history of car radios
Soon after radio sets started appearing in the more well-to-do homes up and down the country in the late twenties, the proud owners naturally started wondering if they could have a set to operate inside their other status symbol, the family car. Fine in theory, but this idea presented a number of problems.
First, there was the question of power supply. Valves require between 100 and 300 volts to operate so how could this be derived from the car's six or twelve volt supply? Then there was the problem of how to make the set compact enough to fit into the car and in a place where it could be controlled from the driving position. Remember how big domestic radios were then compared to now Finally, a solution to the problem of reception interference from the ignition had to be found. Gradually, however, solutions to the problems were devised and from about 1932 onwards sets were available, though at prices only the wealthy could afford.
To overcome the accommodation problem, many early sets had amplifiers, tuners and power supplies contained in separate 'boxes', while some manufacturers, particularly Americans, produced sets as one large 'box' but with a separate control box connected to the set by Bowden cables. Thus, the main part of the radio could be mounted wherever convenient in the car and the cables run to the control box somewhere on the dashboard. These early sets were very expensive new, but well made and, unlike most modern 'printed circuit' devices, they can be overhauled. Surprisingly enough, the highstreet radio retailers seemed slow to realise the potential sales of car radios. In 1939, only 25% of total sales were through radio specialists; all the rest were through the motor trade.
During the war car radios were banned for security reasons. The hostilities, however, provided an ideal opportunity for manufacturers to gain experience in building mobile radios for military purposes and, when the first sets after the war appeared, the development was obvious. Valves were now much smaller and many of the sets themselves were more compact though still large by presentday standards, but prices were even higher than they had been in 1939. A push-button Radiomobile cost £27 6s 0d, plus £10 4s 6d purchase tax in 1946 which, incidentally, was the year Radiomobile were formed as a joint venture by HMV and Smiths Motor Accessories. For a considerable period after the war Radiomobile operated a Star dealer network and, for those traders not fully au fait with radio installation and the often complex suppression problems, they had a fleet of green vans with experienced fitters who called at garages and carried out the fitting for them.
From the late fifties onwards, transistors started to appear in car radios, initially with valves, but the much smaller size and current consumption from transistors eventually won the day; valves had disappeared completely by about 1964/5.
