Computer RFI Kits

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

BA-4-250
$19.95
In stock
1
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 - Computer RFI Kits

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These RFI kits are specifically selected to cure most household computer device RFI problems. It contains ferrite toroids for AC or DC power supply protection and Snap On ferrite spli beads selected to eliminate RFI from 1 to 1000 Mhz. The beads are easy to use, don’t require modification of the protected equipment and work in almost all cases, even when plug-in filters fail. 

 

 

Typical Installations

 

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Ethernet Cable on F-240 Toroid – 7 turns

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Ethernet Cable on FSB-1/2 – 3 turns for 9X Impedance

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Ethernet Cable on FSB-1/4

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AC Cable on F-240 Toroid – 6 turns

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DSL Modem DC Power Supply on F114-43 Toroid – 5 Turns