Folks,
Apologies for not replying earlier to the
helpful suggestions. I meant to reply and
got sidetracked.
I found my portable SW radio wasn't able
to pick up signals in the 160M band, it
leaves a big hole in reception and worse,
no option for a directional antenna. As
this interference stops just above the AM
broadcast band, that radio was mostly
useless in RFI finding.
However, I just bought an interesting
portable receiver that might well be what
I need. It's a County Comm "general
purpose World Receiver". A handheld
digital unit that comes with an attachable
ferrite antenna as well as a built-in
extendible antenna.
As with all things digital, it's not plug
& play, I have found time consuming ways
to get the frequency & mode to select what
I want but I'll keep reading the manual
and find the quick easy method.
I'll check out the neighborhood when the
interference is there & I'll see what I
find.
If/when I find something I'll keep you
posted.
73,
Gary
KA1J
> From the hand drawing of the noises, it looks as if there may be two
> different noises.
>
> Most of the time, noise sources spaced 10 to 100 kHz apart are
> switching power supplies or similar devices. They exhibit the
> following characteristics:
>
> 1. The noise appears at intervals across a band, typically 10 to 100
> kHz apart. 2. The noise can be very carrier like, but usually is
> not, having a strong 6o- or 120-Hz component to it. This is usually
> best determined by listening to the noise in the AM mode. 3. There is
> no "digital" sound to the noise, with nothing that sounds like data
> being transmitted. 4. Switching devices are usually a little drifty,
> so the frequency one occupies tends to drift up and down as the
> temperature of the device varies. 5. Switchers are also sensitive to
> line voltages, so glitches such as power surges or dips will usually
> cause a brief frequency change from time to time.
>
>
> Ed, W1RFI/0
> ________________________________________
> From: RFI [rfi-bounces@contesting.com] on behalf of Cortland Richmond
> [ka5s@earthlink.net] Sent: Sunday, October 28, 2018 4:34 PM To:
> rfi@contesting.com Subject: Re: [RFI] Signals on 160
>
> Ed will remember the AT&T modems on 80 meters.
>
> I had good luck tracking them down in Petaluma and locating each one
> to specific rooms in a development of single-story duplexes.
>
> It was Super Bowl Sunday and when people sharing cable co. services
> saw someone with antennas on his car and a "sniffer" (AOR 8000 with an
> untuned loop) they were running behind their houses to remove the
> illegal taps.
>
> A 3-6 inch loop of rigid or even fairly stiff coax can be directive
> enough to find these harmonics and then at lower frequencies march
> right up to the source. H-field coupling drops off VERY fast away from
> a radiating conductor.
>
> Cortland
> KA5S
>
>
> On 10/28/18 3:54 PM, Hare, Ed W1RFI wrote:
> > "What is it?" is the wrong question. If someone said that it is a
> > model Z-123 Netstuff modem, that really wouldn't help much. The
> > real question is: "Where is it?" Finding the house or location where
> > the noise is originating is what you will get to eventually, so
> > start with that question.
> >
> > Many noisy devices can sound similar, so if someone tells you that
> > it is a Z-123, and it is really a lighting ballast instead, you will
> > be on a wild-goose chase.
> >
> > Ed, W1RFI
> >
> >
> > ________________________________________
> > From: RFI [rfi-bounces@contesting.com] on behalf of
> > donovanf@starpower.net [donovanf@starpower.net] Sent: Sunday,
> > October 28, 2018 3:04 PM To: rfi@contesting.com Subject: Re: [RFI]
> > Signals on 160
> >
> > Hi Gary,
> >
> >
> > Of course, the first thing you should do is turn off all of the AC
> > power -- including UPSs -- in your own home to determine if any of
> > the RFI disappears.
> >
> >
> >
> > I don't think anyone will be doing you a favor by helping you guess
> > what these signals might be. By far the best way to determine what
> > they are is to build -- or if necessary buy -- a simple small loop
> > antenna. A loop antenna has a deep, narrow azimuth null off of each
> > side of the antenna that allows to quickly identify the RFI source.
> >
> >
> > Good luck!
> >
> >
> > 73
> > Frank
> > W3LPL
> >
> > ----- Original Message -----
> >
> > From: "Gary Smith" <Gary@ka1j.com>
> > To: rfi@contesting.com
> > Sent: Sunday, October 28, 2018 5:31:51 PM
> > Subject: [RFI] Signals on 160
> >
> > I've been encountering some strong signals
> > on 160 recently. I made some approximate
> > guesses at the frequency using the P3
> > markers to measure them. Here's the
> > signals at 1:20PM local time with a center
> > frequency of 1.848.67
> >
> > The main signals are about 42 KHz apart.
> > The lesser spikes in-between appear at
> > somewhat regular intervals.
> >
> > http://doctorgary.net/spikes-on-p3.jpg
> >
> > Here's the measured values of the main
> > signals
> >
> > http://doctorgary.net/frequencies.jpg
> >
> >
> > Any idea what might be the source of
> > signals spaced like this?
> >
> > 73,
> >
> > Gary
> > KA1J
> > _______________________________________________
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> > RFI@contesting.com
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> >
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> >
>
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