1:1 Baluns/Ununs/Chokes

Ladder Line baluns are used to match the impedance seen at the end of the ladder line to a coaxial cable, usually 50 ohms, but a ladder line balun can also be used to match to 75 ohm coax like RG-6/U used for cable and satellite installations. While RG-6 doesn’t have the same power rating as larger cable, it is very useful for beverage antennas or receiving antennas which don’t carry a lot of power.

The impedance seen at the end of the ladder line will not be the same as the characteristic impedance of the ladder line (typically 300 or 450 ohms). Good ladder line antenna designs try to have the impedance at the end of the ladder line attachment to the balun close to 200 ohms so that a 4:1 balun can be used to match to 50 ohm coax.

A typical ladder line antenna is shown in the picture below:

Ladder Line antenna Diagram - 1:1 Baluns/Ununs/Chokes

Palomar Engineers has ladder line to coax 4:1 baluns in both kit form and also assembled in a variety of 1 watt to 10KW power levels to suit the needs of many customers. The ladder line baluns are designed for balanced output and are generally used at the end of a run of ladder line from the antenna. The baluns connect to the ladder line and then transition to coax cable to you antenna tuner or radio station.

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HF 1-61 MHz coax feed line common mode chokes

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.