How to read CRT tube part numbers


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All picture tubes, whether monochrome or color type are identified by a specific code consisting 
of numbers and letters. The codes are different from each other because different tubes have 
different characteristics. 

For example, a certain monitor colour picture tube may have the designation, M34AFA63X03 that 
can breakdown into 6 parts: M/34/AFA/63/X/03

Part 1: Application 

Computer monitor tubes start with the letter "M” while for a TV picture tube,  it start with “A”.

Part 2: Screen diagonal measure in centimeters (cm) 

The “34” means the diagonal viewing measure is a minimum of 34cm which refers to 14” tube, 36cm 
is 15”, 41cm is 17” and so on.

Part 3: Family code 

The three letters “AFA” designate a family of tubes that have similar physical and electrical 
characteristic. These letters are assigned alphabetically beginning with “AAA”, followed by “AAB”,
“AAC” etc.

Part 4: Family number  

The number 63 shows a specific tube within the family code. A different number is assigned to 
tubes within the same family that have different neck diameters, for example a single digit would 
be a monochrome tube, but this two-digit number shows it is colour.

Part 5: Phosphor Type 
The fifth symbol gives the phosphor designation. The letter X here corresponds to P22 for colour 
picture tubes. Colour monitor tubes can have any other single letter (excluding I, O, or W) to 
designate other phosphor type for various applications. For monochrome pictures, the phosphor 
symbol is WW, corresponding to P4. Monochrome monitor tubes also can use WW or some 
other two-letter combination (excluding I and O).

Part 6: Integral neck components
The sixth symbol is assigned only for tubes having integral neck components, such as the 
deflection yoke. The specs are only apply to a particular tube manufacturer. The primary 
consideration here is winding inductance. The yoke coils have different sensitivity i.e. 
deflection per Amp in both horizontal and vertical.
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