47 CFR § 73.760 - Alternate main transmitters.
The licensee of an international broadcast station may be licensed for alternate main transmitters provided that a technical need for such alternate transmitters is shown and that the following conditions are met: Both transmitters:
(a) Are located at the same place;
(b) Shall have the same power rating; and
(c) Shall meet the construction, installation, operation, and performance requirements of good engineering practice.