[RFI] Other Noise Challenge For Ed!

Wed Jul 29 11:44:25 EDT 2015

I am not an engineer. I do have many years of successful DFing experience
locating a wide variety of interference sources.

The method David used to locate his 7 MHz source in an area supplied by
underground utilities is more sophisticated than my approach and likely
resulted in finding the source faster than I would have. However, the
underlying concept is the same as I have often promoted on the RFI list.

That is, locating a source can be accomplished by using the right tools to
hear the source and get directional indications that will lead you to it.
In short, DFing the source, no matter what frequency it may be on.

If an interference signal is very strong (over S9) on the affected receiver
and it is present continuously, it should be easy to pinpoint using good
tools. Directional antennas are available for all frequencies between 1.6
MHz and 1 GHz. While it would be nice if one antenna system could do it
all, that simply isn't the case. Fortunately, there are good receivers with
signal strength indicators and built-in attenuators that cover that
frequency range. Antennas that cover segments of the spectrum can be built
or bought.

I work as an Interference Investigator for a large electric utility in
Florida. Over the years, I have put together a small but effective
collection of antennas and receivers that allow me to search for sources
all across the spectrum. It has been said that DFing signals in the 1.6 to
30 MHz range can be challenging. Without good tools, that statement is
true. But good tools for HF DFing can be had for less than $500.

This is an area where ham radio clubs can shine again. Decades ago, radio
clubs had committees dedicated to helping hams who had "TVI" problems.
TeleVision Interference was a pretty common problem long ago. Modern
conveniences like Cable TV and Satellite TV have largely eliminated the
problem. Instead we have the opposite problem today. Our stations are being
dramatically impacted by consumer electronic devices and faulty power line
devices. Instead of our neighbors coming to us complaining, the tables have
turned and now we often have to approach our neighbors.

As has been recently pointed out here, approaching "lay persons" about
interference problems is an art all its own. Radio clubs can usually afford
to build a collection of good tools. Regular practice builds competence.
The increasing number of interference issues provide ample opportunities
for practice. Club members with great interpersonal skills can be the
diplomats who intercede and smooth the process of resolution.

I see Interference Resolution as an area that can build radio club
involvement and participation. I still firmly believe that increasing radio
spectrum pollution is a problem for which the ham radio community must be
better equipped.

For Joe, if there is no local club or local interference support, building
an HF DFing kit, practicing its use and getting competent at zeroing in on
sources may be fun, if not necessary.

Frank N. Haas KB4T
Utility Interference Investigator
Florida

On Tue, Jul 28, 2015 at 2:06 PM, David Cole <dave at nk7z.net> wrote:

> Hi Ed,
> Sorry, but I no longer have it...  It was ugly and hand drawn contour
> lines...  I now use Google Maps and GIMP to draw things...  They look
> much better that way!
>
> If you want, I can send you, (not on the list), the package of data I
> collect for the FCC should a RFI situation get out of hand, and need to
> be reported...
>
> BTW, the walk around was at 135 MHz, just above the Aircraft band in AM
> mode...  I use one of those little MFJ 135 MHz broadband VHF beams,
> works like a champ most of the time.
>
> --
> Thanks and 73's,
> For equipment, and software setups and reviews see:
> www.nk7z.net
>
> For MixW support see;
> http://groups.yahoo.com/neo/groups/mixw/info
> For Dopplergram information see:
> http://groups.yahoo.com/neo/groups/dopplergram/info
> For MM-SSTV see:
> http://groups.yahoo.com/neo/groups/MM-SSTV/info
>
>
> On Tue, 2015-07-28 at 17:57 +0000, Hare, Ed W1RFI wrote:
> > I'd love to see that graph, or the measured data, if you still have it.
> It may be useful on RFI web pages or publications.
> >
> > -----Original Message-----
> > From: RFI [mailto:rfi-bounces at contesting.com] On Behalf Of David Cole
> > Sent: Monday, July 27, 2015 10:14 PM
> > To: rfi at contesting.com
> > Subject: Re: [RFI] Other Noise Challenge For Ed!
> >
> > Joe,
> >
> > A few years ago, I had a RFI source from an area with underground
> utilities.  I located a source by driving to each underground transformer
> and taking a reading at 7 MHz, using a short antenna and a standard
> procedure for pointing etc.  I wanted to have a standard way of reading the
> signal levels.  I did the same thing at each transformer I could find, then
> took the data and plotted it on a Google map of the area, then hand drew
> contour curves to the various S meter levels I had gotten...  Much to my
> surprise it formed a great big target ellipse.  I think I got very lucky,
> but it might be worth a try for you.  I then walked around with a 123MHz
> beam and TH-F6 in the suspect area.
> >
> > Found the house in short order...  Contacted the owner, and a few weeks
> later the RFI was gone.
> >
> > As Ed said, in each case, "First Contact" is so important...  If you
> come on strong, and tell the person they are in violation of anything, they
> get really quiet...  If you approach them as a neighbor, things go really
> well...
> >
> > --
> > Thanks and 73's,
> > For equipment, and software setups and reviews see:
> > www.nk7z.net
> >
> > For MixW support see;
> > http://groups.yahoo.com/neo/groups/mixw/info
> > For Dopplergram information see:
> > http://groups.yahoo.com/neo/groups/dopplergram/info
> > For MM-SSTV see:
> > http://groups.yahoo.com/neo/groups/MM-SSTV/info
> >
> >
> > On Mon, 2015-07-27 at 18:09 -0700, Joe Wolfe wrote:
> > >
> > > Ed, perhaps you can shed some sense to this.  Up until 4 years ago, I
> > > had no noise to speak of...1 to 2 s units, tops.
> > >
> > > Then, one November day, I turned on the radio to 40 meters (7.205), at
> > > noon, and was blasted with a 20 over *white noise*.
> > >
> > > Did not go away, and it permeated 75 meters as well.  20 and 17 are
> > > tolerable, 15 and up have acceptable noise levels.
> > >
> > > Again, this is just very loud white noise, unwavering in pitch.
> > >
> > > I hooked my radio (Kenwood TS-2000) to a battery, then switched of the
> > > main breaker, so no power was present in the house.  Noise was
> unchanged.
> > >
> > > Further research revealed:  On 40, the noise dropped to below 3 S
> > > units, and stayed low all night.  Around 9-10 in the morning, the
> > > noise starts to rise, reaching its crescendo around noon.  75 meter
> > > noise does not decrease much, at any time of day or night.
> > >
> > > I have walked the neighborhood with the AM radio, Kenwood TH-F6A, and
> > > found....nothing.
> > >
> > > The noise is present in all HF radios I have, Drake's, Yaesu's, even
> > > tried an ICom..
> > >
> > > Mobile HF, drive 2 miles away, and the noise is gone.
> > >
> > > There are no overhead wires in my neighborhood.  There is a high
> > > tension line 2 miles from the house, but it is quiet it's 8 miles run,
> > > down to town from the crest of the mountain it comes across from the
> > > North.  (I have driven it)
> > >
> > > I run an off-center fed dipole, 6 to 80 meters, at 20 feet on 1 side,
> > > 26 feet the other side.  (Fence is on a drop down berm..we live in the
> > > hills (Each house in the neighborhood is 6 to 8 feet higher [or lower]
> > > than its
> > > neighbor]) I have no problems being heard anywhere, on any band,
> > > but...heh, if you can't hear, what the sense?!!!
> > >
> > > Thoughts?
> > >
> > > Joe Wolfe - W7RKN
> > >
> > > _______________________________________________
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> > > RFI at contesting.com
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> >
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-- 
Frank N. Haas KB4T
Utility Interference Investigator
Florida