Total posts : 45366
First of all, I think that you can safely ignore that post from Rich – he has his own agenda and motives that don’t coincide with most of the REAL Part 15 broadcasters that are on this Forum.
As far as the Part 15 rules go, there are absolutely no range limits stated explicitly. For AM broadcasting, you either have to 1) have a certain field strength for your station (can’t remember off hand what that is) OR 2) have a transmitter that provides 100mw input to its final stage and have a feedline+antenna+ground wire (or wire to ground) that is at maximum 10 feet in length.
What the rules also don’t define is ground (and because of that, it’s been the subject of lively discussion here many times). In the past, an elevated metal mast has been acceptable to FCC inspectors as a suitable ground, so you could have an elevated transmitter+antenna, and then run your ground wire to that mast. These days, the inspectors don’t tend to allow that. And since they have a lot of discretion as to what to allow and not, it’s probably safer to go either with a non-elevated installation.
The one big exception is the Talking House combined with an ATU – somehow the manufacturer convinced the FCC that the ATU was the final stage, so the coax that connects the transmitter to the ATU is not considered a feedline. You still have to treat the ATU as essentially a transmitter, and probably should mount it at ground level with a short ground wire to ground rods and radials.
Of course, you can mount any transmitter at any height if you’re not going to ground it, and some broadcasters here have reported good results, but it’s not particularly safe unless you’re in an area with no chance of lightning strikes.
So, no range limitations per say, other than those that come as a direct result of the field strength OR transmitter power/antenna+feedline+ground length.