Looks like a lot going on here. Purchase price appears to be $50,000 for the station, which does not include the transmitter site that is being sold to a third party for residential development.
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WBIG Aurora being sold.
- Thread starter JJSPC
- Start date
That model of operation is becoming ubiquitous. They need more than 99 watt (the most common in large cities due to IF Beat restrictions) and 250 watt translators though, to replace AM stations in all but the smallest towns.
Their translator is only 70 watts, that's less than a LPFM station. Unless they have a plan to upgrade the translator power, I don't see how this can be a financially viable situation.
Do please keep in mind that there's a difference between translator and LPFMs, which is height.
An LPFM is limited to 100 watts at 30 meters HAAT, or the equivalent thereof.
A translator has NO height limit, so as soon as you start getting up above 30 meters (which isn't very high at all), height does a lot of the work that power doesn't. 250 watts at more than 100 meters starts to creep up to the equivalent of a class A full-power FM.
The WBIG 105.5 translator is 57 meters up, so it's significantly bigger than an LPFM could be on that channel. An LPFM at that height would have only about 30 watts.
An LPFM is limited to 100 watts at 30 meters HAAT, or the equivalent thereof.
A translator has NO height limit, so as soon as you start getting up above 30 meters (which isn't very high at all), height does a lot of the work that power doesn't. 250 watts at more than 100 meters starts to creep up to the equivalent of a class A full-power FM.
The WBIG 105.5 translator is 57 meters up, so it's significantly bigger than an LPFM could be on that channel. An LPFM at that height would have only about 30 watts.
Correct. The 99 watt limit on FM translators 10.6 and 10.8 MHz apart from strong local signals is based to a large degree on the fact that 100 watt LPFMs do not have an IF Beat restriction in the US, at least those not near an international border, which do have distance separation requirements shown in Section 73.807 to allotments and stations outside the US. There are Tables for Canada and Mexico. It's based on the 91 dBu free space electromagnetic field for 100 watts. Free space field strength is only dependent on distance, and is not dependent on HAAT. 1 kW ERP (based on a half wave dipole) produces a free space field of 222 mV/m at one km. Refer to Reitz and Milford and Corson and Lorain E and M textbooks for how this is derived.
The late great Harold Munn recognized that there were problems with very low ERP penetrating buildings, and didn't recommend that Class As use excessive HAAT and ERP reduction. The equivalence point HAAT for a 250 watt translators to a 3 kW/100 meter Class A is 348 meters/1142 feet HAAT to the 60 dBu F(50,50), which is about 24.2 km. Note that translators are not protected from nearby full power stations, often Class As and Bs, but high translator HAAT often interferes terrain holes of the nearby full power stations within their protected service areas, which was explored by the WIOT case. Usually the nearby stations have 100 to 150 meters HAAT, nowhere near 348 meters. That's why the old FCC curves do not tell the whole story, which truncated some Longley Rice terms before computers and L-R software were widely available for more accurate prediction.
You can explore the longstanding propagation model FCC equivalency by using the following site.
FM and TV Propagation Curves
This function uses the FM or TV television propagation curves to compute the distance to a service or interfering contour, or the corresponding field strength at a given contour distance.
Linking the Cornell Law site, which I often use rather than ecfr, Here's Section 73.807.
47 CFR § 73.807 - Minimum distance separation between stations.
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