Mullard-Philips tube designation
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In Europe, the principal method of numbering vacuum tubes was the nomenclature developed and used by Mullard in the UK and applied Europe-wide thanks to their parentage by Philips who had subsidiaries in Germany (Valvo) and France. This system, in use until the end of the tube era, sought to allocate meaningful codes to tubes with a clear understanding of their function.
It also allowed for easy cross-referencing with the American RETMA tube designation and other systems in use such as Marconi-Osram tube designation, and military numbering systems such as Common Valve (CV) numbering in the UK and the JAN tube designation in the USA.
Although the nomenclature was agreed amongst all the tube manufacturers in Europe there were exceptions in the UK with MOV (Marconi-Osram) and Brimar (STC) adopting their own systems. The vast majority of MOV valves (tubes) were copies of RCA types (as the two companies had cross-licencing agreements) but with a British designation, thus a MOV X63 valve was the same as an RCA 6A8 tube, whilst Brimar, which stood for "British Manufactured American Radio" (valves), used all American designations. Brimar/STC was a UK subsidiary of the American giant ITT International Telephone and Telegraph. Another British manufacturer, Mazda, had a different designation system again.
Special quality tubes for military use were sometimes identified by placing the numerical part of the designation between the heater rating and the tube type. For example an EF80 manufactured as a special quality tube would be designated 'E80F'. The system was not universal as other special quality designation systems existed. An EF91, in its special quality version was designated 'M8084' (the 'M' meant Mullard).
- 1st letter: Heater rating
- A 4V
- B 180mA AC/DC
- C 200mA AC/DC
- D 0.5 - 1.5V
- E 6.3V AC
- F 12.6V car battery
- G 5V
- H 150mA AC/DC
- I 20V
- K 2V DC
- L 450mA AC/DC
- O Cold cathode
- P 300mA AC/DC
- T 7.4V; Misc.
- U 100mA AC/DC
- V 50mA AC/DC
- X 600mA AC/DC
- Y 450mA AC/DC
- Remaining letters: Type(s) of device(s)
- A diode (excluding rectifiers)
- AA double diode with separate cathodes (excluding rectifiers)
- B double diode with common cathode (excluding rectifiers)
- C Triode (excluding power triodes)
- D Power triode
- E Tetrode (excluding power valves)
- F Pentode (excluding power valves)
- H Hexode or Heptode (of the Hexode type)
- K Octode or Heptode (of the Octode type)
- L Output tetrode, beam tetrode or pentode
- M Tuning indicator
- N Gas filled triode or thyratron
- P Secondary emission
- Q Nonode
- S TV sync oscillator
- T Beam tube
- W Gas rectifier
- X Gas fullwave rectifier
- Y Halfwave rectifier
- Z Fullwave rectifier
- Figures: Base type & serial number
- 1-10 Various side contacts, octals, specials (exceptions are ECH3G, ECH4G, EK2G, EL3G, KK2G which have octal bases)
- 11-19 8-pin German octal
- 20-29 Loctal B8G; some octal; some 8-way side contact (Exceptions are DAC21, DF21, DF22, DL21, DLL21 which have octal bases)
- 30-39 International Octal
- 40-49 Rimlok B8A
- 50-59 B9G; Loctal B8G; Octal; 3-pin glass; Disk-seal; German 10-pin with spigot; min. 4-pin; B26A; Magnoval B9D
- 60-69 B9G; some submins
- 70-79 Loctal Lorenz; wire submins
- 80-89 Noval B9A
- 90-99 B7G
- 100-109 B7G; Wermacht base; German PTT base
- 110-119 8-pin German octal; Rimlok B8A
- 130-139 Octal
- 150-159 German 10-pin with spigot; 10-pin glass with one big pin; Octal
- 160-169 Flat wire submins; 8-pin German octal
- 170-179 RFT 8-pin; RFT 11-pin all glass with one offset pin
- 180-189 Noval B9A
- 190-199 B7G
- 200-209 Decal B10B
- 230-239 Octal
- 270-279 RFT 11-pin all glass with one offset pin
- 280-289 Noval B9A
- 300-399 Octal
- 400-499 Rimlok B8A
- 500-529 Magnoval B9D; Novar
- 600-699 Flat wire-ended
- 700-799 Round wire-ended
- 800-899 Noval B9A
- 900-999 B7G
- 1000- Round wire-ended; special nuvistor
- 2000- Decal B10B
- 3000- Octal
- 5000- Magnoval B9D
- 8000- Noval B9A
