PaoloC wrote:

Motherboards and other circuits have some/many pass-through ferrite
beads which I find very useful to recycle as RF-block inductors in my
circuits.
(snip)
Unfortunately I have never been able to find any datasheet for those beads.
(snip)

Fair-rite makes many of these beads, and their catalog has some
impedance versus frequency data for them:

http://www.fair-rite.com/products.htm

You can also roughly sort ferrite material roughly versus frequency
capability by measuring the resistance with an ohm meter. Low
frequency power types measure in the hundred or thousands of ohms
between contact points, RF suppression types measure in the high kilo
ohms, while high Q RF types measure in the meg ohms. Having a few
known samples for calibration purposes helps.

--
John Popelish