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

[Gerd Loch]

Hallo Graham,

thanks for the information, especially about the manufacturer of the cores.
I will get additional information there and hope to then understand all
properties of the magnetic materials which is not really simple.

I am aware which materials to choose within one material category (i.e. iron
powder). But perhaps you could explain me why to use only iron powder for
resonant circuits. (besides the request for lower permeabilties, or is this
the only reason?).

On the other side iron powder is also used for broadband (power)
applications such as baluns as they can transform power with less loss.

But I will no longer ask silly questions as long as I have not read all
infos from MicroMetals.

73 Gerd
DJ8AY


-----Original Message-----
From: Graham Haddock [mailto:KE9H at austin.rr.com] 
Sent: Wednesday, July 25, 2007 6:38 PM
To: g.loch at nt-electronics.de
Subject: Re: [Hpsdr] Alex TX-Filter - Material for Ringcores


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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