Oh why not, another RFI thread

[SCPD]

So I've been fighting another RFI source but this one is tricky. Here are my notes:

** It's not consistent. It also comes and goes at odd hours. About 2-3 days ago, it went off at roughly 7pm local time. Tonight, it came back at roughly 8pm local time. It'll stay on for a day or two and then go off.

** Vertically polarized only. Switching to a horizontal wire -- nothing! Power/Utility/Light pole?

** The pattern is like a splatter.

** Freq range is rather odd. Seems to show up on x.800 (almost the entire HF band) Strongest freq is 10.780 (and BW is short - around 200khz)

** Freq is definitely not local (not from my house.) Portable just outside house barely registers any noise. Seems worse to the south of me.

** Searching with portable revealed so many noise sources from around the neighborhood, I wasn't sure if I had found the source. I did isolate one utility pole, but I don't think it was the same source.

Finally, a video record for you RFI junkies:

http://home.comcast.net/~cnick6/rfi2.wmv

You'll see switching from vertical (Ant 1) to horizontal and then sweeping the band downward.

Any ideas?

 

[kb2vxa]

That's an easy one, a ragged 60Hz note loaded with harmonics is characteristic of electrical arcing. Man made impulse noise is vertically polarized, another characteristic that belies its origin(s), simple power line noise caused by leakage across bad insulators, rubbing tree branches, and if the voltage is high enough, corona discharge.

"Searching with portable revealed so many noise sources from around the neighborhood, I wasn't sure if I had found the source."

You didn't and probably never will because of multiple "noise sources" which BTW are points along the line where RF is being radiated and not the actual source(s) which are the faults generating the RF in the first place. Confusing? You bet, to the point where the average non technical person especially when lacking specialized equipment and training can't tell the difference between a noise generator and a noise radiator.

Here's what you do, by telephone locate who is in charge of this sort of thing and deal with him/her/the department two ways, live on the phone and by good old fashioned snail mail. The latter is a legal backup to other correspondence provided you keep hard copies to be used only if push comes to shove, never threaten, notify the FCC or take legal action prematurely. In most cases the power company will be eager to locate and fix the problem(s) since leakage represents waste which cannot be billed to the customer as it cannot be metered.

Here's wishing you luck, there are two extremes in attitude I have dealt with; one that thumbs its nose at complaints until a fault ends up damaging or destroying company equipment leaving customers without power and one that sends an engineering truck out within a few days. I can't praise Atlantic Electric enough, their engineer worked closely with me locating every fault in the neighborhood (even a couple of touch control lamps) and I got to see a truck better equipped than the FBI van at Waco (saw that one too BTW).

 

[SCPD]

Thanks for the information. Our power company is pretty good about these sort of things. I was just hoping to isolate it down to a specific utility pole.

I understand your point about not locating the noise source. Have you seen this web site? PowerLineNoise.com - Home

This guy goes around with a handheld 70cm Arrow antenna and a 70cm radio (set to 440 Mhz AM.)

Would this work in trying to locate it? Again, I know I don't have to but it would help to speed the repair.

 

[SCPD]

Located the source...

I found the source of my RFI issue. Apparently, T-Mobile has set up a cell repeater (that sits on a standard utility-like pole, albeit thicker.) Down the pole runs several (long) lengths of coax. I'm guess that the sheilds of the coax (I'm thinking four runs, one for each repeater panel) are probably acting like a vertical antenna and putting out some bad hash -- which also explains why I'm hearing faint digital hash in the background.

Next to this pole (about 6ft away) is a massive service spot with a power meter, a internet access junction (from Qwest) a couple of huge 240v power boxes and even a 240v generator access point. There's also an underground box which probably houses the T-Mobile equipment.

This also explains the time elements. Around 5pm, the RFI is extremely bad and consistent. (Rush hour traffic and probably the busiest usage time of the repeater.) At roughly 9pm, the RFI stops... which is (in my guess) the time where the repeater either shuts down and/or goes into some sort of low-power/standby mode.

I'm going to file a report with the power company (whom will contact T-Mobile) if necessary.

BTW, I used my BC346XT scanner on 27.8 Mhz in AM mode and it worked great. I was able to isolate it with this. I put the Sony 7600GR next to this repeater pole and the speaker nearly blew out.

 

[radioman2001]

Arcing is a common interference on HF, but it can effect even higher. Last evening I got a panic call from my sister-in-law that her power was acting weird, half the house was flickering and going on and off. I told her to call the power company, who informed her of no problems reported in the area. I went over because I was hoping it wasn't a loss of the neutral, which could cause serious damage to her appliances, oil burner etc. I opened up the breaker panel, and could see rust coming out of the main breaker, I tapped on it and immediately got internal arcing in the breaker. I replaced the breaker and informed her that an new panel should be installed due to the water and arcing damage.
Later when see went to make a phone call she mentioned that there no longer was a noise on her cordless phone a 5.8g model, also no more noise on her cell phone 800/2.1g and their wireless router was working again 2.4g. That breaker must have been going for quite a long time since she mentioned that she dropped Verizon phone and wireless because of the noise 6 month ago, after nearly a year of problems.

 

[kb2vxa]

Something tells me that's not a cell phone repeater; first, they're usually located in buildings where normal coverage is spotty or absent, second, you mentioned an "internet access junction" which tells me this is most likely a normal "cell tower". That having being said (;->) it seems to me there is arcing somewhere inside that "service spot with a power meter" or one of the cell transceivers that is the actual source of the noise, the faint digital sounds are incidental. I have a nasty feeling rain water got in and like Radioman's case will eventually lead to a service outage. You have one of two options, notify the cell provider or wait for it to crap out when they'll send a crew to fix it.

Since I doubt your patience can wait that long I rather expect you to go with your first option (;->) but how do you know which service provider owns the equipment? Never mind the rhetorical question since I don't expect an answer when the point is unless you notify the correct one your complaint will be ignored. FYI power companies locate leakage noise two ways, a VHF receiver in AM mode (<30MHz is HF and loaded with noise to begin with while VHF is static free) and listening for ultrasonics with a parabolic mic. If there is arcing or corona discharge in an outdoor location "audible" noise is easily heard.

For Radioman, water ingress is usually through the conduit or Romex cable connecting the HWH meter on the outside to the panel inside the structure but be aware the leak(s) can be anywhere all the way to the cobra cap. If the damage is severe enough a licensed electrician should replace it and NOT overlook replacing the outside wiring and properly weather sealing it and inspecting the meter housing. Since it wasn't weatherproofed the first time somebody didn't make a proper job of it and you don't want it to happen again. BTW if you state your case right he won't think you're insulting his intelligence and telling him how to do his job, he might even thank you for your expert knowledge (don't tell him it's second hand <giggle>) and concern. Oh, good thing you spotted the trouble and replaced the breaker before the panel went up in flames.

 

[SCPD]

Something tells me that's not a cell phone repeater; first, they're usually located in buildings where normal coverage is spotty or absent, second, you mentioned an "internet access junction" which tells me this is most likely a normal "cell tower".

Yep you're correct, I'm interchanging the words albeit incorrectly. It's a cell site or tower.

 

[SCPD]

Yep, I've contacted the power company and still trying to get T-Mobile to respond. I called their 24/7/365 NOC and they were like "don't bother us, we're playing xbox"

All kidding aside, they didn't seem to care much. They routed me to some property management group. :roll:

 

[SCPD]

BTW, here's a picture for you:

 

[kb2vxa]

A property management group? That would make T Mobile a landlord, something doesn't make sense here. From what you say it sounds like they're passing the buck, in short, giving you the runaround. To quote a line from an old cartoon show; This is a job for Superm... er... This is a job for the FCC!

Unfortunately this is the court of last resort but there is an old proverb; if they won't move, light a fire under them. Oh and BTW, how much do you want to bet rain water gets into the conduit carrying the AC mains and/or the RF feed-lines? I don't see a drip loop or cobra cap up there, do you?

 

[SCPD]

Success!

Finally.... after 3 1/2 months of frustrating and irritating RFI -- it turns out to be an electric company issue.

The RFI tech was out in my area about 45 days ago but the RFI seem to stop and was very random. At the time, the weather was quite poor and very wet. The RFI seem to stop when the rain was around. Sure enough, when the dry weather came, it started acting up again.

The tech just happen to call a couple of days ago and said he was planning another trip up to my area (for multiple complaints.)

So they came out today and they tracked the sucker down.

The problem spot was only about 1/16th of a mile away. The initial suspect was coming from a house mains wire touching the neutral guy wire. The tech pulled on the guy wire from ground level and the noise changed drastically.

On their spectrum analyzer, it was splattering from DC to over 500 megahertz. They also had an ultrasonic parabolic receiver. I got to use this for a minute. I aimed it right at the spot they were talking about -- and it started hashing exactly at the spot they initially suspected. Just for grins, they also aimed a 4ft-long 240mhz handheld yagi which also produced a stronger splatter noise. The ultrasonic device was neat because it was super directional. It had pistol-like aiming posts and you had to be aiming it *exactly* at the affected spot -- or nothing would register.

Their suggested solution was likely to be a long sleeve placed over the upper section of the guy wire.

The process took 20 minutes.

I'll post a few pictures I snapped later tonight. I also have a video of the RFI that I'll post on YouTube.

I didn't ask directly but these guys report directly to the power company so it'll probably only take a few days at most to get this resolved.

Relief at last...

 

[ridgescan]

I know from my own experience what you're feeling right now-I bet you're already into some clean dx about now good for you Nick!

 

[SCPD]

Well, not quite yet Ridge but it probably won't be but a couple of days at most. The power guys around here are fairly quick to get things done.

Here are a couple of shots from the offending utility pole:

 

[SCPD]

Here's the youtube video of the actual noise on the radio:

&#x202a;Powerline RFI on 10m&#x202c;&rlm; - YouTube

 

[ridgescan]

Nick how's that station sounding now-did this open up a bunch of DX possibility for you?

 

[SCPD]

Nick how's that station sounding now-did this open up a bunch of DX possibility for you?

Sadly, it's still not fixed yet. The RFI went away for two days and then came back big time. I thought they fixed it -- but alas no.

I emailed the RFI Tech and hopefully they'll push the fix soon.

I'm using my Perseus SDR now almost full-time and its Noise Blanker is a life-saver. Without it, I would be dead in the water from about 10 Mhz and up.

 

[ridgescan]

damm! well that blows cause you DX some cool stuff in here that I enjoy learning from-thank God for your handy alternative. Hope they take care of ya Nick.

 

[SCPD]

Yeah I think they will take care of it Ridge. The offending pole is on someone's property so it's possible they have to give notice to the houses they would be blocking for an hour or two.

I've been driving by the pole the past few days so I should see the fix.

 

[darticus]

Finding similar problems at my house. Lights with Wireless switches going on and off, TV remote not changing channels, Wireless weather stations (3) not sending info and car not starting with remote starter only at my house. It does work all over town. This started to happen about the middle of July. I did hear a hum in the tree area in front of my house and reported it. Things getting better now with some days good and others tricky. Called the Remote car starter installer up and told him don't come to fix it "I have a lot of stuff going on around here". I even mentioned to "stay away from my house as this stuff is powerful medicine" and beware! I don't think Ghost busters can help. Stay away from Sparta NJ. Some crazy stuff around here. I'LL LET YOU KNOW WHEN ITS SAFE! Ron

 

[E-Man]

Nice trouble shooting Nick. You should put an application in at the Power Company.

Another tool used to locate hot spots is a Temperature Gun Infrared Thermometer w/ Laser Sight. Here is a cheepie version of what the Power Company's use:

Amazon.com: HDE Temperature Gun Infrared Thermometer w/ Laser Sight: Home Improvement

(of course if it's intermittent, like every time the wind blows, then it will be harder to locate)