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  Tube Number Systems  

  • European system after 1934
  • Philips system before 1934
  • Mazda numbering system
  • Russian numbering system
  • Brimar type designation code
  • Tesla numbering system
  • European system after 1934 (pro-electron)
    See also: Type Designation Code from "Preferred Types of Electron Tubes 1967".
    1st letter heater indication
    0 tubes without filament
    A 4 V AC parallel connection
    B 180 mA DC
    C 200 mA AC/DC series or parallel connection
    D <= 1.4 V DC dry-battery, parallel connection
    E 6.3 V AC or carbattery, parallel connection
    F 13 V carbattery
    G 5V AC parallel connection
    H early: 4V DC battery. later: 150mA AC/DC series connection
    I 20V AC/DC parallel connection
    K 2 V battery
    O 150 mA AC/DC series connection
    P 300 mA AC/DC series connection
    U 100 mA AC/DC series connection
    V 50mA AC/DC series connection
    X 600 mA AC/DC series connection
    Y 450 mA AC/DC series connection

    2nd+next letters tube systems
    A single detection diode
    B double detection diode
    C small-signal triode
    D power triode
    E small-signal tetrode (or 2nd emmission tube EE1)
    F small-signal pentode
    H hexode or heptode
    K octode
    L power pentode or power tetrode
    M indicator tube
    N thyratron
    Q enneode
    W single gasfilled rectifier diode
    X double gasfilled rectifier diode
    Y single vacuum rectifier diode
    Z double vacuum rectifier diode

    digits socket & order
    x P (some are V) (except U-series (e.g.UBL1), those are octal)
    1x Y8A
    2x W8A, Loctal (except D-series (e.g. DL21), those are octal)
    3x K8A, A08, octal
    4x A8A, B8A, Rimlock
    5x T9A, B9G, Enne-al and C2R and some special bases
    6x Subminiature
    7x Subminor8p
    8x, 18x, 8xx B9A, noval
    9x, 19x, 9xx B7G, miniature-7p (Exception: The ECC99 is a poorly chosen tube type number, as it comes with a noval base.)
    2xx, 2xxx decal
    5xx B9D, magnoval

    Examples Description
    CBL1 output pentode with dual detection diode, heater 200mA, P base
    EABC80 tripple signal diode with triode, heater 6.3V, noval base
    ECC83 dual triode, heater 6.3V, noval base
    GZ34 dual vacuum rectifier, heater 5V, octal base
    PFL200 pentode and power pentode, heater 300mA, decal base
    UCH21 triode and heptode, heater 100mA, base loctal

    Philips system before 1934
    1st letter heater current
    A 0.06 to 0.10 A
    B 0.10 to 0.20 A
    C 0.20 to 0.40 A
    D 0.40 to 0.70 A
    E 0.70 to 1.25 A
    F > 1.25 A

    2nd digit or 2nd+3rd digits heater voltage
    x heater voltage < 10 V
    xx heater voltage >= 10V

    last 2 digits description
    xx amplification factor for triodes
    41, 51 etc tetrode with spacecharge grid (2nd grid is control grid)
    42, 52 etc tetrode with screen grid (1st grid is control grid)
    43, 53 etc power pentode
    44, 54 etc triode with diode or tetrode with diode
    45, 55 etc hf tetrode with variable gain
    46, 56 etc hf pentode
    47, 57 etc hf pentode with variable gain
    48, 58 etc hexode frequency changer
    49, 59 etc hexode with variable gain

    Suffix letter Description
    H ?
    N ? New, later version
    S ? Series connection allowed
    T ?

    Examples Bases usually: A or O
    E499 triode, If=1A , Vf=4V, gain=99
    F443N power pentode, If=2A, Vf=4V
    B2046 hf pentode, If=0.18A, Vf=20V

    First number indicates heater or filament rating
    1 1.4V (parallel or series)
    6 6.3V (parallel or series)
    10 0.1A (series)
    20 0.2A (series)
    30 0.3A (series)
    Following letter or letter sequence indicates class of valve
    C Frequency changer with special oscillator section
    D Signal diode(s)
    F Voltage amplifier tetrode or pentode
    FD Voltage amplifier tetrode or pentode with diode(s)
    FL Voltage amplifier tetrode or pentode with voltage amplifier triode
    K Small gas triode or tetrode
    L Voltage amplifier triode or double triode including oscillator triode
    LD Voltage amplifier triode with diode(s)
    M Tuning indicator
    P Power amplifier valve, tetrode or pentode
    PL Power amplifier valve, tetrode or pentode with voltage amplifier triode
    Final number distinguishes between different valves in the same class

    MAZDA NUMBERING SYSTEM Power rectifier valves

    Letters indicates heater or filament rating
    U High vacuum half-wave
    UU High vacuum full-wave
    Final number distinguishes between different valves in the same class

    The regulation GOST 5461-59 applies to tubes manufactured from 1959 and semiconductors manufactured from 1959 to 1963. Every symbol consists of four elements. If an element is absent, a dash should be written at its place.
    Note: There are exceptions. Not all Russian tubes are numbered according this system.

    First element
    Generator (transmitting) tubes up to 25 MHz
    UKF generator (transmitting) tubes 25-600 MHz
    Centimeter range generation (transmitting) tubes
    Modulator tubes
    High power rectifiers
    Voltage stabilizers
    Current stabilizers
    Gas-discharge rectifiers
    Mercury gas-discharge rectifiers
    , Photocells and photomultipliers
    Approximate (usually full volts) heater voltage Receiving tubes
    Screen diameter in cm Picture tubes
    Semiconductor diodes

    Second element
    Double diodes
    Power pentodes and tetrodes
    Remote cut-off pentodes
    Sharp cut-off pentodes
    Secondary emission pentodes
    Mixing tubes with two signal grids
    Pentodes with one or two diodes
    Triodes with one or more diodes
    Tuning indicators
    Triodes with hexode, heptode or octode
    Double triodes
    Double tetrodes and pentodes
    Triode - pentodes
    Type sequence number Gas-discharge tubes, power rectifiers
    Gas thyratrons
    Mercury thyratrons
    Cold cathode thyratrons
    Oscillograph tubes with electrostatic deflection
    Oscillograph tubes with electromagnetic deflection
    TV picture tubes
    Type sequence number Semiconductors

    Third element
    Receiving, picture, generator and modulator tubes
    voltage and current stabilizers
    photocells and photomultipliers
    cold cathode thyratrons
    Type sequence number
    Semiconductors Subtype, group (letter)

    Fourth element
    none Metal Receiving tubes; voltage and current stabilizers
    HF glass, side leads
    Miniature glass 19 and 22.5 mm
    Subminiature > 10 mm
    Subminiature 10mm
    Subminiature 4 mm
    Subminiature 6 mm
    Disc leads
    Water cooled Generator (transmitting) and modulator tubes
    Air cooled
    letter Luminophor color code Picture tubes
    X/Y X = average current in A
    Y = reverse voltage amplitude in kV
    Thyratrons (non cold cathode), Gas-discharge, power rectifiers

    After symbol dash and postfix of one or more letters may be added:
    high reliability tube (military)
    long life tube (military)
    designed for impulse operation
    vibration resistant

    Current Regulators
    [A][V1-V2] [A] is the current (in amperes) and [V1-V2] is voltage range

    Brimar type designation code for Receiving Valves
    First Number Indicates the Construction
    1 Half Wave Rectifiers
    2 Diodes. Single
    3 Triodes, Output
    4 Triodes, High-mu
    5 Tetrodes, Straight
    6 Tetrodes, Vari-mu
    7 Pentodes, Power and Video
    8 Pentodes, R.F. Straight
    9 Pentodes, R.F. Vari-mu
    10 Diodes, Double
    11 Triodes with Double Diode
    12 Pentodes, A.F. with Double Diode
    13 Triodes Double, High-mu
    14 Triodes Double, Class B Output
    15 Heptodes
    16 Triodes Output, D.C. Coupled
    17 Pentodes R.F. with Double Diode
    18 Pentodes with Triode
    20 Hexode/Heptode with Triode

    Letter Indicates the heater rating
    A 3.6 to 4.4V Indirectly Heated
    B 2V Directly Heated
    C Directly Heated other then 2 or 4V
    D All other heater ratings Indirectly Heated other then 4V

    Number Serial number
    Serial Numbers are allocated in chronological order as new valve types are introduced

    leading digits heater indication
      Approximate (usually full volts) heater voltage

    middle letters tube systems (a subset of European system)
    A single detection diode
    B double detection diode
    C small-signal triode
    F small-signal pentode
    H hexode or heptode
    L power pentode or power tetrode
    M indicator tube
    Y single vacuum rectifier diode
    Z double vacuum rectifier diode

    trailing digits socket and order
    1x octal K8A, A08
    2x loctal W8A
    3x heptal B7G
    4x noval B9A
    5x special; mostly, 9 out of 10 pins 1.25mm on a circle diameter 25mm
    6x submagnal B11A (no actual tube in this system known)
    7x duodecal B12A (no actual tube in this system known)
    8x diheptal B14A (no actual tube in this system known)
    9x free wires

    Examples Description
    35Y31 Single rectifier, heptal (7pin miniature) socket; 35V/150mA series heater; otherwise, European UY1N in heptal format
    4L20 HF power pentode; filament 2x2.4V / 325mA, Soviet 4П1Л; German RL4,2P6 in loctal format
    6CC42 VHF double triode; 6.3V/350mA heater, noval; equivalent to 2C51
    6F24 Telecom pentode, 6.3V/450mA heater, loctal; not similar to later Mazda's 6F24
    1M90 Subminiature indicator tube, 1.4V/25 mA filament, European DM70

    leading 2 digits screen specification
      Approximate screen diameter or diagonal, in centimeters

    3rd digit type order

    middle letters focusing and deflection
    QP magnetic focusing, magnetic deflection (early TV tubes)
    QQ electrostatic focusig, magnetic deflection (later TV tubes)
    QR electrostatic focusing and deflection (oscilloscope tubes)

    trailing digits screen color and persistence

    Examples Description
    7QR20 Oscilloscope tube, 7cm diameter, green fluorescence, middle persistence
    430QP44 TV tube, 43cm diagonal, magnetic focusing and deflection, white fluorescence, pentode system, 90 degrees deflection angle
    430QQ44 TV tube, 43cm diagonal, electrostatic focusing, magnetic deflection, white fluorescence, tetrode system, 110 degrees deflection angle
    431QQ44 Identical to 430QQ44, except with metal-backed screen

    1st letter tube category
    R HF tube
    Z modulator tube
    U gas-filled power rectifier

    2nd letter tube systems
      see receiving tubes

    digits power level
      Anode dissipation in watts or kilowatts

    trailing letters cooling system (optional 1st letter), tube order
    X air cooling
    Y water cooling

    Examples Description
    RA0007B Ballast diode controlled by filament current; max anode current 0.7mA
    RD1,5XA Air-cooled power triode up to 30MHz, 1.5kW anode dissipation
    RE40AK KT88 by Tesla Vršovive (in production)