Topband: Boradband noise on 160 meters tracked down to apartment complex

[GeorgeWallner]

Don,

I have referred to VFD-s in an early posting as "RF 
Weapons of Mass-Destruction". Still, they are useful and I 
got one in my house.

As the contractor in your description did, I installed a 
line filter on the input side. I also installed a three 
wire common mode choke on the three phase output (6 turns 
on a large #31 core) very close to the output terminals. I 
also added three 3.3 nF high voltage mica caps on the load 
side between each phase wire and ground. I used a wide 
braid strap for grounding. My RX antenna is about 200 feet 
from the drive but its noise is now well below my noise 
floor and I can not tell when the drive is running.

Good luck getting rid of the rest of noise.

Unfortunately, for all of us, we will increasingly see 
more of these drives residential buildings.

GW


On Wed, 13 May 2015 11:41:28 -0700
  Jim Brown <jim at audiosystemsgroup.com> wrote:
> On Wed,5/13/2015 11:14 AM, Don Kirk wrote:
>> The local technician is now planning on additional 
>>changes since the input
>> line filters have not totally mitigated the problem (but 
>>they sure helped),
>> and will provide an update when I have new information 
>>to share.
> 
> Hi Don,
> 
> You might want to refer the people working on the 
>problem to this Power Point for a tutorial workshop that 
>I've taught to pro audio and video people. The principles 
>are no different when the interference is at RF.
> 
> http://k9yc.com/InfoComm-Grounding2012.pdf
> 
> Henry Ott's excellent text on EMC includes a sub-chapter 
>on these very nasty RFI sources. His book is widely used 
>as an EE text, and considered "the EMC bible."
> 
> http://www.amazon.com/Electromagnetic-Compatibility-Engineering-Henry-Ott/dp/0470189304
> 
> 73, Jim K9YC
> 
> 
> 
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