AM Broadcast RFI Kits

50:50 ohm (1:1) Common Mode Choke HF Balun Kit - 1500 watt PEP, 1.8-31 MHz

SKU BA-1-1500
$29.97
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50:50 ohm (1:1) Common Mode Choke HF Balun Kit - 1500 watt PEP, 1.8-31 MHz
Product Details
Input ohms/Output ohms: 50 in, 50 out
Frequency Range < 2:1 SWR (MHz): 1.8-30
PEP Power Rating (watts): 1500

Model BA-1-1500 is a 1:1 balun kit used to translate a 50 ohm unbalanced input to 50 ohms unbalanced at power levels up to 1500 watts PEP when used with a matched load. With a matched load the SWR will not exceed 1.5 over the frequency range 1.8 to 30 MHz. 1,500 PEP watt rating on a 25% duty cycle.

The kit consists of a F240 ferrite core, two colors of selected insulated wire, two SO-239 connectors (one for input and one for output connections) with stainless steel hardware, and an illustrated instruction manual with directions to assemble the kit as a 1 to 1 balun (unbalanced coax to balanced antenna/load) or unun (unbalanced to unbalanced). Leave one of the SO-239 connectors off on the output side and connect to your balanced antenna (dipole, beam driven elements, etc). To use as a line isolator/common mode choke, use both SO-239 connectors and insert in series with the coax feed line. For best results use one at the antenna and one for the rig side at the antenna tuner. The number of turns on the toroid can be changed to emphasize the low, mid or high portion of the 160-10 meter bands range as well as the choking impedance (see graph below). Assembly time is about 30 minutes. You can vary the number of turns to emphasize different frequency ranges.

BA 1 5000 ZMAG 1024x565 - AM Broadcast RFI Kits

BA-1-1500 Choking Z magnitude – 14 Turns and 10 Turns

Just add your custom enclosure, or optional enclosure box below, with the kit and you have a compete 1:1 current balun/unun.

When considering solutions for AM broadcast (550 Khz – 1.8 Mhz) you should consider Mix 77 ferrites available in a variety of shapes and sizes.  Choose a size to give the maximum number of turns of the affected wire or cable.

AM broadcast transmits on a low frequency with large antennas.  Consequently it takes a large antenna to receive the signals.  Typical “antennas” are AC house wiring, phone lines, long satellite or cable TV cables, DSL/CAT5 lines running between rooms, etc.  The device wires that connect to these  “antennas” need to be choked with as many turns through the ferrite as possible.  Some installation examples are shown below on this page.

For AC/ DC power cords and coax cables the F240-77 (2.4″ OD, 1.4″ ID) “Donut” toroid is the most popular.  Also available are smaller toroid donuts and Mix 77 beads. Shown below is a graph with 8, 10, and 12 turns through the toroid – obviously more turns has higher choking impedance.  Mix 77 toroid products are HERE and Mix 77 small beads (for small wires) are HERE

F240 77 Turns Comparison 1024x648 - AM Broadcast RFI Kits

F240-77 Turns Comparison from .1 – 8.1 Mhz

Shown below is a graph of frequency response verses choking magnitude for a F240-77 in the AM Broadcast band for a 12 turn coil around the toroid. (Same info as above but different frequency range).

AM Band Choking Graph F240 77 1024x648 - AM Broadcast RFI Kits

F240-77 Choking Impedance in AM Broadcast Band

 

 

Typical Installations for Donut/Ring Toroids

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AC Cable on F-240 Toroid – 6 turns

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Ethernet Cable on F-240 Toroid – 7 turns

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Audio or Mic cable on F240- 12 turns

 

 Extra Mix 75 Snap On Beads  HERE – VERY effective for AM Broadcast RFI