Like all businesses, the radio industry experienced growing pains brought by technological advances. For radio stations, one of the growing pains was a labor cost growing out of the need to hire several employees for a disc jockey program. In the early days of radio, three employees were often needed to broadcast a program: two engineers (one to operate the audio console and to play transcribed materials and another to operate the station's transmitter) and an announcer to present spoken materials. As the industry grew, and as the control room and transmitter operating equipment became more sophisticated, station managers concluded they could save money by using "combo" announcers who could also perform the functions of engineers.

     In the infancy of radio, the control room of a radio station operated as follows: the announcer was positioned by a microphone to read, or possibly to ad-lib, material that went on the air. The written material was called continuity and consisted of a daily file of all commercials and public service announcements, in chronological order, to be broadcast by the station. The station log provided a schedule of the announcements and programs, notifying both the announcer and the engineer of what should be read when.

     So that the announcer could read a given announcement on the air, the engineer operating the audio console would turn on the microphone using the proper switch and volume control. The volume control, more commonly known as a "fader," "pot," or "mixer," was used to control the volume of audio current. The console contained a number of these faders, located in parallel series near the bottom of the unit. Each microphone, turntable, tape recorder, and network input had its corresponding fader. Another fader was used to control the input of a network into the console. The control room engineer had the responsibility of turning on the correct microphones or turntables and then using the fader to "ride gain," or maintain the appropriate volume for each microphone, each turntable, and so on.

     The engineer at the audio control console was responsible for regulating the volume during a specific program or through a series of them. This was especially complex when radio stations broadcast live orchestras or bands, live vocalists, and live announcers. The engineer's responsibility was to regulate the volume so that the quality of transmission would not vary and so that distortion or inaudibility would not distract listeners.

     In a relatively simple program, such as one in which an announcer hosted transcribed music, the engineer would turn on the switch for the correct microphone and then cue the announcer by pointing at him to begin reading or talking. During the message, the engineer would make certain the volume level was correct and would prepare to turn on the next microphone, turntable, and so on. Once the message had been read, the announcer would indicate completion of the message by pointing back at the engineer. This would be the signal for the engineer to turn off the microphone and to activate other switches for the next source of sound.

     As broadcast equipment improved, stations adopted combo operations, and by the 1950s most small-market stations were combo. By "going combo," one person could operate the control room console, turntables, and tape recorders while also announcing live copy. A combo announcer had to combine several traits: an adequate voice to perform announcing duties and sufficient manual dexterity to simultaneously operate the equipment. Not all people could fulfill both roles.

     Station managers also had the combo announcer read and record meters on the station transmitter and make necessary adjustments. Because many AM stations were required to sign off at night or were required to prevent interference with other stations by using directional transmission patterns to control the station's signal, correct transmitter operation was essential.

     To perform transmitter adjustments at stations transmitting a directional pattern, a Federal Communications Commission (FCC) First Class radiotelephone operator's license, known as "First Phone," was needed until 1981. Many announcers enrolled in schools that taught them the basic knowledge needed to obtain a First Phone. A person who acquired a First Phone could announce, operate control room equipment, and make transmitter adjustments. First Phone announcers were often paid more than announcers who did not have the First Class FCC license, but the financial savings were important to smaller stations. Paying one combo announcer somewhat more than an announcer without a First Phone was financially preferable to paying several staff members.

     Not all AM (and eventually FM stations) employed combo announcers. Stations with union agreements generally continued to subdivide the announcing, engineering, and control room operations. However, the majority of nonunion AM and FM radio stations now use combo announcers.

     The introduction of digital technology has further altered combo operations. At many stations, recorded material, including music, commercials, and station promotional items, are placed on the hard drive of a computer. The announcer operates the audio console, but the computer controls the programming of the other items, that is, music, recorded commercials, and so on. The announcer only stops the computer for live inserts and then restarts it once the live insertion is complete. The rest of the time, the computer plays recorded music, recorded commercials, and so forth on the air in the correct order. In other cases, the announcer can also prerecorded the verbal inserts he or she will include between commercials or recordings, and the computer can present the entire recorded program.