Can't do this at my home. Dish on the roof. 28v SWM system. I could check the voltage from the HR21-100 compared to the HR24-200. If the older unit doesn't have higher voltage output I will be surprised.
As I said, at the time I was trying to find the reason for a " Can't Communicate With Dish" error. I just went straight to the receiver, trying to make sure I had the dish pointed. Never said this before, but this was not the first time I had seen this phenomenon.
I replaced the PI with a new one and all was back to normal.