Simple Dipole Feed Line Choke for 1/4" coax (1.8-61 MHz)
The simplest, most cost effective feed line choke is a ferrite ring installed as shown in the picture (at the antenna feed point).
Improves antenna pattern by preventing your dipole from becoming a tripole
Prevents pesky coax braid radiation and RFI
for best results use multiple turns through center
Use one choke for each antenna feed line - take a 3 foot piece of G-8X (part# RG8X-3) and wrap 10-12 turns thru center for a good feed line choke.
12:1 Ununs are useful between coax and long wires with a load impedance near 600 ohms like a beverage antenna. Shortwave listener antennas also can benefit with the 12:1 unun and it may provide a better match than 9:1 ununs – this means quieter noise levels and stronger signals so you can hear distance stations easier.