It was inevitable that the two communication techniques of car and radio would not come together sometime. During the 1920’s there were many enthusiasts who at certain occasions combined car and radio. As so often when it comes to technique it started in USA.

1925 On January 1^st Radiotjänst started their official transmissions on behalf of Telestyrelsen. There were only three senders owned by the state: Stockholm, Gothenburg and Malmoe. There were more transmitters starting during the year. Through cooperation between the Telegrafstyrelsen and radio amateurs in a number of small towns another 30 % of the license payees can hear the broadcast.

1926 In the USA radio began to be seriously introduced in cars. In principle the radios were portable and battery driven - so called travel radios.

Motor interference, weak loudspeakers besides the difficulties in adjusting the transmitters lead to the development of special radios intended to be installed in cars. More was required of radios that were to be installed in cars regarding vibration, temperatures etc. W.M. Heina applied for and received patent for the installation of radios in cars through his firm Heinaphone which also manufactured car radios.

For example one of several problems was power supply. The available tubes had grids for 2 or 4 volts. This meant a special "A" battery for grid current was needed as well as a "B" battery with a voltage of 90 to 120V for the plates.

Car radios were designed as separate units. The receiver was a unit which was placed on the fire wall or behind the dashboard where one had to make holes for the knobs. If the radio was placed on the firewall maneuvering was accomplished with two wires from a remote control placed on the steering column or under the dash board. "A" and "B" batteries were placed in their own boxes under the seat or sunk in the floor. The aerial was often placed as a mesh on the roof (the roof was made of wood) or as a thread under one of the running boards.

Some manufacturers used one or two insulating plates under the car in the back as aerial.

In principle the loud speakers were headphones which meant one got insufficient volume. It still was not possible to listen while driving. It was necessary to stop the car and shut off the motor. The receivers were only supplied with middle wave band.

1927 A break through for car radio was the invention of damp resistance. It became possible to listen to the radio when the motor was running, at least near a transmitter.

1929 Several manufacturers now made special models intended for installation in cars. Many automobile manufacturers install wireaerials in the roof to ease the possible installation of car radios.

1930 Superheterodyne was now generally introduced. Even the loudspeakers became better. Some manufacturers connect the grids in series with resistance so that power can be supplied from the car battery and one avoids the "A" battery.

1931 The loudspeakers were improved. Radio tubes with 6.3 voltage grids are now available. With the new tubes one could develop techniques with automatic volume control. In the "Swedish Motoring Magazine" page 792, you can read about a test on the PHILCO 72 car radio. It was probably among the first imported sets to Sweden. Testing was very positive and a great future was predicted for car radio.

1932 Two inventions were introduced of which one stayed until the transistor took over. This regarded the possibility to convert the car battery's voltage to high voltage for the radio tube plates. The first type is the so called dynomotor and motor generator transformer. In principle this is a generator driven by an electric motor powered by the car battery.

The P.R. Mallory Company and their Elkon division presents another solution - the vibrator power supply. The advantages with this device are several; smaller size, less interference, better efficiency factor and the possibility to place the unit inside the radio case. It's "singing" noise will for a long time be connected with car radios.

Both of these types were manufactured as accessories to be able to replace the "B" battery on the earlier models.

The first car radio manufactured in Europe is presented.

1933 Car radios were now beyond the experimental stage. In the USA Ford installed the markets first specially built car radio for a certain car model tailor made for the dashboard. New radio tubes were introduced. These are types 6A7, 6B7 and 6F7.

BOSCH launches the Blaupunkt company. Blaupunkt would become the market leader in Europe for many years after.

1934 The European manufacturers designed at this time only universal models.

1937 Ford in the USA are the first to use a steel rod as aerial.

1938 The telescope type aerial is presented.

1941 American Ford advertises a radio which can be preset for 5 stations and be operated to the desired station by a foot operated switch.

1948 Led by W.Shockley researchers at the Bell laboratories succeeded in inventing the first transistor. The three scientists were given the Nobel physics prize in 1956.

1957 In Germany they further developed an American radio tube that only needs 6/12 V for the plates suitable for car radio sets. In 1958 a similar tube for UKW is presented.

1958 Car radio sets came on the market where the vibrator was replaced by a transistor converter.

1970 In 1932 the car radio had a volume of around 10 litres compared to present day 1 litre.

1995 Swedish radio together with the BBC begins the worlds first digital audio broadcasting -DAB.