CMNF-5000HF for transmitter/receiver coax lines up to 5000 watts PEP - 1.8-60 MHz!
For coax feed lines with receive and transmit signals, you will love the small size, wide frequency range and excellent attenuation of common mode noise interference
- Reduces broadband common mode receiver noise* picked up on the outside of the antenna coax feed line.
- Wide frequency range works on all brands of radios and coax fed antennas from 1.8-60 MHz
- Common mode noise rejection up to 15-38 DB (2-5 "S" units) depending on frequency
- Simple plug & play installation: plug a short jumper from the CMNF-5000HF to your amplifier output and plug the feed line (or a jumper to your antenna tuner) into the other SO-239 CMNF-5000HF input. Either connector can be input or output. Rated at 5000 watts PEP.
- will work with Bias-T antenna switches and will pass DC voltage from input to output with no attenuation
* not effective for noise from AC power lines or noise received directly by antenna
Installation Note: For best results, and to reduce co-interference between choked and unchoked coax feed lines with multiple antennas, ALL antenna feed lines entering the radio room need to have a separate feed line choke particularly if they are at a different frequency then HF, like VHF or UHF.
if you use a antenna switch for multiple antennas in the 1.8-61 MHz range, place the CMNF-5000HF in the "common" line of the antenna coax switch and the antenna tuner/amplifier.
For additional common mode noise reduction, consider the CMNF-500HF (500 watts PEP) placed between the receiver and the amplifier.
Got Common Mode Noise? Not Sure - Find out now by clicking link below:
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