Frank's Electron tube Pages Tube Number Systems

European system after 1934 Philips system before 1934 Mazda numbering system Russian numbering system

European system after 1934

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	tetrode (or 2nd emmission tube EE1)
F	small-signal pentode
H	hexode or heptode
K	octode
L	power pentode
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)
1x	Y8A
2x	W8A, Loctal (except UY1 and D?2x types types which 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
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

MAZDA NUMBERING SYSTEM Signal valves

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

RUSSIAN NUMBERING SYSTEM

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
	Thyratrons
	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
	Transistors

Second element
	Diodes
	Double diodes
	Triodes
	Tetrodes
	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
	Rectifiers
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
	Glass
	HF glass, side leads
	Ceramic
	Miniature glass 19 and 22.5 mm
	Subminiature > 10 mm
	Subminiature 10mm
	Subminiature 4 mm
	Subminiature 6 mm
	lock-in-key
	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