[RFI] Powerline noise question

[Pete Smith N4ZR]

I find it very useful for spotting sources like SPS because of their 
periodic nature. It jumps out at you on a spectrum display.

73, Pete N4ZR

On 12/30/2022 1:38 PM, Dave (NK7Z) wrote:
> 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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