http://CBC.am/ wrote:
US MW STATIONS - FCC TOWER HEIGHT RULES

In DXLD 3-144 Richard Howard inquired why so called clear channel
stations often used longer antennas than the 1/4 wavelength antennas
used by most smaller stations. Does the FCC mandate tower height
limits?

The FCC does not mandate MW tower height. They do mandate that new

This is not strictly true. 47CFR73.189 establishes minimum tower
heights for AM stations, depending on class and frequency. For example,
a Class C station above 1200KHz must use a tower at least 45m tall,
while a Class A station on 650 must use one at least 165m in height.

Under certain circumstances these requirements can be waived if the
station can meet field-strength requirements with a shorter tower.
--
Doug Smith W9WI
Pleasant View (Nashville), TN EM66
http://www.w9wi.com