THE GREAT MULLARD MAGIC BLOG — OCTAL

I thought I would write a series of blog articles on what is inside a valve.  Famously, the head of Mullard UK, the ex-Philips SS Eriks once stated that the only British thing inside a Mullard valve was the vacuum and after I recently waffled on to some poor chap about electrode cage construction, pinches and getter flashing, they were bemused so I thought that I had better expand on the great Dutch master's scathing comment, so, without further ado, let's talk about......... what's in a valve.................................. The picture below shows a sectioned Mullard EL37 output pentode, as you can see, this...

  Mama Mia!  An e-mail from Vigata in Sicily enquiring about when certain valve bases were introduced.   I know a valve dealer from Sicily you know, he's from Messina and ever such a nice chap but I digress........ There exists a whole raft of valve bases, however, I shall deal with only the most commonly seen bases and their dates of introduction in the following table:- Year of Introduction Valve Base Type Descriptive notes 1916 B4 Introduced by French valve manufacturer Duclos-Fivre 1927 B4 + side screw Introduced for indirectly heated cathodes 1928 B4 + top cap VHF/ UHF anode...