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VACUUM TUBE INFORMATION

USA code
UK Military
German Army
Mullard Code
GEC Code
Philips codes before 1934
Mazda Code



USA code:

Codes consist of digits, letters, digits, possibly further letters

First digits give heater _voltage_ rating, with the exception that the codes 7 and 14 are
used to indicate 6.3V and 12.6V valves with a locatal base.

Letters specify the type of valve, but there appears to be no consitency of coding. S often
indicates a single-ended (no top cap) version of an earlier valve with such a cap

Second digits give either the number of active electrodes, or the number of external
connections.

Final letters often specify the type of envelope. The code is
G - large glass envelope.
GC - Glass Compact - a tubular glass envelope
GT - Glass Tubular - the smallest glass envelope
M - Metal Envelope
WA - High Quality version

VT numbers are USA miliary valves. Unfortunately no way to decode.



UK Airforce:

Code consists of letters followed by digits. The letters have the following meanings:

VCR - valve cathode ray (CRT)
VGT - valve gas triode (thyratron)
VI - valve indicator (tuning eye)
VR - valve receiving (general RX valve)
VS - valve stabilising (gas stabiliser)
VT - valve transmitting (general TX valve)
VU - rectifier

UK Army:

Again, letters followed by digits. The letter part gives the valve type as follows:

ACR - Army CRT
AR - Army RX valve
ARD - Army RX Diode
ARDD - Army RX Double Diode
ARH - Army RX Hexode
ARP - Army RX pentode
ARS - Army RX Screen Grid (Tetrode)
ARTH - Army RX Triode Hexode
ARTP - Army RX Triode Pentode
AT - Army TX valve
ATP - Army TX Pentode
ATS - Army TX Screen Grid (Tetrode)
AU - Army Rectifier
AW - Army Stabiliser

UK Navy:

Another Letters followed by digits code. The letters give the type of the valve, as follows:

NC - Navy CRT
NGT - Navy Gas Triode (thyratron)
NR - Navy RX valve
NT - Navy TX valve
NU - Navy Rectifier

Others:

CV (common valve) numbers replaced the above 3 codes during WW2. There is no way to
decode these.

BVA numbers (British Valve Association) were assigned to valves used for civillian
replacements in WW2.



German airforce:

standard number: LXY

with Y a number and X:
B = kathodebeam tube
D = sendtube (Hf)
F = ionoscope, photocel, and more
G = rectifier
K = stabiliser, ballast
M = magnetic deflection tube
S = sendtube (Lf)
V = amplification tube (Lf)

Example: LD2 is an airforce Hf send tube, LV3 is an airforce Lf amplification tube.

German army:

Standard number: RXNNYMM

number is build up with usage (X), heather voltage (NN), tube type (Y) and a number (MM),
giving the amplification of pretubes and the maximum power dissipation of powertubes.
And with X:
D = Hf tube
G = rectifier
L = Powertube or sendtube
K = kathode beam tube
V = receiver tube

And Y:
A = magic eye
D = full wave rectifier
G = rectifier
H = hexode
L = "laufzeit" tube
M = magnetic deflection tube
MM = double magnetic deflection tube
MS = magnetic and electric deflection tube
P = pentode
SS = double electric deflection tube
T = triode

Example: RL12T15 is 12 volt heated 15 W power triode, RV12P2000 is a 12 volt heated
receiver pentode with a theoretically mu of 2000



Mullard Code (Used for UK and European valves):

 This consists of a string of letters followed by a string of digits. E.g. ECC83, EL34 First letter gives heater rating

 A - 4V
C - 200mA series connection
D - 1.4V (Normally directly heated)
E - 6.3V (By far the most common)
G - 5V
H - 450mA series connection
K - 2V
O - cold cathode/semiconductor device
P - 300mA series connection
U - 100mA series connection

 Rest of the letters give the types of device in the valve. They are normally listed in alphabetical order.

 A - signal diode
AA - 2 diodes with separate cathode
B - double diode with common cathode
C - signal triode
D - power triode (e.g. TV shunt stabiliser)
E - signal tetrode
F - signal pentode
H - hexode/heptode (Hexode structure)
K - heptode or octode (octode structure)
L - output tetrode, beam tetrode, or pentode
M - magic eye (seeing eye ? ) tuning indicator
N - gas filled triode / thyratron
Q - Nonode
X - gas-filled full-wave rectifier/double diode
Y - half wave rectifier/single diode
Z - vacuum full-wave rectifier/double diode

 Digits indicate the base (first digit) and a code to distiguish valves that would otherwise have identical numbers (e.g. EL84 and EL85 are both output pentodes with a 6.3V heater on a B9A base. They are otherwise different).

 First digit
0,1 - misc base - P base, side contact, etc
2 - B8B Loctal
3 - International Octal
4 - B8A
5 - B9G, B9D, misc
6,7 - Subminiatures
8 - B9A
9 - B7G



GEC Code (Marconi/Osram Brands also):

Consist of Letter (or Letters) followed by digits (e.g. L63, KT88). The digits are simply to
distinguish similar valves (like all triodes), and cannot be decoded. The letters have the
following meaning.

A - Industrial valve (Maybe almost anything - power triode, etc)
B - Double triode
D - Diode
GU - Gas-filled rectifier
GT - Gas Triode (Thyratron)
H - signal triode (high impedance)
KT - Kinkless tetrode (beam tetrode)
L - signal triode (low impendance)
MU - indirectly heated rectifier
N - output pentode
P - output triode
QP - Quiescent push-pull double pentode
S - Tetrode (Screen Grid Valve)
U - rectifier
VS - variable mu tetrode
W - variable mu pentode
X - triode hexode, heptode, octode, frequency changer
Y - tuning indicator
Z - HF pentode



Philips codes before 1934:

Compiled by Frank Philipse. The old Philips tube code consists of a letter followed by 2 or
more digits and sometimes a suffix letter.

1st letter gives 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 - higher than 1.25 A

2nd digit or 2nd+3rd digits gives the heather voltage.

x - heater voltage < 10 V
xx - heater voltage >= 10V

The last 2 digits give the type of device in the tube.

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

The suffix letter gives additional information about the tube.

H - ?
N - New, later version
S - Special, enhanced type
T - ?

Examples

E499 - triode, If=1A , Vf=4V, gain=99
F443N - power pentode, If=2A, Vf=4V
B2046 - hf pentode, If=0.18A, Vf=20V



Mazda Code:

Consists of digits, Letters, digits. Do not confuse with a US code.

First digits give heater voltage, except that 10, 20, 30 indicate 100mA, 200mA, 300mA for
series connection.

Letters give type of valve
C - Frequency changer
D - signal diode
F - signal tetrode/pentode
K - Thyratron
L - signal triode
M - tuning indicator
P - output tetrode/pentode
U - half wave rectifier
UU - full wave rectifier

Mazda codes tend not to double up letters - L is used for mulitple triodes also.

Final digits distinguish between otherwise identical codes.


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