[RFI] RFI Digest, Vol 115, Issue 23.....identification or rfi

Dave Cole dave at nk7z.net
Fri Aug 24 20:56:07 EDT 2012


I may have gotten really lucky today...  Someone from the Electric Ops
of the local Power Company was at my house to check out some locates, (I
am switching to gas), and I mentioned the noise...  

He got very interested, and pulled out something I have never seen...
It is a long hand held blue unit, maybe 4 feet long, and 7 inches wide,
with a LCD display on one end, and some sort of sensor on the other...
In any case, he grabbed that, and we ventured up to the suspect
transformer...  It was in quiet mode, (only S9 at my place, not 15 over
like each evening, and morning), so I expected to see no real result...
To my surprise he listened to it on his unit, (which pegged), and said
that he suspects a loose ground, and wow this is not right!  He also
said he would pass on my noise graphs to the Electric Ops folks so they
can actually fix it before it fails, and for me to expect a call

WOW...  I may have gotten rid of my noise of two years finally!!!!! 

More Monday...

http://www.nk7z.net for equipment reviews, propagation, and more...
For JT65 Discussions:

On Fri, 2012-08-24 at 13:42 -0500, stbradford wrote:
> Hello Dave,
> I have spent a couple of years cleaning up rfi with the local power
> company. The ARRL and the company were very helpful in resolving many
> faults.
> Your noise is the product of a discharge on the power grid. It's at
> 120 cycles because both the positive and negative sides of the ac are
> arcing somewhere.
> I use an 3 element yagi tuned to 135 mhz with a 40db attenuator that
> can be inserted into the antenna line. When you get close the receiver
> can be overloaded, so the pad was needed. 
> Most of the problems here in southern Indiana turned out to be loose
> hardware and a few incorrect bell insulator installations. Once the
> rfi gets on the power line you have a jim dandy antenna. But with the
> 40db pad I can stand between two poles, but not in line with them, and
> see which direction the signal is coming from. You kind of form a
> triangle with you at the top and the poles at the bottom angles.
> I went of the deep end and made an 40 khz acoustic detector using a
> 19" parabolic dish to spot the actual arc location. RFI really sounds
> of at 40 khz. But you must be near to the noise. I would stand back
> from the pole and scan the hardware with the acoustic detector, it
> will get you very close to the problem area.
> Dave, I have attached a few photo's of the equipment I built. Both are
> in the ARRL archives. The antenna article by Jim Hanson I think. The
> ultrasonic detector
> author has slipped my mind. I expect the reflector to strip the
> photo's so is someone else wants the photo's drop me a line.
> Smith Bradford
> On 8/24/2012 11:00 AM, rfi-request at contesting.com wrote:
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> >    1. Can someone ID this source of RFI? (Dave Cole)
> >    2. professional question (K1TTT)
> >    3. Waveforms of RFI... (Dave Cole)
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