From: phil_a@tpg.com.au   
      
   "Doug Bannard"   
   >   
   > Well Bob...you're wrong again!   Concentric winding and parallel winding   
   > are NOT the same.   
      
   **   Kinda obvious really .....   
      
      
   > In a concentric winding, one winding is wound on top of the other with   
   > insulation separating them.  Could be a secondary wound on top of a   
   > primary, or a secondary wound on top of another secondary.  This is the   
   > usual and rather conventional construction for an inexpensive  power   
   > transformer.   
   >   
   > A parallel winding occurs when two (or more) strands of magnet wire are   
   > wound together.   
      
      
   ** A technique also known as " bi-filar " winding.   
      
        Much loved by the RF brigade.   
      
      
      
   > They may be then connected to form a centre tapped winding with equal half   
   > winding resistances if you like, and this is often done on low voltage   
   > transformers.  It is NEVER done on a high voltage secondary and I can   
   > assure you that Hammond would never construct a high voltage centre-tapped   
   > winding in this way.   
      
      
   ** For the simple reason that the enamel insulation between adjacent turns   
   would not stand up to the voltage stress ( same as the voltage of whole   
   winding ) for very long.   
      
      
   > Balancing the resistance of HV windings is a piece of cake even with   
   > concentric construction, without even changing the wire gauge...just costs   
   > a bit more.   
      
   **  Resistors are cheap.   
      
      
      
   ....  Phil   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)