common mode noise

common mode noise

Antennas : Baluns

• VHF Baluns: Fact and Fancy - Our ideas about HF baluns have changed dramatically in recent years. The focus today is very much on suppressing unwanted common-mode RF currents, to reduce both the received noise levels and the risks of causing interference on transmit.
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• Common mode currents - Common mode currents can flow in all sorts of systems, not just antenna feed lines. This article explain how Common mode noise can be isolated from the desired signal
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• Common mode chokes - Excellent article on limiting noise using chockes by Chuck Counselman, W1HIS
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• Noise Reduction on 40m - DF9CY implementation of W1HIS suggestion of inserting a common mode choke into a 40m antennas feed-line.
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• Chokes and Isolation Transformers for Receiving Antennas - Chokes and isolation transformers are essential for receiving antennas to mitigate common mode current, which induces noise and interferes with signal quality. Common mode chokes, formed by winding feedline through ferrite cores, block unwanted current effectively. Proper selection of core material and winding turns ensures resonance near the operating frequency, reducing interference. Isolation transformers further minimize interference, crucial for multi-transmitter stations.
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• Common-Mode Noise - Receiving Common Mode Noise shows how lack of a balun can contribute to system noise
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• Common-mode chokes Measurements - Common-mode chokes are useful solutions for RFI reduction. Winding a few turns of coaxial cable on the FT 240-31 toroid can reduced the noise below the received noise floor. In this article author measure different chokes
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• DIY EMC/RFI Mains Filter for a Clean Shack - Utilizing snap-on ferrite cores and practical insights, the author enhances their shack's cleanliness against electromagnetic interference. With meticulous experimentation and installation, they improve noise levels across HF bands, reflecting on the effectiveness of their filter in minimizing common-mode disturbances. Updates underscore ongoing refinement and cautionary advice for optimal filtering and radio reception amid changing RF environments.
  [ Hits: 153 | Votes: 1 | Rating: 10 ]