[RFI] New RFI

Tue Jan 12 18:07:20 EST 2021

Hi Pete,

As the previous poster mentioned, this is more geared towards new, or 
unknown conditions...  Most of the issues across the past five years, 
here in Eugene Oregon, are Pot Grows.

Ninety percent of the growers are fine, normal folks, who quickly fix 
things, say thanks for telling them, then offer to share, (which I thank 
them for, but tell them no thanks), and we part with no hard feelings on 
either side.  I may have to call on them again, so I never leave them 
ticked off if possible.

However every now and then I get a "interesting" one...  Here is a 
short, and now humorous, (although it was not at the time), story from 
the RFI hunting annals:

RFI  starts, I trace it to a home.  I knock on the door.  The person 
comes out and we talk a bit, all very friendly, and he indicates he will 
fix the issue.  All while his girl friend is wandering around half naked 
on the porch twenty feet behind him.  He fixes the RFI in short order, 
and I figure things are finished...  Oh no they are not!

A few weeks later I get a call from him asking about building a Faraday 
cage around his bed.  He now believes that the "rays" from the RFI are 
harming him, and he wants to, (and I quote), "protect himself from the 
RFI rays".  He has evidently been caught up in all the "5G will kill 
you", propaganda going around, and convinced himself the "RFI rays" from 
the grow lights will kill him in the long run.

At this point, I decide I want no more to do with him at any distance, 
and I tell him I don't know anything about how to build Faraday cages. 
This was a few years ago ago.

I was just told, a few months ago, by a neighbor, that sometime shortly 
after my encounter with him, Law Enforcement was out for a "friendly" 
visit-- why?

Because he was in front of his house, with an AR-15, shooting at 
Tannerite cans he had placed all around his front yard!

According to the neighbor, you would hear pop, boom, pop, boom, pop, 
boom-- which I assume is what got the police called on him.

I live in a pretty decent neighborhood, not a farming community; it is 
urban in town living, in one of the better areas in town...  This was 
two blocks from my home.  That is when I decided to NEVER enter an 
unknown home, under any circumstances, for any reason.  He seemed so 
normal when we first chatted...

That is why I take such a strong position...  Liability is only part of 
the issue...

73, and thanks,
Dave (NK7Z)
https://www.nk7z.net
ARRL Volunteer Examiner
ARRL Technical Specialist, RFI
ARRL Asst. Director, NW Division, Technical Resources

On 1/12/21 1:22 PM, N4ZR wrote:
> I was a little surprised by Dave's strong advice against entering a home 
> where RFI is located.  On two occasions at my former townhouse QTH, I 
> discovered that the source of RFI was "clickless" light switches in 
> neighbors' houses.  This could only be identified by zeroing in on the 
> faulty switch and toggling it off and on to confirm the find.  On 
> another, the source was the thermostat on an electrically-heated dog 
> dish.  Without entering the yard (with the owner's permission, of 
> course), I would never have found it.
> 
> Granting that these two episode occurred 20 and 10 years ago, I think 
> points 4-7 are unduly absolute - it depends a lot on the neighborhood 
> and the neighbor.
> 
> 73, Pete N4ZR
> Check out the new Reverse Beacon Network
> web server at <http://beta.reversebeacon.net>.
> For spots, please use your favorite
> "retail" DX cluster.
> 
> On 1/12/2021 12:02 PM, Dave Cole wrote:
>> Some of the techniques for fixing these issues are:
>>
>> 1.  I added a attenuator to the MFJ device.  I moved the actual 
>> receiver down the mast, and ran coax, then added a step attenuator.
>>
>> 2.  Once I "think" I have the signal located, and, I have contacted 
>> the person responsible, I set up a test whole home shutdown with them, 
>> (if possible), while listening to the RFI both at the remote site 
>> using a handheld radio, and at my home, via a cell call to my 
>> landline, with the handset set in front of the speakers of my main rig.
>>
>> 3.  When I first approach, I have a portable radio on, and the RFI 
>> slightly too loud.  That helps in convincing folks that the RFI is a 
>> problem...  I think.
>>
>> 4.  I never enter a home, period for obvious reasons.
>>
>> 5.  I never approach alone, period, again for obvious reasons.
>>
>> 6.  I never suggest a fix, period.  I tell them what has worked in the 
>> past for me...  If I suggest a fix, and they blow up the install, and 
>> their home burns down, my liability is increased.
>>
>> 7.  I never tell the person responsible it is fixed, I tell them that 
>> it no longer is an issue for me.  Why?  If I tell them it is fixed, 
>> and later on, the local PD or whoever approaches them, they can say, 
>> so and so said it was fixed, and your liability increases...
>>
>> 73, and thanks,
>> Dave (NK7Z)
>> https://www.nk7z.net
>> ARRL Volunteer Examiner
>> ARRL Technical Specialist, RFI
>> ARRL Asst. Director, NW Division, Technical Resources
>>
>> On 1/12/21 8:31 AM, K9MA wrote:
>>> I've also had success with the MFJ-856. However, when you get close 
>>> to a strong source, it can overload and lock up. My solution was to 
>>> make two wide straps of thin aluminum with which to short out the 
>>> antenna, receiver, or both. When I'm right next to a very strong 
>>> source, I can hear it with both straps on.
>>>
>>> The other caveat, which I've mentioned before here, is to make sure 
>>> you're hearing the same source that's causing the problem. The 
>>> MFJ-856 is very sensitive, and will detect a lot of weak sources 
>>> which, at least in an urban area, are usually not the main problem.
>>>
>>> 73,
>>> Scott K9MA
>>>
>>>
>>>
>>> On 1/12/2021 7:25 AM, Dave Cole wrote:
>>>> Hello,
>>>>
>>>> I have some RFI location information at:
>>>>
>>>> https://www.nk7z.net/i-have-rfi-now-what-locating-it/
>>>>
>>>> I use the MFJ-856, (https://mfjenterprises.com/products/mfj-856), 
>>>> when looking for VHF RFI.  It will pinpoint an RFI source and in 
>>>> most cases you can tell which part of the house the RFI is coming 
>>>> from, if you are on the sidewalk in front of the home.
>>>>
>>>> Your RFI could be anything, is it on a schedule, does it change 
>>>> strength, lots of questions to answer first.
>>>>
>>>> IDing via signature can sometimes work, (not too often), but nothing 
>>>> has worked for me better than getting out on foot and looking for 
>>>> the RFI source.
>>>>
>>>> Once you have it located that is another entirely different matter.
>>>>
>>>> 73, and thanks,
>>>> Dave (NK7Z)
>>>> https://www.nk7z.net
>>>> ARRL Volunteer Examiner
>>>> ARRL Technical Specialist, RFI
>>>> ARRL Asst. Director, NW Division, Technical Resources
>>>>
>>>> On 1/11/21 8:45 PM, RALPH GRANCHELLI wrote:
>>>>> Hello inteference investigators,
>>>>>
>>>>> I have new RFI issue that started about a week ago.
>>>>>
>>>>> I have eliminated the house /  items as a source.
>>>>>
>>>>> Killed all breakers, ran the XCRV from batt. No change. 
>>>>> Disconnected ext antenna, used in house antenna and no noise. So 
>>>>> noise coming in from ext antenna.
>>>>>
>>>>> The RFI is strongest on 80 meters however it is present up to vhf 
>>>>> with diminished magnitude.
>>>>>
>>>>> I took a screen shot of it on the spectrum scope.
>>>>>
>>>>> Does anyone recognize the signature?
>>>>>
>>>>> https://www.youtube.com/watch?v=uOdzw2ev5eE 
>>>>> <https://www.youtube.com/watch?v=uOdzw2ev5eE>
>>>>> <https://www.youtube.com/watch?v=uOdzw2ev5eE 
>>>>> <https://www.youtube.com/watch?v=uOdzw2ev5eE>>
>>>>> TNX & Rgds,
>>>>>
>>>>> N6XLQ
>>>>>
>>>>>
>>>>>
>>>>> _______________________________________________
>>>>> RFI mailing list
>>>>> RFI at contesting.com
>>>>> http://lists.contesting.com/mailman/listinfo/rfi
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