Roger Conroy wrote:

A comment slightly off the original subject, but might be of use to others.

Are these any good for RF use or should they go into the trash?

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.

In dead-bug construction style the use of these beads is very easy, and
usually kills unwanted RF propagation channels (such as power supply
lines to/from oscillator, buffer, amplifier, ...).

Unfortunately I have never been able to find any datasheet for those beads.

Roger, please post your results if you try your "donuts" for RF
applications.

73,
Paolo ZYW