Coax will probably still be the cable of choice for most feedline applications, but it’s nice to know there are alternatives. And who knows—if you stick to QRP work, maybe Cat 6 could even be ...

Cat 6 is cable that's more reliable at higher speeds than Cat 5 or Cat 5e. They look pretty much the same; in fact, Cat 6 is backward compatible with Cat 4, so you can mix and match.