In article ,
beginner wrote:
It is FT82-75 and the resistance is only 5 KOhm, so the mix is accurate.

I will have to make use of them in wideband tranmission transformers.
Can you folks suggest a frequency range?

I can get ferrite #61 or #63, but iron core only comes in mix #2 or #6
locally.

Thanks for all the help!

Digging out an old Amidon spec. sheet, they used #61 and #33 for their
ferrite (antenna) rods. Type #61 for medium wave and up to 10 MHz, and
type #33 for VLF.

The real question is "Are you using it in a tuned circuit?", where you
want the coil loss to be negligable. If you're making an antenna coil
that's tuned with a capacitor for AM broadcast (.54-1.7 MHz), use the
type 61.

For wideband transformers, where frequencies are higher than tuned
circuit use, Amidon specs type 61 as good for 10-200 MHz, and type 63
as good for 25-200 Mhz. For HF use #43, #77, #72, or #F.

Mark Zenier Washington State resident