Section 90.427 - Precautions against unauthorized operation(a) Each transmitter shall be so installed and protected that it is not accessible to or capable of operation by persons other than those duly authorized by and under the control of the licensee. Provisions of this part authorizing certain unlicensed persons to operate stations, or authorizing unattended operation of stations in certain circumstances, shall not be construed to change or diminish in any respect the responsibility of station licensees to maintain control over the stations licensed to them (including all transmitter units thereof), or for the proper functioning and operation of those stations and transmitter units in accordance with the terms of the licenses of those stations.(b) Except for frequencies used in accordance with § 90.417 , no person shall program into a transmitter frequencies for which the licensee using the transmitter is not authorized.43 FR 54791, Nov. 22, 1978, as amended at 52 FR 47570, Dec. 15, 1987