Topband: Low band noise

[David Aslin]

Bruce,
I live in 'wind farm central' (Devon, southwest UK) and have direct experience of wind generator EMI.
The small generators (up to 50kW) almost universally use an induction principle and are RF silent.  But the type that sit on 160-300ft towers and generate in the 1-5MW range are effectively SMPS on a stick.  The generator+inverter that converts the mechanical rotation to a steady state voltage is just like a switch-mode power supply and is most often located at the hub - perfect for radiating anything from the electronics!  That said the EMI level is relatively low, but detectable as a slight noise floor lift with a cyclic component out to 2-3 miles from a big wind farm array (K3 + 9ft whip antenna on SUV, 1.8-30MHz sweep at 1-5 mile radius from the center of the wind array).  Unlike domestic SMPS they don't seem to generate major trash, so maybe the European EMI standard is set at a good level and actually achieved (amazing!).  But a top band enthusiast won't want a wind farm closer than a couple of miles if you can avoid it.
Just my 2c/2pence
73
David G3WGN  M6O  WJ6O