Slip On Sleeve Chokes
Palomar 1:1 feed line choke kits are current baluns (split output) or ununs (coax output). They consist of several models with 5-15 large ferrite beads that slip over the coax (but will not slip over a connector). Also included are three lengths of shrink tubing to enclose the balun and hold the beads in place on the cable. They work from 1.8-300 MHz (see impedance table for each product for measured choking impedance levels for 5-15 beads) and allow use of full power rating of the coaxial cable at an SWR of 1:1. No tools are required for installation, just a source of heat to shrink the tubing using a heat gun, lighter, matches.
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.