International Research
& Consulting


Vacuum Tube Numbering Schemes,

Bases & Bulbs

Compiled by Jürgen Ewert

- Woodstock Vermont - USA -


based on information from:

Duncan Amps http://www.duncanamps.com/

Frank’s http://www.tubedata.org/

Klausmobile  http://www.klausmobile.narod.ru/

- 070420 -


American | British | British CV | European | European (old) | Japanese | French | Russian | | Bases | Bulbs | Glossar


American - USA - RETMA system

Radio Electronics Television Manufacturers Association

American | British | British CV | European | European (old) | Japanese | French | Russian | Bases | Bulbs | Glossar

Go to the Top


 


First number: filament voltage

 

0

Cold cathode (e.g. voltage regulator tube).

 

1

0.1 - 2.0

 

2

2.1 - 2.9

 

3

3.0 - 3.9

 

n

n.0 - n.9

 


Letter or letters: sequence code

 

One or two letters to indicate the sequence code.  When the single character codes were used up, double character codes were introduced.

Note that U - Z generally (but not always) as the only character, or last character, are used for rectifiers

 

 


Final number: Element count

 

The number of elements in the tube, the filament counting as 1.  For example, the 6SN7 has two cathodes, two grids, two plates, and a filament.

 


Additional letters:

 

A

Controlled heater warmup time, although can also be used to denote increased ratings or performance over and above the non-A model.

 

B

Improved ratings/performance.

 

C

Ditto.

 

G

Glass bulb.

 

GT

Glass tubular.

 

W

Ruggedised version.

 

X

Low loss ceramic base.

 

Y

Low loss phenolic base.

 


Examples:

 

6SN7GT:  Filament rating is between 6.0 - 6.9V, SN=sequence code, 7 elements, glass tubular envelope.

 

6V6GTY: Filament rating is between 6.0 - 6.9V, V=sequence code, 6 elements, glass tubular envelope, low loss phenolic base.

 

12AY7:  Filament rating is between 12.0 - 12.9V, AY=sequence code, 7 elements.

 


Brimar

- British designation code for Receiving Valves -

American | British | British CV | European | European (old) | Japanese | French | Russian | Bases | Bulbs | Glossar

Go to the Top


 

First Number: 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

19

 

20

Hexode/Heptode with Triode

 

 

Letter: 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

 


CV numbers

American | British | British CV | European | European (old) | Japanese | French | Russian | Bases | Bulbs | Glossar

Go to the Top


 

 

Format is CV followed by up to 5 digits, e.g. CV4004. 

Used by the British Military to codify vacuum tubes, gas tubes, and latterly, some semiconductor devices.

 

CV numbers can be directly mapped onto NATO numbers, as 5960-XX-000-YYYY where XX is the country code, and YYYY is the CV number. 

For example, 5960-99-000-4004 = CV4004 (12AX7WA), with 99 indicating country of origin as UK.

 


European (Mullard/Philips)
 
- after 1934 -
(pro-electron)

American | British | British CV | European | European (old) | Japanese | French | Russian | Bases | Bulbs | Glossar

Go to the Top


 

 


First letter: Filament

 

0

 tubes without filament

 

A

 4V

 

B

 0.18A (series)

 

C

 0.2A (series)

 

 1.4V (series/parallel)

 

E

 6.3V (series/parallel)

 

F

 12.6V

 

G

 5V (parallel)

 

H

 0.15A (series)

 

I

 20V AC/DC parallel connection

 

K

 2V battery

 

L

 0.45A (series)

 

O

 0.15A AC/DC series connection

 

P

 0.3A (series)

 

U

 0.1A (series)

 

V

 0.05A (series)

 

X

 0.6A (series)

 

Y

 0.45A (series)

 


Second and subsequent letters: tube systems, construction

 

A

  Diode - single detection diode (excluding rectifiers)

 

B

 Double detection diode (excluding rectifiers)

 

C

 Triode (small-signal, not power)

 

D

 Power output triode

 

E

 Tetrode (small-signal, not power)

 

F

 Pentode (small-signal, not power)

 

L

 Power output tetrode or pentode

 

H

 Hexode or heptode (of the hexode type)

 

K

 Octode or heptode (of the octode type)

 

M

 Tuning indicator

 

N

 Thyratron

 

Q

 Nonode. Enneode

 

W

 Diode single gasfilled rectifier

 

X

 Diode double gasfilled rectifier

 

Y

 Half wave rectifier

 

Z

 Full wave rectifier

 


First digit: Basing, Socket

 

1

 Miscellaneous

 

2

 Miniature 10 pin.

 

3

 International octal

 

4

 Miniature 8-pin (B8A)

 

5

 Magnoval (B9D)

 

6

 Subminiature

 

7

 Subminor 8p

 

8

 Noval (B9A)

 

9

 Miniature (B7G)

 


Remaining digits: sequence number

 

*   Note that signal pentodes and tetrodes which end in even numbers are sharp cutoff tubes. 

Those ending in odd numbers, are remote cutoff tubes.

 


Examples

 

EF86   6.3V filament, signal pentode, Noval base, sharp cutoff.

 

GZ34  5V filament, full wave rectifier, International Octal base.

 

PCL82: 0.3A series string filament, signal triode + power pentode, Noval base.

 

E88CC:  Special Quality version of the ECC88, swapping of the second and third field was commonplace to denote "SQ" tubes.

 


European (old Philips) -
- before 1934 -

American | British | British CV | European | European (old) | Japanese | French | Russian | Bases | Bulbs | Glossar

Go to the Top


 


Frank Philipse kindly translated the Dutch text to English from:

Gegevens en schakelingen van moderne ontvang-en versterkerbuizen. (1940 Philips).

Frank says "Initially type coding of Philips tubes was done in the following way: The type number consisted of a capital letter, followed by 3 or 4 digits. The capital letter indicated the heater current as follows:"

 


First letter: Heater current

 

A

 0.06 to 0.10A

 

B

 0.10 to 0.20A

 

C

 0.20 to 0.40A

 

D

 0.40 to 0.70A

 

E

 0.70 to 1.25A

 

F

 1.25A and higher

 

 

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