A large ferrite toroid for use with a QRO CobWeb balun (2 ferrites are required if you're making your own) and both our 9:1 UnUn products. This ferrite is not suitable for general-purpose baluns/chokes across HF - use a 31-mix , 43-mix or a 75-mix.
Need help choosing a ferrite? See our page on selecting the best size/type here.
Toroid sizes/types are easy to ID, the "240" translates to 2.4" (diameter) and the "61" is the ferrite mixture. What type do you need? 61 is good for an UnUn, 43 is good from 7MHz and up (and a good general-purpose 7-30MHz solution) while 31 is good for lower HF bands. Remember, you can stack the cores for increased choking and power-handling. As always, ratings need to factor in the aerial (SWR) match and duty-cycle.