An RFI choke (also known as a common-mode choke or coax balun) is an essential accessory for any HF or VHF antenna installation. By suppressing common-mode RF currents flowing on the outside of the coax braid, it prevents RF interference from entering your shack via the feedline, reduces TVI and BCI, and improves antenna pattern symmetry. This choke uses five #31 ferrite mix sleeve beads — the optimal ferrite mix for HF and lower VHF use, covering 1–300 MHz. Built on 12" of Mil-Spec Mini-8 coax cable with two SO-239 double-female (barrel) adapters for inline installation, and protected by 10" of black 3:1 polyolefin heat shrink for maximum weatherproofing. Can be installed at the antenna feed point or directly behind the antenna tuner. 300W SSB power rating. Key Features 5 x #31 ferrite mix sleeve beads — optimal for HF & lower VHF Frequency coverage: 1–300 MHz 300W SSB power rating Suppresses common-mode RF currents on coax outer braid Reduces RFI, TVI & BCI in the shack Built on 12" Mil-Spec Mini-8 coax cable 2 x SO-239 double-female (barrel) adapters for inline installation Protected by 10" black 3:1 polyolefin heat shrink Install at antenna feed point or behind ATU Technical Specifications Type: Common-mode choke / coax balun Ferrite mix: #31 (5 sleeve beads) Frequency range: 1–300 MHz Max power: 300W SSB Cable: 12" Mil-Spec Mini-8 coax Connectors: 2 x SO-239 double-female adapters Protection: 10" black 3:1 polyolefin heat shrink
