CABLE TV/Satellite RFI Noise Filter for AM broadcast & shortwave from 1-60 MHz – Receive Only - F connector I/O - 75 ohm input/output, will pass DC straight thru
Purpose. The CMNF-TV is used to suppress RFI noise and common mode interference on the coaxial input line of satellite and cable TV receivers often caused by nearby transmitters
The filter is designed to have a high RF impedance to noise and interference from common mode currents on the outside of the coax braid while passing RF signal currents on the center conductor and inside of the coax braid to the antenna.
The effectiveness of the filter is dependent upon the amount of common mode noise encountered on the feed line. If your receive system has a large amount of common mode noise current then you should experience a reduction of common mode current which usually as heard as background noise level. Typical choking impedance is shown in the gallery picture.
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The filter was quite effective. Was surprised that it actually reduced the noise level more than the signal so S+N/N improved by 1.9 S units. Bill
Also make sure you connect a good RF ground to the transceiver ground post.
Note to Flex Radio users: Use snap on ferrites for firewire cable, speaker cable and mic cable, Ring ferrites for Antenna output and DC power.
For additional RFI suppression, use a feed line choke at the antenna to suppress common current on the coax feed line – see our store for feed line choke alternatives for use at the antenna.
If you use a linear amplifier we have RFI kits for linear amplifiers that help suppress RFI in your shack or in your neighbor’s house.