If you get no ERR with no B, and ERR with B, then you do not have the newer B version with Pre2. Pre2 can be turned on on the upper 5 bands. When you tap and get PRE flashing, that is Pre2 and you should hear an increase in noise floor... and an increase in S-Meter (unless you have SMTR MD set to ABS=absolute). Keith WE6R Elecraft K3/K4 Tech