Thank you for responding, and I admit, I am not great at electronics. I am adding a picture of the Manco product I have. Maybe you can tell me what it's designed for. I was having signal issues around 2000 thru 2005 and Dale and I talked a lot. My situation was totally corrected with earth ground wiring. The new Legacy equipped engines run so great, no signal issues. Thanks fir this thread.
That is the booster for the output of the serial port (DB 9 connector on the Legacy Base) as it pertains to running multiple TPCs and some Z Stuff drivers. It has been "replaced" by Lionel with the SER2 module used with LCS and provides a higher power output from the serial port.