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Author Topic: Power Line Noise - No wall-wart here.  (Read 1752 times)
N2GEW
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Posts: 13




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« on: October 29, 2017, 04:21:17 PM »

Hello
This is an "intermittent" that I have logged at separate occasions on 160, 75, 20 and now 15 meters. It is always random,
always the same "flickering" effect and normally morning and evenings with several seconds to several minute durations:
and seemingly when moisture is present.

I don't think there are any edges, at least in the HF bands.

All thoughts are welcome but it seems to blanket several blocks (minimum) along the road in my neighborhood.

https://www.youtube.com/watch?v=cQXHQM4qOY8

N2GEW
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KE2KB
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Posts: 633




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« Reply #1 on: October 30, 2017, 03:18:03 PM »

Wow! That's a lot of noise! Looks like you've got a decent noise floor otherwise. Maybe something arcing? A pole transformer getting ready to blow?
Just to rule out your computer - have you tried running the software on another PC/Mac?
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N3HEE
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Posts: 433


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« Reply #2 on: November 01, 2017, 09:28:03 AM »

Power line noise (bad lightning arresters, cracked insulators, etc.) tend to get quiet when they get wet or damp due to improved ground path.  If your noise is centered around dusk and dawn then perhaps there is a bad street light near your QTH. 

Have you eliminated your QTH as the source by killing circuit breakers ?

How long does this noise last once it starts ?  Minutes, hours, all day ?

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Joe
N3HEE
CW Academy Advisor (Level II)
N4UE
Member

Posts: 704




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« Reply #3 on: November 01, 2017, 10:15:10 AM »

My RFI Investigator (a fellow ham and EXCELLENT!), asks me to keep a log.
He requests, frequency, heading, time, date, anything that helps him.
Normally, I can pretty much pin-point the noise to a particular direction within a few degrees with one of my long boom VHF antennas.
One tool I've used in the past with the previous RFI Investigator (a non-ham, but a nice guy), was to make a WA5VJB cheap yagi for 130 MHz or so.
Walking around the neighborhood with my Icom R10 receiver worked excellent.
I was going to buy one of the new MFJ parabolic dishes to locate some noise, but my RFI guy talked me out of it.
He said his equipment was FAR superior.....

ron
N4UE
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KE0CU
Member

Posts: 145




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« Reply #4 on: November 01, 2017, 11:18:11 AM »

You have your own "RFI Investigator"? I want one of those! Where did you get him?

Hank/ke0cu
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N2GEW
Member

Posts: 13




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« Reply #5 on: November 01, 2017, 05:56:48 PM »

Thanks for all the great feedback and suggestions.
I have chased RFI before resolving issues in the house (battery chargers, Maytag washer, wireless Asus router, etc), a power line insulator nearby and with an Alpha Technologies Power Supply/Inverter (Comcast) across the street. In all these cases, I would say they were relatively easy to find the source.
Many of the ideas here will work very well as long as the signal is continuous and/or consistent and predictable on when it occurs.

Unfortunately, this isn't the case. Last night, I had several "episodes" of this and each lasted several minutes in duration. I was able to make it to the car and begin a sweep. I right away received it on 530 AM or 1710 AM radio and started to follow it several hundred yards to try and determine what direction in might be strongest. Unfortunately, several minutes just isn't long enough and I did return to the house immediately and document on the SDR waterfall that the signal had abated minutes before. I have several frequencies in the SDR  memory and was able to switch and see the same intensity on 160, 75, 41, 31, 22, 20 and 15 meter bands. In AM or SSB, take you pick. Definitely the same source.

Perhaps, next time, I will be more ready.

ARRL has weighed in and with some slight reserve, declared this power line noise. I will need to "camp outside" with a yagi and 130 MHZ AM portable, but if I had chosen tonight, for example, it would have been unprofitable as nothing other than a few seconds have appeared now by 9.00 PM.
Last night, the intensity was best around 8.00 PM and there was at least 10-minutes I could have worked with.
Tonight, zippo.............
When will I get another chance?
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N3HEE
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« Reply #6 on: November 02, 2017, 04:41:32 AM »

Is it windy outside when the noise appears ?  Perhaps there is loose connection somewhere ?
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Joe
N3HEE
CW Academy Advisor (Level II)
N2GEW
Member

Posts: 13




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« Reply #7 on: November 03, 2017, 04:29:01 AM »

After reviewing this and timing for about a month, it is not wind related. We had a big blow through here recently and it does not seem to increase the incidence of when it occurs.
My theory is moisture related (dew, rain) as perhaps in a cracked insulator: varying conditions of some moisture and dirt allow an electrical discharge or ground path and as the discharge matures, heats and "drys things out", the potential changes.

After a period of time, the conditions repeat. Theory, of course.

I cannot think of another course of action other than a science project involving time,  a small handheld yagi with a VHF receiver and trying to get a directional fix: the process of elimination.
N2GEW
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AE5GT
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Posts: 43




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« Reply #8 on: November 03, 2017, 01:02:57 PM »

I ahve heard of instances of dust or salt accumulation on insulators  . Rain  can washes it away , and everything seems fine. After a dry spell dust or salt accumulates again and the noise returns. You might hear the arc popping if your standing nearby.
 It might also be a bad knife on the pole that starts arcing when a large load is on the circuit. At night you might see the arc. . 
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ZENKI
Member

Posts: 1424




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« Reply #9 on: November 04, 2017, 01:41:49 AM »

Dont also forget to check Ethernet cables. Things like network cables and IP cameras running on POE can cause a lot of broadband hash.

I have replaced all my Ethernet  CAT6 cable with Fibre Optic media converters. Cleaned the trash from 160 and 80 meters.

Also check your mouse  and its cables. Many of the current model Mice/Mouse? cause high frequency interference especially above 18mhz.

Fighting noise is a war that is never going to end  for hams unless politicians start doing something about this issue and take back the high moral technical ground.

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N3QE
Member

Posts: 4881




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« Reply #10 on: November 04, 2017, 06:28:01 AM »

I have a very similar noise in my neighborhood. At least I think it's in my neighborhood! If you and me are hearing the same noise I wonder if we are both hearing the same (distant) arcing insulator?

I think it's more likely we are both hearing intermittent local noises.

Mine is rarely on for more than a few minutes at a time but the way it sputters and starts and stops makes me think that it's an arcing utility company component and not a wall wart or switching PS.

Sometimes it might be days between me hearing my noise.

Since it's so intermittent, and I have been unable to tie to any particular weather/temperature/humidity conditions, I am reluctant to call the power company.

I have had some past utility noises that I was able to pin on, for example, "only happens on coldest driest days", and that fact was actually useful to the utility guys.
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K5LXP
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« Reply #11 on: November 04, 2017, 10:02:57 AM »

One technique I use to help DF a signal like that is to see how high up in frequency I can pick it up at a given location.  Generally speaking, the higher in frequency you can pick it up the closer you are to the source.  Keeping a log and detailed notes on times and observations can help you create potential locations to search the next time the signal appears, minimizing retracing past routes.  On several occasions now I've started with RFI that could only be picked up around AM BCB and 80M and have literally walked right up to the source with an HT that can pick up AM through VHF.

Mark K5LXP
Albuquerque, NM
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