5000 Watt Rated 1:1 CUBE™ Choke - .2-5 MHz (effective to 100 KHz)
Th CU-1-5000LF unun is useful as common mode feed line chokes or coax to antenna interfaces. SO-239 output models can also be used with balanced antennas if a short coax cable “pigtail” is used on the output and connected to the antenna. Rated 5000 Watts PEP from .2-5 Mhz. Use as line isolator, antenna interface, or as a common mode choke to keep RF on the antenna and off the outside of the coax braid.
These high powered chokes are more effective then our sleeve feed line chokes due to multi-turn ferrite bead topology using high permeability ferrite cores which provides a higher choking impedance over a broad frequency range. Typical common mode rejection (CMRR) is 30-42 over the frequency range (see graph) For most effective results, use 1 choke at the antenna feed point to keep transmit RF off the coax braidand another at the radio end of the coax. Helps reduce noise floor too by choking off common mode neighborhood noise picked up on outside of coax braid.
Available in 1.5K and 5K PEP models. Picture shows 1.5KW model, but 5KW model is same size and frequency specs but 5KW PEP.
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 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).
F240-77 Choking Impedance in AM Broadcast Band
Typical Installations for Donut/Ring Toroids
 AC Cable on F-240 Toroid – 6 turns |
 Ethernet Cable on F-240 Toroid – 7 turns |
 Audio or Mic cable on F240- 12 turns |
Extra Mix 75 Snap On Beads HERE – VERY effective for AM Broadcast RFI