Icom 746/756/765/775/781 RFI kit is designed to be installed on your radio transceiver to reduce Radio Frequency Interference (RFI) caused by common mode current on the coax output of your radio, the AC/DC power, USB, ALC/Send, mouse,mic and additional interconnect cables. Standard 756PRO Kit has 4 ferrite ring filters and 10 ferrite snap on filters and instruction manual or you can choose the optional CMNF-500-50 coax noise filter option for one or two antenna ports.

This kit will help reduce or eliminate:

1. “Hot mic” RFI caused by poor grounding of antennas or common mode currents from linear amps feeding unbalanced (coax fed) antennas without baluns/line isolators.

2. RFI to neighbor’s electronic devices including audio/video systems, computers, telephones, garage door openers, etc.

3. RFI to your other radios, audio/video systems, computers, telephones, etc.

A side benefit is a reduction in noise floor in your receiver depending on the amount of noise being introduced by common mode currents (which are blocked/reduced by the chokes in this kit).

These chokes use a special mix of ferrite core material, Mix 31, that is effective in suppressing radio frequency interference from transmitters and high noise floor on receivers.

The split beads beads are easy to use, don’t require modification of the protected equipment and work in almost all cases, even when plug-in filters fail.

Use of the chokes often helps cure SWR problems between transceiver and a linear amp and between transceiver and antenna tuner or direct to antenna. The DC power line choke helps keep common mode current out of the power line which could cause interference to other devices connected to the same power line if not suppressed.

Purpose. This kit is designed to choke common mode currents going into or exiting from your transceiver. Use of the chokes often helps cure SWR problems between transceiver and a linear amp (if used) and your antenna.The AC/DC power line choke helps keep common mode current out of the power line (or into your radio) which could cause interference to other devices connected to the same power line if not suppressed.

The Deluxe RFI Filter Kit includes the CMNF-500-50 coax common mode noise filter option which is highly effective in suppressing common mode noise carried in (or out) on the coax shield braid external surface.The ring filters used on the coax connector, the I/O cable filters and the DC power supply filter are effective from 1 to 300 MHz.

*CMNF Connector Note:

First CMNF-500-50 comes with Double Male Barrel Connector (DMBC) for connection to chassis of radio.

Second CMNF-500-50 comes with 6 in RG-400 coax jumper for connection to radio since the spacing of the antenna jacks is too close for both noise filters to be connected.

Typical Installation Guidelines

RF I/O:Standard Kit: Ring filter – 8-10 turns of ¼”coax cable thru center

Deluxe Kit: Use CMNF-500-50 Coax noise filter with double male barrel connector or short coax jumper cable

AC/DC Input: Ring filter – 3-7 turns of AC/DC power cable

Send/ALC Amp Cable:Snap On – multiple turns through choke – ½” diameter hole

Band Control: Snap on – multiple turns through choke – ½” diameter hole

Audio I/O: Snap on – multiple turns through choke – ½” diameter hole

Digital Interfaces: Snap on – multiple turns through choke – ½” diameter hole

Note: if you have more I/O cables then ferrite filters, you can put more than one signal type wire through the same ferrite snap on.The ferrites filter the RFI/noise current common to all wires, but do not affect the differential signals internal to the wires.

Also make sure you connect a good RF ground to the transceiver ground post.Use multiple turns wherever possible to increase RFI suppression effectiveness.