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 20-38 DB (3-6 "S" units) depending on frequency - Simple plug & play installation: plug a short jumper from the CMNF-1500HF to your amplifier output and plug the feed line (or a jumper to your antenna tuner) into the other SO-239 CMNF-1500HF input. Either connector can be input or output. Rated at 1500 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-1500HF 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: 
CMNF-1500HF for transmitter/receiver coax lines up to 1500 watts PEP - 1.8-60 MHz, -38 dB Common Mode Suppression
For RFI common mode suppression use, mix 31 is effective from 1-300 Mhz, mix 43 works from 25-300 Mhz, Mix 61 is for 200-2000 Mhz, and mix 77 favors .1-50 MHz. These frequencies are those of the interfering signal to be eliminated, not the operating frequencies of the equipment to be protected. See Mix Selection for other applications.
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Bead dimensions are shown in the picture below and in the table as A, B, C
Ferrite Bead Dimensions
Application Note: Use impedances for each bead at your desired frequency to select number of beads needed for desired Z. For example if you have a 50 ohm RG-8 coax cable and want a choking impedance of 500 ohms at 10 Mhz, you can check the FB102 column (since FB102 will pass RG-8 through its center ID) at 10Mhz and find that Mix 31 has a Z of 108 ohms/bead and Mix 43 has a Z of 91 ohms/bead. For 500 ohms we would need 5 mix 31 beads or 6 mix 43 beads to have greater than 500 ohms. Mix 31 has better response below 10 Mhz but above 10 Mhz mix 31 and mix 43 are very close. If you need more Z, just use more beads in series on the cable or use more windings thru a larger ID bead (e.g. USE FB102-31 for 4 turns of RG-8X for 16X increase in Z per bead – see pictures below for examples). Use Mix 61 for VHF and above for RFI/EMI suppression and below 30 Mhz for multi-ratio impedance transformers (baluns/ununs). See Mix Selection for other applications.
For extra large cables use the FB400-31 which has an inside diameter of 3 inches (76mm).
Frequency Range Comparison Chart
(FB56-xx size)
Multi-turn Common Mode Choking Impedance Increase Example (FB56-43)
Ferrite Bead relative size comparison
Left to right sizes: FB56 (ID = .25″), FB102 (ID=.505″), FB103 (ID=.77″)
SLIP ON Sizes for Heliax and Coax Cable
Cascaded Common Mode Chokes/Line Isolators/1:1 Baluns
 RG58 4 turns on 2 FB102-31 for 2000 ohms choking impedance |
 RG58 12 turns on FT240-43 for 4000-6000 ohms choking impedance |
Handy Wire Size reference for ferrite bead sizes needed
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Connector already on cable? See Snap On Ferrite Beads for convenient installation on cables with connector already installed.