Some quick measurements on a DK2DB balun.
It is a W1JR-style wound balun with a AMIDON 140-43 FT core.
Also check the measurements on a flea market find BALUN.
Transmission loss / Durchgangsdämpfung
Common-mode attenuation / Gleichtaktdämpfung
Symmetry error / Symmetriefehler
