90.281—Restrictions on operational fixed stations in the 421-430 MHz band.
        
        (a) 
         Except for control stations, operational fixed facilities will not be authorized in the 421-430 MHz band. This does not preclude secondary fixed tone signaling and alarm operations authorized in  § 90.235.
    
    
        
        (b) 
         Control stations associated with one or more mobile relay stations will be authorized only on the assigned frequency of the associated mobile station. Use of a mobile service frequency by a control station of a mobile relay system is subject to the condition that harmful interference shall not be  caused to stations of licensees authorized to use the frequency for mobile service communications.
    
    [52 FR 6158, Mar. 2, 1987, as amended at 54 FR 38681, Sept. 20, 1989]