The British Radio and Valve Manufacturers' Association (BVA) was a 20th-century cartel of vacuum tube (valve) manufacturers in the United Kingdom of Great Britain and Northern Ireland (UK) that was designed to protect their interests from foreign competition. This cartel dictated (among other things), the price of valves (vacuum tubes) and how they were numbered.
The numbering scheme was supposedly designed to make it difficult to identify American equivalents, which were typically half the retail price in their home country; however American types manufactured in the UK by companies such as Brimar sold at the same price as their UK counterparts due to the BVA's insistence. All manufacturers eventually published their own lists of 'equivalents' between their own valves and those of other manufacturers including American types, so cross-referencing became easy, in the UK at least.
The BVA dictated that no more than one electrode structure could be contained within one envelope, because the association levied a charge of initially £1 per valveholder, to cover royalties on any of its members' patent rights. Pressure from set-makers for multi-structure valves to overcome the BVA's edict led to British and European manufacturers introducing multi-structure valves and these eventually became common.
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Compactrons are a type of vacuum tube, which contain multiple electrode structures packed into a single enclosure. They were designed to compete with early transistor electronics and were used in televisions, radios, and similar roles.
A vacuum tube, electron tube, valve, or tube, is a device that controls electric current flow in a high vacuum between electrodes to which an electric potential difference has been applied.
A cartel is a group of independent market participants who collude with each other in order to improve their profits and dominate the market. A cartel is an organization formed by producers to limit competition and increase prices by creating artificial shortages through low production quotas, stockpiling, and marketing quotas. Cartels can be vertical or horizontal but are inherently unstable due to the temptation to defect and falling prices for all members. Additionally, advancements in technology or the emergence of substitutes may undermine cartel pricing power, leading to the breakdown of the cooperation needed to sustain the cartel. Cartels are usually associations in the same sphere of business, and thus an alliance of rivals. Most jurisdictions consider it anti-competitive behavior and have outlawed such practices. Cartel behavior includes price fixing, bid rigging, and reductions in output. The doctrine in economics that analyzes cartels is cartel theory. Cartels are distinguished from other forms of collusion or anti-competitive organization such as corporate mergers.
A steam locomotive is a locomotive that provides the force to move itself and other vehicles by means of the expansion of steam. It is fuelled by burning combustible material to heat water in the locomotive's boiler to the point where it becomes gaseous and its volume increases 1,700 times. Functionally, it is a steam engine on wheels.
The pentagrid converter is a type of radio receiving valve with five grids used as the frequency mixer stage of a superheterodyne radio receiver.
Mullard Limited was a British manufacturer of electronic components. The Mullard Radio Valve Co. Ltd. of Southfields, London, was founded in 1920 by Captain Stanley R. Mullard, who had previously designed thermionic valves for the Admiralty before becoming managing director of the Z Electric Lamp Co. The company soon moved to Hammersmith, London and then in 1923 to Balham, London. The head office in later years was Mullard House at 1–19 Torrington Place, Bloomsbury, now part of University College London.
KT66 is the designator for a beam power tube introduced by Marconi-Osram Valve Co. Ltd. (M-OV) of Britain in 1937 and marketed for application as a power amplifier for audio frequencies and driver for radio frequencies. The KT66 is a beam tetrode that utilizes partially collimated electron beams to form a low potential space charge region between the anode and screen grid to return anode secondary emission electrons to the anode and offers significant performance improvements over comparable power pentodes. In the 21st century, the KT66 is manufactured and used in some high fidelity audio amplifiers and musical instrument amplifiers.
Tube sockets are electrical sockets into which vacuum tubes can be plugged, holding them in place and providing terminals, which can be soldered into the circuit, for each of the pins. Sockets are designed to allow tubes to be inserted in only one orientation. They were used in most tube electronic equipment to allow easy removal and replacement. When tube equipment was common, retailers such as drug stores had vacuum tube testers, and sold replacement tubes. Some Nixie tubes were also designed to use sockets.
A beam tetrode, sometimes called a beam power tube, is a type of vacuum tube or thermionic valve that has two grids and forms the electron stream from the cathode into multiple partially collimated beams to produce a low potential space charge region between the anode and screen grid to return anode secondary emission electrons to the anode when the anode potential is less than that of the screen grid. Beam tetrodes are usually used for power amplification, from audio frequency to radio frequency. The beam tetrode produces greater output power than a triode or pentode with the same anode supply voltage. The first beam tetrode marketed was the Marconi N40, introduced in 1935. Beam tetrodes manufactured and used in the 21st century include the 4CX250B, KT66 and variants of the 6L6.
The 6V6 is a beam-power tetrode vacuum tube. The first of this family of tubes to be introduced was the 6V6G by Ken-Rad Tube & Lamp Corporation in late 1936, with the availability by December of both Ken-Rad and Raytheon 6V6G tubes announced. It is still in use in audio applications, especially electric guitar amplifiers.
The EL84 is a vacuum tube of the power pentode type. It is used in the power-output-stages of audio-amplifiers, most commonly now in guitar amplifiers, but originally in radios. The EL84 is smaller and more sensitive than the octal 6V6 that was widely used around the world until the 1960s. An interchangeable North American type is the 6BQ5.
The Radio Electronics Television Manufacturers' Association was formed in 1953, as a result of mergers with other trade standards organisations, such as the RMA. It was principally responsible for the standardised nomenclature for American vacuum tubes - however the standard itself had already been in use for a long time before 1953; for example, the 6L6 was introduced in July 1936.
In Europe, the principal method of numbering vacuum tubes was the nomenclature used by the Philips company and its subsidiaries Mullard in the UK, Valvo(de, it) in Germany, Radiotechnique (Miniwatt-Dario brand) in France, and Amperex in the United States, from 1934 on. Adhering manufacturers include AEG (de), CdL (1921, French Mazda brand), CIFTE (fr, Mazda-Belvu brand), EdiSwan (British Mazda brand), Lorenz (de), MBLE(fr, nl), RCA (us), RFT(de, sv) (de), Siemens (de), Telefunken (de), Tesla (cz), Toshiba (ja), Tungsram (hu), and Unitra. This system allocated meaningful codes to tubes based on their function and became the starting point for the Pro Electron naming scheme for active devices.
The Utility Radio or Wartime Civilian Receiver was a valve domestic radio receiver, manufactured in Great Britain during World War II starting in July 1944. It was designed by G.D. Reynolds of Murphy Radio. Both AC and battery-operated versions were made.
A valve audio amplifier (UK) or vacuum tube audio amplifier (US) is a valve amplifier used for sound reinforcement, sound recording and reproduction.
The manual vacuum cleaner was a type of non-electric vacuum cleaner, using suction to remove dirt from carpets, being powered by human muscle, similar in use to a manual lawn mower. Its invention is dated to the second half of the 19th century, when patents were granted to inventors in the United States, Britain, France, and elsewhere.
A magic eye tube or tuning indicator, in technical literature called an electron-ray indicator tube, is a vacuum tube which gives a visual indication of the amplitude of an electronic signal, such as an audio output, radio-frequency signal strength, or other functions. The magic eye is a specific type of such a tube with a circular display similar to the EM34 illustrated. Its first broad application was as a tuning indicator in radio receivers, to give an indication of the relative strength of the received radio signal, to show when a radio station was properly tuned in.
Lincoln Industrial Corporation (Lincoln) is a manufacturer of automated lubrication systems, manual lubrication equipment and industrial pumping systems, and subsidiary of Svenska Kullagerfabriken AB (SKF). Founded in 1910, the company has been responsible for many of the inventions that established modern lubrication practices in automotive maintenance and industry.
An AC/DC receiver design is a style of power supply of vacuum tube radio or television receivers that eliminated the bulky and expensive mains transformer. A side-effect of the design was that the receiver could in principle operate from a DC supply as well as an AC supply. Consequently, they were known as "AC/DC receivers".
The type SY4307A is the STC version of the Western Electric 307A, a power output pentode possessing a similar power rating, but significantly different characteristics to the far more common type 807 thermionic valve/vacuum tube. The "SY" prefix denotes the site of manufacture as being Sydney. The plant, operated by Standard Telephones and Cables Pty. Ltd. was located on Mandible Street in the suburb of Alexandria and existed under that corporate entity from 1937 to 1970.. Although the remaining structure postdates the depicted device, this device was likely assembled on an adjoining property upon which the structures have been demolished and site re-purposed.
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