[RFI] Powerline noise question
Dave (NK7Z)
dave at nk7z.net
Fri Dec 30 21:12:24 EST 2022
Hi Scott,
I programmed up 30 or 40 memories, (following someone's suggestion
here), starting at .5 MHz, and ending at 450 MHz, in almost equal steps,
all AM. I just go into memory mode, look at the RFI both on the
waterfall, and on the O-Scope, dip the offending source if possible, and
move up in frequency by turning a single knob to the highest frequency I
hear the RFI at. I then move to a new spot and do it again... I also
use a program on my iPhone called SigTrax. (see:
https://apps.apple.com/us/app/sigtrax/id714920367), I have attached two
of the resultant run results.
I also use the O-Scope in the IC-705, in addition to the waterfall...
As you said, all in one package... It for my money, is the best RFI
hunting setup I can afford right now... I would love one of the RADAR
units, but alas, cost is an issue for that device...
73, and thanks,
Dave (NK7Z)
https://www.nk7z.net
ARRL Volunteer Examiner
ARRL Technical Specialist, RFI
ARRL Asst. Director, NW Division, Technical Resources
On 12/30/22 13:17, nm8rmedic wrote:
> Don't overlook the audio waveform 'oscilloscope' functionality of the
> IC705 as a means of identifying 60 and 120 Hz components of an arcing
> source. It's all there, in one easily portable package.
>
> I second NK7Z's use of the '705. Mine in combination with a National
> HFDF loop system made it easy to track down the 6 M Wireless headset
> interference I was experiencing. Ed and Steve of the ARRL were very
> helpful in that endeavor.
>
> Scott
> NM8R
>
>
>
> Sent from my Verizon, Samsung Galaxy smartphone
>
>
> -------- Original message --------
> From: "Dave (NK7Z)" <dave at nk7z.net>
> Date: 12/30/22 13:39 (GMT-05:00)
> To: "Hare, Ed, W1RFI" <w1rfi at arrl.org>, rfi at contesting.com
> Subject: Re: [RFI] Powerline noise question
>
> I use the waterfall only for pattern recognition for DFing... I gave up
> long ago trying to define what is causing RFI! :)
>
> 73, and thanks,
> Dave (NK7Z)
> https://www.nk7z.net
> ARRL Volunteer Examiner
> ARRL Technical Specialist, RFI
> ARRL Asst. Director, NW Division, Technical Resources
>
> On 12/30/22 09:58, Hare, Ed, W1RFI wrote:
> > The SDR waterfall will not be very helpful with power-line noise, but
> > they are great at identifying switching power supply noises and noises
> > that pulse on and off in a regular pattern.
> >
> > Most of the time, though, we are less concerned with "what is it" as we
> > are with "where is it?"
> >
> > ------------------------------------------------------------------------
> > *From:* RFI <rfi-bounces+w1rfi=arrl.org at contesting.com> on behalf of
> > Dave (NK7Z) <dave at nk7z.net>
> > *Sent:* Friday, December 30, 2022 12:08 PM
> > *To:* rfi at contesting.com <rfi at contesting.com>
> > *Subject:* Re: [RFI] Powerline noise question
> > Something else that might help you differentiate one source from another
> > source in the pile of other signals-- a portable SDR.
> >
> > I now use an Icom IC-705 as my goto RFI hunt tool when mobile... Self
> > contained for power, and it has a waterfall!
> >
> > The waterfall makes it a simple matter to ID one source, (most of the
> > time), then as you rotate your flag, or loop, you see only that source
> > dip... You know you have the right signal, and can DF only that one...
> >
> > 73, and thanks,
> > Dave (NK7Z)
> > https://www.nk7z.net <https://www.nk7z.net>
> > ARRL Volunteer Examiner
> > ARRL Technical Specialist, RFI
> > ARRL Asst. Director, NW Division, Technical Resources
> >
> > On 12/29/22 20:07, Don Kirk wrote:
> >> Hi Rick,
> >>
> >> Sorry that my last message was blank as I typed it on my cell phone and
> >> then accidentally deleted the text prior to hitting the send key.
> >>
> >> You can use your MF/HF loop to do some triangulation on the source
> but you
> >> often need to get far away from existing power lines to avoid receiving
> >> conducted signals along the lines versus the signal direct from the
> >> source. As an example when out in the country I will often walk out
> into
> >> the middle of farm fields to get away from overhead power lines when
> >> obtaining bearings. As you get closer to the source you can go
> higher in
> >> frequency if it really is power line noise (arcing hardware). As an
> >> example you can go to 40 meters then 20 meters and then 10 meters as you
> >> get closer to the source as a form of attenuation and to also help
> you get
> >> multiple wavelengths away from objects that might otherwise skew your
> >> readings. Adjustable RF gain and/or attenuators are also very helpful.
> >>
> >> If it really is power line noise (arcing hardware) you should be able to
> >> hear the source using an AM receiver with a 3 or 4 element yagi when you
> >> are within approximately 0.25 miles of the source (and sometimes
> upto 0.5
> >> or more miles away). Make sure the yagi is tuned for the frequency
> you are
> >> using in order to assure the correct antenna pattern. When you get very
> >> close to the suspect pole you will typically need to throw in 20 to
> 30 dB
> >> of attenuation in order to determine the exact pole (in rare cases you
> >> might even need 40 dB of attenuation).
> >>
> >> One thing that is great is that it sounds like your source has a
> specific
> >> pattern that will help you differentiate it from other sources but
> if the
> >> pattern is always a very specific 0.9 second pattern that never changes
> >> regardless of what day you listen, etc. that makes you wonder if
> something
> >> else is going on, but the fact that it goes away when it rains is
> typically
> >> a good indicator that it's indeed power line noise (arcing hardware).
> >>
> >> Don (wd8dsb)
> >>
> >> On Thu, Dec 29, 2022 at 10:46 PM Don Kirk <wd8dsb at gmail.com> wrote:
> >>
> >>>
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