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Re: [RFI] Urban noise

To: rfi@contesting.com
Subject: Re: [RFI] Urban noise
From: Jim Brown <jim@audiosystemsgroup.com>
Reply-to: jim@audiosystemsgroup.com
Date: Fri, 12 Feb 2016 09:23:42 -0800
List-post: <rfi@contesting.com">mailto:rfi@contesting.com>
On Thu,2/11/2016 7:23 PM, Tom Thompson wrote:
Yesterday, a friend of mine drove down a main street in the suburbs of Denver using a Perseus radio and a wide band antenna. On the 20 mile trip we experienced 45 dB of change in band noise due to various RFI sources.

Was this a surprise? If so, why? Certainly you must have been aware of the proliferation of switch-mode power supplies and other noisy electronics, some of it part of infrastructure for street signalling and lighting, traffic cameras, etc. Those switch-mode power supplies are part of virtually ALL modern electronics, whether internal or a wall wart or a cord lump, they are used as battery chargers for everything from power tools to mobility scooters. And they are used as power supplies for low voltage lighting, including track lighting, fancy architectural fixtures, and so on. The vast majority of this crap is NOT suppressed and much of it lacks an FCC compliance sticker.

All of this noise is radiated by attached wiring, both on the 120V side and on the low voltage side.

73, Jim K9YC


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