The images below feature some Mullard promotional material for the A56-120X picture tube as introduced in the single standard 22″ G6 sets and all the G8s. (by the time of the G8 other screen sizes had been introduced into the range). Other makers used this tube too.
General CRT Data
Some general CRT data for the period:
“Delta gun tubes in Philips sets:-
G6 duals: A63-11X (25″ sets) and the A56-120X in the later rare G22K503
G6 singles: A56-120X, A63-120X and A66-120X (22″, 25″ and 26″)
Note: the difference between the – A63-11X and the -120X was the former had a rimband and the latter used the more usual ‘push through presentation’ as it was called. So you could replace a -11X with a -120 but not vice versa.
G8: A56-120X in the 22″ sets, A66-120X in the 26″ and A51-220X in the 20″ 560
G9: A66-140X 110-degree delta gun (26″ only)
G11: A51-510X (rare 20″ with offset EHT connector) A56-510X and A66-510X for 22″ and 26″ sets; early models may have -500x with different heater current.
KT3, KT4 – A51-570X for 20″ models (short-lived in-line)
K30, K35, K40 – 30AX series A56-540X and A66-540X
Then later models such as the 2A used both 30AX and 45AX FST tubes. That’s getting a bit too modern, I suspect!
“The 30AX (A..-540X) was first introduced on the continent in the K12i and K12Z chassis, if I remember correctly. The K11 chassis and the K12 without a suffix had a 20AX tube. “