[RFI] Is a Micrometals T44-52 a useful Ham toroid?

Tim Groat tcgroat at mesanetworks.net
Sat Jul 7 17:33:40 EDT 2007

Technical information can be found at 
<http://www.micrometals.com/materials_index.html>. In general, #52 is a 
"power conversion" material: mu = 75, but poor Q at RF. The low 
permeability allows it to handle considerable DC current without 
saturating. That makes it useful for differential-mode power line filters 
and the like. Mix #52 is often used for output filters of switch-mode power 

However, like all iron powder cores #52 won't perform as well as ferrite 
for common-mode suppression because it has much lower permeability. It 
won't easily replace beads and snap-on cores when you need to suppress 
common-mode currents, because it takes many turns to equal the impedance of 
one turn in a ferrite core.

The low Q of #52 mix makes it undesirable for transmitter output filters, 
tuned circuits, and other applications where RF loss would be a problem. 
For high Q circuits, choose a low-loss mix that's made for RF (such as #2, 
#6, or #17).

I hope this helps!

--Tim (KR0U)

kd4e <kd4e at verizon.net>:

>I have come upon a source of toroids 5/8" x 5/8" x 3/8"
>They contain a 7/16" diameter powdered iron core
>(Micrometals T44-52) wound with approximately 7 turns
>of copper wire for a nominal inductance of 1.7 uH at
>0 DC current.
>They are marked with the part numbers; HM00-98502, BI 9839 M
>Would these be useful as-is or rewound for dealing with
>RF problems in the Shack or elsewhere?
>Does the size or type indicate power handling capacity
>and frequency relevance?

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