Model CU-9-5000 is a 9:1 multi-core unun housed in a NEMA enclosure box (4″ x 4″ x 2″) 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. Usable to 61 MHz under 2:1 SWR with 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
4:1 impedance transformers (Baluns and Unun configurations) are available in kit form or assembled form in a weatherproof Current Unun and Balun Enclosure which we call CUBE Baluns™ and CUBE Ununs™. All 4:1 impedance transformers use ferrite cores and the kit forms can be configured as a balun with balanced output of 200 ohms or as ununs with one side grounded.
4:1 baluns are designed for 50 ohm unbalanced (coax) input to 200 ohm output (either balanced or with one side grounded).
4:1 Baluns are useful between balanced lines for center fed Zepps, Off-center fed (OCF) dipoles with coax, G5RV antennas, full wave loops, NVIS dipoles that are close to ground and have impedance levels near 200 ohms or high impedance feeds for log periodic beams.
4:1 ununs are useful between coax and vertical antennas, monopole verticals or long wires with load impedances near 200 ohms.