Common mode 1:1 HF balun for kW power level. 2012-07-19 OH7SV

Other names for this type of balun are
- Common mode choke
- Current balun

Dipole and other balanced antennas need always a balun. Here is one proper construction.

Ferrite core Amidon FT-140-43. Works down to 1.8MHz. Note the winding style for symmetry.

2 x 9 turns PTFE wire held in parallel. Common mode reactance XL = 1696ohms@3.5MHz and 872@1.8MHz

Coaxial connector screwed to insulation support. I don't use any water shield, it will last long without that.

Toroidal core fixed with straps thru the support. Extra holes will arrest the antenna wires.