Mullard no print code BG2 D1F4

[Uncletom1123]

I’ve a mullard tube that starts E80??

The etched code is BG2 D1F4

Can anyone interpret this code to give me the type of valve - it has a pinched waist !

 

[Kay Pirinha]

This is an E80CF, 2nd version (whatever that means...), made by Valvo, Hamburg, in the 4th week of June 1971.

Best regards!