[RFI] Working with Utilities

Mon Sep 13 09:14:40 EDT 2021

I've been seeing this topic for a few days now and I'm sorry I've been too busy to comment. What Ed is saying is absolutely correct. If the source of this problem is a power line noise, meaning generated on the power line, it will be in Arkansas. The arcing source radiates from 0 to well over a gig. The closer to the source you get the hiring frequency it can be detected. The methodology that it explains is absolutely correct. If you have a noise that's generated on UHF are you HF yaggy will most certainly detect it if close enough to the source. 
One thing to consider when replacing hardware, when the linemen changes those old bells it frequency creates a lot of disturbance in the hardware. This means he's shaking hardware for several spans and frequently will disturb the noise source even if it isn't on that pole. It's very common for bells to be changed and stop a noise that's three spans away. I have done this in the past and actually disturb the noise over a quarter of a mile away. Routinely I could disturb the noise source. A very very valuable lesson to learn.
As for the use of ultrasound, ultrasound detection is only as good as the success of the previous steps. Step one is for the interference investigator to come into your home or business or wherever the antennas connected to the radio and connect his receiver to the antenna receiving the noise. He should record the pattern of the noise and then go into the field and find the noise that matches that pattern. Once he does that and is sure that the structure he's pointing at is the one containing the source that's affecting the receiving antenna then he can use ultrasound. Ultrasound most definitely will detect bells and any other arc on the pole provided it has a good line of sight in the source is strong enough. Things that keep the source from being strong enough are things like not having direct line of sight with the spark. If it's behind something it's greatly attenuated. So in looking at bells for sparking sources you need to look between the Bell joints to detect The Arc that's up inside of there and makes a big difference. Med Ed or PPL uses a the radar engineers model 250 and 251 ultrasonic detector. They have fantastic sensitivity however two or three feet closer can make a big difference. I have actually stood up on the bumper of my truck and heard a noise that I couldn't hear from any other position so this is very important. Bells as all sparking sources on poles do emit ultrasound and can be detected if all the criteria is met. 
Remember this, be patient with these guys this is not a primary job for any of them they have many duties and tasks they have to address and noise is only one and typically a very small one. They rarely get much experience so it takes time for them to locate the source. The more rushed they are to get this done the harder it is for them to get it done in the more likely to be incorrect and their assessment. Remember when you tell a utility worker where the noise is if he is incorrect he stands the chance of causing more noise that wasn't already there and that only makes the process more complicating.

⁣Be safe,
Mike Martin
RFI Services
51 W Bay Front Rd
Lothian, MD 20711
240-508-3760

On Sep 11, 2021, 12:43 PM, at 12:43 PM, AA5CT via RFI <rfi at contesting.com> wrote:
>
>re: "That is half of the equation."
>
>Beg your pardon here Ed Hare. 
>
>I don't know what you read into my reply Ed, but, that is not my
>experience with 
>this technique! Note I said UHF, not VHF and with a handheld Yagi
>antenna. I have
>even tried a 900 MHz Yagi to do the DF, but the amount of signal there
>is notably
>down from that at UHF (450 MHz). 
>
>Ed, it becomes QUITE apparent when using this UHF DF technique in the
>field
>WHERE the source is, where the RF is coming from, and its definitely
>NOT from 
>'all along the line' as you seem to indicate. AND its easy to note if
>it comes from
>a house or from hardware up on a pole.
>
>There is even a POLARITY associated with these noise sources -
>orienting the
>Yagi vertically and horizontally results in changes in signal strength.
>
>I don't know that you've ever tried this UHF AM rcvr plus beam
>technique in the
>field, Ed, but it becomes quite apparent when actually using this
>technique just 
>where the noise, where the signal originates. 
>
>Again, walk around, sniff the noise source with your HAND-HELD UHF beam
>and note WHERE the signal is strongest. You'll find it. Note: Use AM rx
>mode
>on the receiver, and you'll hear the characteristic 60/120 Hz (base rep
>rate) 
>'buzz' of the arcing source.
>
>This technique (USED to find the individual offending pole) has not
>failed me yet. 
>And, AGAIN, I use other techniques (LIKE HF DF) to locate down to the
>vicinity
>of the offending pole.
>
>THIS response, this e-mail, was directed to the original poster in this
>thread to 
>help ID and note an arcing set of BELL insulators, that was all. But Ed
>took it
>in a more general direction. 
>
>
>de AA5CT Jim
>
>---------------------------------------------------------------------------
> 
>
>On Saturday, September 11, 2021, 10:03:02 AM CDT, Hare, Ed, W1RFI
><w1rfi at arrl.org> wrote: 
>
> 
>That is half of the equation.  The lines are radiating, even on VHF, so
>what you need to do it to go across the street from the pole you think
>the source is.  Do note that the noise gets stronger when you point at
>the pole. Make a note of the s-meter reading. Now, go up the street to
>the next pole, across the street at the same aprpriximate distance. 
>Get an S meter reading If it is stronger, your first pole was not the
>pole. Keep going.  The noise will be significantly stronger on the
>actual pole. 
>
>Now, if the source is NOT on the pole but from a nearby house, you will
>find that it is stronger on the pole that has a transformer connected
>to the offending house.  In that case, compare poles with transformers,
>and when you find that pole, point the Yagi at nearby houses.
>
>Keep in mind that in this day and age, people will be very suspicious
>of you, so you either need to let the police know what you are doing,
>or be prepared to offer explanations when they arrive. 
>
>From: RFI <rfi-bounces+w1rfi=arrl.org at contesting.com> on behalf of
>AA5CT via RFI <rfi at contesting.com>
>
>
>
>Sent: Saturday, September 11, 2021 9:13 AM
>To: RFI List <rfi at contesting.com>; Stephanie WX3K <wx3k at ptd.net>
>Subject: Re: [RFI] Working with Utilities 
> 
>
>
>
>
>Hand-held UHF Yagi - can you point a Yagi at the offending pole with
>those
>insulators and demonstrate THAT is the source of noise?
>
>It's most convincing when you can swing the beam back and forth and
>the noise picks up when pointing at the offending hardware.
>
>Reference:  https://powerlinenoiseallentexas.wordpress.com/df-equipment/
>
>
>de AA5CT Jim
>
>-----------------------------------------------------
>
>
>
>On Friday, September 10, 2021, 9:42:33 PM CDT, Stephanie WX3K via RFI
><rfi at contesting.com> wrote: 
>
>
>
>
>
>All
>
>I live near the territory boundary of two utilities. My work with PP&L
>has fruitful and they have been very cooperative in resolving RFI
>issues i would report to them over the years.
>
>I have been struggling with MetEd for the same powerline noise for at
>least 5 years now. I recently got their attention again and reopened a
>new work order. I spoke to their tech today and learned they have been
>replacing cut-outs and repairing resistive connections. All good but my
>RFI issue continues mostly driven by drier windier weather conditions,
>the RFI swamps the 25-150 MHz spectrum.
>
>https://www.dropbox.com/s/ekn6xpl0960qrm7/IMG_9711.MOV?dl=0
>
>
>There are old bell type insulators on poles near this suspected line
>area. I consistently request they replace those problematic antiquated
>bell insulators that are notorious for RFI issues. They(MetEd) seem to
>avoid this. With my work with PP&L, replacing those bell insulators
>have completely resolved those reported issues. The techs from MetEd
>use their ultrasonic detectors to find issues but it is my impression
>these bell type insulators do not show up as issues when they look
>around with their ultrasonic detectors. True statement ? How does one
>convince a utility to actually listen to the RF spectrum for issues ?
>Is there a specific model spectrum analyzer that the utilities tend to
>use to scan for RFI ???
>
>Stephanie WX3K
>
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