Description
The 4115et 4:1 balun 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 and windings while maintaining the required 100 ohm characteristic impedance.
This design utilizes two separate cores wound as 100 ohm, 1:1 choke baluns which are cross connected to create a 4:1 (200 to 50 ohm) current balun with excellent isolation and high choking impedance. Consequently, this balun is a good choice if you have RFI problems or RF in your shack due to imbalanced ladder line