47 CFR § 80.169 - Operators required to adjust transmitters or radar.
(a) All adjustments of radio transmitters in any radiotelephone station or coincident with the installation, servicing, or maintenance of such equipment which may affect the proper operation of the station, must be performed by or under the immediate supervision and responsibility of a person holding a First Class Radiotelegraph Operator's Certificate, Second Class Radiotelegraph Operator's Certificate, Radiotelegraph Operator License, or General Radiotelephone Operator License.
(b) Only persons holding a First Class Radiotelegraph Operator's Certificate, Second Class Radiotelegraph Operator's Certificate, or Radiotelegraph Operator License must perform such functions at radiotelegraph stations transmitting Morse code.
(c) Only persons holding an operator certificate containing a ship radar endorsement must perform such functions on radar equipment.