Today, we are going to look at the Mullard CRT numbering system which gave type numbers as two letters followed by two groups of numbers which translated as below: - 

the first letter

D - electrostatic focussing  and deflection CRT as used in oscilloscopes.

M -  magnetic focussing and deflection CRT  as used in TV and radar.

the second letter

B - screen phosphor gives a blue short persistence trace.

F - screen phosphor gives an orange long persistence trace.

G - screen phosphor gives a green medium persistence trace.

P - screen phosphor is double layer combining a blue short persistence trace with a yellow long persistence afterglow.

R - screen phosphor is single layer giving a long persistance green trace.

W - screen phosphor gives a medium persistence white luminance for television picture tubes. 

first figure group

4 - screen diagonal or diameter of 4 cm or 1.75 ins.

6 - screen diagonal or diameter of 6 cm or 2.5 ins.

31 - screen diameter of 31 cm or 12 ins.

36 - screen diameter of 36 cm or 14 ins.

41 - screen diameter of 43 cm or 17 ins.

second figure group

This figure grouping which is generally separated from the first grouping by a hyphen is a design development reference, for example the MW36-22 and MW36-24 are both direct viewing television picture tubes designed for magnetic deflection and focussing with a 36 cm or 14 ins screen - the only difference is the 22 suffix was superceded by the 24 suffix unit.