Purpose. Model BA-9-1000 is a 9:1 balun/unun kit (assembly required from parts supplied) used to translate a 50 ohm input up to 450 ohms at RF power levels up to 1000 watts when used with a matched load. It provides conversion from unbalanced coax to balanced ladder line/antenna feed point and gives a 9:1 impedance step-up to reduce SWR on the coax. Place at the junction of the balanced line and the coax to convert from balanced line to unbalanced coax.It can also be wired as an UNUN with unbalanced coax input to unbalanced output such as an end fed antenna.
KIT Contents. The kit consists of a F240-61 ferrite toroidal core, three colors of insulated wire, a SO-239 UHF connector with stainless steel hardware, and an instruction manual.
Assembly time: About 1 hour
Radio Club idea:
Buy 10 for a club do it yourself construction project - you can learn something and also build an end fed antenna (just add wire).
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.