THE GREAT MULLARD MAGIC BLOG — valve date code

I have just received an e-mail asking for details of military valve markings so here's a little primer for anyone who might have a similar interest. Valves used by the British military Armed Services were marked with a  CV or common valve name which was defined by the  Inter-Service Technical Valve Committee in 1941.     Often, below the CV number,  a two part  alpha code of the form KB/xx  or JB/xx will be seen  which gives the devices manufacturing specification and qualification .  For the first part of the alpha code, the K designates a valve manufactured to specification K1001 or K1006; similarly a J designates a...