Does anyone have a link to the old Section 73.213 with the Grandfathered Short Spacing Zones? I have looked at David's site and the Broadcasting Yearbook has them conspicuously absent.
They were in place until about the time Section 73.215 and Docket 80-90 far-under-class ERP/HAAT based class downgrade sunsets were implemented.
Some of the more popular provisions were that 50 kW/500 feet nondirectional Grandfathered Short Spaced Cochannel Class Bs were allowed at 125 miles apart and 20 kW /500 feet nondirectional were allowed at 100 miles. First adjacent 50 kW/500 feet nondirectional Grandfathered Short Spaced Class Bs were allowed at 80 miles, 20 kW/500 feet at 65 miles, and 10 kW/500 feet at 50 miles.
This covered the vast majority of Short Spaced Class B situations that occurred when low ERP and HAAT from side mounting on Class II, Class III, and Class IV AM towers were common, and when contour based (1 mV/m protected contour for all classes) protection was the rule. This was common even though the AM sites were often below 0 HAAT at 0 feet AGL, because that was the swampy low areas that were best for AM.
This was also the origin of the 2 dB per 10 degree directional pattern rule, which was supposed to prevent overlap at all angles near the azimuth connecting the two sites under the provisions of Section 73.213. duTriel, Lundin, and Rackley tried unsuccessfully to convince the FCC that 15 dB maximum to minimum and the 2 dB per 10 degree rule were unnecessary because Section 73.215 required no contour overlap. They altenatively proposed the 20 dB maximum to minimum rule from the Treaty with Canada (not sure about Mexico).
They were in place until about the time Section 73.215 and Docket 80-90 far-under-class ERP/HAAT based class downgrade sunsets were implemented.
Some of the more popular provisions were that 50 kW/500 feet nondirectional Grandfathered Short Spaced Cochannel Class Bs were allowed at 125 miles apart and 20 kW /500 feet nondirectional were allowed at 100 miles. First adjacent 50 kW/500 feet nondirectional Grandfathered Short Spaced Class Bs were allowed at 80 miles, 20 kW/500 feet at 65 miles, and 10 kW/500 feet at 50 miles.
This covered the vast majority of Short Spaced Class B situations that occurred when low ERP and HAAT from side mounting on Class II, Class III, and Class IV AM towers were common, and when contour based (1 mV/m protected contour for all classes) protection was the rule. This was common even though the AM sites were often below 0 HAAT at 0 feet AGL, because that was the swampy low areas that were best for AM.
This was also the origin of the 2 dB per 10 degree directional pattern rule, which was supposed to prevent overlap at all angles near the azimuth connecting the two sites under the provisions of Section 73.213. duTriel, Lundin, and Rackley tried unsuccessfully to convince the FCC that 15 dB maximum to minimum and the 2 dB per 10 degree rule were unnecessary because Section 73.215 required no contour overlap. They altenatively proposed the 20 dB maximum to minimum rule from the Treaty with Canada (not sure about Mexico).