Jim,
What surprised me was the magnitude. 45 dB above the band noise is a lot!!
Tom W0IVJ
On 2/12/2016 10:23 AM, Jim Brown wrote:
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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