its all about termination not branches branches are not always a problem they are the problem when they are long and not terminated if the unused branch was terminated there would be no echo to cause the problem its a little confusing as its the ac impendance at the tail of the branch and in the frequency range of interest that would be deciding whether its terminated or not it could be terminated for one frequency and not terminated for another but the main point is that the lack of the device on the unused branch that is causing the echo any moron can see that the branch with the users device on it could also cause an echo if branches cause echo all three branches could cause echo what is the difference the lack of a device on the unused branch also the signal travelling down the branch is no problem of it self its the coming back that is the problem