John Popelish wrote:

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

OUCH! I never thought ferrite beads could end up in such a complete
catalog! I feel quite stupid :-) I'm reading the PDF as fast as kids do
with Harry Potter's latest adventures :-)

You can also roughly sort ferrite material roughly versus frequency
capability by measuring the resistance with an ohm meter. Low

[snip]

Thanks for the extra-useful tips John. I owe you a drink if you happen
to pass by here :-)

Paolo ik1zyw