AM/FM Portable Radio
The history of the AM/FM portable radio provides valuable information. Knowing how the transistor was discovered and developed and the subsequent revolution in AM/FM portable radios will help you become more knowledgeable about transistor radios. Despite the beliefs of Lee DeForest, the self-proclaimed father of radio who claimed that the vacuum tube would never be replaced, research to find a replacement for the vacuum tube was carried out in several locations. As World War II progressed, researchers developed techniques for creating pure germanium and silicon knowing that silicon and germanium could be used as a crystal detector.
This solid-state detector was the equivalent of the first vacuum tube, known as a diode. The difficulty was how to develop a triode which would allow signals to be amplified. Bell Labs put together a team of three top physicists who believed in theory at least that the development of a triode was possible. In 1947, this triumvirate demonstrated the first point-contact solid-state amplifier and dubbed it the transistor and predicted that it would quickly replace tubes in all applications. To drive this point home Bell Labs produced the first AM/FM portable radio in which all the tubes had been replaced by transistors. Initially the invention received little fanfare probably because the mass production of transistors proved to be difficult. In addition, early production of transistors produced low yields. As few as one in five transistors performed as expected which kept the prices of transistors too high for widespread adoption. By 1950 most of the bugs in producing transistors had been worked out and Western Electric began producing transistors in large enough quantities to sell them for about $20 each. But tubes sold for about $1 each so transistors were hardly economical and were widely written off as impractical. So it was to be much longer than originally and boldly predicted that transistors replaced tubes due mostly to the fact that their cost has not dropped to a point to make it economically feasible to use them in the mass production of consumer products. The first breakthrough in the use of transistors came in hearing aids. Hearing aid using existing vacuum technology were already high-priced at nearly $300 so using transistors was economically feasible and within a short time the price of hearing aids had dropped to $100. This was enough to convince Texas Instruments of the promise of using transistors in consumer products. In 1954 TI set out to produce the first AM/FM portable radio. Since TI had never attempted to produce an AM/FM portable radio perhaps they were oblivious to the fact that previous attempts to market portable radios had failed. Or perhaps they realized the opportunity transistors created considering older AM/FM portable radios had been built with larger vacuums instead of transistors. A short time later TI introduced the first successful AM/FM portable radio and a new era of portable radios began. |
