This is a balun originally designed by Guanella and subsequently improved by Dr. Jerry Sevick (W2FMI). By utilizing Thermaleze wire inserted in teflon tubes, Dr. Sevick was able to substantially increase the breakdown voltage between both conductors while maintaining the required 100 ohm characteristic impedance for the wire pair used for the windings.
The result is a current balun that will handle moderate power from 1.5 to 54 MHz. It's a good choice to transform ladder line fed multiband doublets and cobra designs to coax and to build an economical Off Center Fed dipole around. Note: This 4:1 current balun is not the type used for an Original Windom which has a vertical coaxial radiator with a choke balun at the end. The model 4125 should be used at the center of an original windom design.
There are a number of interesting designs for OCF dipoles available on our website under
Antenna Design Links listed in the Support & Downloads tab at the top of the page
|Core Material|| Custom mix low permeability ferrite by Fair Rite Products for maximum bandwidth.
Core is coated and sealed for long term durability.
|Winding Type||Single core with wire pairs wound as 4:1 current balun.|
|Winding Material|| 2 bifilar windings of 14 gauge Heavy build polyamideimide Allex 240 Winding Wire.
Windings are inserted into Teflon tubes increasing total breakdown to 10,000 volts.
|Power Rating|| 1 to 35 MHz - 3kW, 35 to 54 MHz - 2kW.
All ratings based on resonant load. High SWR will reduce power handling ability.
|Useable Frequency||1 to 54 MHz|
|Insertion Loss|| Less than 0.2db
|Connectors|| SO-239 connectors are silver plated with Teflon insulation.
Studs and eyebolts are 1/4 inch.
Alternate connectors and Mounting Options are available in the Accessories section.
|Hardware||All Stainless Steel|
|Enclosure Type|| NEMA rated 4x marine grade junction box for outdoor installations.
Cover utilizes integral neoprene gasket for weatherproof integrity.
|Dimensions||4x4x2 inches for main body of unit|
|Additional Info|| Very high efficiency (98-99%). Weight 1lb 3oz