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Re: [RFI] Powerline noise question

To: "RFI Mail list at contesting.com" <rfi@contesting.com>
Subject: Re: [RFI] Powerline noise question
From: "Dave (NK7Z)" <dave@nk7z.net>
Date: Fri, 30 Dec 2022 18:12:24 -0800
List-post: <mailto:rfi@contesting.com>
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@nk7z.net>
Date: 12/30/22 13:39 (GMT-05:00)
To: "Hare, Ed, W1RFI" <w1rfi@arrl.org>, rfi@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@contesting.com> on behalf of
 > Dave (NK7Z) <dave@nk7z.net>
 > *Sent:* Friday, December 30, 2022 12:08 PM
 > *To:* rfi@contesting.com <rfi@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@gmail.com> wrote:
 >>
 >>>
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