Total posts : 45366
Are you sure that you are reading the ad correctly? There is no such thing as unlimited range.
As for your question, the FCC does not limit the range of AM part 15 transmitters. They limit the input power, out of band emissions, antenna length, ground length, and transmission line length. If you set up your station according to these rules you are legal even if you can be heard 100 miles away.
If you mean by “advertisement in the Hamilton Rangemaster” following their elevated installation instructions using a long mast or ground lead then you will not be legal because the length of your antenna plus ground lead exceeds the 3 meter rule.
This is going to start another arguement about the ground length rule. Let me head it off by saying that I have HEARD reports where FCC field engineers say that the elevated ground is OK, but I have READ FCC replies to this question where they say it is not. I tend to go with what I have read.