[Amps] KK5DR's ferrite loaded

[Jim Brown]

On Wed, 20 Jan 2010 18:27:06 +0100, Angel Vilaseca wrote:

>But on the other hand, a choke wound on a ferrite rod is used as the 
>filament choke in the cathode circuit of almost every triode power amp 
>design. So it must work very well.

>How is this? 

Several reasons. First, there are many different KINDS of ferrites, and 
their properties are VERY DIFFERENT. Second, an RF choke in a filament 
line sees a LOT less RF that one in a plate circuit. 

>Also, the type of ferrite used for the bifilar filament chokes that I 
>have seen in most published designs does not seem to be very critical. 
>Is it for the same reason?

>Would a toroid be better than a rod for the filament choke?

I suggest you STUDY the material on ferrites in my tutorial (link 
previously cited), and in the 2010 version of the ARRL Handbook, and 
incorporate what you learn in the design of these chokes. 

73,

Jim Brown K9YC