AM Broadcast RFI Kits

CUBE Feed Line Choke/Unun, 4KW PEP, 500 KHz-5 MHz, Use for AM Broadcast, 160, 80 Meter Common Mode Noise Reduction (-42 dB)

SKU CU-1-4000BCI
$129.95
In stock
1
Product Details

Purpose. The CU-1-4000BCI is a 50Ω to 50Ω feed line choke/line isolator/noise filter, for the AM broadcast band frequencies, 160-60 meters with SO-239 coax input and output connectors. The choke is rated at 4 KW watts PEP into a matched load for .5-5 MHz. The choke is designed to have a high RF impedance to common mode currents on the outside of the coax braid while passing RF currents on the inside of the coax braid to the antenna (see graph below). Effective choking impedance > 3K to 5 MHz, over 10K in AM broadcast band. This choke is a very good common noise coax noise filter from for 160-60 meters operation.Excellent choke for AM broadcast and 160 meter band common mode noise reduction.

For maximum common mode current protection (and receiver noise floor reduction due to common mode current pickup by the coaxial braid), use one common CU-1-4000BCI at the antenna and another at the transmitter equipment connection or between antenna tuner and amplifier.



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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

20131210 114716 150x150 - AM Broadcast RFI Kits

AC Cable on F-240 Toroid – 6 turns

20131210 115137 150x150 - AM Broadcast RFI Kits

Ethernet Cable on F-240 Toroid – 7 turns

20131222 125533 150x150 - AM Broadcast RFI Kits

Audio or Mic cable on F240- 12 turns

 

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