Maxi-Core® 20 Baluns and Feedline Chokes reduce or eliminate currents on the outside of your feedline allowing you to hear and to be heard much better. They keep more RFI/BCI out of your antenna and receiver and transfer more of your transmitted signal to the antenna for higher efficiency, the best antenna pattern and maximum performance. Hear and be heard with DXE Maxi-Core® 20 Baluns and Feedline Chokes!

The DXE-MC20-FC - 1:1 Feedline Choke is a high common mode impedance (CMI) line isolator that is designed for use in-line on 50 ohm coaxial feedlines. This RF choke is often used at the shack end of the feedline. It also be used at the antenna end of the feedline, or at the base of a tower where a feedline is terminated to a ground or a switch. The purpose of this choke is to prevent stray signals and noise RF current flow through the choke or on the outside of the shield from getting inside of the coax shield or to the antenna or station. This feedline current choke can effectively reduce noise and RFI to the equipment in the station and provide a lower noise floor and improved reception.

For other antenna and ladder line applications, click Suggested Parts above or click here: Balun/Choke Selection Chart. Descriptions of each Maxi-Core® 20 model appear below.

DXE-MC20-FC Maxi-Core® 20 Feedline Choke

Maxi-Core® 20 Feedline Choke features high quality silver-plated PTFE dielectric SO-239 (UHF female) input connectors. The SO-239 connector limits power handling to 5 kW or less at low SWR and reduced power at elevated SWR. These feedline chokes exhibit very low insertion loss and inherently low SWR. Maxi-Core ® 20 Feedline Chokes are built into a convenient weather resistant NEMA enclosure that is mounted easily with optional brackets. They have weep holes at all four corners of the “bottom” side of the enclosure, so they work properly for vertical or horizontal mounting for all types of antennas.

The optional mounting bracket and plate, also listed in the suggested parts tab,  DXE-MC20K-BRKT is used for for verticals or on a beam antenna. Mounting the choke perpendicular to the metal support pipe provides better performance.The DXE-WA-BMB for wire antennas allows the addition of a Coax Strain Relief

Signaling a new era of RF performance across the 1.8 to 54 MHz frequency range, DX Engineering Maxi-Core® 20 Baluns and Feedline Chokes handle full-legal-power-plus and provide higher common mode impedance (CMI) across a greater frequency range than competing models and even previous DX Engineering and Comtek models. Years of R&D coupled with major advancements in test equipment and techniques combined with custom ferrite materials have allowed our engineering team to design the DX Engineering Maxi-Core® 20 Baluns and Feedline Chokes.

Common mode impedance (CMI), also known as choking impedance, is a measure of how well a Balun or Feedline Choke reduces exterior RF currents traveling through it and on the outside of the coaxial cable. Unwanted RF signal and noise currents that travel on the outside of the coax will re-radiate signals directly to your antenna and then travel to your receiver. Even with a Feedline Isolator (choke) or Balun at the antenna end of the transmission line, many times a Feedline Isolator is necessary at the transceiver side in order to squelch the noise currents picked up by the feedline on the way to the radio.

Modern testing methods clearly show that coiled coax, sometimes known as an “ugly balun,” and inexpensive baluns provide minimal CMI over just narrow frequency segments of the HF range. DX Engineering Maxi-Core® 20 Baluns maintain a much higher CMI over the 160 meter through 6 meter bands.

Maxi-Core® 20 Baluns and Chokes have high CMI across the AM Broadcast band and the HF/6M spectrum, which is essential to provide sufficient suppression of unwanted transmitted and received RFI/BCI current on the feedline shield exterior. Hear and be heard with DXE Maxi-Core® 20 Baluns and Feedline Chokes!

DXE-MC20-1-1 Maxi-Core® 20 - 1:1 Current Choke Balun - For all HF-6m balanced antennas with a 50 ohm feedpoint, including resonant dipoles, loops, Yagis, beams, etc.DXE-MC20-FC  Maxi-Core® 20 - 1:1 Feedline Choke – This high CMI line isolator is perfect for use in line on 50 ohm coaxial feedlines, at the antenna, at the tower and at the shack end of the feedline. DXE-MC20-1-1T  Maxi-Core® 20 - 1:1 Current Choke Balun – This 1:1 "T" model is for force feeding antennas with a tuner. Use it at the end of ladder line of any impedance or mounted on a coax fed non-resonant antenna. This model tolerates operation at high SWR on non-resonant multi-band antennas. Typically, for higher efficiency, this is the balun to use at the end of any impedance ladder line that is feeding a non-resonant doublet. If higher losses are acceptable, it may be mounted on a coax fed antenna. This model tolerates operation at high SWR on non-resonant multi-band antennas. But, in either case, not all frequencies are available on a single dipole, as this is a choke balun, not a tuner.DXE-MC20-C4-1  Maxi-Core® 20 - 4:1 Current Choke Balun - For use on antennas with a 200 ohm feedpoint and on any impedance ladder line, especially antenna systems with higher impedance. This model tolerates operation at high SWR on non-resonant multi-band antennas.DXE-MC20-V4-1   Maxi-Core® 20 - 4:1 Voltage Balun -  A 200 ohm to 50 ohm transformer for use on random long-wire and OCF antenna applications. This true voltage balun is intentionally designed with low CMI for antennas that need a transformer without RF choking for easier antenna tuner operation. This model tolerates moderately elevated SWR.