For use in baluns and chokes/isolators. More than enough for UK legal power so perfect for your QRO balun project. Type 75 is used for VLF projects and not recommended for use above 10MHz. They have a distinct profile on their top+bottom making them easy to identify among other FT240-size ferrites.
USE : Choke/Balun up to 10MHz (eg: Long Doublet for 160-80-60-40m) - they have more resistance than a 31-mix <10MHz but other properties change as you climb through HF making a 31-mix a better choice as an "all rounder". This 75-mix may also be effective on electrical cables to reduce noise transmission/RFI.
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 "75" is the ferrite mixture. What type do you need? 61 is used in the G3TXQ CobWebb balun, 43 is good from 7MHz and up (and a good general-purpose 7-30MHz solution), 31 is better if you use the lower HF bands while 75 is good for VLF projects. 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. See our video on Ferrite Toroids and Baluns here...