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

Name: 50:200 ohm (4:1) HF Balun or Unun Core Kit, 3-31 MHz, 250 watts
Brand: Palomar Engineers
SKU: BA-4-250
Price: 19.95 USD
Availability: InStock
Rating: 4.0 (1 reviews)

4.0

1 review

Store/Antenna Products/CUBE Impedance Transformers (<1:1, 1:1, >1:1)/50:200 ohm (4:1) Transformers

SKU BA-4-250

$19.95

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Wade B.

Suquamish,

United States

Sep 20, 2025

I bought two of these kits for some antenna and tuner projects. They arrived promptly and appear as advertised. Their 250 watt ratings are more than enough for my needs. Besides the core, the packaging included an SO-239 and enough well-insulated wire to make winding the core easy. I have done this sort of thing many times over the last half century and had no trouble, but I do think that for a beginner a better set of winding instructions and diagrams would be very helpful. In my opinion the included instructions are somewhat vague and difficult to interpret, so 4 stars. WA7DE

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

Store/Antenna Products/CUBE Impedance Transformers (<1:1, 1:1, >1:1)/50:200 ohm (4:1) Transformers

Product Details

Input ohms/Output ohms: 50 in, 200 out

Frequency Range < 2:1 SWR (MHz): 1-31

PEP Power Rating (watts): 250

Model BA-4-250 is a 4:1 voltage balun/Unun kit (assembly required from parts supplied) 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 - Store