Cannot find part number for ferrite ring torroid

Hi,
I am trying to find the part number for a ferrite ring toroid in our lab.
It has OD= 26.6mm; ID = 13.7mm; Thickness = 10.4mm; AL = 2140
(ie 21 turns on it gives 945uH)
It is coated in some red coating
Any ideas?

One other piece of info would help is to make a simple transformer and find out what frequency it will operate to. I think that should give you an idea of the core type.

Thanks, also its red, and i think that means made of MnZn?

I've only done some designing with torroids trying to make a voltage controlled inductor. I seemed to be pretty successful, but I need more information to continue. The answer was:
1. I was successful in creating the inductor over the specified range.
2. It was Linear over the range,
3. I never fixed my Keithley current source
4. I found a nice paper that I had to buy showing the technology is sound.
5, I don't know the frequency of operation needed. Only a guess.
6. I don't know the mapping required. Inductance vs independent variable.
7. Knowing frequency and DC offset, I think I could map it.
8. The frequency ultimately determines the material.
9. Any DC on the unknown circuit would affect the inductance.
10. Lots of variability in the property needed.
11. No point in developing a circuit.
12. It was fun.

KeepItSimpleStupid said:

've only done some designing with torroids trying to make a voltage controlled inductor.

Click to expand...

Magnetic amplifiers - they were quite common in older machine tools, for such as controlling the spindle or chuck/table motor.
Those types usually looked like conventional transformers, except the way they were configured in the motor circuit.