50:75 ohm (1.5:1) CUBE™ Balun/Unun, 1.8-61 MHz, 1.5KW PEP, DipoleProduct DetailsType: BALUN/UnunInput ohms/Output ohms: 50 in/75 outFrequency Range < 2:1 SWR (MHz): 1.8-61 MHzPEP Power Rating (watts): 1500Insertion Loss (dB): <.2Input Connector: SO-239 UHFOutput Connector(s): Top Studs/Side Eyebolts/So-239Transformer Topology: broadband binocular coreHardware Type: Stainless SteelEnclosure Size: 4" x 4" x 2"Weight (pounds): 2Available as a Unun for 50 ohm coax to 75 ohm coax or 75 unbalanced load or as a Balun for 50 ohm coax to balanced load such as a low (less than a wavelength high) dipole with either side eye bolts and halyard hoist or as post mountable top studs output.
This is an impedance transformer for 50 to 75 ohms and may require a additional feed line choke to keep common mode current off the coax braid.
CB-1.5-1500EB is useful for a dipole center feedpoint for low dipoles with 75 ohm antenna impedance.
Top stud version also useful for 75 ohm ladder line to coax interface
HF 1-61 MHz coax feed line common mode chokes
Available as a Unun for 50 ohm coax to 75 ohm coax or 75 unbalanced load or as a Balun for 50 ohm coax to balanced load such as a low (less than a wavelength high) dipole with either side eye bolts and halyard hoist or as post mountable top studs output.
This is an impedance transformer for 50 to 75 ohms and may require a additional feed line choke to keep common mode current off the coax braid.
CB-1.5-1500EB is useful for a dipole center feedpoint for low dipoles with 75 ohm antenna impedance.
Top stud version also useful for 75 ohm ladder line to coax interface
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.