> The ferrites used in chokes, inductors, and
> transformers are "soft" and do not retain much magnetism.)
>
Yes they do.
If you put an ampere turn or so through a high permeability
ferrite, it will magnetize and permanently lose a lot of inductance.
You can of course fix this by heating above the curie
temperature.
I cringe when I see people putting ferrite beads on one
leg of a 20A power supply. The 20 ADC magnetizes the bead
into saturation the first time you turn it on. What you want to do
is run BOTH wires through the bead so there is no net
DC.
Rick Karlquist N6RK
richard@karlquist.com
www.n6rk.com
www.karlquist.com
>
> So frying this ferrite did _not_ change its magnetic properties.
>
> When you burn out a choke/balun/transformer with a ferrite core,
> salvage the ferrite, which is usually the most expensive part.
>
> 73 de Chuck, W1HIS
>
|