Manfred,
I'm about to try one. I'll let you know if it melts.
Jerry W0ZD
-----Original Message-----
From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com] On
Behalf Of Angel Vilaseca
Sent: Wednesday, January 20, 2010 12:27 PM
To: Manfred Mornhinweg
Cc: amps@contesting.com
Subject: Re: [Amps] KK5DR's ferrite loaded
Manfred Mornhinweg wrote :
>
> That's right. And in the situation originally described, a plate choke
> wound on a ferrite rod, the permeability of the material isn't very
> relevant at all, because the total equivalent permeability of teh entire
> path is dominated by the air, through which the flux lines have to
> return. This allows obtaining almost the same inductance with a material
> having pemeability 10, than with one having 1000! So it's a good case
> for using a low permeability material, even as low as what's provided by
> powdered iron. The 43 material with its 850 permeability is certainly
> out of place here.
>
>
Hi, Manfred,
You explained why a plate choke wound on a ferrite rod won't be better
than one wound on the usual ceramic rod.
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? Is it because the cathode circuit is a low impedance
circuit and the plate circuit a high-impedance 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?
73
Angel Vilaseca HB9SLV
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