1:1 Current Choke
Up to now, I had fed most of my antennas directly with coax. Doing eSSB I wanted to keep as much common mode (RF) out of the shack and help keep the RF on the antenna where it belongs anyway. I suppose it is good engineering to do this anyway, so I started looking into ways of doing this. The 1:1 choke is the device, but there are different ways to achieve this. The infamous "ugly balun" (Or is it really an unun?) is one way. It requires no additional parts, just wind the coax at the antenna on a form. 12 turns of RG-8 on a 5 inch form is about 18μH at 160m. That means just over 15 1/2 feet of coax is used to make the choke. With prices usually running about $1.20/ft, that's around $20 in feedline and you still need the PVC form and end caps to make a nice choke that will last. My estimates as of January 2022 put that at about $30. It is also a considerable amount of weight at the center of an antenna. 200ohm of impedan...