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Old June 18th 05, 10:44 PM
w_tom
 
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Take a long wire antenna. Ground the far end. Notice the
grounding does not eliminate signals. And yet is AC electric
faults to that antenna wire, then it is a complete short
circuit. Wire is not a perfect conductor. Therefore with
frequency (and other electrical) differences, then how wire is
affected by ground varies completely.

A tall steel and concrete building is completely one big
grid of earth grounds. That is why long wave and near low
microwave signals don't propagate well. However, that same
network of steel girders earthed at the bottom can still be a
good radio antenna for some frequencies.

Noise is quite complex. For example noise from appliances
can propagate through the air OR it can be carried by utility
wires. Some noise on AC electric only exists when the
receiver 'measures' a voltage difference between any/all
incoming AC wires and earth. This last type of noise is
called longitudinal noise. Just another reason why sometimes
the best solution to noise is either a stronger signal or
solutions applied to the noise creating appliance.

There is no simple ground and there is no simple solution to
noise which might explain why so many EMI/EMC engineers are
bald.

An excellent earth ground is obtained by connecting to the
steel girders. Wall receptacle ground is (typically) not
earth ground. The two grounds are connected by a wire. How
well connected can be determined by length, routing, and what
that wire passes through. The window may or may not be a
connection to building earthing depending on how that window
attaches to the steel building frame. If connected, then the
window is but another way to use the building steel girders as
a big antenna. To better understand it all, first learn the
wavelength of that frequency. Frequency in hz times
wavelength in meters is 3.0E8 (meters per second).

Welcome to an art: grounding.

Lucky wrote:
I was trying to do the right thing according to manuals and some
articles I read, plus lower the noise floor. I always thought this
unwanted "noise, static, clicks, lightning and other garbage"
needed somewhere to go. That you wanted to provide a path for it
so it didn't find it's way to the radios speaker and then your ears.

I bascially do BCB during the day, some Hams, shortwave programs
during the early night and Hams again later at night. I live in
Florida and like listening to the Southern Hams late at night.
Some stay on very late.

I'm bascially talk programs during the day and all over the night
frequencies at night. Whatever catches my interest. I even
listen to the Liberty net every so often for fun.

Thanks
Lucky

 
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