Thanks to Richard McKee
Facebook : Baluns, ununs and Tuners.
Gang, "ALL TOROIDS ARE NOT CREATED ALIKE"!
Just because it's a toroid doesn't make it right for the job at hand.
There are many different materials used for the many different applications. You must match the material and size of toroid to the frequency range, power level, and job you want it to perform.
You can simply just pick out a "TOROID" from a bargain basement supplier and expect it to work.
So, before you pay out your hard-earned cash, make sure you are getting what you need in the first place and it will save you a lot of frustration!
The one pictured below is a mix 2, powdered iron core for example - not a ferrite core. But I see folks all the time trying to make baluns, ununs, chokes, and transformers with them, only to find out it doesn't work like they thought it should.
Powdered iron cores are fine for use as inductors in tuned circuits such as low pass filters and such, but not for the reasons mentioned above - at least not for HF purposes. Anyway, do some research, ask questions, and research some more before buying toroid's and do it right the first time.