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Cathode Ray Tubes

European - One letter followed by two groups of numbers and one or two letters: Ann-nnAA

1st letter A TV display for domestic use
D Single trace oscilloscope tube
E Multiple trace oscilloscope tube
F Radar display, direct view
L Display storage tube
M TV display for professional use, direct view
P Display tube for professional use, projection
Q Flying spot scanner

1st figure group: for rectangular screens the diagnonal in cm; for round screens the diameter in cm.

2nd group of figures is the serial number

Final letters indicate the screen properties:

A Reddish purple, purple, bluish purple
B Purplish blue, blue, greenish blue
D Blue-green
G Blueish green, green, yellowish green
K Yellow-green
L Orange, orange-pink
R Reddish orange, red, pink, purplish pink, purplish red, red-purple
V Greenish yellow, yellow, yellowish orange
W 'standard white' TV tube phosphor
X Tri-colour screen
Y Greenish-yellow, yellow, yellowish-orange

2nd letter is a serial letter to denote other specific difference in screen properties.

Designation EIA number Colour Persistence
New Old Fluorescence Phosphorescence
BA C   Purplish blue   Very short
BC V   Purplish blue   Killed
BE B P11 Blue Blue Medium short
BF U   Purplish blue   Medium short
GE K P24 Green Green Short
GH H P31 Green Green Medium short
GJ G P1 Yellowish green Yellowish green Medium
GK G   Yellowish green Yellowish green Medium
GL N P2 Yellowish green Yellowish green Medium short
GM P P7 Purplish blue Yellowish green Long
GP   P2 Bluish green Green Medium short
GR   P39 Green Green Long
GU     White White Very short
LA D   Orange Orange Medium
LB E   Orange Orange Long
LC F   Orange Orange Very long
LD L P33 Orange Orange Very long
W W P4 White    
X X P22 Tri-colour screen    
YA Y   Yellowish orange Yellowish orange Medium

Type GK is used in projection screens.

CRTs - European - old system

Two letters followed by two sets of figures

1st letter indicates type of focussing and deflection

A Electrostatic focussing and electromagnetic deflection
D Electrostatic focussing and deflection
M Electromagnetic focussing and deflection

2nd letter indicates the phosphor.

B Blue fluorescence and phosphorescence, short persistence
C Blue/Violet fluorescence and phosphorescence, very short persistence
F Orange fluorescence and phosphorescence, very long persistence
G Green fluorescence and phosphorescence, medium persistence
L Orange fluorescence and phosphorescence, long persistence
N Blue-green flouorescence and green phosphorescence, long persistence
P Blue fluorescence and green phosphorescence, very long persistence
R Greenish-yellow fluorescence and yellow phosphorescence, long persistence
W Picture tube, white screen colour, short persistence

1st figure group is the screen diameter in cm for round tubes, or the screen diagonal in cm for rectangular tubes.

2nd figure group is the serial number.

CRTs - American RETMA system

Figure(s), letter(s), P, figure(s)

1st figure(s) For round screen, diameter in inches; for rectangular screen, diagonal in inches
1st letter(s) Serial coding applying to tubes of the same diameter or diagonal
P followed by a number: Screen characteristics See Screen Characteristics
Suffix letter, if present Indicates a later and modified version (A, B, C etc). The letter W indicates a military type, and preceeds any further suffix letter.

Mazda TV tube code

Starting with a C, followed by the screen size in mm, the 2 letters and a number. 1st letter=deflection M=magnetic, S=electrostatic; 2nd letter is screen colour B=blue, G=green, R=radar long-persistence, W=white. Final number is sequential.

Screen characteristics

Designation Colour/persistence Application
P1 Green / Medium General purpose oscilloscope
P2 Blue-Green / Green / Long Special oscilloscopes and radar displays
P3 Yellow / Medium  
P4 White / Medium Television receivers
P5 Blue / Very short Photographic recording equipment
P6 White / Short Originally in TV receivers
P7 Blue-White / Short
Light-Yellow / Long
Radar indicators (boue-white short trace leaves yellow long trace)
P8 Obsolete  
P9 Obsolete  
P10 Magenta - Dark trace / Very long Outside light source. Persistence from seconds to months
P11 Blue / Short Oscilloscopes
P12 Orange / Medium Radar indicators
P13 Light red / medium  
P14 Purple-White / Short
Light-Orange / Long
Radar indicators
P15 Blue-Green and near ultraviolet / Very short TV pick-up of flying spot scanners
P16 Violet and near ultraviolet / Extremely short TV pick-up of flying spot scanners
P17 Greenish-Yellow / short and long Cascade phosphor, combines P7 and P15 characteristics
P18 White / Medium Low frame rate TV applications
P19 Yellow / Medium long Radar indicators
P20 Yelllow / Short  
P21 Yellow-Orange / Medium long  
P22 Red-Blue-Green / Medium Colour TV tubes
P23 White / Medium Similar to P4 TV tubes
P24 White / Short Colour flying spot scanner
P25 Orange / Long  
P26 Yellow-Orange / Very long  
P27 Orange-Red / Medium  
P28 Yellow-Green / Long  
P29 Two colour stripe pattern  
P30 Not registered  
P31 Green Fast, used for oscilloscopes
P32 Blue-Green -Yellow-Green / Long  
P33 Orange / Long  
P34 Blue-Green - Green  
P35 Blue-White  

The following screen characteristic codes were used to describe CRTs, in particular those in the CV datasheets:

1st letter (flash)2nd letter (afterglow)3rd letter (afterglow duration
BBlueBBlueL> 5s
GGreenGGreenM1s to 5s
YYellowYYellowS0.1s to 1s
RRedRRedN1ms to 0.1s

An alternate last digit was introduced later replacing the LMSNK code with a number as follows:

1-10µsKilled (K)
210µs100µsUltra short (US)
3100µs1000µsVery short (VS)
41ms10msShort (S)
510ms100msMedium short (MS)
6100ms1000msMedium (M)
71s10sMedium long (ML)
810s100sLong (L)
9100s-Very long (VL)

So, BBK became BB1 and BYL became BY8

Afterglow is given as the time taken from cessation of excitation for brightness to decay from a level of 1 equivalent foot candle to 1% of that valve.

The information in this page has been compiled from a variety of sources available on the web. As with the rest of this website there are no guarantees that it is correct or complete.

This file was last modified 11:45:38, Thursday April 14, 2022