In 1931 RCA introduced a new line of Superette radio receivers. These used the superheterodyne principle but were lower cost than earlier products, in an attempt to maintain sales during the onset of the Great Depression.
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In 1931 RCA introduced a new line of Superette radio receivers. These used the superheterodyne principle but were lower cost than earlier products, in an attempt to maintain sales during the onset of the Great Depression.
Edwin Howard Armstrong invented the superheterodyne receiver in 1918. [1] Armstrong and RCA (under David Sarnoff) had a business and technical relationship, that would last into the 1940s.
Funded by RCA, Armstrong designed a radio that can receive stations easily without complex tuning or interference from other stations. Early radio designs by Armstrong and others produced radios that were very sensitive but hard to keep under control due to the nature of radio waves operating at higher frequencies. Armstrong's superheterodyne receiver converted these high frequencies into one lower frequency. This allow the radio to be more stable or easier to tune, with less interference. [2]
The result was the RCA Radiola AR-812 and Radiola VIII Superheterodynes in 1924, the world's first consumer superheterodyne receivers. In 1924, these cost $224 and $475 respectively. [3] Up to 1930, RCA controlled the superheterodyne patent, and any radio manufacturer that wanted to build one had to pay royalties to RCA. In 1928 RCA launched their first AC operated superheterodyne radio, the Radiola 60 ($147 in 1928 dollars). [4]
All these superhets were large and expensive. In the 1930s the depression was in full force. The trend in radios were smaller, more compact and lower cost. RCA introduced the Superette line in 1931 with the R7 table and R9 console.
From 1931 RCA produced a range of small mantel radios called the Superette, which at introduction sold for $57.50 not including the vacuum tubes. [5] [6] "Super" was derived from superheterodyne. Probably the most well known is the Model R-7, which was produced in several versions.
RCA also produced a console version, the model R-9. The R-7 and R-9 share identical chassis (using RCA tubes 280, 227, 235, 245 and 224). There were several versions of the R7 table (mantel) version: the R-7A using pentode output tubes (RCA 247), R-7DC and R-9DC for 110 VDC power, and the R-7 LW for long wave listening. These early superheterodynes had no AVC so stronger stations were louder than weaker ones.
RCA produced spinoffs of the Superette during the 1931-32 model year. These models are based on the R-7 design but are not called Superette in RCA's literature. [7] [8] "Superette" was reserved for the R-7 and R-9 models. [7]
Edwin Howard Armstrong was an American electrical engineer and inventor, who developed FM radio and the superheterodyne receiver system. He held 42 patents and received numerous awards, including the first Medal of Honor awarded by the Institute of Radio Engineers, the French Legion of Honor, the 1941 Franklin Medal and the 1942 Edison Medal. He was inducted into the National Inventors Hall of Fame and included in the International Telecommunication Union's roster of great inventors. Armstrong attended Columbia University, and served as a professor there for most of his life.
The RCA Corporation was a major American electronics company, which was founded in 1919 as the Radio Corporation of America. It was initially a patent trust owned by General Electric (GE), Westinghouse, AT&T Corporation and United Fruit Company. In 1932, RCA became an independent company after the partners were required to divest their ownership as part of the settlement of a government antitrust suit.
A superheterodyne receiver, often shortened to superhet, is a type of radio receiver that uses frequency mixing to convert a received signal to a fixed intermediate frequency (IF) which can be more conveniently processed than the original carrier frequency. It was long believed to have been invented by US engineer Edwin Armstrong, but after some controversy the earliest patent for the invention is now credited to French radio engineer and radio manufacturer Lucien Lévy. Virtually all modern radio receivers use the superheterodyne principle.
In communications and electronic engineering, an intermediate frequency (IF) is a frequency to which a carrier wave is shifted as an intermediate step in transmission or reception. The intermediate frequency is created by mixing the carrier signal with a local oscillator signal in a process called heterodyning, resulting in a signal at the difference or beat frequency. Intermediate frequencies are used in superheterodyne radio receivers, in which an incoming signal is shifted to an IF for amplification before final detection is done.
A tetrode is a vacuum tube having four active electrodes. The four electrodes in order from the centre are: a thermionic cathode, first and second grids and a plate. There are several varieties of tetrodes, the most common being the screen-grid tube and the beam tetrode. In screen-grid tubes and beam tetrodes, the first grid is the control grid and the second grid is the screen grid. In other tetrodes one of the grids is a control grid, while the other may have a variety of functions.
In electronics, a remote control is an electronic device used to operate another device from a distance, usually wirelessly. In consumer electronics, a remote control can be used to operate devices such as a television set, DVD player or other home appliance. A remote control can allow operation of devices that are out of convenient reach for direct operation of controls. They function best when used from a short distance. This is primarily a convenience feature for the user. In some cases, remote controls allow a person to operate a device that they otherwise would not be able to reach, as when a garage door opener is triggered from outside.
A regenerative circuit is an amplifier circuit that employs positive feedback. Some of the output of the amplifying device is applied back to its input to add to the input signal, increasing the amplification. One example is the Schmitt trigger, but the most common use of the term is in RF amplifiers, and especially regenerative receivers, to greatly increase the gain of a single amplifier stage.
The pentagrid converter is a type of radio receiving valve with five grids used as the frequency mixer stage of a superheterodyne radio receiver.
In radio communications, a radio receiver, also known as a receiver, a wireless, or simply a radio, is an electronic device that receives radio waves and converts the information carried by them to a usable form. It is used with an antenna. The antenna intercepts radio waves and converts them to tiny alternating currents which are applied to the receiver, and the receiver extracts the desired information. The receiver uses electronic filters to separate the desired radio frequency signal from all the other signals picked up by the antenna, an electronic amplifier to increase the power of the signal for further processing, and finally recovers the desired information through demodulation.
The term All American Five is a colloquial name for mass-produced, superheterodyne radio receivers that used five vacuum tubes in their design. These radio sets were designed to receive amplitude modulation (AM) broadcasts in the medium wave band, and were manufactured in the United States from the mid-1930s until the early 1960s. By eliminating a power transformer, cost of the units was kept low; the same principle was later applied to television receivers. Variations in the design for lower cost, shortwave bands, better performance or special power supplies existed, although many sets used an identical set of vacuum tubes.
The R. L. Drake Company is a manufacturer of electronic communications equipment located in Springboro, Ohio. It is also known for its line of equipment for amateur radio and shortwave listening, built in the 1950s through the 1980s. The company operates as a separate entity owned by Blonder Tongue Laboratories, Inc.
A grid leak detector is an electronic circuit that demodulates an amplitude modulated alternating current and amplifies the recovered modulating voltage. The circuit utilizes the non-linear cathode to control grid conduction characteristic and the amplification factor of a vacuum tube. Invented by Lee De Forest around 1912, it was used as the detector (demodulator) in the first vacuum tube radio receivers until the 1930s.
The Neutrodyne radio receiver, invented in 1922 by Louis Hazeltine, was a particular type of tuned radio frequency (TRF) receiver, in which the instability-causing inter-electrode capacitance of the triode RF tubes is cancelled out or "neutralized" to prevent parasitic oscillations which caused "squealing" or "howling" noises in the speakers of early radio sets. In most designs, a small extra winding on each of the RF amplifiers' tuned anode coils was used to generate a small antiphase signal, which could be adjusted by special variable trim capacitors to cancel out the stray signal coupled to the grid via plate-to-grid capacitance. The Neutrodyne circuit was popular in radio receivers until the 1930s, when it was superseded by the superheterodyne receiver.
A communications receiver is a type of radio receiver used as a component of a radio communication link. This is in contrast to a broadcast receiver which is used to receive radio broadcasts. A communication receiver receives parts of the radio spectrum not used for broadcasting, including amateur, military, aircraft, marine, and other bands. They are often used with a radio transmitter as part of a two-way radio link for shortwave radio or amateur radio communication, although they are also used for shortwave listening.
An antique radio is a radio receiving set that is collectible because of its age and rarity.
The autodyne circuit was an improvement to radio signal amplification using the De Forest Audion vacuum tube amplifier. By allowing the tube to oscillate at a frequency slightly different from the desired signal, the sensitivity over other receivers was greatly improved. The autodyne circuit was invented by Edwin Howard Armstrong of Columbia University, New York, NY. He inserted a tuned circuit in the output circuit of the Audion vacuum tube amplifier. By adjusting the tuning of this tuned circuit, Armstrong was able to dramatically increase the gain of the Audion amplifier. Further increase in tuning resulted in the Audion amplifier reaching self-oscillation.
In electronics, a plate detector is a vacuum tube circuit in which an amplifying tube having a control grid is operated in a non-linear region of its grid voltage versus plate current transfer characteristic, usually near plate current cutoff, to demodulate amplitude modulated carrier signal. This differs from the grid leak detector, which utilizes the non-linearity of the grid voltage versus grid current characteristic for demodulation. It also differs from the diode detector, which is a two-terminal device.
A shortwave radio receiver is a radio receiver that can receive one or more shortwave bands, between 1.6 and 30 MHz. A shortwave radio receiver often receives other broadcast bands, such as FM radio, Longwave and Mediumwave. Shortwave radio receivers are often used by dedicated hobbyists called shortwave listeners.
Lucien Lévy was a French radio engineer and radio receiver manufacturer. He invented the superheterodyne method of amplifying radio signals, used in almost all AM radio receivers. His patent claim was at first disallowed in the United States in favour of the American Edwin Howard Armstrong, but on appeal Lévy's claim as inventor was accepted in the US.
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