I can relate a real happening in this respect.
I volunteer at Little Thompson Observatory (<starkids.org>) on the grounds
of Berthoud, Colorado HS. I was the last neutron that caused
supercriticality wrt radio astronomy. Our first installation was on 20.1
MHz for Solar and Jupiter emissions. Initially, we were plagued by a
nearby irrigation pump house. It turns out that the 10-horsepower 3-phose
motors were electronically controlled - two motors and two controllers.
The controllers involved two power switchers and were AC-to-AC converters
to manage the pumps. They were noisy as He--!! To make a long story
shorter, they were installed, two of them, with absolutely no filtering or
decoupling for HF energy. They were nasty, to put it mildly - most
switchers are, but these were especially bad due to the high power ratings
and load. I found them online and looked up the regulatory testing for FCC
that made them legal to import. Of course, they were Chinese. There was
only a store front on the West Coast that distributed them in the US. The
report filed with the FCC and EU clearly indicated that filters were
required for any installation in the US or Europe. The filters were listed
as a separate item on the price list of 'accessories'. If its required for
FCC and the European Union, they should not be accessories, but required!
I've seen this way too often from China. It's a loophole. The installer
had chosen not to order the required two filters at $3k each for monetary
reasons. We wrote a very professional report to the school board. The
following winter when the irrigation was off, they bought and installed the
filters. Our problem with HF went away, well, mostly. As bad as it
initially was, we were in heaven. Beware of ANYTHING from China ! ! ! ! !
! ! ! ! ! !
Hope this helps after the holidays.
Dave - WØLEV
EMC Design & Test, LLC
Volunteer: Little Thompson Observatory
<starkids.org>
On Tue, Dec 19, 2017 at 12:09 AM, jimk8mr--- via RFI <rfi@contesting.com>
wrote:
> I've recently discovered a major RF noise source at our Florida condo -
> pumps or other swimming pool related equipment about 200 feet from my attic
> dipole. I'm not planning to do any followup with management until after the
> holidays, but I've been doing some thinking about it.
>
> There are some pumps outdoors, but any breaker panels or disconnect
> switches are inside a locked room I've not yet been inside to inspect. I
> suspect it would be easier to install toroid chokes inside - if so, are
> there any issues with NEC, or any other issues, about using twisted pair AC
> wiring inside (PVC) conduit between those panels and the outdoor motors?
>
>
> 73 - Jim K8MR
>
>
>
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>
--
*Dave - WØLEV*
*Just Let Darwin Work*
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