[RFI] Noise Cancellers - RFI Survival Guide

Hare, Ed W1RFI w1rfi at arrl.org
Sat Nov 11 11:37:38 EST 2017

Noise cancellers can be 30 to 50 dB effective against a single source of noise.  They work by positioning a sense antenna that will pick up more noise than signal and combining that out of phase with the signal plus noise from your main antenna.  That can be very effective. 

They do have disadvantages, though. They don't work against multiple noise sources. They are tricky to set up and tune and if you QSY a few tens of kHz, you need to retweak the settings.  They will also change the receive pattern of your antenna, so if you are using a directional antenna, your "noise" antenna will pick up signals from all directions, perhaps degrading your front-to-back ratio.  And, no matter what, they will put a null in your receive pattern in the direction of the noise, so in that direction, you will pick up less signal, too.

Ed, W1RFI/5

From: RFI [rfi-bounces at contesting.com] on behalf of Tom Lewis via RFI [rfi at contesting.com]
Sent: Saturday, November 11, 2017 8:39 AM
To: RFI List
Subject: [RFI] Noise Cancellers - RFI Survival Guide

Does anyone know if this works?
73 Tom N4TL

Earlier this year, I published a series of articles on my web site called "Noise
Cancellers - RFI Survival Guide". The purpose of this information was to help hams and
shortwave listeners lower their local HF noise floor and improve reception.

RFI from neighbors is a constant challenge.  Properly set up, noise cancellers are
amazingly effective in cleaning up or reducing RFI. Sucesss depends on understanding what
kind of noise you can fight, how noise cancellers work, and most important, designing and
installing noise probe antennas around your location. This five-article series does just
that. It also includes a detailed video demonstrating effective noise cancellation.

Please take a moment to review these articles. If you find them to be useful, please
consider passing these along to your members or contacts.

You can use these articles by linking to them on your web site, Twitter feed, Facebook
page or by e-mail. The URL is:

Thanks for your consideration. If you have any questions or suggestions, please contact

73 John Fallows VE6EY
Calgary, Alberta
RFI mailing list
RFI at contesting.com

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