Topband: Low band noise

[Charlie Cunningham]

Well, Bruce, if they are using inverters forf the DC-AC conversion, I would
expect I to be pretty nasty - some sort of "modified square wave" or
"modified sine-wave" approximation. Like a HUGE switching power supply! And
if it's tied to the grid or to transmission or distribution lines, it will
be connected to large radiators that can radiate considerable harmonic
energy over considerable distances. A cleaner way to do DC-AC inversion is
with rotating machines (DC motors driving AC generators) but much more
difficult to synchronize with the power grid. I doubt that those folks are
paying a lot of attention to Power Quality!

Regards,
Charlie, K4OTV

-----Original Message-----
From: Topband [mailto:topband-bounces at contesting.com] On Behalf Of Bruce
Sent: Tuesday, February 11, 2014 3:58 PM
To: topband at contesting.com
Subject: Topband: Low band noise

Getting noise from my NW direction. Does not seem to be local. Started
wondering what, at distance,  could be causing it. At times it seems to have
a rhythm like a motor.

There are a lot of power generating wind mills showing up.  Checking through
Google, they generate DC and convert to  3 phase AC it with an inverter. The
frequency and phase of the inverter is controlled with a sample from the
power grid. 

Could their inverters have enough sine wave distortion to have harmonic
energy?

So my question is: Does anyone have first hand knowledge of interference on
the low bands from  power generator wind mills? 

Bruce-K1FZ
www.qsl.net/k1fz/beveragenotes.html
www.qsl.net/k1fz/pennantnotes.html
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