This is a departure from the normal 1:1 isolation/choke balun and utilises a bifilar pair designed to maximise inter winding breakdown voltage. The balun functions to transform balanced twin lead, ladder line or open wire to unbalanced coaxial feed line while providing high levels of choking impedance to stop common mode currents from entering equipment.

This balun is NOT wound with the normal 50 ohm pair, rather the design criteria is maximising inter-conductor breakdown voltage. Consequently, this balun is intended primarily for use with multi band wire antennas such as doublets and loops where there will be a wide range of impedance values generated across the different bands and a tuner is required for the final match. Use with coaxial fed monoband wire antennas is not recommended.

With wire antennas being used primarily on the lower HF bands, choking impedance for this balun has been shifted to provide maximum performance on the 160m through 40m bands. However, this ferrite mix also provides excellent common mode control on the upper HF bands where high choking impedance levels are not as critical. It is best installed outdoors to minimise the chance of RF entering the operating position from the balanced feed line.

Typically this balun is utilised with a tuner that can easily match a wide set of impedance values. If you have a tuner with limited range, consider using the Model 4114 balun to reduce the required impedance match and thereby assist the tuner.