I would have thought that sending 12v up to the aerial would require some protection at the tuner end. So, what you're saying is that you need to connect 12v to the aerial feed from tuner module, sounds rather worrying to me...

Let me clarify, I'm talking about a power feed that is actually the central conductor of aerial wire, ie. there's RF AND 12v on it, not a separate wire to feed a box of tricks.