b2670c17   
   From: phil_a@tpg.com.au   
      
   "Roger Jones"   
      
   > I just came across a very dead EL84/6BQ5 (from a P-P audio amplifier   
   > with a leaky coupling cap to its g1 - take note!) Just for interest, I   
   > cut the glass off just above the base with a Dremel-type cutting disk   
   > (use glasses and gloves!) Then, I pulled off the plate assembly to   
   > look at the electrodes.   
   >   
   > The RCA tube manual calls this tube a "Beam Power Tube" but there are   
   > NO beam plates, rather just a lose spiral grid 3. (Indeed, the word   
   > tetrode is NOT used by RCA) But to me it looks like a power pentode.   
      
      
   ** It's a patent issue.   
      
   The EL34 and EL84 are both "power pentodes" with original patents held by   
   Mullard and Philips.   
      
   RCA made a beam tube equivalent of the EL34  and called it the 6CA7.   
      
   Later, other makers labelled EL34s as 6CA7s or used both numbers - eg AWV   
   here in Australia.   
      
   Makers other than RCA labelled EL84s as 6BQ5s  -  to increase sales.   
      
   If you ever find an actual RCA brand 6BQ5 from the 1950s -  lemme know if it   
   has beam plates.   
      
   Whacky.   
      
      
      
   ...  Phil   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)