This is a list of vacuum tubes or thermionic valves, and low-pressure gas-filled tubes, or discharge tubes. Before the advent of semiconductor devices, thousands of tube types were used in consumer electronics. Many industrial, military or otherwise professional tubes were also produced. Only a few types are still used today, mainly in high-power, high-frequency applications.
Heater or filament ratings
Receiving tubes have heaters or filaments intended for direct battery operation, parallel operation off a dedicated winding on a supply transformer, or series string operation on transformer-less sets. High-power RF power tubes are directly heated; the heater voltage must be much smaller than the signal voltage on the grid and is therefore in the 5...25 V range, drawing up to hundreds of amperes from a suitable heater transformer. In some valve part number series, the voltage class of the heater is given in the part number, and a similar valve might be available with several different heater voltage ratings.
Tube bases and envelopes
Abbreviations used in this list
ST – Shouldered tube
GT – Glass tube
MT – Miniature tube, such as Noval B9A or Miniature 7-pin B7G
FL – Subminiature all-glass elliptical body and flat bases with long, inline "flying leads" (wire-ends) that are soldered into the circuit SL – Subminiature all-glass elliptical body and flat bases with short inline leads that can be soldered or can be mated with a special socket. (Flying leads can be cut short to fit into inline sockets.) R8 – Subminiature all-glass round body and base with 8 flying leads or stiff pins arranged in a circle
Numbering systems
North American systems
RETMA receiving tubes system
RETMA is the acronym for the Radio Electronic Television Manufacturers Association formed in 1953 - however the standard itself had already been in use since 1933, when RCA/Cunningham introduced the 1A6, 2A3, 2A5, etc. The first character group is a number representing the heater voltage rounded to the nearest whole number; 0 indicates a cold-cathode tube. One or two letters assigned to the devices in order of development. A single numeral that represents the number of active elements in the tube. Suffix letters distinguish revisions or variants: A, B, C – Improved backward compatible versions E – Export version G – Glass bulb, ST-12 to ST-16 size GT – Glass bulb, T-9 size GT/G – Glass bulb, T-9 size interchangeable with G and GT types L – Loctal LM – Loctal-metal LT – Locking base M – Metal envelope MG – Metal-glass ML – Metal-Loctal S – Spray shielded W – Ruggedised, or military grade WA, WB – Improved, backward compatible military/industrial variants X – Low loss ceramic base for RF use Y – Low loss mica-filled phenolic resin ("Micanol") base for RF use Lastly, manufacturers may decide to combine two type numbers into a single name, which their one device can replace, such as: 6DX8/ECL84 (6DX8 and ECL84 being identical devices under different naming schemes) or 6BC5/6CE5 (sufficiently identical devices within the RETMA naming system) and even 3A3/3B2, or 6AC5-GT/6AC5-G (where the single type number, 6AC5-GT/6AC5-G, supersedes both the 6AC5-G and the 6AC5-GT).
Often designations that differed only in their initial numerals would be identical except for heater characteristics.
For examples see below
RMA professional tubes system
The system was used in 1942–44 and assigned numbers with the base form "1A21", and is therefore also referred to as the "1A21 system". The first numeric character indicated the filament/heater power rating, the second alphabetic character was a code for the function, and the last 2 digits were sequentially assigned, beginning with 21
For examples see below.
EIA professional tubes system
A four-digit system was maintained by JETEC since 1944, then by EIA since 1957 for special industrial, military and professional vacuum and gas-filled tubes, and all sorts of other devices requiring to be sealed off against the external atmosphere.
Some manufacturers preceded the EIA number with a manufacturer's code: CK, RK – Raytheon Company ECG – Philips/Sylvania F – Federal Telephone and Radio (ITT division) GL – General Electric Corp. (not British General Electric Company) ML – Machlett Laboratories, Inc. NL – National Electronics, Inc. (Geneva, Illinois, USA) NU – National Union Electric Corp. (Orange, New Jersey, USA) PL – Philips N.V. SV – Svetlana: formerly only PJSC "Svetlana/ПАО Светлана", St. Petersburg, Russia now also a brand of New Sensor Corp., Long Island City, New York, USA, manufacturing in Saratov, Russia WL – Westinghouse Electric Corp. For examples see below.