You are correct about the connections. The 18v out can be used to power/charge some meters and the 119 unused on a SWM3. As for the box being disconnected, when I used an Acutrac having the box connected would kill the meter at some point during the boot process. Kill, I guess, is an overstatement but it would no longer work until turned off, disconnected and then reconnected. I am connected like you and stuck an A/B switch to the top of the box. I use it to break the connection so the box can boot and I can use the meter at the time. As I said before, you could have just used a DTV splitter with the the red terminal to the PI the other to the meter and the top one to the dish. I learned that after I bought the ASL-1.