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. Consequently, there was a significant amount of hostility by neighbors of "regen" set users over maladjusted radios transmitting squealing noises and blocking reception on nearby properties.Įarly 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. 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. Reaction sets, also known as regenerative receivers, rely on positive feedback to achieve adequate gain. "High Fidelity" was not to become a radio marketing concept until the mid-1930s and was not realized until the advent of FM broadcasting. Audio reproduction quality of TRF sets was limited by the available loudspeakers. 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). 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. Speakers widely used on TRF sets included: 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. 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. These used several valves (tubes) to provide RF amplification, detection, and audio amplification. Tuned radio frequency sets (TRF sets) were the most popular class of early radio, primarily because the Radio Corporation of America (RCA) had a monopoly on the superheterodyne circuit patents and it was more profitable for companies to jump into radio manufacturing TRF sets. Some crystal set users added a carbon amplifier or a mechanical turntable amplifier to give enough output to operate a speaker. 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. They were popular among the less wealthy due to their low build cost and zero run cost. They would receive only very strong signals from a local station. These basic radios used no battery, had no amplification and could operate only high-impedance headphones.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |