Chasing Down and Reducing Local QRM

Posted on by basingstokearc

In our March meeting Steve VK6WN / M0CRX gave us a presentation on “Chasing Down and Reducing Local QRM”. A very relevant topic to most, if not all of us!

Steve covered his noise problem, and close encounters of the third kind, before presenting his comprehensive four part solution to reducing his local QRM problem, these included (with some quick takeaways):

  • Common mode chokes – Buy the good ones!
  • Mains power filters – Feed Everything through filters
  • Ferrite everywhere – Ferrite everywhere
  • QRM phase nulling – (Noise + Signal) – Noise = Signal

Each of these filtering techniques have different methods of reducing RF, and reasoning for why you might/might not want to use them. A very interesting talk with lots of discussion at the end.

Along with the presentation, Steve also brought along some of his noise reduction kit for us to see and aid discussion, including a beautiful DIY common mode choke, smaller chokes, a wide band antenna + noise canceller/phaser setup, and a DIY mains filter.

Turnout was again strong, many thanks to Steve VK6WN/M0CRX and those that came along for the evening!