Sec. 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 
Sec. 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]