A reflex receiver is a type of radio circuit in which a single transistor or amplifying device is used to perform two functions: amplifying the incoming radio frequency (RF) signal and, after detection, amplifying the resulting audio frequency (AF) signal. This dual use of the same component allows for a more compact and cost-effective design, as fewer components are needed. Reflex receivers were popular in early radio designs, especially where minimizing size and cost was crucial. However, their use in modern cybersecurity or communications equipment is rare due to advancements in technology and the availability of more efficient circuits.