Products & Product Reviews

Ferrite—An Inexpensive Way for Hams to Improve Their Time on Air PART 3: DX Engineering Bead Choke Standoff Kits

In our last blog post exploring DX Engineering ferrite products, we looked at High Impedance Common Mode RF Choke Kits, which include either 30 or 40 ferrite toroid bead chokes (Mix 31) designed to stop stray RF riding on the outside shield of a feedline. These kits have proven to be significantly more effective than other methods in preventing tuning problems and interference. They achieve the best possible RF isolation of the feedline from the antenna and provide completely balanced currents at the feedpoint. Plus, they provide quieter reception with reduction of common mode noise.

Despite their advantages, ferrite beads, as Hams have discovered, don’t perform as well when placed directly onto the metal boom at the feedpoint of beam antennas. The solution? You could jerry-rig a contraption to keep the coax away from the boom, or you could make it easy on yourself by choosing a DX Engineering Bead Choke Standoff Kit, specifically made to fix this problem.

DX Engineering Bead Choke Standoff Kits hold RF bead chokes and feedlines four inches away from the metal beam of an antenna boom (or four inches away from the metal mast of a dipole). By maintaining the optimal choking performance of ferrite beads on coax, these mounting systems:

  • Prevent feedline radiation of RF
  • Preserve current balance for proper beam antenna pattern
  • Prevent collected noise and signals on the feedline’s exterior from entering the antenna and interior of the feedline, resulting in lower noise floor and enhanced reception

The kits are made of fiberglass, PVC, and stainless steel hardware. Choose from four versions: Two sizes of PVC cradle tubes handle two different types of RF bead chokes: 3/4 inch O.D. ferrite beads on RG-400 size cable, and 1 inch O.D. ferrite beads on RG-213 size 0.405 inch coax cable. Each are offered with two different boom size clamps: 2 inch O.D. and 3 inch O.D.

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