fm-engineer said:
They find some defunct AM, apply for a translator simulcast, find a really tall tower, and then operate the translator just like a real FM station. Anyone else has to follow the 300' or 500' above average terrain rule or reduce ERP. Not these stupid translators.
.... Also, when they do this, there are no spacing requirements to other same channel FM's unless documented listener interference can be proven. I think Clear Channel is the only owner to prove listener reported interference so far.
There are a couple of points that should be mentioned for the sake of clarity and completeness. To begin with, the typical non-fill-in translator is limited to 250W at 30 meters (approx. 100ft), not 300 or 500 feet. A maximized non-fill-in has a typical service range of about 7km. Also, the HAAT for a translator is calculated per radial not averaged, so the non-fill-in translator's power is limited to the HAAT above the tallest radial.
Fill in translators are limed only in power, but, as mentioned, not in height. To that end there are fill-in translators that do rival the coverages of class A stations, however, there are two limitations that were not mentioned.
First, for AM stations, the service contour must not extend beyond the 2mV predicted contour of the AM station. Also for AM stations, the 1mV of the translator cannot extend past 40kM, even if the 2mV does. For FM stations, the 1mV of the translator cannot exceed the 1mV of the primary, but there is no additional 40kM limitation.
Second, all translators are authorized based on contour limitations. That is to say, the predicted interfering contour of the translator cannot overlap the protected contour of any other station. This is how all stations, including full service, in the reserved portion of the band are authorized. So, while some translators do exist with 250W, operating from very high antennas, there are lots of others that operate from short towers and low powers (some as little as 1 Watt), even though they are fill-ins. It's fairly hard to find mega translators in dense urban areas, though there are a few of them, for sure. Most that are high powered are also using directional antennas. It's a lot more common to find lower powered translators operating in the urban areas (by low powered, I really mean reduced coverage areas, not specifically power).
So, while it is true that translators cannot cause any actual interference, before they get to that point, they must demonstrate, on paper, that they won't cause predicted interference, nor will they extend the primary station's signal.
Finally, it's noteworthy that translators are always at risk of being displaced. Translators receive no protection from full powered stations, so if a station makes a change that conflicts with the translator or if a new station gets authorized that conflicts, then the translator may be forced off the air, even if it has operated for years.
