All You Ever Needed to
Know--and Even More--
About European Tube-Numbering Schemes
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Collectors of vintage
radios take note:
Some popular, identical, tubes had more than 120 different names. But
also, some totally different tubes had the same names! Whether you
collect "bottles" for their historic interest, or want to restore a
European-made radio, you will find something of interest here.
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Nomenclature
The history of European
tube nomenclature can be divided into three phases:
Chaotic--at
the beginning of commercial tube production; Individual--varying
with the different manufacturers from the mid 20s and Systematic--from
about 1934--the onset of mass-production of tube-driven radio and
television receivers.
At the beginning of
commercial tube production, in the 20s, there was no perceivable
systematic approach. Tubes were marked with cryptic combinations of
letters and numbers or even with melodious names like SUPERDYN, POLYDION,
GIGANT or even TYP1. To decipher these tube types, you had to have the
corresponding data sheet. With the fast growing radio industry in the
early 1930s, the number of tube manufacturers increased rapidly. Some of
the companies used elaborate numbering schemes for their tubes. From
that time on, the most popular tubes manufactured in Europe were those
from Telefunken.
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Telefunken Numbering
Scheme
Some popular, identical,
tubes were available from different manufacturers under more than 120
different names. But it also happened that totally different tubes were
listed under the same name! This calamity led the major
manufacturers to create a new numbering scheme, introduced by Telefunken
and Valvo, in about 1934. Most companies generally adopted this scheme.
European tubes manufactured in the last 65 years can be identified by
means of this system. The filament data, tube construction, standard
application and base types are encoded in these tube numbers. Also, from
all of these combined data, the tube's approximate time of introduction
can be deduced.
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Common European
Numbering Scheme
Starting about 1938,
Armed Forces all over the world introduced their own numbering schemes.
At the beginning the aim was to select high quality tubes from
commercial production and to design manufacturer-independent
special-purpose tubes for military equipment. In the course of time,
advancing to higher frequencies necessitated a miniaturization of the
tubes and the development of entirely new tubes with special bases. I
include the German Armed Forces scheme here as it is very systematic.
These tubes were widely used and a lot of them were still available
after World War II. Those remaining tubes were used for civilian
equipment, and were reproduced and copied in the USA for a long time
after 1945.
I would like to mention
the Russian tubes that have flooded European hamfests in the last few
years. They use yet another separate numbering scheme. Those tubes,
duplicated in Russia, come under the same scheme as the equivalent
American tubes, but the letters are replaced by the corresponding
Cyrillic letters. For example, 6F8 becomes 6F8.
Most European tubes can
be analyzed with the help of the above schemes. There are of course many
more numbering schemes in use, especially as each manufacturer continued
to use its own individual coding system for special technology tubes, eg
Valvo for transmitting tubes. To list all these would fill a whole book.
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Table 1: Early German
tube-numbering system.
TELEFUNKEN; Germany; 1918 - 1934 |
Example: RENS 1284 d |
RENS |
12 |
8 |
4 |
d |
1. Construction |
2. Heater Current |
3. Serial Number |
4. Heater Voltage |
5. Special Attribute |
1.
The leading characters define the construction and/or the
application of the tube:
-
RE
receiver tube, directly heated, see 6.
-
REA
external control receiver tube
-
REN
receiver tube, indirectly heated
-
RES
receiver tube with screen grid, directly heated
-
RENS
receiver tube with screen grid, indirectly heated
-
REZ
twin triode, directly heated
-
RENZ
twin triode, indirectly heated
-
RGL
charging rectifier
-
RGN
mains Rectifier, N does not mean indirectly heated
-
RFG
television rectifier, serially numbered, see 6.
-
RG
high voltage rectifier, serially numbered, see 6.
-
RGQ
rectifier, gas filled, half wave, special number code, see
7.
-
RGQZ
rectifier, gas filled, full wave, special number code, see
7.
-
RSQ
rectifier, gas filled, grid controlled, special number code,
see 7.
-
RS
transmitter tube, serially numbered, see 6.
-
RV
output amplifier tube, serially numbered, see 6.
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2.
The first digit of a three digit number or the first two digits,
in case of a four digit number, define the heater current given
in 0.1 Ampere, eg 12 = 1.2 A, 0 means less than 0.1A, but not
always very exact, eg REN 804, REN 904 and REN 1004 have all 1.0
A at 4 V.
Exception: 18 means 0.18 Ampere, serially
heated. |
3.
This field is a serial number and has no special meaning |
4.
The last digit gives the heater voltage in volts, eg RENS 1234
with 1.2 A and 4 V heater.
Exception: Serially heated tubes with 0.18
A current, most of them have 20 V heater voltage independent of
number, eg RENS 1854 with 0.18 A and 20 V heater. |
5.
Additional letters define special attributes of the tube:
-
bi
bifilar filament
-
d
side contact for grid connection
-
n
neutro, low internal capacities
-
s
serial heating
-
t
Telefunken socket
-
w
2 side contacts
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6.
Exceptions: Very early Telefunken tubes (1918-1927) were
serially numbered and do not follow this numbering scheme, eg
RE1, RE2, RE11, RE20 and so on. Systematic coding starts at
RE034. Also RFG, RG, RV, and the popular RS transmitting tubes
are serially numbered and the number has no special meaning. |
7.
Note: The gas filled rectifiers RGQ, RGQZ, and RSQ are marked
with two numbers, eg RSQ7,5/2,5. Here, the first number
identifies the plate voltage in kV, the second the plate current
in A, i.e. 7.5 kV at 2.5 A. |
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Table 2: Common European
tube-numbering system.
Common Code, European Tube Manufacturers,
starting 1934 |
Example: ECC 801 S |
E |
CC |
801 |
S |
1. Heater Supply |
2. Construction |
3. Base |
4. Special Attribute |
1. The first letter identifies the heater
supply:
-
A
4 V, parallel
-
B
180 mA, DC, series
-
C
200 mA, series
-
D
1.4 V, DC, parallel (also 0.625, 1.2, or 1.25 V)
-
E
6.3 V, parallel
-
F
13 V, parallel
-
G
5V, parallel
-
H
150 mA, series
-
K
2 V, DC, parallel
-
M
1.9 V, DC, parallel (see 6.)
-
N
12.6 V, parallel (see 6.)
-
O
cold device, not heated
-
P
300 mA, series
-
Q
2.4 V, parallel (see 6.)
-
S
1.9 V, parallel (see 6.)
-
U
100 mA, series
-
V
50 mA, series
-
X
600 mA, series
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2. The second and the following letters
identify the construction and/or the application of the tube.
Multi system tubes have one letter for each system integrated in
the tube. The letters are sorted in alphabetical order:
-
A
diode, except rectifiers
-
B
twin diode with common cathode, except rectifiers
-
C
triode, except power triodes
-
D
power triode
-
E
tetrode, except power tetrodes
-
F
pentode, except power pentodes
-
H
hexode or heptode, hexode mode
-
K
octode or heptode, octode mode
-
L
power pentode or power tetrode
-
M
tuning indicator, magic eye
-
P
secondary emission tube, used as 3rd letter only
-
Q
enneode
-
X
full wave rectifier, gas filled
-
Y
half wave rectifier, high vacuum
-
Z
full wave rectifier, high vacuum
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3. The digits identify the base. Additionally
for tetrodes and pentodes, odd-numbers identify remote-cutoff
tubes, even-numbers identify tubes with a linear
characteristics. The numbers are also used to distinguish tubes
that would otherwise have identical numbers, eg EF83 and EF85.
Both are remote-cutoff signal pentodes with 6.3V heater on a B9A
base. But they are different; the first is an af, the second an
rf pentode. The number also reflects the approximate date of
market introduction. Early tubes have small numbers.
-
1
... 10
pin type, side contact and others
-
11
... 19
metal tube Y8A
-
20
...
29
8 pin loctal and octal B8G, K8A
-
30 ... 39
octal K8A
-
40 ... 49
Rimlock B8A
-
50 ... 60
9 pin loctal
-
61 ... 79
subminiature
-
80 ...
89
noval B9A
-
90
... 99
miniature B7G
-
110
... 119
metal tube Y8A
-
140
... 149
Rimlock B8A
-
150
... 159
metal tube Y10A
-
180
... 189
noval B9A
-
190
... 199
miniature B7G
-
200
... 299
decal B10C
-
410 ... 419
Rimlock B8A
-
500 ... 599
mag-noval B9D
-
700 ... 799
subminiature
-
800 ... 899
noval B9A
-
900 ... 999
miniature B7G
Four digit numbers identify tubes for
professional applications. The first digit labels the base: (4,
6, 7 are used for other base constructions)
-
1xxx
subminiature
-
2xxx
decal B10C
-
3xxx
octal K8A
-
5xxx
mag-noval--novar--B9D
-
8xxx
noval B9A
-
9xxx
miniature B7G
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4. A large number of special applications, eg
in telecommunications, medical equipment, and early computers
required special tubes with higher reliability under rough
working conditions. To fulfill such requirements these tubes
were manufactured with special production processes and checked
with special test methods. These tubes were superior by up to
five features: higher reliability, longer lifetime, tighter
tolerances, vibration and shock proof, and special cathodes to
withstand longer periods of heating without plate current. The
pins of special tubes are very often gold coated. See also 5.
Exceptions.
S special tube, eg EL 803 S = special EL
803 |
Exceptions: Most special purpose tubes are
labeled by exchanging construction and base codes. The meaning
of letters and digits remain the same:
E 88 CC = special ECC 88 |
The heater code letters M, N, Q, and S were
used to mark special armed forces tubes. They are not very
common. They were substituted for tubes following a special
German armed forces scheme in 1938. The number is a sequence
number with no meaning for a base. Example: NF 2 , SF 1, most
are Telefunken |
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Table 3: Germany Air Force
special-tube numbering-system
Armed Forces, Air Force, Germany, 1938
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Example: LD 1 |
L |
D |
1 |
1. Air Force |
2. Construction |
3. Number |
1. The first letter L identifies special air
force tubes.
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2. The second and the following letters
identify the construction and/or the application of the tube:
-
B
cathode ray tube
-
D
decimeter transmitting tube (f >300 MHz)
-
F
photocell, other optical devices
-
G
diode, rectifier, pulse generators
-
K
stabilizer, regulating resistor, glow lamp
-
M
magnetron
-
S
transmitting tube (f <300 MHz)
-
V
amplifier tube (f<300 MHz)
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3. Numbers 1--18 are sequence numbers,
example: LV 1
For transmitting and amplifier tubes,
numbers from 30--1500 identify the maximum plate dissipation in
watts, eg LS300.
For cathode ray tubes, the first number
gives the screen diameter, the second the tube length in cm, eg
LB 7/15. |
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Table 4: German Army and Navy tube-numbering system.
Armed Forces, Army and Navy, Germany, 1938
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Example: RV 12 P 2000 A |
R |
V |
12 |
P |
2000 |
A |
1. Army, Navy |
2. Application |
3. Heater |
4. Construction |
5. Code Number |
6. Option |
1. The first letter R identifies special army
and navy tubes.
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2. The second letter identifies the
application of the tube:
-
D
decimeter transmitting and receiving tube (f >300 MHz)
-
G
diode, rectifier
-
L
power amplifier, transmitting tube
-
K
cathode ray tube
-
V
receiving and amplifying tube
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3. The number gives the heater voltage in
volts:
-
1
1.2 V
-
1,5
1.5 V -- 1.8 V
-
2
1.9 V
-
2,4
2.4 V
-
4
4.0 V
-
4,2
4.2 V
-
4,8
4.8 V
-
12
12.0 V
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4. The letter shows the construction of the
tube:
-
A
magic eye, cathode ray indicator
-
D
twin diode
-
G
rectifier
-
H
hexode
-
L
klystron
-
M
magnetron
-
P
pentode
-
T
triode
-
MM
double magnetic deflection, only for cathode ray tubes
-
MS
magnetic and electrostatic deflection, only for cathode ray
tubes
-
SS
double electrostatic deflection, only for cathode ray tubes
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5. The code number has different meanings
depending on the construction of the tube:
For pentodes it is the amplification
factor, eg RV 12 P 2000 (μ = 2000)
Remote cutoff pentodes have a 1 in the
last digit, eg RV 12 P 2001
For power tubes the number shows the plate
dissipation, eg RL 12 P 35 (35 W)
For power rectifiers the number shows the
plate current, eg RG 12 D 60 (60 mA)
For rf rectifiers it is a sequence number,
eg RG 2,4 D 1
For all other tubes it is a sequence
number , eg RK 12 SS 1
From end of 1942 new tubes where marked
with small letters, eg RV 12 P a |
6. Baseless variants are marked with an
additional capital letter A, eg RL 2 P 3 A |
To make changing tubes easier, the most
common tubes were additionally color-coded, eg RV12P2000 white,
RV12P2001 green, RV12H300 orange.
From the number codes printed on the tube,
the production place and the date can be read. The date on the
base is the production date, the date on the glass shows the
date of the final test, eg 22/41 = 22nd week 1941 |
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