Category: Evolution of Radio Receivers
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Evolution of Radio Receivers – Part 2: The Superheterodyne Architecture Explained
1. Introduction The first commercial radio broadcast began in the 1920s. In the early days, radio receivers were constructed with an antenna feeding a LC tuned circuit which was followed by a simple crystal detector or a vacuum tube amplifying stage and then a diode detector to recover the audio. This is the basic Tuned…
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Evolution of Radio Receivers – Part 1: The 2-Transistor Reflex TRF Receiver
Introduction In the mid 1950s, while almost all table-top radios used vacuum tubes, pocket-size transistor radios started to appear. Most of these radios employed the superheterodyne architecture which needed at least 4 transistors for adequate performance. However transistors at that time were very expensive. For cost saving, a few low-end models used the tuned radio…
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