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. [1] [2] [3]
When war broke out in 1939, British radio manufacturers devoted their resources to producing a range of military radio equipment required for the armed forces. This resulted in a shortage of consumer radio sets and spare parts, particularly valves, as all production was for the services. The war also prompted a shortage of radio repairmen, as virtually all of them were needed in the services to maintain vital radio and radar equipment. This meant it was very difficult for the average citizen to get a radio repaired, and with very few new sets available, there was a desperate need to overcome the problem. [4]
The government solved this by arranging for over forty radio manufacturers to produce sets to a standard design with as few components as possible consistent with the ability to source them. Earlier, the government had introduced the "Utility" brand to ensure that all clothing, which was rationed, was produced to a reasonable quality standard as, prior to its introduction, a lot of shoddy goods had appeared on the market; the brand was therefore adopted for this wartime radio. [3] [1]
The Utility Set had limited reception on medium wave and lacked a longwave band to simplify the design. The tuning scale listed only BBC stations. After the war a version with LW was made available and modification kits to retrofit existing sets were marketed. [5]
About 175,000 sets were sold, at a price of £12 3s 4d each. [4] The set is sometimes characterized as the British equivalent of the German Volksempfänger "Peoples' Receiver"; however there were dissimilarities. The Volksempfänger were radio sets designed to be inexpensive enough for any German citizen to purchase one but higher quality consumer radios were always available to Germans who could afford to pay higher prices. By contrast, the Utility Set was the only consumer radio receiver available for purchase on the British market for much of the latter part of the war. [6] Starting in June 1942, manufacture of consumer radio receivers in the United States also ceased due to military production needs. [7] [8]
The sets used a four-valve superhet circuit with an audio output of 4 watts at 10% total harmonic distortion; they performed as well as many pre-war sets. The valve complement consisted of a triode-hexode frequency mixer, a variable-μ RF pentode IF amplifier and a high slope output pentode. A "Westector" solid-state copper oxide diode was used for demodulation, which saved one valve and allowed use of an available type of pentode for the audio stage. [1] The HT line was derived from a full wave rectifier. All valves were on International Octal sockets apart from the rectifier which was on a British 4-pin base. There were minor variations between set makers; for instance Philips used IF transformers with adjustable ferrite cores (so-called slug tuning) rather than the conventional trimmer capacitors. [3]
More than 40 manufacturers, such as Pye Ltd. and Marconiphone, made Utility radios. The manufacturer of a particular set was not readily apparent to the general public, although each manufacturer stamped a code letter on the radio to identify themselves to dealers. UK makers often used different designations for the same valve (tube), while octal tubes might be of USA origin. All valves in the Utility radio used standard designations prefixed by BVA (for British Valve Association). They were produced by valve makers such as Mullard, MOV, Cossor, Mazda and Brimar. Dealers, knowing the maker of a set and which valve manufacturer that maker used, could easily deduce which pre-war types these were and make warranty claims on the manufacturer. [5]
Compactrons are a type of thermionic valve, or 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 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.
A valve amplifier or tube amplifier is a type of electronic amplifier that uses vacuum tubes to increase the amplitude or power of a signal. Low to medium power valve amplifiers for frequencies below the microwaves were largely replaced by solid state amplifiers in the 1960s and 1970s. Valve amplifiers can be used for applications such as guitar amplifiers, satellite transponders such as DirecTV and GPS, high quality stereo amplifiers, military applications and very high power radio and UHF television transmitters.
The pentagrid converter is a type of radio receiving valve with five grids used as the frequency mixer stage of a superheterodyne radio receiver.
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.
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.
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.
A pentode is an electronic device having five electrodes. The term most commonly applies to a three-grid amplifying vacuum tube or thermionic valve that was invented by Gilles Holst and Bernhard D.H. Tellegen in 1926. The pentode was developed from the screen-grid tube or shield-grid tube by the addition of a grid between the screen grid and the plate. The screen-grid tube was limited in performance as an amplifier due to secondary emission of electrons from the plate. The additional grid is called the suppressor grid. The suppressor grid is usually operated at or near the potential of the cathode and prevents secondary emission electrons from the plate from reaching the screen grid. The addition of the suppressor grid permits much greater output signal amplitude to be obtained from the plate of the pentode in amplifier operation than from the plate of the screen-grid tube at the same plate supply voltage. Pentodes were widely manufactured and used in electronic equipment until the 1960s to 1970s, during which time transistors replaced tubes in new designs. During the first quarter of the 21st century, a few pentode tubes have been in production for high power radio frequency applications, musical instrument amplifiers, home audio and niche markets.
The Volksempfänger was a range of German radio receivers developed by engineer Otto Griessing at the request of Joseph Goebbels, the Reich Minister of Propaganda of the Nazi regime.
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.
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.
A valve audio amplifier (UK) or vacuum tube audio amplifier (US) is a valve amplifier used for sound reinforcement, sound recording and reproduction.
A double diode triode is a type of electronic vacuum tube once widely used in radio receivers. The tube has a triode for amplification, along with two diodes, one typically for use as a detector and the other as a rectifier for automatic gain control, in one envelope. In practice the two diodes usually share a common cathode. Multiple tube sections in one envelope minimized the number of tubes required in a radio or other apparatus.
A.C. Cossor Ltd. was a British electronics company founded in 1859. The company's products included valves, radios, televisions and military electronics. The company was purchased by Raytheon in 1961.
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".
In the field of electronics, the EF50 is an early all-glass wideband remote cutoff pentode designed in 1938 by Philips. It was a landmark in the development of vacuum tube technology, departing from construction ideas of the time, that was essentially unchanged from light bulb designs. Initially used in television receivers, it quickly gained a vital role in British radar, and great efforts were made to secure a continuing supply of the device as Holland fell in World War II.
