THE GREAT MULLARD MAGIC BLOG — mullard valve numbering

My erstwhile inquisitor was referring of course to the type numbers, screen printed with printers ink on a valve envelope - what do they mean?    Well, let's start with what is commonly termed 'The Mullard System' and here is a nice little table to help you to decipher what the alphanumeric type codes mean, enjoy:-  I can hear some of you exclaiming 'Oho, but what about the second number ala ECC83?'   Well, the second number is what is known as the development type number, in the case of the ECC83, it was the third 6.3V heater, twin triode,...