Just N. Qvigstad  LA9DL

v.1.3 (13.12.2023)

This website is a help in determining a tube base type. In the manufacturers' tube documentation, the tube bases are often difficult to decipher, pictures are missing, measurements are often in a separate table and there is far too much unnecessary information in the base diagrams which make them difficult to read. Therefore, most of the base charts are redrawn in a grey scale and only with needed measurements for base type determination. Since tolerance measures have been dropped, it must be taken into account that all measures are nominal. Octal and sub-miniature tubes have many varieties. Therefore, the octal tubes are divided into subgroups and the sub-miniature tubes (tube diameter less than 12 mm) are sorted by the diameter of the tube (T1 to T3) and not by the number of pins/wires. To make it easier to distinguish the all-glass tubes, these have also been given T-size in the text, since the all-glasses has the same dimensions as the tube base (see Tube bulb size)

Tube base names and base codes are very often confusing. Manufacturers, sales companies, and documentation books very often have different description of the same base. Some bases have no name or base code at all, just a simple base drawing. In the early days of vacuum tubes, the various manufacturers had their own base names and tube codes.

In 1944, JETEC in the US was the first country to standardize the American tube bases. This list (JEDEC bases) is a detailed information of the tube dimensions, socket, pin orientation, caps, and terminals.

British Standard Institute released "Specification for dimensions of United Kingdom Electronic Tubes" in 1953 with supplements until 1973 (BS-448-2).

The UK Ministry of Aviation made a "Joint Service Specifiaction K1001, Issue No 6" in 1964 of UK Electonic Vaves.

The only international tube standardization is the IEC publication 67 from 1953 with several updates until 1985. This publication has the same information set-up as JETEC and was adopted by all major tube manufacturers (including countries such as USA, USSR, China, Japan, and many Europeans).

Base codes from these four publications are used in this guide. Commonly used, but not approved national base codes are in (brackets).


1-pin and disc-seal 18mm base
1-pin and disc-seal 23mm base

2-pin Base 16mm
2-pin Base 16x22mm
2-pin All-glass
2-pin Medium base thick pins
2-pin Pencil
2-pin Base with window
2-pin Base B2A
2-pin Base twist lock

3-pin Philips 4mm pins
3-pin Philips 6mm pins
3-pin Blade base
3-pin Arcotron
3-pin PeeWee
3-pin Base De-Forest US Navy
3-pin Europe B3
3-pin In-Line base B3G
3-pin Base B15A3
3-pin Base LK121
3-pin Base WE 212A
3-pin Big TX Base
3-pin Base Ediswan
3-pin Base Telefunken
3-pin / 1-socket Base Telefunken

4-pin Franko-British
4-pin Europe
4-pin Europe side-terminal base
4-pin French Y-base
4-pin UV199 base
4-pin UV base
4-pin Tx base WE
4-pin US tapered shell
4-pin Dwarf shell
4-pin US Small Shell metal base
4-pin US Metal Shell
4-pin US Medium Shell
4-pin US Medium metal shell with bayonet
4-pin US Medium shell with bayonet (UX4)
4-pin US Medium ceramic disk B4A
4-pin US Skirted medium shell with bayonet
4-pin US Skirted medium metal shell bayonet
4-pin US Skirted medium metal shell
4-pin Philips Telefunken medium pin
4-pin Philips British base (BC4) long pin
4-pin Jumbo short metal shell
4-pin Jumbo medium shell
4-pin Jumbo medium metall shell long pin
4-pin Jumbo medium metal skirted shell, Type 1, Type 2, Type 3
4-pin Jumbo large ventilated metal shell
4-pin Super Jumbo small shell
4-pin Super Jumbo medium metal shell long pin
4-pin Super Jumbo medium shell
4-pin Super Jumbo medium metal shell
4-pin Super Jumbo large metal shell with bayonet and slot
4-pin Super Giant
4-pin Giant metal shell with bayonet
4-pin British L4-base
4-pin Philips W4 big skirted-base
4-pin EMI Cossor CRT B4E-base
4-pin Midget Hivac
4-pin Mini-base
4-pin Telefunken wafer key
4-pin Telefunken medium pin bayonet
4-pin Base WD (1 thick + 3 thin pins)
4-pin / 1-socket baseTelefunken
4-pin Large base 212 WE
4-pin Base 316A
4-pin Base 703A
4-pin Base metal tube 416 WE

5-pin Cosmos (3 long + 2 short pins)
5-pin Europe
5-pin Europe side-terminal base
5-pin EU Telephone
5-pin French D-base (Bi-Grille)
5-pin French Bi-Grille with side-terminal
5-pin French D-base 2x side-terminals
5-pin French base PTT210
5-pin Midget Hivac
5-pin Miniature USSR
5-pin US Small shell
5-pin US Medium shell
5-pin US Wide shell with barrier
5-pin Giant base
5-pin Giant medium shell with bayonet
5-pin Giant metal shell with ventilated base
5-pin Super Giant
5-pin Super Giant metal base
5-pin Super Giant metal base with 3-keys
5-pin Telefunken bayonet
5-pin Septar

6-pin Europe
6-pin Continutal EU
6-pin French Tri-Grille
6-pin US Small shell
6-pin US Medium shell
6-pin US Medium long shell
6-pin Siemens
6-pin Loewe bayonet bayonets
6-pin Loewe with senter-contact and bayonets

7-pin Miniature
7-pin Miniature with pumping stem
7-pin Mini-miniature
7-pin Telephone EU
7-pin British B7
7-pin Continental EU
7-pin French Q-base Bi-Grille
7-pin US Small shell
7-pin US Medium shell
7-pin US Medium shell with bayonet
7-pin Septar medium molded flare
7-pin Septar medium button
7-pin Septar small wafer
7-pin Septar large button
7-pin Septar jumbo button
7-pin Giant medium metal shell with bayonet
7-pin Giant ventilated metal shell
7-pin Special (2+5 pins)
7-pin Jumbo keyed annular
7-pin Siemens all-glass Octal with thin pins

8-PIN OCTAL (see link)

8-pin US Lock-in
8-pin Loctal EU mini base
8-pin Loctal EU medium base
8-pin Loctal EU large base with plastic spigot
8-pin Loctal EU large base
8-pin Loctal TX

8-PIN (not Octal / Loctal):
8-pin Ditetrar with small button glass tip
8-pin Super Ditetrar with small base glass tip
8-pin Neo-Ditetrar
8-pin Eightar
8-pin Neo-Eightar
8-pin German medium shell Y8A
8-pin German short medium shell Y8A
8-pin German medium wafer Y8A
8-pin German large wafer
8-pin Rimlock metal shell
8-pin Rimlock glass wafer
8-pin Rimlock all-glass
5-pin Rimlock all-glass
8-pin Rimlock metal shell spigot
8-pin All-glass small PTT49 base glass wafer
8-pin All-glass medium PTT49 base
8-pin All-glass large PTT49 base
8-pin All-glass Ø13 mm base, long glass tip - short index pin
8-pin All-glass Ø18 mm base, long glass tip - short index pin
8-pin All-glass Ø30 mm base, short glass tip - thick index pin
8-pin All-glass Ø26 mm shell, long glass tip - short index pin
8-pin All-glass Ø34 mm shell, short glass tip - thick index pin
8-pin All-glass Ø34 mm shell, long glass tip - thick index pin
8-pin All-glass Ø34 mm shell, light base spigot - thick index pin
8-pin Gnom base
8-pin All-glass with plastic HT barrier wafer

9-pin Loctal base
9-pin Loctal big base
9-pin Loctal Plastic-spigot
9-pin Loctal mica disc
9-pin Loctal small base

9-pin British B9
9-pin Telephone
9-pin FJ-base
9-pin Gundelach
9-pin Noval
9-pin Neo-Noval large button base
9-pin Ninar (Noval base with glass base tip)
9-pin Novar US small button base
9-pin Magnoval EU small button base
9-pin Novar US small button base glass tip
9-pin Magnoval small button base glass tip
9-pin Novar US large button base
9-pin Magnoval EU large button base
9-pin Miniature T4

10-pin Decal
10-pin Decar
10-pin German Y10A with Large wafer
10-pin German Y10A  with Flared shell
10-pin Telefunken All-glass with base tip
10-pin Telefunken G10G
10-pin All-glass (8-pin Loctal + 2 thick pins)
10-pin Diheptal with HT barrier pin

11-pin All-glass miniature base
11-pin All-glass oval base
11-pin Gnom base
11-pin Elevenar large wafer
11-pin Magnal small shell
11-pin Magnal medium shell
11-pin Sub-Magnal small shelll
11-pin Neo-Submagnal small shell                   
11-pin Unidecar small button
11-pin Special shoulder CRT
11-pin Large Nuvistor

12-pin All-glass oval base
12-pin All-glass B12F
12-pin Duodecal small shell
12-pin Duodecal dwarf shell
12-pin Duodecal ultra short small shell
12-pin Duodecal short small shell
12-pin Duodecal base cap
12-pin Duodakar small buttom (Compatron)
12-pin Duodakar large buttom (Compatron)
12-pin CRT B12B
12-pin Twelvar medium ceramic wafer (Nuvistor)
12-pin Loewe base

13-pin All-glass B13B
13-pin All-glass special

14-pin All-glass base with glass tip
14-pin All-glass standard, oval base
14-pin Diheptar all glass with short spigot
14-pin Diheptar all glass with long spigot
14-pin Diheptal B14A small shell
14-pin Diheptal B14A medium shell
14-pin Small wafer, plastic filled base
14-pin Neo-Diheptal B14F
14-pin Miniature

15-pin All-glass

16-pin All-glass WE

17-pin All-glass B17A
17-pin All-glass Jumbo
17-pin All-glass Jumbo side viewing
17-pin All-glass Jumbo large

20-pin Bidecal small shell

21-pin All-glass, plastc spacer bottom base-tip

25-pin large base (15+10 pin)
25-pin Special base (15+10 pin)

26 / 27-PIN:
26-27-pin Special all-glass

29-pin Twentyfyninar small button

35-pin Thirtyfivar

4-radial pins (Acorn)
5-radial pins (Acorn 5AA)
5-radial pins (Acorn 7AA)
5-radial pins wide (Acorn P7A)
6-radial pins (Acorn Fivre)
4-radial pins small keyed base
6-radial pins small keyed base
7-radial pins (Acorn Fivre)
7-radial pins (Acorn 7AB)
7-radial pins (Acorn P7)
8-radial pins medium keyed base lock-in spigot
8-radial pins large keyed base
12-radial pins (Acorn)

4-side-contact British B4E
4-side-contact SCA Base
4-side-contact small pins
5-side-contact Continental EU
6-side-contact 14 mm base Camera tube
8-side-contact Continental EU
12-side-contact CRT B12D
12-side-contact CRT P12
13-side-contact CRT B13D
18-side-contact CRT


T-3 pin tube:
5-pin subminiature round base
8-pin subminiature round base
8-pin subminiature T-3 Metall-glass
9-pin subminiature, Japan
14-16 pin Sub-Miniature T3

T-2x3 pin tube:
4-pin press-base
5-pin press-base


T-1 wired tube:
4-wire round-base
5-wire round-base
4-wire round-base

T-1.5 wired tube:
2-wire round press base
3-wire round press base
4-wire round special-base

T-1.5 wired in-line tube:
4-wire round in-line base
5-wire round in-line base

T-1.5x2 wired tube:
5-wire press-base

T-2 wired tube:
4-wire round press-base
5-wire round-base

T-2 wired tube center wire:
5-wire round base center wire

T-2 wired tube special base:
3-wire round special base
5-wire round special base

T-3 wired tube:
6-wire round special base
5-wire-round base
6-wire round base
7-wire round base
8-wire round base

T-3 wired tube press-base:
2-wire round press-base
3-wire round press-base
4-wire round round press-base
5-wire round press-base
6-wire round press-base
7-wire round press-base

T-2x3 tube press-base:
3-wire press-base
5-wire press-base
7-wire press-base


2-straps 23mm wide
2-straps 35mm wide
7-straps Miniature base
9-straps Loctal base
4-wire medium metall shell with lugs
7-wire Miniature base (T-5.5 tube)
8-wire Loctal
12-semiflexible leads (T-6 tube)
12/13-leads Thirteennar
14-wire Miniature

3- Clip base
6- Clip base
7- Clip base
11-Clip base

3-socket German base Ø: 66mm
3-socket German base Ø: 82mm
4-socket German base Ø: 51mm
4-socket German base Ø: 65mm

Bayonet Small B10
Bayonet Medium B15
Bayonet Large B22
Bayonet Big B27

Edison Miniature screw E10
Candilabre screw E11 / E12
Edison Small screw E13
Edison Big screw E26
Edison Goliat screw E39

COAXIAL BASE: coaxial, 6299
4-contact, YD1060
4-contact, 7289
4-contact, 8245
4-contact disk seal

2-blade contact large Ø16x15mm
2-blade contact small Ø10x11mm

2-cap contact Ø15mm

2-contact Type-1 Strip and pin
2-contact Type-2 Strip and pin
2-contact cap + 2-contact nuts
4-contact cap (envelope)
2-NUB base
4-NUB peanut
4-NUB small
2-contact Soffitte / Festoon type 1
2-contact Soffitte / Festoon type 2

Screw terminal M3
Screw terminal M4

"JEDEC list all bases"

"JEDEC Octal Bases"

"Tube bulb size"

"LA9DL Home page"

Copyright 2011-2023 Just N. Qvigstad - Regarding copying pictures and text please send me an E-mail.