HF Impedance Transformer Kits

50:200 ohm (4:1) HF Balun or Unun Core Kit, 3-31 MHz, 250 watts

SKU BA-4-250
In stock
Product Details

Model BA-4-250 is a 4:1 voltage balun/Unun kit used to translate a 50 ohm input up to 200 ohms at power levels up to 250 watts when used with a matched load. With a matched load the SWR will not exceed 2:1 over the frequency range 1.8 to 30 MHz.

The kit consists of a 1.4" diameter ferrite core, two colors of insulated wire. a UHF connector with stainless steel hardware, and an instruction manual with directions to connect the kit as a 4 to 1 balun (balanced coax to balanced antenna like zepp or from 450 ohm feeder line to coax for a tuner) or 4 to 1 unun (unbalanced coax to unbalanced antenna like end fed or random wire).

This balun will also transform at 4:1 for a wide variation of load impedances. Shown below are AIM 4170 SWR results for a 200 ohm load. This balun gives near perfect transformation through 30 Mhz with a SWR under 1.25 . Light blue vertical bars are ham bands starting at 160 meters at left to 10 meters at right.

BA 4 250 SWR 1 31 Mhz png - HF Impedance Transformer Kits

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These impedance transformer kits have been designed for the Do-It-Yourself (DIY) enthusiast and Instructor workshops on baluns and ununs for antenna matching and RFI use.

The impedance transformers are classified in ratios of 2:1 (100:50 ohm) to 16:1 (800:50 ohm).  The outputs can be configured as balanced (Balun) or as unbalanced (unun) with respect to the inputs which are considered all unbalanced coax at 50 ohms.  All impedance transformers are designed for 1.8-31 MHz unless otherwise specified.