1500 Watt PEP Rated 1:1 CUBE™ Balun for dipoles
* Help keep RF out of the shack.
* Provides maximum transfer of RF to the antenna.
* Suppress radiation from the feeder cable
* Makes the antenna radiation pattern predictable.
* Outperforms the competition by 24 dB common mode rejection! (see graphs)
* Reduces QRN and TVI to the neighbors.
The CB-1-1500 balun is useful as common mode feed line chokes or unbalanced coax to balanced antenna interface. SO-239 input to side terminal/eyebolt output. . Rated 1500 Watts PEP from 1-61 MHz. Common mode rejection up to -38dB over the frequency range. The CB-1-1500 is the balun version and the CU-1-1500 is the unun version (coax in and coax out).
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. Much more effective then our snap on ferrite beads as this balun which provides a higher choking impedance over a broad frequency range.
For most effective results, use another feed line choke (coax noise filter) at the radio. Helps reduce noise floor too by choking off common mode neighborhood noise picked up on outside of coax braid acting as secondary receive antenna
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