[hpsdr] [Hpsdr] Alex TX-Filter - Material for Ringcores

[Graham Haddock]

Hello, Gerd:

There are no broadband transformers in this design, so no ferrites.

For HF resonant circuits, all toroids are powdered iron.  Depending on
frequency, selected for best "Q" or lowest losses at the corner
frequency, the individual cores could be mix -1, -2, -6, or -10.

All T-50 size, as sold by Amidon.  Actual manufacturer is MicroMetals.
If you want to dig deeper into the core magnetics, I recommend you
look at the MicroMetals web site.  They provide much more technical
information than Amidon.  The cheapest source for purchasing them,
here in the USA, is "Parts and Kits, the Toroid King."

http://www.micrometals.com/

http://www.partsandkits.com/toroids.asp

I'll provide more information as to which mix was selected for which
filter, but I typically choose:
-1 mix for 1 to 4 MHz.
-2 mix for 5 to 14 MHz
-6 mix for 21 to 30 MHz, and
-10 mix for above 30 MHz.

The frequency boundaries are not firm, and overlap a lot.
The 33 and 50 MHz filters might end up using air would coils.

--- Graham / KE9H

==

Gerd Loch wrote:
> ***** High Performance Software Defined Radio Discussion List *****
>
> Hi,
>
> I would like to understand the basic properties of magnetic materials:
>
> which types of magnetic materials should be used for lowpassfilter toroid
> cores?
> Iron-powder cores or ferritcores (NiZn, NiMn..)
>
> For example: material no.2(iron powder, Amidon, Ferrite) is specified for
> frequencies 2-30Mhz
> Material no.43 (Ferrite) is specified for the frequency range 1-50MHz in
> broadband applications.
>
> What are the main differences in the range of 2-30MHz besides
> permeabilty/Al-value and which material is the best choice for which
> application?
>
> Which materials are you going to use for Alex?
>
> Gerd, DJ8AY
>

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