Section 73.6010 - Class A TV station protected contour(c) A Class A TV station will be protected from interference within the following predicted signal contours:(1) 43 dBu for stations on Channels 2 through 6;(2) 48 dBu for stations on Channels 7 through 13; and(3) 51 dBu for stations on Channels 14 through 36.(d) The Class A TV station protected contour is calculated from the effective radiated power and antenna height above average terrain, using the F(50,90) signal propagation method specified in § 73.619(b)(1) .(e) A digital Class A DTS station will be protected from interference within its Class A DTS protected area as defined by § 73.6023(d) . 86 FR 66213 , Nov. 22, 2021, as amended at 86 FR 21227 , Apr. 22, 2021 86 FR 21227 , 4/22/2021; 86 FR 66193 , 12/22/2021; 89 FR 7263 , 3/4/2024