I need to build another 9:1 unun and I start searching for my toroids... (I have build 2-3 something like 4 years ago)... In parallel I checked on Google about the correct toroid etc so I found 2-3 pages with designs. My focus is on power loss as I run QRP on batteries.
What do you think regarding power losses and materials? Which toroid should I use? (I already have the *-61 and the *-2).
Regarding wires for the turns, some use enameled copper wire, some 3-colour for like a power socket.
The unun is not for portable. So a size 200-240 is okay for some future proofing.
If I can get ok losses down to 80m, I'll be very happy, I mainly use 15 to 40m.
It's for a “random wire” end fed. Probably around 58ft max. Or maybe 53ft (space restricted)