[genewitch]

Type 31:

> Mix 31 excellent for 1-10 MHz common mode suppression, then about same as 43 up to 250 MHz, NOT recommended for multi-ratio impedance transformers (baluns/ununs) due to material characteristics and power handling capability – ok for ham radio 1:1 feed line choke applications. Curie temperature >130 C

But in looking for concise relevant information i found https://palomar-engineers.com/ferrite-products/ferrite-cores... which i quoted above

edit: also, thank you