THE GREAT MULLARD MAGIC BLOG — cv number

Picture this, its the 2025 North West Audio Show and two chaps have timidly entered the Orange Amps demo room.... Well, we sidled into the demonstration room under the stern and glacial visage of the brand impressario in attendance, our eyes fixed firmly on his little valve tester.  I nudged Sandeep and he nudged me back  "Steve  - you ask him." he hissed. "No, you ask him."  I  quavered. We timidly approached our nemesis and gave that fateful cry pitched with just the right level of longing and pathos, "Please Mister, can we play with your valve tester?"   Why...

OK, previous blog entries have described the “3 Services” legacy valve numbering systems as well as the GPO numbering system and as we have seen there was little if no commonality. Something had to be done and in 1941 everyone agreed to use a common system of nomenclature known as the COMMON VALVE or CV numbering. The agreement was a bit of a compromise as it only applied to NEW valves so there would always be old system labelled valves kicking about in stores.  However, a volte-face occurred in 1943 as the Navy kicked up a fuss, so all valve...

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...