tictac1 wrote:
I checked Fair-rite's site but couldn't find anything about frequency
characteristics of toroidal cores.

???

On the main page, under "Technical Articles", "Use of Ferrites in
Broadband Transformers" has a large amount of information about
frequency characteristics. So does "How to Choose Ferrite Components for
EMI Suppression".

Also, you know, as a homebrewer i
can't buy parcels of material like toroids, and I don't think that
distributor can sell small number of items, can they? Anyway, doesn't
anyone use Philips toroids, or is there no such thing as Philips cores?

I'm puzzled. . . does Philips sell small numbers of cores directly
either? I'm sure some of the folks here can recommend retailers who sell
a small number of cores from various manufacturers. The last time I
checked -- some time ago -- Amidon was still selling Micrometals
powdered iron cores and ferrites from Fair-rite and Magnetics.

Roy Lewallen, W7EL