Coax Inline Common Mode Choke Unun - 500 Watts 25-300 MHz- 10, 11, 6, 4, 2 MetersProduct DetailsBrand: Palomar EngineersMPN: FC-8X-3-31Effective Frequency Range (MHz): 25-300 MHz (3 bead)PEP Power Rating (watts): same as coax cable ratingEstimated Insertion Loss (db): .025Input Connector Type: noneOutput Connector Connector Type: noneGround Connector (Y/N): noneEnclosure Size (LxWxH inches): noneASSEMBLED COAX FEED LINE CHOKES
Many customers have requested an assembled sleeve unun or balun 1/4" size cable and we have one all completed with shrink tubing and PL-259 end connectors or open ended on one end for a balanced connection such as a beam, dipole, etc.
All you need to add are 2 barrel connectors (Part # DFBC-1) to insert into your coax cable. For best results add one feed line choke at the antenna to keep the RF on the antenna and another feed line choke at the station entrance to reduce the common mode noise picked up by the antenna braid and fed into the station. Rated 500 watts from 25-300 MHz into 1:1 SWR load.
Common Mode Rejection Ratio up to 20 dB (over 3 "S" units) - see graph for specifics..
Available with PL-259 output or solder lug output (for attachment to a balanced output such as a yagi antenna for dipole fed antenna
HF 1-61 MHz coax feed line common mode chokes
ASSEMBLED COAX FEED LINE CHOKES
Many customers have requested an assembled sleeve unun or balun 1/4" size cable and we have one all completed with shrink tubing and PL-259 end connectors or open ended on one end for a balanced connection such as a beam, dipole, etc.
All you need to add are 2 barrel connectors (Part # DFBC-1) to insert into your coax cable. For best results add one feed line choke at the antenna to keep the RF on the antenna and another feed line choke at the station entrance to reduce the common mode noise picked up by the antenna braid and fed into the station. Rated 500 watts from 25-300 MHz into 1:1 SWR load.
Common Mode Rejection Ratio up to 20 dB (over 3 "S" units) - see graph for specifics..
Available with PL-259 output or solder lug output (for attachment to a balanced output such as a yagi antenna for dipole fed antenna
1:1 feed line Chokes (also known as feed line current chokes, common mode chokes, line isolators, current mode chokes, and 1:1 baluns/ununs) are available in kit form or assembled form in a weatherproof Current Unun and Balun Enclosure which we call a CUBE™. All 1:1 chokes are ferrite based and are designed for 50 ohm coaxial cable input and 50 ohm output. 1:1 Ferrite toroidal or bead chokes have a higher choking impedance than our popular Sleeve Chokes and various models are available for specific frequency ranges and power levels.
1:1 Chokes are useful for choking common mode currents that may flow on the exterior of the coax cable shield while allowing the signals on the interior of the shield and the center conductor to flow unaffected and keeping the common mode current on the antenna. They isolate the coax shield and prevent it from becoming part of the antenna system.
1:1 Chokes are useful between balanced lines for center fed dipoles at their fundamental frequency (468/f (MHz), beam antennas with a 50 ohm balanced driven element, G5RV, loops, yagis, NVIS antennas, mobile installations, portable antennas and anywhere common mode current (or RFI) is a problem. They are also helpful between transmitter and linear amplifier or between linear amp and antenna tuner or as isolation chokes where higher choking impedance is needed (in the range of 2K-7K ohms).
1:1 Chokes are also very useful as feed line current chokes at the “radio end” of the antenna (we call them coax noise filters) where they choke/filter common mode current induced onto the coax shield from radiated waves (from your antenna, and other sources such as DSL routers, computer devices, plasma TVs, etc. originating in your house or your neighbor’s house). For RFI issues see RFI/EMI Solutions for general use or for specific radios and devices.
For best results we recommend a 1:1 choke at the “antenna end” of the coax and a coax noise filter at the “radio end” of the coax. (A side benefit is a reduction in noise level caused by common mode currents). 1:1 chokes are also available as Sleeve Chokes (Slip on or Snap on) for ease of installation and light weight on the antenna.