[CQ-Contest] RFI Issue

Andy Blank n2nt at comcast.net
Mon Aug 29 09:37:36 EDT 2005

   Joe, I have had 2 similar sources of noise.
Both of them turned out to be coming from the same house.
I could never figure out a pattern for the noise. Same thing with the power 
lines, no luck.
My neighbor is directly at 45 deg, and the noise peaked there.
I finally called and had them shut stuff off until it went away. The first 
time it was a small battery charger.
During the charge cycle it would be fairly quiet, but after a full charge 
it would take off. Wiped out 15 mtrs with
S5 noise.
   About a year later, a similar noise occured. They had installed a new 
kitchen with low voltage lighting under the cabinets. If that power supply 
is left on overnight, the same thing happens. Wideband noise with spikes 
that peak every 15khz or so. They are good about not leaving it on, but I 
have been wiped out in more than one contest over the years. Took me about 
4 years to figure it out :-).
The electric feed to their house is not underground, and I think the 25 
foot high drop line radiates the noise.
Before the contest season, I am going to give them a power line filter, 
which should eliminate my problem.

Check all the neighbors in the 60 deg direction. It might be the answer.

73, Andy N2NT

At 05:11 PM 8/28/05, Joe Stepansky wrote:
>I hope the group doesn't mind me taking a little bandwidth on this, but
>I've been searching for a solution to an RFI for months to no avail.  If
>anyone knows what this might be, or has seen this before, I'll be in your
>eternal debt.  It's my luck that this is roughly in the direction of Europe.
>Since about April I've had RFI issues on 20 through 10 meters, but loudest
>on 15.  I have an IC756PROII, and on the scope it appears to be a series of
>spikes moving right to left (seems to be a switching power
>supply?...unstable and decreasing frequency).  When it's just the spikes
>the noise has a grinding sound on SSB.  But there's another
>component.  This is a series of little blobs moving very quickly left to
>right on the scope, which I take to mean unstable and increasing
>frequency).  This is accompanied by a rushing water sound (best I can
>describe it).
>Here's another kicker....it NEVER occurs during rain.  Never.  The local
>power company has now been out four times trying to find this thing and
>have tightened the hardware on a number of poles, but the noise
>persists.  I'm convinced it's not the power company.
>To give you an example of the sequence, today is a good example.  It rained
>last night/this morning, no noise.  Then the sun came out about 11 AM, the
>little spikes appeared, moving right to left on the scope.  The the little
>blobs appear.  This goes on for about an hour, then it's only the spikes
>and then the noise (and spikes) abruptly stops.  Then, the little spikes
>(and grinding noise) appear sporadically for maybe 2-3 seconds at a time.
>I've never seen the noise appear at night,  And though it never appears
>when it's raining or damp, it's not there all the time when the sun's out,
>I've pegged the direction at 60 degrees, and have drawn a line with that
>heading from my QTH on the map I use for APRS.  I've driven that way a
>number of times, but nothing.  I've often come home to find the noise gone,
>so it's possible I was chasing a ghost.  Oh, I've shut off breakers in my
>house and it doesn't matter (besides the house is not at 60 degrees, but
>who knows?)
>My wife was all set to drive me around this afternoon when the noise, once
>again, stopped.
>Does anyone have a clue what this might be?  If you got this far, thanks
>for reading.
>73, Joe KQ3F
>CQ-Contest mailing list
>CQ-Contest at contesting.com

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