Editing Tube socket

{{short description|Plug-in vacuum tube holder}}
[[Image:Tube sockets.agr.jpg|thumb|300px|Left to right: octal (top and bottom view), loctal, and miniature (top and side view) sockets. An early transistor socket and an [[integrated circuit]] socket are included for comparison.]]

'''Tube sockets''' are [[Electrical connector|electrical sockets]] into which [[vacuum tube]]s (electronic valves) 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 store]]s had vacuum [[tube tester]]s, and sold replacement tubes. Some [[Nixie tube]]s were also designed to use sockets.

Throughout the tube era, as technology developed, sometimes differently in different parts of the world, many tube bases and sockets came into use.<ref>{{cite web
 | last = Qvigstad
 | first = Just N. 
 | title = Sokkel oversikt radiorør
 | work = Vacuum tube bases overview
 | publisher = Radio amateur LA9DL
 | year = 2012
 | language = no
 | url = http://www.la9dl.no/Ror/Ror%20base/sokkel-innhold.html
 | access-date = 9 January 2013 }}</ref><ref>{{cite web|title=Tube Bases|url=http://www.tubedata.org/bases.html|work=Frank's Electron Tube Pages|access-date=20 July 2013}}</ref>  Sockets are not universal; different tubes may fit mechanically into the same socket, though they may not work properly and possibly become damaged.

Tube sockets were typically mounted in holes on a sheet metal chassis and wires or other components were hand [[solder]]ed to lugs on the underside of the socket. In the 1950s, [[printed circuit board]]s were introduced and tube sockets were developed whose contacts could be soldered directly to the printed wiring tracks. Looking at the bottom of a socket, or, equivalently, a tube from its bottom, the pins were numbered clockwise, starting at an index notch or gap, a convention that has persisted into the [[integrated circuit]] era.

In the 1930s, tubes often had the connection to the [[control grid]] brought out through a metal [[top cap]] on the top of the tube. This was connected by using a clip with an attached wire lead. An example would be the 6A7 [[pentagrid converter]]. Later, some tubes, particularly those used as radio frequency (RF) power amplifiers or horizontal deflection amplifiers in TV sets, such as the 6DQ6, had the plate or [[anode]] lead protrude through the envelope. In both cases this allowed the tube's output circuitry to be isolated from the input (grid) circuit more effectively. In the case of the tubes with the plate brought out to a cap, this also allowed the plate to run at higher voltages (over 26,000 volts in the case of rectifiers for color television, such as the 3A3, as well as high-voltage regulator tubes.) A few unusual tubes had caps for both grid and plate; the caps were symmetrically placed, with divergent axes.

[[Image:Tube 75.jpg|thumb|upright|right|Tube 75 from the 1930s with UX-6 base and top grid cap]]

==The first tubes==
The earliest tubes, like the ''[[Lee de Forest|Deforest]] Spherical [[Audion]]''<ref>{{cite web|last=Stone|first=Howard|title=Deforest Spherical Audion|url=http://www.stonevintageradio.com/description.php?II=97&UID=20130720104245|work=Stone Vintage Radio Museum|access-date=20 July 2013}}</ref> from {{circa|1911}}, used the typical light bulb Edison socket for the heater, and flying leads for the other elements. Other tubes directly used flying leads for all of their contacts, like the ''Cunningham AudioTron'' from 1915,<ref>{{cite web|last=Stone|first=Howard|title=Cunningham Tubular Audio Tron|url=http://www.stonevintageradio.com/description.php?II=170&UID=20130720104245|work=Stone Vintage Radio Museum|access-date=20 July 2013}}</ref> or the ''Deforest Oscillion''.<ref>{{cite web|last=Stone|first=Howard|title=Deforest Oscillion 250 W Transmitting Tube|url=http://www.stonevintageradio.com/description.php?II=542&UID=20130720104247|work=Stone Vintage Radio Museum|access-date=20 July 2013}}</ref> Type C6A xenon [[Thyratron|thyratrons]], used in servos for the U.S. Navy [[Ship gun fire-control system|Stable Element Mark 6]], had a [[Edison screw#Mogul|mogul screw base]] and L-shaped stiff wires at the top for grid and anode connections.<ref>{{cite web|title=C6A|url=https://www.radiomuseum.org/tubes/tube_c6a.html|website=Radiomuseum.org|access-date=4 November 2019}}</ref> Mating connectors were machined pairs of brass blocks with clamping screws, attached to flying leads (free hanging).

==Early bases==
[[File:4-6 pin.jpg|thumb|251x251px|Two early tubes with four- and six-pin bases]]When tubes became more widespread, and new electrodes were added, more connections were required. Specially designed bases were created to account for this need. However, as the world was suffering from [[World War I]], and the new electronics technology was just emerging, designs were far from being standardized. Usually, each company had their own tubes and sockets, which were not interchangeable with tubes from other companies. By the early 1920s, this situation was finally changing, and several standard bases were created. They consisted of a base (ceramic, metal, [[bakelite]], etc.) with a number of prongs ranging from three to seven, with either a non-regular distribution or with one or two of the prongs of bigger diameter than the other, so that the tube could only be inserted in a certain position. Sometimes they relied on a bayonet on the side of the base. Examples of these are the very common USA bases UX4, UV4, UY5 and UX6, and the European B5, B6, B7, B8, C7, G8A, etc. Tubes in the USA typically had from four to seven pins in a circular array, with adjacent pairs of larger pins for heater connections.

Before [[alternating current]] (AC) line/mains-powered radios were developed, some four-pin tubes (in particular, the very common UX-201A ('01A)) had a bayonet pin on the side of a cylindrical base. The socket used that pin for retaining the tube; insertion finished with a slight clockwise turn. Leaf springs, essentially all in the same plane, pressed upward on the bottoms of the pins, also keeping the bayonet pin engaged.

The first hot-cathode CRT, the [[Western Electric]] 224-B, had a standard four-pin bayonet base, and the bayonet pin was a live connection. (Five effective pins: It was an electrostatic-deflection gas-focused type, with a diode gun and single-ended deflection. The anode and the other two plates were common.)<!-- Ref.: Rider's Encyclopedia on C.R. Oscilloscopes and Their Uses; sorry; I'm exhausted! -->

An early exception to these types of bases is the Peanut 215, which instead of using prongs had a tiny bayonet base with four drop-like contacts. Another exception is the European Side Contact series commonly known as P, which instead of using a prong, relied on side contacts at 90 degrees from the tube axis with four to twelve contacts.

==Octal {{anchor|Octal base}} ==
{{multiple image
| align     = right
| direction = vertical
| width     = 170
| image1    = Heathkit_Vibrator.jpg
| caption1  = 
| image2    = Octal_base_crystal.jpg
| caption2  = Because of the ubiquity of the octal socket, many other components used it for their pin configuration including [[relay]]s (not shown), [[Vibrator_(electronic)|vibrators]] (top), [[crystal oscillator]]s (bottom) and small-signal [[transformer]]s (not shown)
}}
In April 1935, the [[General_Electric#Public_company|General Electric Company]] introduced a new eight-pin tube base with their new metal envelope tubes.<ref>Editors, [https://worldradiohistory.com/Archive-Radio-Engineering/30s/1935/Radio-Engineering-1935-04.pdf "Metal Tubes for Receivers"], ''Radio Engineering'', April 1935, pp. 18 - 19</ref><ref>G. F. Metcalf, J. E. Beggs, [https://worldradiohistory.com/Archive-Electronics/30s/Electronics-1935-05.pdf "All-metal receiving tubes, the manufacturing technique"], ''Electronics'', May 1935, pp. 149 - 150</ref> The new base became known as the ''octal base''.<ref>Editors, [https://worldradiohistory.com/Archive-Electronics/30s/Electronics-1935-09.pdf "Making Metal Tubes"], ''Radio Engineering'', Sept. 1935, pp. 31, 34</ref> The octal base provided one more conductor with a smaller overall size of the base than the previous line of U. S. tube bases which had provided a maximum of seven conductors. Octal bases, as defined in IEC 60067,<ref>IEC 60067: "Dimensions of electronic tubes and valves. IEC dimensions" (1966). Also published as BS 448-1:1981.</ref> diagram IEC 67-I-5a, have a 45-degree angle between pins, which form a {{convert|17.45|mm|in|frac=16|abbr=on}} diameter circle around a {{convert|7.82|mm|in|frac=16|abbr=on}} diameter keyed post (sometimes called a ''spigot'') in the center. Octal sockets were designed to accept octal tubes, the rib in the keyed post fitting an indexing slot in the socket so the tube could only be inserted in one orientation.

When used on metal tubes, pin 1 was always reserved for a connection to the metal shell, which was usually grounded for shielding purposes. This reservation prevented tubes such as the 6SL7/6SN7 dual triodes from being issued with metal envelopes, as such valves need three connections (cathode, grid, anode) for each triode (making six total) plus two connections for the paralleled heaters. The octal base soon caught on for glass tubes, where the large central post could also house and protect the "[[evacuation tip]]" of the glass tube. The eight available pins allowed more complex tubes than before, such as dual triodes, to be constructed. The glass envelope of an octal base tube was cemented into a [[bakelite]] or plastic base with a hollow post in the center, surrounded by eight metal pins. The wire leads from the tube were soldered into the pins, and the evacuation tip was protected inside the post.

Matching plugs were also manufactured that let tube sockets be used as eight-pin [[electrical connector]]s; bases from discarded tubes could be salvaged for this purpose. Octal sockets were used to mount other components, particularly [[electrolytic capacitor]] assemblies<ref>{{cite web|last=Schmid|first=Kurt|title=R-390A plug-in multi-section electrolytic capacitor kit|url=http://www.schmid-mainz.de/elco.pdf|work=Schmid-Mainz|access-date=20 July 2013}}</ref> and electrical [[relay]]s; octal-mount relays are still common.<ref>A socket similar to the standard otcal but with 11 pins also exists, and is also called "octal". It is an industry standard, developed mainly for industrial 3-phase relays (3PDT or TPDT) in order to accommodate three changeover contacts. It was also used in some older power supplies but was never used for tubes.</ref>

Most octal tubes following the widespread European designation system have penultimate digit "3" as in ECC34 (full details in the [[Mullard–Philips tube designation]] article). There is a different, totally obsolete, pre-world-war-II German octal type.{{citation needed|date=January 2013}}

Octal and miniature tubes are still in use in tube-type audio [[hi fi|hi-fi]] and [[guitar amplifier]]s. Relays were historically manufactured in a vacuum tube form,<ref>{{Cite web|title = Amperite {{!}} Time Delay Relays {{!}} Flashers {{!}} Controlling Devices {{!}} Relay Requirements|url = http://www.amperite.com/history.html|website = www.amperite.com|access-date = 2016-01-22}}</ref> and industrial-grade relays continue to use the octal base for their pinout.<ref>{{Cite book|title = Advantages of a Full Featured, Octal 700 Series Relay|publisher = Magnecraft|url = http://www.serelays.com/library/section1/105A_750.pdf}}</ref><ref>{{Cite book|title = Amperite Relay Catalog|publisher = Amperite|url = http://www.amperite.com/assets/Documents/Amperite%20Catalog%20Printed%206.0%20Reduced.pdf}}</ref>
<gallery>
File:6P3S.jpg|An octal base tube, Soviet 6Π3C, similar to the [[6L6]].
File:6SN7 octal base.jpg|Octal base of a [[6SN7]] 
File:Vacuum tube octal socket.jpg|An octal socket
</gallery>

==Loctal==
[[File:Heksoda i trioda UCH21.jpeg|thumb|upright|A loctal-base tube, Polish Telam UCH21 next to a wooden match for size comparison]]
A variant of the octal base, the B8G '''loctal base''' or ''lock-in'' base (sometimes spelled "loktal"&nbsp;— trademarked by Sylvania), was developed by [[Sylvania Electric Products|Sylvania]] for ruggedized applications such as automobile radios. Along with B8B (a British designation out of date by 1958), these eight-pin locking bases are almost identical and the names usually taken as interchangeable (although there are some minor differences in specifications, such as spigot material and spigot taper, etc.).<ref>{{cite book|author1=Staff of 'Wireless World'|title=Radio Valve Data|date=1958|publisher=Iliffe $ Sons Ltd|location=London|page=87|edition=Sixth|chapter=Explanation of Valve-Base Connections}}</ref> The pin geometry was the same as for octal, but the pins were thinner (although they will fit into a standard octal socket, they wobble and do not make good contact), the base shell was made of aluminium, and the center hole had an electrical contact that also mechanically locked (hence "loctal") the tube in place. Loctal tubes were only used widely by a few equipment manufacturers, most notably [[Philco]], which used the tubes in many table radios. Loctal tubes have a small indexing mark on the side of the base skirt; they do not release easily from their sockets unless pushed from that side. Because the pins are actually the [[Fernico]] or [[Cunife]] lead-out wires from the tube, they are prone to intermittent connections caused by the build-up of electrolytic corrosion products due to the pin being of a different metallic composition to the socket contact.

The loctal tube's structure was supported directly by the connecting pins passing through the glass "button" base. Octal tube structures were supported on a glass "pinch", formed by heating the bottom of the envelope to fusing temperature, then squeezing the pinch closed. Sealing the pinch embedded the connecting wires in the pinch's glass and gave a vacuum-tight seal. The connecting wires then passed through the hollow base pins, where they were soldered to make permanent connections.

Loctal tubes had shorter connecting lengths between the socket pins and the internal elements than did their octal counterparts. This allowed them to operate at higher frequencies than octal tubes. The advent of miniature "all-glass" seven- and nine-pin tubes overtook both octals and loctals, so the loctal's higher-frequency potential was never fully exploited.

Loctal tube type numbers in the USA typically begin with "7" (for 6.3-volt types) or "14" for 12.6-volt types. This was fudged by specifying the heater voltage as ''nominally'' 7 or 14 volts so that the tube nomenclature fitted.<ref>{{cite web|title=Sylvania Type 7A8|url=http://frank.pocnet.net/sheets/108/7/7A8.pdf|access-date=20 July 2013}}</ref> Battery types (mostly 1.4-volt) are coded "1Lxn", where ''x'' is a letter and "n" a number, such as "1LA4". Russian loctals ''end'' in L, e.g. 6J1L. European designations are ambiguous; all B8G loctals have numbers either in the range:
* 20–29, (such as EBL21, ECH21, EF22) except for early tubes in the series: DAC21, DBC21, DCH21, DF21, DF22, DL21, DLL21, DM21 which have either B9G or octal bases, the change to Sylvania's locktal standard coming in 1942<ref>{{cite web|title=DAC21|url=http://www.radiomuseum.org/tubes/tube_dac21.html|access-date=25 August 2012}}</ref>  
* or 50–59 (special bases, including the European 9-pin lock-in base), but other types are in the same range (e.g. while EF51 is B8G loctal, the EF55 is 9-pin loctal, B9G, and the EL51 has a side-contact P8A base).

===Other loctals===
* Nine-pin loctal bases, B9G, include the 1938 Philips [[EF50]], EL60 and some type numbers in the European 20–29 and 50–59 range;
* There is a different "loctal Lorenz" in the [[Mullard–Philips tube designation]] <!--COMMENT (B8D, given numbers in the 70–79 range?)-->.

==Miniature tubes==
[[File:12AU7.jpg|thumb|left|A pair of 12AU7As (ECC82) showing both triodes.]]
Efforts to introduce small tubes into the marketplace date from the 1920s, when experimenters and hobbyists made radios with so-called '''peanut tubes'''<ref>[http://www.stonevintageradio.com/images/573.jpg Photo of 1920s era peanut tube.]</ref> like the Peanut 215 mentioned above. Because of the primitive manufacturing techniques of the time, these tubes were too unreliable for commercial use.

RCA announced  new miniature tubes in [[Electronics (magazine)|''Electronics'']] magazine, which proved reliable. The first ones, such as the 6J6 ECC91 [[Very high frequency|VHF]] dual triode, were introduced in 1939. The bases commonly referred to as "miniature" are the seven-pin B7G type, and the slightly later nine-pin B9A (Noval). The pins are arranged evenly in a circle of eight or ten evenly spaced positions, with one pin omitted; this allows the tube to be inserted in only one orientation. Keying by omitting a pin is also used in 8- (subminiature), 10-, and 12-pin ([[Compactron]]) tubes (a variant 10-pin form, "Noval+1", is basically a nine-pin socket with an added center contact).

As with loctal tubes, the pins of miniature tube are stiff wires protruding through the bottom of the glass envelope which plug directly into the socket. However, unlike all their predecessors, miniature tubes are not fitted with separate bases; the base is an integral part of the glass envelope. The pinched-off air evacuation nub is at the top of the tube, giving it its distinctive appearance. More than one functional section can be included in a single envelope; a dual triode configuration is particularly common. Seven- and nine-pin tubes were common, though miniature tubes with more pins, such as the Compactron series, were later introduced, and could fit up to three amplifying elements. Some miniature tube sockets had a skirt that mated with a cylindrical metal electrostatic shield that surrounded the tube, fitted with a spring to hold the tube in place if the equipment was subject to vibration. Sometimes the shield was also fitted with thermal contacts to transfer heat from the glass envelope to the shield and act as a [[heat sink]], which was considered to improve tube life in higher power applications.

Electrolytic effects from the differing metal alloys used for the miniature tube pins (usually [[Cunife]] or [[Fernico]]) and the tube base could cause intermittent contact due to local corrosion, especially in relatively low current tubes, such as were used in battery-operated radio sets. Malfunctioning equipment with miniature tubes can sometimes be brought back to life by removing and reinserting the tubes, disturbing the insulating layer of corrosion.

Miniature tubes were widely manufactured for military use during World War II,<ref name=sixj6>[http://www.r-type.org/exhib/aaa0399.htm The National Valve Museum: 6J6]</ref> and also used in consumer equipment. The Sonora Radio and Television Corporation produced the first radio using these miniature tubes, the "Candid", in April 1940.<ref name=schiffer>{{cite book|last=Schiffer|first=Michael Brian|title=The Portable Radio in American Life|year=1992|publisher=University of Arizona Press|isbn=978-0816512843|pages=123–125}}</ref> In June 1940 RCA released its battery-operated '''Model BP-10''', the first [[superheterodyne receiver]] small enough to fit in a handbag or coat pocket.<ref>[http://www.nostalgiaair.org/PagesByModel/428/M0015428.pdf Schematic of RCA Model BP-10]</ref><ref>[http://vintage-electronics.com/photos/1183.JPG Photo of RCA Model BP-10]</ref>  This model had the following tube lineup:  '''1R5'''&nbsp;— [[pentagrid converter]]; '''1T4'''&nbsp;— [[Intermediate-Frequency_(IF)_amplifier|I.F. amplifier]];  '''1S5'''&nbsp;— [[Detector_(radio)|Detector]]/AVC/AF Amplifier;  '''1S4'''&nbsp;— Audio Output. The BP-10 proved so popular that Zenith, Motorola, Emerson, and other radio manufacturers produced similar pocket radios based on RCA's miniature tubes.<ref name="schiffer" /> Several of these pocket radios were introduced in 1941 and sold until the suspension of radio production in April 1942 for the duration of World War II.<ref>{{cite journal|title=Miniature Radio Tubes|journal=Radio Age|date=April 1945|pages=19|url=http://www.vacuumtubeera.net/RadioAge-1945-04.pdf|access-date=20 July 2013}}</ref>

After the war miniature tubes continued to be manufactured for civilian use, regardless of any technical advantage, as they were cheaper than octals and loctals.<ref name=sixj6/>

{{anchors|Miniature seven-pin base|Miniature 7-Pin}}
=== Miniature seven-pin base ===
The '''B7G''' (or "'''small-button'''" or "'''heptal'''") seven-pin miniature tubes are smaller than Noval, with seven pins arranged at 45-degree spacing in a 9.53&nbsp;mm (3/8th inch) diameter arc, the "missing" pin position being used to position the tube in its socket (unlike octal, loctal and rimlock sockets). Examples include the 6AQ5/EL90 and 6BE6/EK90. European tubes of this type have numbers 90-99, 100-109, 190-199, 900-999. A few in the  100-109 series have unusual, non-B7G bases, ''e.g.'', Wehrmacht base.

{{anchors|Noval|Noval base|Miniature nine-pin base|Miniature 9-Pin}}
=== Noval base ===
The nine-pin miniature '''Noval''' B9A base, sometimes called button 9-pin, B9-1, offered a useful reduction in physical size compared to previous common types, such as octal (especially important in TV receivers where space was limited), while also providing a sufficient number of connections (unlike B7G) to allow effectively unrestricted access to all the electrodes, even of relatively complex tubes such as double triodes and triode-hexodes. It could also provide multiple connections to an electrode of a simpler device where useful, as in the four connections to the grid of a conventional grounded-grid UHF triode, ''e.g.'', 6AM4, to minimise the deleterious effects of lead inductance on the high-frequency performance.

This base type was used by many of the [[United States]] and most of the European tubes, ''e.g.'', [[12AX7]]-ECC83, [[EF86]] and [[EL84]], produced commercially towards the end of the era before [[transistor]]s largely displaced their use.

The IEC 67-I-12a specification calls for a 36-degree angle between the nine pins of 1.016&nbsp;mm thickness, in an arc of diameter 11.89&nbsp;mm.

European tubes of this type have numbers 80-89, 180-189, 280-289, 800-899, 8000-8999.

=== Duodecar base ===
The '''Duodecar''' B12C base (IEC 67-I-17a) has 12 pins in a 19.1&nbsp;mm diameter circle and dates from 1961. It was also called the [[Compactron]] T-9 construction/E12-70 base<ref>Sylvania Receiving Tubes Technical Manual, 14th Edition</ref> It is generally similar in form to a Noval socket, but larger. In the center is a clearance hole for a tube evacuation pip, which is typically on the bottom of a Compactron tube. <!-- also CRTs, fairly sure. Regards, user:nikevich --> (It should not be confused with the similar-sounding but differently sized '''Duodecal''' B12A base.)

=== Rimlock base ===
The '''Rimlock''' (B8A) base is an eight-pin design with a pin circle diameter close to Noval, and uses a nub on the side of the envelope to engage with a guide and retaining spring in the socket wall. This provides pin registration (since the pins are equi-spaced) and also a fair degree of retention. Early tubes with this base type typically had a metal skirt around the lower ~15mm of the envelope to match the socket wall, and this offered a degree of built-in screening, but these were fairly soon replaced by "skirtless" versions, which had a characteristic widening in the glass to compensate physically for the absence of the skirt. In the European naming scheme, rimlock tubes are numbered in the ranges 40-49, 110-119 (with exceptions), and 400-499, ''e.g.'', EF40. Although virtually unknown elsewhere, this was a very common base type in European radios of the late 1940s through the 1950s, but was eventually displaced by the ubiquitous B7G and Noval (B9A) base types.

==UHF tubes==
[[File:AcornTubeSockets.agr.jpg|thumb|upright|A box of Acorn sockets.]]
By 1935 new tube technologies were required for the development of radar and telecommunications. [[UHF]] requirements severely limited the existing tubes, so radical ideas were implemented which affected how these tubes connected to the host system. Two new bases appeared, the [[955 acorn triode|acorn tube]] and the lighthouse tube, both solving the same problems but with different approaches. Thompson, G.M. Rose, Saltzberg and Burnside from RCA created the acorn tube by using far smaller electrodes, with radial short connections.<ref>{{cite book|title=History of Electron Tubes|year=1994|publisher=IOS Press|isbn=978-9051991451|page=27|url=https://books.google.com/books?id=VHFyngmO95YC|editor=Sōgo Okamura}}</ref> A different approach was taken by the designers of the lighthouse tube, such as the octal-base [[2C43]],<ref>[http://www.r-type.org/pdfs/2c43.pdf 2C43 data sheet]</ref> which relied on using concentric cylindrical metal contacts in connections that minimized inductance, thus allowing a much higher frequency.

[[Nuvistor]]s were very small, reducing stray capacitances and lead inductances. The base and socket were so compact that they were widely used in UHF TV tuners. They could also be used in small-signal applications at lower frequencies, as in the [[Ampex]] MR-70, a costly studio [[tape recorder]] whose entire electronics section was based on nuvistors.

==Other socket styles==
There are many other socket types, of which a few are:
* '''Decal''' B10B base (IEC 67-I-41a) 10 pins with 1.02&nbsp;mm diameter in an 11.89&nbsp;mm diameter circle, e.g. PFL200
* '''Decar''' B10G base (IEC E10-73) A 10th pin added to the center of a standard 9-pin miniature base, e.g. 6C9
* '''Magnoval''' B9D base (IEC 67-I-36a) 9 pins with 1.27&nbsp;mm diameter in a 17.45&nbsp;mm pin circle diameter arc, e.g. EL503, EL509, PD500, etc. - not to be confused with...
* '''Novar''' B9E base, 9 pins with 1.02&nbsp;mm diameter in a 17.45&nbsp;mm pin circle diameter arc, one of several Compactron types, which looks similar to Magnoval (but a Novar tube in a Magnoval socket will not make good pin contact, and a Magnoval tube in a Novar socket may damage the socket).
* '''Sub-Magnal''' B11A base (American), 11-pins.  Also used as industrial relay socket and HV power supplies. Amphenol / WirePro (WPI) / Eaton 78-series, Socket (female) part number: 78-S-11.  Matching Plug (male) is part number: 86-CP-11
* '''Neo Eightar''' base (IEC 67-I-31a) 8 pins in a 15.24&nbsp;mm diameter circle
* 5-pin sub-miniature wire-ended B5A base (no socket used; e.g. EA76)

A remarkably wide variety of tube and similar sockets is listed and described, with some informal application notes, at a commercial site, Pacific T.V.,<ref>{{cite web |url=http://www.pacifictv.ca/socket.htm |title = Pacific T.V. - Vacuum Tube Sockets}}</ref> including nuvistor, eight-pin subminiature, vidicon, reflex klystron, nine-pin octal-like, 10-pin miniature (two types), 11-pin sub-magnal, diheptal 14-pin, and many display tubes such as Nixies and vacuum fluorescent types (and even more). As well, each socket has a link to a clear, high-quality picture. <!-- I'm not keen on offering commercial sites, but this is seriously exceptional! I'm a 75-year-old retired lifetime electronic tech, and several of the tube sockets, much less exotica such as 20-pin relay sockets (iirc!) were new to me. Regards, user:nikevich -->

Some subminiature tubes with flexible wire leads all exiting in the same plane were connected by subminiature inline sockets. <!-- No luck with a Google image search -- user:nikevich - Does the EA76 fit this description?-->

Some low-power [[reflex klystron]]s such as the 2K25 and 2K45 had small-diameter rigid coaxial outputs parallel to octal base pins. To accommodate the coax, one contact was replaced by a clearance hole.

Vacuum tubes for high-power applications often required custom socket designs. A jumbo four-prong socket was used for various industrial tubes. A specialized seven-pin socket (Septar or B7A), with all pins in a circle with one pin wider than the others, was used for transmitting tubes. Subminiature tubes with long wire leads, introduced in the 1950s, were often soldered directly to printed circuit boards. Sockets were made for early [[transistor]]s, but quickly fell out of favor as transistor reliability became established. This also happened with early integrated circuits; IC sockets later became used only for devices that may need to be upgraded.

==Summary of base details==

<ref>"Philips Data Handbook: Electron Tubes, Part 4", April 1969l</ref><ref>{{cite web |url=http://www.dl7avf.info/charts/roehren/bilder.html |title = Abbildungen - Figures}}</ref>
{| class="wikitable sortable"
|-
! Common Name !! Standard Name !! Other names 
! data-sort-type="number" | Base Pins !! Pin Layout 
! data-sort-type="text" |  Pin thickness !! Specification 
! data-sort-type="number" | Period !!  Examples !! [[Mullard–Philips tube designation|European]] / [[Pro Electron]] numeric range
|-
! Pee-Wee 
|| B3A || US Pee Wee 3p || 3 || 08.7mm triangle with pins 1&3 closest<ref>{{cite web|title=Appendix - Figures|url=http://www.dl7avf.info/charts/roehren/bilder.html|publisher=KyteLabs|access-date=7 January 2013}}</ref>  || 2.36mm<ref>{{cite web|title=Pee Wee 3p|url=http://www.tubedata.org/bases/030_pw3.gif|publisher=Frank Philipse|access-date=7 January 2013}}</ref> ||  || 1937 - || ZA1004 || -
|-
! Mazda subminiature 
|| B3G<ref>{{cite web|title=Base B3G|url=http://www.r-type.org/static/baseb3g.htm|work=The National Valve Museum|access-date=20 July 2013}}</ref>  || ''European special all-glass miniature'' || 3 (+top) || 06.0mm line with 3mm spacing || 1mm || Mazda || 1937 -|| D1, EA50<ref>{{cite web|title=EA50 Signal Diode|url=http://www.radiomuseum.org/tubes/tube_ea50.html|access-date=25 May 2014}}</ref> || -
|-
! European 3-pin
|| H3A ||  British 3-pin, Eu-3<br> <small>''(or B4, ignoring pin 4)''</small>  || 3 || 16mm isosceles triangle, <small>greatest distance between pins 2 & 3</small> || 3.2mm || || 1920s to early 1930s<br> <small>''(superseded by Octal and P8)''</small> || RE4120, 1832<ref>{{cite book|title="Miniwatt" Technical Data|year=1958|publisher=The "Miniwatt" Electronics Division of Philips Electrical Industries Pty. Limited|location=Australia|pages=158|edition=6th}}</ref> || -
|-
! UV4
|| B4B ||WD-4-Pin || 4 || 09.8mm rectangle with large pin 2 <small>''(usually anode)''</small> || 2.3mm x3 <br>3.1mm  <small>''(pin 2)''</small>|| || 1914 - 1920's <br> <small>''(superseded by UX4)''</small> || [[WD-11]] || -
|-
! UX4
|| U4A || American 4-pin base <small>''with or without bayonet pin''</small> || 4 || 11.9mm rectangle with thicker pins 1 & 4.<br> Superseded the UV4 base || 3.2mm <small>''(pins 2&3)''</small><br> 4.0mm <small>''(pins 1&4)''</small> || A4-10 || 1920s - 1930s<br> <small>''(mostly superseded by Octal, but still used for some currently produced directly heated triodes)''</small> || A-P Oscillator (1920),<ref>{{cite web|title=A-P_Oscillator|url=http://www.radiomuseum.org/tubes/tube_a-p_oscillator.html|access-date=7 January 2013|quote=Saga of the Vacuumtube, Tyne page 176}}</ref> 2A3, [[300B]], B405, X99, WW313A (1938), [[866A]]|| -
|-
! B4 
|| A4A || British 4-pin, A4, European 4-pin || 4 || 16.25mm kite || 3.2mm || || 1915<ref>{{cite web|title=Base B4|url=http://www.r-type.org/static/baseb4.htm|access-date=25 May 2014}}</ref> to early 1930s<br> <small>''(superseded by Octal and P8)''</small>|| B405, BL2, R-type || -
|-
! UY5 <br> UX5
|| U5A <br> B5C || US 5-contact <br> American Small 5-pin, USS5 || 5 
|| 19mm (3/4") circle,<br> 3x60° between pins 1,2 and 4,5,1,<br> 2x90° between pins 2,3,4  <!-- <br> <small>Note: some databooks<ref>{{cite book|title="Miniwatt" Technical Data|year=1958|publisher=The "Miniwatt" Electronics Division of Philips Electrical Industries Pty. Limited|location=Australia|pages=158|edition=6th}}</ref> and websites<ref>{{cite web|title=807, Tube 807; Röhre 807 ID3358, Beam Power Tube|url=http://www.radiomuseum.org/tubes/tube_807.html|publisher=radiomuseum.org}}</ref>  use UX and UY seemingly interchangeably. Yet one has equal-sized pins and the other has pins 1&5 thicker</small> --> 
|| 3.? || A5-11 || 1920s  || UY227, 2E22, 1D4, 49, 807 || -
|-
! B5
|| O5A || British 5-pin, European 5 -pin, Europa || 5 || 16.25mm kite; B4 with central 5th pin added <br> <small>''a B5 socket will accept European 3-pin (H3A) and 4-pin (A4A) tubes''</small> || 3.2mm || || 1928<ref>{{cite web|title=Base B5|url=http://www.r-type.org/static/baseb5.htm|access-date=25 May 2014}}</ref> to early 1930s<br> <small>''(superseded by Octal and P8)''</small>  || B443|| -
|-
! UX6<ref>{{cite web|title=Base UX6|url=http://www.r-type.org/static/baseux6.htm|publisher=The National Valve Museum}}</ref> 
|| U6A || US 6-pin  || 6 ||19mm (3/4") circle,<br> 6x60° ||3.2mm x4, 3.9mm <small>''(pins 1 & 6)''</small> || || 1930's<br> <small>''(superseded by Octal)''</small>  || 1F6, 2A5 || -
|-
! B7
|| M7A || British 7-pin  || 7 || 23.1mm x 18.2mm oval<ref>{{cite web|title=Base B7|url=http://www.r-type.org/static/baseb7.htm|publisher=The national Valve Museum|access-date=9 January 2013}}</ref>  || 3.2mm ||  || 1930s <small>''(ultimately superseded by Octal)''</small>  || AC3/Pen, TDD4, AL60, 18013 || -
|-
! UX7
|| U7A || US 7-pin small || 7 || 19mm (3/4") circle,<br> 3x52°,4x51° || 3.2mm x5,<br>3.9mm  <small>''(pins 1&7)''</small> || ||  1930's<br> <small>''(superseded by Octal)''</small>  || 2B7, 6A7 || -
|-
!Septar
|B7A
|
|7
|26mm circle
|2.7mm x6, 4.0mm
|
|
|6C33, 829B, 3C33, 3E29, 832A, 5894, FU-29, GZ67-C
|
|- 
! [[Tube socket#Miniature seven-pin base|Miniature 7-Pin]]
|| B7G || Miniature, Button, Mi-7 || 7|| 09.53mm (3/8") circle,<br> 6x45° then 90° between pins 7 & 1|| 1.016mm || IEC 67-I-10a || 1939 - ''present''|| 1S4/DL91, [[6AQ5]], 6X4 || 90-99, <small>''some 100-109'',</small> 190-199, 900-999
|-
! Transcontinental
|| P8A || P-Type, '''Ct8''', Philips 8, Side-contact 8 || 8 || 29.5mm circle of side-contact pins,<br> 3x30° (pins 1-4),<br>5x54° || Side-contact|| Philips || 1930s  || AL3 || 1-9 ''usually''
|-
! [[Tube socket#Octal|Octal]] 
|| K8A<ref>{{cite web|last=Philipse|first=Frank|title=Frank's Electron tube Pages - Tube Bases|url=http://www.tubedata.org/bases.html|access-date=26 May 2014}}</ref> || IO, International Octal, '''A08''', American octal base, Oc-8  || 8 ||  17.45mm (11/16") circle, equal 45° spacing, 7.8mm spigot || 2.36mm|| originally: RCA<BR> IEC 67-I-5a || 1935 - ''present'' || [[EL34|6CA7/EL34]], [[6L6|6L6/5881]], [[6SN7]], [[6V6|6V6GT]], [[Kinkless tetrode|KT63/KT66/KT77/KT88/KT90]], 6550, 7591 || 3G, 30-39, 300-399
|-
! Mazda&nbsp;Octal<ref name="bmo" />
|| K8B || MO8, Octal-8 GB, MO<ref name=bmo>{{cite web|title=Base Mazda Octal|url=http://www.r-type.org/static/basemo.htm|publisher=The National Valve Museum|access-date=7 January 2013}}</ref>  || 8 || 18.5mm circle, 55,5° between pin 1 and 8, 43,5° between the other pins,<ref name=amtel>{{cite web|title=ATP4 tube|url=http://amateurtele.com/index.php?nav=1&artikel=101|publisher=The AmateurTele.com|access-date=10 February 2015}}</ref> 8.7mm spigot || 2.36mm || Mazda || 1938 - ?<br>''(short-lived)''||ARP12, AR8, SP42, ATP4 <ref name="amtel"/> || -
|- 
! [[Tube socket#Loctal|Loctal]]
|| B8G<ref>{{cite web|title=Appendix - Figures|url=http://www.dl7avf.info/charts/roehren/bilder.html#B8G|publisher=KyteLabs}}</ref>  <br>or B8B<ref>{{cite web|title=Base B8B|url=http://www.r-type.org/static/baseb8b.htm|publisher=The National Valve Museum|access-date=8 January 2013}}</ref> || 8-pin Loktal, Lo-8, Locking Octal || 8 ||   17.45mm (11/16") circle, equal 45° spacing, 6.7mm spigot || 1.3mm ||  Sylvania || 1939 || 1LN5, EF22, ECH71 || 20-29 and some others
|-
! [[Tube socket#Rimlock base|Rimlock]] 
| B8A || European 8-pin Miniature base, Ri-8 || 8 || 11.5mm (0.453") circle, 45° || 1.015mm|| IEC 67-I-11b || 1940s <br>''quickly edged-out by Noval, etc''|| [[ECH42|6CU7/ECH42]],EL41 || 40-49
|-
! [[Tube socket#Other loctals|Loctal]]-'''9'''pin
|| B9G<ref>{{cite web|title=Base B9G|url=http://www.r-type.org/static/baseb9g.htm|access-date=25 May 2014}}</ref> || 9-pin Loctal, Lo-9 || 9 ||  21.0mm (13/16") circle, equal 40° spacing,<br><small> spigot connected to can</small> || 1.3mm || [[Philips]] || 1938<ref>{{cite web|last=Dekker|first=Ronald|title=EF50 - The Development of the All-Glass Valve.|url=http://www.dos4ever.com/EF50/EF50.html#all_glass|access-date=25 May 2014}}</ref> <br><small>announced Sept. 1938 and available to [[Pye Ltd.|Pye]]; general availability early 1939.<ref>{{cite journal|last=Prakke|first=F. |author2=J.L.H. Jonker |author3=M.J.O. Strutt|title=A New "All-Glass" Valve Construction|journal=The Wireless Engineer|date=May 1939|url=http://www.dos4ever.com/EF50/wireless_engineer_1939.pdf|access-date=26 May 2014}}</ref></small> || EC52 [[EF50]] EF54 EL60 || 50-60 <small>''with some exceptions''</small>
|-
! [[Tube socket#Noval base|Noval]] (Miniature 9-pin)
|| B9A || American Small Button, Button 9-pin || 9 || 11.89mm (15/32") circle,<br> 8x36° then 72° spacing between pins 9 & 1 || 1.016mm|| IEC 67-I-12a<BR>JEDEC E9-1 || 1948 - ''present <small>(still very popular)</small>'' ||[[12AX7|12AX7/ECC83]], [[EL84|6BQ5/EL84]]|| 80-89, 180-189, 800-899
|-
! Magnoval 
|| B9D || || 9 || 17.45mm (11/16") circle,<br> 8x36° then 72° spacing between pins 9 & 1 || 1.27mm|| IEC 67-I-36a<BR>JEDEC E9-23 || 1960s-1970s<br>''died out when TVs went fully solid-state'' || E55L, ED500, PL504|| 500-599 
|-
! Novar 
|| B9E || 9-pin compactron|| 9 || 17.45mm (11/16") circle, 9x36° then gap between pins 9 & 1 <br><small>''Note: Novar sockets can be damaged by inserting Magnoval tubes''<ref>{{cite web|url=http://www.antiqueradios.com/forums/viewtopic.php?t=158036 |title=Novar vs Magnoval Vacuum Tube Sockets |website=Antique Radio Forums |date=2011-02-17}}</ref></small> || 1.02mm || JEDEC E9-65<BR>JEDEC E9-89 || 1959 - <br>''limited use; mainly TV horiz. output, damper''|| 6JF6, 22JG6A, 7868  ||  -
|-
! Decal
|| B10B<ref>{{cite web|title=Base B10B|url=http://www.r-type.org/static/baseb10b.htm|publisher=The National Valve Museum|access-date=7 January 2013}}</ref> <BR> ''or B10C?<ref>{{cite web|title=PCF201|url=http://www.radiomuseum.org/tubes/tube_pcf201.html}}</ref> <small>often incorrectly stated</small>''  || Dekal ||10|| 11.89mm (15/32") circle,<br> 9x34° then 54° gap between pins 10 & 1 || 1.016mm  || IEC 67-I-41a <BR>JEDEC E10-61 || 1960s - 1970s || PFL200, ECC2000, ECH200, PCF201 ||200-299<br>2000
|-
! Decar
|| B10G || Dekar || 10 || 11.89mm (15/32") circle as Noval, with additional center pin || 1.016mm || Sylvania<br>JEDEC E10-73 || Mid-Late 1960s || 6C9, 17C9
|-
!
|Y10A
|G10A (G8A tubes fit with pins 6 & 10 unused)
|10
|28mm circle, 2 groups of 5 pins with two gaps
|
|
|
|AZ11, EC156
|-
! Sub-Magnal
|| B11A || Magnal, B11 || 11 || 17.45mm (11/16") circle as Octal || 1.27mm || RCA? || 1940s to present || 
|-
! DuoDecal 
|| B12A || Duodekal, B12 ||12 || 27mm  (1.063") circle,<br> 30° angles || 2.36mm || B12-43  || 1950s - 1970s ||  DG7-31, E1T, MW61-80 || -
|-
! [[Tube socket#Duodecar base|Duodecar]] 
||B12C || 12-Pin-[[Compactron]], E12-70, E12-74 ||12 || 19.1mm (3/4") circle,<br> 11x 27.7° then gap between pins 12 & 1 ||1.02mm || E12-70(T9)<BR>E12-74(T12)<ref>{{cite web|author1=KyteLabs|title=KyteLabs InfoBase - Electron Tubes & Valves Data|url=http://www.qsl.net/dl7avf/roehren/sockel1.html|access-date=13 October 2014|location=Table A.4.1 - Sockeltypen - Basing Types|language=de, en|date=2014-02-19}}</ref>|| 1960s - 1970s ||  1BY2, 6BD11, 12BT3 || -
|-
![[Nuvistor]]
|
|E5-65
|5
|only pins 2, 4, 8 10, 12 used from Twelvar
|<1mm
|E5-65
|
|8393
|
|-
! Nuvistor
|| B12K || Twelvar E7-83, E12-64, E12-65 ||12 || 11.2mm circular envelope with mixed-spacing field of pins || <1mm || IEC 67-I-17a <BR>JEDEC E12-64(5/12)|| 1959 - ||  7586, 6DV4, 6DV8, 13CW4<ref>{{cite web|title=Nuvistor 13CW4|url=http://www.tubedata.org/bases/Nuvistor_13CW4.jpg|work=Tube Data|access-date=20 July 2013}}</ref>  || -

|}

==References==
{{reflist|30em}}

==See also==
{{Portal|Electronics}}
* [[Nuvistor]]
* [[Compactron]]
* [[Amphenol]]
* [[List of vacuum tubes]]
{{Commons category|Vacuum tube sockets}}

{{Thermionic valves}}

{{DEFAULTSORT:Tube Socket}}
[[Category:Vacuum tubes]]