OCF antennas are very convenient as they will allow multiple bands of operation with a simple wire antenna which is fed off center with a 4:1 OCF Current balun with built in feed line choke,
Model CU-9-5000 is a 9:1 multi-core unun housed in a NEMA enclosure box (6″ x 6″ x 4″) with top stud/eyebolt output used to translate a 50 ohm input up to 450 ohms at RF power levels up to 5000 watts PEP (SSB) when used with a matched load.
Great for end fed antennas - FT-8 and digital mode power ratings are approximately 30% of PEP ratings into a matched 450 ohm load. For non-resonant end fed antennas, you will need a feed line choke on the coax. See typical antenna configuration notes below for details.Non-Resonant End Fed Antenna Configuration Notes