[RFI] Noise from Switcher on 80/160

Dave Cole dave at nk7z.net
Mon Oct 10 20:28:35 EDT 2016

On Mon, 2016-10-10 at 12:00 -0400, Mike Wetzel wrote:
> I have been experiencing a noise on 160 and 80 for the past couple of
> months that peaks N/NE from my qth. It has peaks every 32.5/65
> KHz  across 80 meters.  I have subdivisions with underground cabling
> on 2 sides of my property (N and NE). Last week, W5LO (who lives in
> the subdivision to my north and also hears the noise) and I took a
> drive in my car with my K3 and we seemed to find the noise peaking in
> or around a specific house in his subdivision. We contacted the owner
> who did cut the power to the house and the noise did not stop.  

Then it is probably not that house...  Ask the owner if he has any UPS
devices, etc., which might have still had power to them...

> A friend of mine, W9KY and I, used his Sony SW receiver and loop
> antenna to try and pin point the noise on Saturday. We heard the noise
> on his radio with a whip antenna at my house and took off walking the
> subdivision.  

Best procedure for locating RFI, loop and being on foot...

> Listening on the loop on 3820 we heard the noise but were not able to
> pin down it's location.  T

If possible listen to the noise, get to recognize it, be it's friend,
take it to lunch, buy it dinner, then move up as high in frequency as
possible where you can still hear it, and begin your DFing again.  

Once you get closer to it, it should be louder, move up in frequency
again, repeat this process until you get to the house...

One of the first things I do prior to going out on foot is to use Google
and get an overview of an area for about a 10 block radius around my
home.  I map out a grid on it, then set up five or ten locations, and go
to each location and take S Meter readings...  I then transfer them to
the Google map.  Also take your beam heading where you have the RFI
peak, and draw it on the map from your home...

About a third of the way down one of my blog entries for RFI, you will
see one of these maps.  See: http://nk7z.net/rfi-at-my-home-qth/

> I am at a loss as to how to proceed and pinpoint this noise
> source.  Anyone I am at a loss as to how to proceed and pinpoint this
> noise source.  Anyone with any ideas?

Start taking bearing readings in TRUE North, and then add them to the
Google map.  In short order you will find if you are close.  If you find
a crossing point, go there, and do it all again, with a closer view map,
and really accurate bearings...  

Once close, listen on the AM band of a VHF radio, you will hear the
issue if you are close.  Then take a 2 Meter beam and start wandering
that neighborhood pointing it at each house while listening to the two
meter AM rig.  At some point you will find the house...  

Be careful in this process, don't do this alone, and don't go into
someone's home.  You may be dealing with a grower, if so they get very
cagey once contacted.  Don't threaten, be a nice guy-- most growers will
work with you, they will be amazed at how easy it was to locate them, in
fact, tell them how easy it is to find them.  Let them hear the radio,
make sure it is turned up really loud...  Remind them often how little
time it took to locate them... They will be happy to reduce RFI after
that.  Above all, be a nice guy, that works better than any single
action you can take to working with someone to reduce RFI.

If you can get someone to do a power off test, and your noise ends, then
you have it knocked...  Be sure to keep a notebook of everything you are
doing, dates, times, who you spoke too, what was said, what were the
results of the power off tests etc.  More than likely you will find the
RFI, and get it corrected.

The ARRL has a very nice handout for giving to possible RFI generating
neighbors.  It is located at:


It is a fillable form, you just add four items, and print it, then hand
it to the person you suspect of generating teh RFI.  It outlines who is
responsible, how a fix can happen, etc.  It works, and works well...  I
have used it for several years now.  Every time I have handed it to
someone, the problem ends within a month on it's own.

I have an RFI section located at:


This link is to all the RFI articles I have on line at this time...  

Hope this helps...  Good luck, and be sure to report progress back
73's, and thanks,
Dave (NK7Z)
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