Icom 746/756/765/775/781 Transceiver RFI Reduction Kit, Coax Noise Filter Option, RFI Range 1-300 MHzProduct DetailsMPN: RFI-ICOM-756PRO, RFI-ICOM-756DLX, RFI-ICOM-756DLX2Type: NEWCountry/Region of Manufacture: United StatesRFI Suppression Range (MHz): 1-300 MHzEnclosure Size (inches): n/aTypical Use:: AC/DC power, RF output x 2, multiple I/O linesIcom 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.
RFI Kit Part #
CMNF-500-50 Coax Noise Filter
F240-31 Ring
FSB31-1/2 Snap On
RFI-ICOM-756PRO
None
4
10
RFI-ICOM-756DLX
1(*) + DMBC
3
10
RFI-ICOM-756DLX2
2 (*) + Coax jumper
2
10
*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.
For additional RFI suppression, use a feed line choke at the antenna feed point to suppress common current on the coax feed line and a CMNF-500-50 coax noise filter at the radio end of the coax to reduce common mode noise during receive. Typical common mode noise reduction is up to 30 dB or 6 "S" units - now you can hear the DX again!
If you use a linear amplifier use an amplifier RFI kit for additional RFI interference suppression.
Note: Icom 756PRO picture shown which is typical of filters and connection cables for all Icom and many other brand radios with similar I/O ports.
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.
|
RFI Kit Part # |
CMNF-500-50 Coax Noise Filter |
F240-31 Ring |
FSB31-1/2 Snap On |
|
RFI-ICOM-756PRO |
None |
4 |
10 |
|
RFI-ICOM-756DLX |
1(*) + DMBC |
3 |
10 |
|
RFI-ICOM-756DLX2 |
2 (*) + Coax jumper |
2 |
10 |
*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.
If you use a linear amplifier use an amplifier RFI kit for additional RFI interference suppression.
Note: Icom 756PRO picture shown which is typical of filters and connection cables for all Icom and many other brand radios with similar I/O ports.
TECH NOTE: We also stock RFI kits to protect effected devices such as garage door openers, computers (laptops, desktops), dsl/cable routers, ethernet hubs and many more devices. If you run a high powered RF amplifier in your ham station also consider a linear amp RFI kit which will cut down RFI transmitted by your station. Remember there is always a “transmitter” and a “receiver” of RFI and the quest is to find and choke the “path” the RFI has selected – you need to add ferrites to both the transmitting side and the receiving side to eliminate RFI problems. The RFI-HTS kit only helps suppress RFI on the receiving side.
Typical RFI Problem/Solution:
Hello, I am Larry, a ham operator and I am having interference issues with my Direct TV system. My station is a FT450D through an Ameritron ALS-600. From the amp through a coax switch to choose between an OCF dipole or an Hustler 5BTV vertical. Any power over 100 watts and my DTV goes off the air and must completly reboot/format. Coax is RG-8. The DTV dish is pointed away from the dipole and separated by about 25'. DTV was totally useless! They suggested I not talk on the radio while she is watching TV! Please help me with a reasonable, cost effective soultion. (The wife gets really pissed when I shutdown the tv!) Thank you, Larry
Hi Larry,
Your RFI problem is quite common and is usually a sign of either a radiating coax feed line or reception of your radiated signal (source) by the Direct TV (the victim) through either the AC power lines acting as “antennas” for your ham signal or the coax braid of the satellite antenna acting as an antenna for your signal.
The solutions are straight forward:
1. To make sure your feed line is not radiating you need a feed line choke at each antenna feed point (also makes your antenna work better since it is not using the coax as part of the antenna). You can use our simple Kit 110 with 5 snap on chokes on each antenna for this purpose. Part # Kit 110 at $27.50 each – one for each antenna. These chokes will keep your feed line from radiating and coupling into your ac power lines. INFO HERE
2. The radiation from your antennas themselves may also be getting into the ac power lines and coax braid of the Direct TV antenna so you need to protect the victim receiver. Depending upon the sophistication of your direct TV setup (e.g. home theater, dvd, tape player, sub woofer speakers, etc), the path of the RFI may be coming thru the AC power lines of any connected device to the video including the video monitor itself! To help solve this problem we have a home theater RFI kit for up to 5 devices (you need a minimum of two – one for the Direct TV receiver(AC and coax input) and another for the video monitor AC power lines and HDMI or video input cable. Our kit part # is RFI-HTS. INFO HERE
These items should help reduce the RFI and let you operate on the air while your wife watches TV.
Bob Brehm, AK6R
Chief Engineer