Once again, it is the facts that are missing that really determine the answer you want. How are the things in your RV connected and how do you aim your dish? Since you just bought the components mentioned, it suggests a tripod setup. So, how do you aim it? If you use a meter like I do (which does not power the SWM itself) you need to have power to the SWM head for alignment, but you CANNOT have the receiver connected while you do this. This is why I picked up an extra PI on ebay for about $10 that I use while aligning the dish.. (And, while a 29 volt PI seems to work with a SWM LNB, the recommended version is the 21 volt unit.) If you use your receiver to aim the dish I would still connect everything before turning on any power. There is absolutely no advantage to turning on the power to your receiver/PI and then going outside to connect it to your dish. As for me, since I do all the alignment before I turn on the receiver, I make all my connections before going inside and powering up my receiver and the PI that powers the SWM for reception. So, a bit more information on your specific setup would help give you a better answer to your question.
Honestly, it is just "best practice" to make all connections before turning on any power no matter what the situation.
I do not have a meter, I aim the dish using the receiver signal meters. Works for me and have not needed a meter.
When I ordered the LNB from Solid Signal it stated it needed the 29v PI so I ordered it. At home I have the 21v. I should have looked closer at the Solid Signal site to find the 21v but did not.
I have a couple of different scenarios:
1. I have the dish mounted on the back of my 5th wheel. Many time I can simply aim the dish without getting out the tripod. The RG6 cable is connected to the dish through a grounding block.
2. There are times when I do need the tripod. That was what prompted my post. In that case I have to disconnect the dish RG6 from the grounding block and connect a longer RG6 to where ever I have the tripod.
From what I hear, I should probably unplug the PI until I am ready to aim the dish, that way I should not run into any problems?????