The simplest, most cost effective feed line choke is a ferrite ring installed as shown in the picture (at the antenna feed point) to stop feed line radiation or at the radio end of the coax to suppress common mode coax noise current on the coax braid.
Great choke for log periodics, HF beams, Transceiver/Amp isolation
Improves antenna pattern by preventing your dipole from becoming a tripole
Suppresses pesky coax braid radiation and RFI
Reduces coax braid common mode current up to -40 dB ( 6 “S” units) on receive
Use one choke for each antenna feed line
Add a double female barrel connector to act as an “extension” of the existing coax.
All Slip On Ferrite Beads
Ferrite beads are used for RF decoupling and parasitic suppression. When placed over a wire, cable or coaxial cable they suppresses common mode current flowing on the wire or wire bundle or the outside of the coax shield but does not affect the signal inside the coax cable or wire (differential current).
For RFI common mode suppression use, mix 31 is effective from 1-300 Mhz, mix 43 works from 25-300 Mhz, Mix 61 is for 200-2000 Mhz, and mix 77 favors .1-50 MHz.These frequencies are those of the interfering signal to be eliminated, not the operating frequencies of the equipment to be protected. See Mix Selection for other applications.
SNAP ON Sizes for Heliax and Coax Cable
Shown below in the table are the SLIP ON and SNAP ON products for various popular Heliax and Coax cables. These are the correct size for making sleeve chokes – See above table for technical details.
