Calling All Cars: Motorola’s Early Police Radios

Galvin Manufacturing Corporation introduced its Motorola brand car radio, one of the first commercially successful car radios, in June 1930. The radio was intended for the general public, but soon police departments and city governments across the Chicago area and United States ordered radios for public safety use. This was the beginning of Motorola’s expertise in mobile communications and long customer relationships.

 Mobile entertainment
When commercial radio broadcasting began in the early 20th century, music and entertainment delighted growing numbers of people. In the 1920s, hobbyists experimented with adapting home radio sets to cars. Taking a risk on a new technology, Galvin Manufacturing developed the Motorola car radio for the commercial market.

Early police communications
meanwhile, police departments struggled to get messages to officers on patrol. Public safety officers used telephone call boxes on the street to contact headquarters, which delayed emergency response time. In an experiment in the late 1920s, a few broadcast stations, including WGN in Chicago, interrupted radio entertainment to broadcast messages from headquarters to patrol cars with car radios. However, the added step of phoning messages from a police station to a broadcaster delayed communications and publicly announced to anyone listening where problems were. Clearly, public safety departments needed a better way to communicate.

A few police departments began to install mobile radio receivers tuned to higher frequencies than the commercial broadcast band. This special use of the airwaves allowed communications that the general public could not hear. Although police departments needed their own transmitters to broadcast, the U.S. Federal Radio Commission considered this radio use experimental and issued licenses conditionally.

Motorola car radio for police
In 1930, shortly after Galvin Manufacturing introduced the Motorola car radio for consumer use, the company began receiving orders from police departments. Company founder Paul V. Galvin, envisioning the potential for this new market, remarked, “There was a need, and I could see it was a market that nobody owned.”

Galvin Manufacturing built its first mobile police radio receivers by adapting its Motorola consumer car radios. A police department specified what frequency its radios should receive. Galvin Manufacturing’s line workers then modified tuning coils and locked condensers by hand. They put police radio chassis into the same housing as consumer Motorola car radios.

Motorola’s first police radio customers
According to Galvin Manufacturing records, sales of Motorola police radios began in November 1930. Among the first customers (all in the U.S. state of Illinois) were the Village of River Forest; Village of Bellwood Police Department; City of Evanston Police; Illinois State Highway Police; and Cook County Police in the Chicago area.

As more police departments used radios, challenges emerged. Rough roads, engine noises, interference, high power consumption, and frequency instability led Paul Galvin to recognize that police departments needed a radio specifically engineered for patrol cars.

Motorola Police Cruiser radio
Galvin engineers designed a new mobile radio in the frequency band of 1550-2800 KHz called the Motorola Police Cruiser radio. Introduced in 1936, this AM radio receiver featured a heavy-duty metal case for protection against rough roads and difficult conditions, an improved speaker and circuitry, a stabilized crystal control (instead of coils) for better tuning, and lower power consumption from the engine. Galvin Manufacturing’s small specialty police radio department built the radios on weekends in order to not interrupt the busy commercial car radio production lines.

Broadcasting from a police station to a car was the first step in mobile communications for police departments. But how would dispatchers know if officers received their broadcasts or needed assistance? Police departments and radio manufacturers began building mobile transmitters so officers in patrol cars could communicate with headquarters.

Mobile two-way communications
Paul Galvin assigned his chief engineer, Don Mitchell, to develop a radio transmitter for the car. In August 1939, Galvin Manufacturing introduced the Motorola model T6920 AM mobile transmitter, which broadcast in the 30-40 MHz range. A model P6912 VHF receiver and base station equipment soon followed.

This complete Motorola two-way radio system was priced about one-fourth as much as the competitions and the transmitters could be installed in cars that already had receivers in the same frequency band. In 1940 the Police Department in Bowling Green, Kentucky, became the first customer for a complete Motorola AM two-way radio system. The radios were so well-designed that Galvin Manufacturing produced the same models for several years, until FM technology replaced them in the 1940s.

According the The Motorola Heritage Services & Archives, Their database shows mid-1940’s when the Police Motorcycle Units started using Motorola radios.

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