In 2 rail an auto reverser system is needed because when the TT rotates 180deg the right rail becomes the left rail and vice versa. In 2 rail a TT becomes its own reverse loop. In 3 rail the center rail is always the center no matter which way the TT track is aligned. Same reason I have all these relays to change which wire powers the frog when the turnout is thrown.
I did some additional tests with a better quality digital meter. Without any of the tracks powered I read 1.3V input and 3.6V output. This time I turned on all the track blocks so there was plenty of load with engines and passenger cars. When PD 8 is turned on The output voltage jumps to 13.5, then drops to 11.5 as before. With the better digital meter I see the input voltage jumps from 1.3 up to 1.7V and stays there.
I need to investigate your idea there is a connection somewhere between earth ground and the track. With the input voltage change that is the most likely cause. In the interim, the system is working.
