Efficient Common-Mode Current Choke for EFRW and other portable antennas (1:1 Guanella)

I was putting together SOTA/POTA portable antenna kit for my son, utilizing EFHW and EFRW antennas and I needed a Common-Mode Current Choke - something not very large and efficient that he can eventually use from QRP to 100W on 40m to 6m. This is just a quick, easy, 15 min. build, and the result is an excellent and pretty efficient CMC Choke (see the measurements below) for only $25, that one can…