looked very professional. It seems to be the only option if a 4CX1600B tube can not be obtained. (Don't know what Alpha will do with it's Alpha 6 amp for 6 meters when their 4CX1600B tube supply is exhausted.?) Good luck, Jim Miller, K4SQR (A Titan Gold owner).