An antique radio is a radio receiving set that is collectible because of its age and rarity. Although there is no precise criterion for a radio being antique, typically a 50-year-old or World War II vacuum tube set, and a pre-1960 transistor set would qualify.
Types of antique radio
Morse receivers
The first radio receivers used a coherer and sounding board, and were only able to receive CW continuous wave (CW) transmissions, encoded with Morse code (wireless telegraphy). Later wireless telephony|transmission and reception of speech became possible, although Morse code transmission continued in use until the 1990s.
All the following sections concern speech-capable radio, or wireless telephony.
The idea of radio as entertainment took off in 1920, with the opening of the first stations established specifically for broadcast to the public such as KDKA in Pittsburgh and WWJ in Detroit. More stations opened in cities across North America in the following years and radio ownership steadily gained in popularity. Radio sets from before 1920 are rarities, and are probably military artifacts. Sets made prior to approximately 1924 were usually made on wooden breadboards, in small cupboard style cabinets, or sometimes on an open sheet metal chassis. Homemade sets remained a strong sector of radio production until the early 1930s. Until then there were more homemade sets in use than commercial sets.
Early sets used any of the following technologies:
Crystal setCrystal set with carbon or mechanical amplifierBasic Tuned Radio Frequency (TRF) SetsReaction SetsSuper-Regenerative ReceiverSuperheterodyne Receiver
Crystal setsEdit
Main article: Crystal radio
These basic radios used no battery, had no amplification and could only operate high-impedance headphones. They would only receive very strong signals from a local station. They were popular among the less wealthy due to their low build cost and zero run cost. Crystal sets had minimal ability to separate stations, and where more than one high power station was present, inability to receive one without the other was a common problem.
Some crystal set users added a carbon amplifier or a mechanical turntable amplifier to give enough output to operate a speaker. Some even used a flame amplifier.
Tuned radio frequency setsEdit
Tuned Radio Frequency sets (TRF sets) were the most popular class of early radio, primarily because the RCA company had a lock on the superheterodyne circuit patents and it was more profitable for companies to jump into radio manufacturing TRF sets. These used several valves (tubes) to provide RF amplification, detection, and audio amplification. Early TRF sets only operated headphones, but by the mid-1920s it was more common to use additional amplification to power a loudspeaker, despite the expense. The sound quality produced from "moving-iron" speakers used on such sets is sometimes described as torturous, although by the late 1920s the Kellogg-Rice dynamic (moving-coil) speaker had begun to find favor due to its superior sound-reproduction ability.
Speakers widely used on TRF sets included:
Moving iron speaker (horn or cone)tin can, magnet & wire based speakersmoving coil speaker
TRF sets used no regeneration, and were merely several stages (typically three) of tuned RF amplifiers in series feeding a detector tube which extracted the audio intelligence from the RF signal. TRF sets, depending on the number of stages they employed, could have poor-to-superb sensitivity (ability of the set to pick up faint signals) and corresponding selectivity (ability to parse adjacent stations from one another). Audio reproduction quality of TRF sets was limited by the available loudspeakers. "High Fidelity" was not to become a radio marketing concept until the mid-1930s and was not realized until the advent of FM broadcasting.
Reaction sets, also known as regenerative receivers, rely on positive feedback to achieve adequate gain. This approach provided high performance with a minimum number of expensive vacuum tubes, but these receivers tended to radiate RF interference in their immediate vicinity. Consequently, there was a significant amount of hostility by neighbors of "regen" set users over maladjusted radiostransmitting squealing noises and blocking reception on nearby properties.
Early TRF sets had typically two or three tuning knobs and tube filament voltage-control rheostats, all of which had to be set correctly to receive a station. Later (late 1920s) TRF sets had ganged tuning (one knob was used to control all stage tuning capacitors simultaneously), AC house current operation, and eliminated the filament voltage adjustments. All of these changes greatly simplified operation and made radio a household appliance that even a small child could operate,