A low Insertion VSWR high Zcm Guanella 1:1 balun for HF – more detail #3 discussed compensation of the Insertion VSWR response of a balun which in that case was wound with coax.
A correspondent wrote of his project with a Guanella 4:1 balun where each pair was wound with a pair of insulated wires, and importantly the output terminals are free to float as the load demands. A Guanella 1:1 balun wound in the same way has the same characteristic.
To preserve balun choking impedance, it is best to preserve balun symmetry, and the use of a short open circuit coaxial stub across the output terminals for InsertionVSWR compensation introduces some asymmetry.
An alternative construction with coaxial cable that is more symmetric is shown above. Continue reading A symmetric compensation stub using coax