Ed & Chuck ~
Ed is correct about how I probably let my layers of RFI sources gradually
build up over time. Looking back over 3+ years of RFI log notes I see that
I was not very good at pinpointing the sources. Fortunately, the excellent
advice on this RFI reflector has allowed me to get better. But, it is also
true that the age of the power lines & hardware means things have continued
to deteriorate.
Chuck mentioned possible techniques for determining which particular
hardware components are the source(s) of the noise. On at least three
separate visits from electric utility linemen - - they have located the
component on the particular pole by me standing on the ground with VHF
receiver (on AM) with the volume way up and the speaker pointed up to them
. . . while they poke at various components with a fiberglass pole. When
they can start and stop the RFI by moving a particular component - then
they know what is the RFI source.
Recently, one utility engineer who was present said - this probing method
works OK when there is no wind or urban traffic noise - but that someone
should rig up a Bluetooth audio connection from the VHF radio on the ground
(or ham receiver in the shack) that the lineman in the bucket truck can
listen to while probing with his fiberglass hot stick.
~ Alan K0AV
On Fri, Oct 1, 2021 at 4:37 PM Charles Plunk <af4o@twc.com> wrote:
> Thanks Eddie.
>
> My utility is small with no RFI experience that I know of. They call
> TVA. My last TVA visit years ago was like this; Took weeks (months?) to
> visit. They arrive and the noise is absent but appears while they are
> off out of sight. They go off in directions my beams were not
> indicating. Give little credence as to the pole I suspected. Mention
> they don't have much time. Wont mention if they will be back. I got the
> vibe they did not want to be here. Seem unfamiliar with the gear they
> have. When asked if they will come back do not say. Etc. It made me so
> angry I channeled that anger into learning more myself. Found it myself
> (on the pole I suspected) and my local utility fixed it. May have been
> about the time I built the ultrasonic dish, do not remember.
>
> Contrast to last April. I hunted that source day and night for months to
> make sure (would have been less time but i had other constraints on my
> time). Located it with methods you, others, and I mentioned. Took
> picture of the request with area circled and other details and emailed
> it to the power co engineer. They fixed in about a week or less.
>
> As I say, the TVA visit was years ago. From recent emails with one of
> them, I am hopeful things are better but really hesitant to depend on
> it. I know things are much better with my local utility. Night and day
> now (long story). And I fully realize they are way to small to have an
> onsite RFI tech. An education initiative like Ed Hare mentioned I hope
> will be a improvement in the utilities knowing their responsibilities
> and what is not their responsibility. Even if my utility bought some
> radar engineers ultrasonic gear that would be huge for me. Even a pole
> mounted ultrasonic sniffer would be huge since that much pinpoint is
> usually where I run into a roadblock. I'm not an employee but would be
> happy to help them understand it. I mentioned this once but no response
> to my email, lol.
>
> I just about salivate over the Radar Engineers gear like high dollar
> transceivers.....
>
> My dish (QST article hombrew) though seems to be working well.
> Yesterday, unfortunately I could not hear suspect pole #2's source but
> one side of the pole I could not get too as it borders a yard that a
> renter recently left and its grown up like a jungle including vines and
> scrubby tree limbs reaching the drop lines to the houses. The other side
> is city park so no issue there. Not much on the pole but the drops, a
> transformer, and single phase run. Luckily all the close by poles with
> the 7.2kv are either on right of ways or in the park so I can somewhat
> access them without trespassing.
>
> Coming back I listened to a pure sinewave sounding tone coming out of a
> CATV box, a bird cleaning its feathers sitting on the line, my feet
> walking on the grass, source #1 still singing, etc so think the dish is
> good.
>
> I do have a phenomenon with the dish. May post in a separate thread. I
> need to do more leg work and gather more data. But the last 3 sources I
> have tracked, all three had certain levels of isolated undergrowth. One,
> had a crepe myrtle growing around the pole but otherwise the yard was
> mowed. The second, a flat trailer by the pole with no bed that was grown
> up but otherwise mowed. And the third, the yard grown up on one side of
> the pole but mowed on the other.
>
> Now here is the phenomenon. Whenever i get close to one of these poles,
> when the arc is active, the dish goes into a odd oscillation of about
> 1-2hz. I can point all around but when I point into the thickest
> undergrowth it gets the strongest. Where the grass is mowed I hear less
> of it. For instance the one with the trailer, only in that small amount
> of undergrowth do i hear this the loudest. Its not focused as much like
> picking up an arc. I am very familiar with what an arc sounds like. Of
> course the oscillation is an annoyance to try and hear the arc but I can
> still hear it. Pointing up at the arc, the oscillation is not near as
> loud, only near the ground. The source currently active/strong with the
> grown up backyard, I cannot get with about 50 feet of it before I start
> hearing this oscillation.
>
> Other poles, other undergrowth, trees, that i tried do not cause this
> oscillation. The dish, when not near anything, normally has a very low
> nice level background noise even with the volume all the way up. Maybe
> the magnetic field off the arc is causing this. Maybe I need to put my
> PC board on the dish in a metal box with feedthrough cap's. Not sure. Odd.
>
> Chuck
> W4NBO
>
>
>
>
>
> On 10/1/21 1:14 PM, EDWARDS, EDDIE J wrote:
> > Excellent points Chuck!
> >
> > You're not just a student. You are also an instructor with personal
> > experience yourself.
> >
> > Back in the TVI days, utilities would have one or more full time RFI
> > investigators on staff. At my utility they rotated the radio
> > technicians around so they all got the experience. Some were better
> > than others. Today with cable TV and now digital TV and internet
> > streaming TV, the RFI complaints are very rare now. Last year we had
> > zero! And only 6 so far this year and half were sources in their own
> > homes. So they don't have a full time investigator anymore. This means
> > it's going to take longer to get them out, and it won't always be
> > there when they do. They sure don't want to pay overtime to have them
> > checking at nighttime as you found necessary sometimes.
> >
> > So it is up to hams as self-educated, technical specialists to do the
> > early footwork if they want RFI located quickly.
> >
> > Hopefully when I retire next year, my employer will take me up on an
> > offer to be an RFI consultant for them. That's why I purchased a new
> > Radar Engineers 243 for the techs to use and for me to borrow! :-)
> >
> > 73, de ed -K0iL
> >
> > Eddie Edwards, P.E.
> > Business Technology - DTS
> > Omaha Public Power District
> > 4302 Jones Plaza, Omaha NE 68105-1099
> > eedwards@oppd.com
> >
> >
> >
> >
> > -----Original Message-----
> > From: RFI <rfi-bounces+eedwards=oppd.com@contesting.com> On Behalf Of
> > Charles Plunk
> > Sent: Wednesday, September 29, 2021 4:40 PM
> > To: Rfi List <rfi@contesting.com>
> > Subject: Re: [RFI] CASE HISTORY - Powerline - Multiple Sources
> > (re-post w/o errata)
> >
> >
> > Yes, great list.
> >
> > That maybe me on #2, lol. I re-transmit the audio from the HF receiver
> > on 440 while DFing on 2m or vica versa with 2 HT's. Could be done with
> > one dual bander I suppose as long as you can listen to both bands at
> > the same time. Seems like nearly all my 120hz noise at some point will
> > develop a distinctive pattern especially as the weather changes but
> > one has to be really patient for this method. Got to be ready to go
> > when it does happen, usually at a non convenient time. But when it
> > does, its obvious by listening to the two sources that you have a match.
> >
> > It helps also to have a rotatable vhf (or possibly uhf) station beam
> > to get you started in the right direction. Listening to the pattern
> > (especially if its intermittent) on vhf and hf at the same time to match.
> >
> > And you maybe able to actually see the arc at night especially with
> > binoculars once you have found the pole. Of course it helps if its
> > dark and no nearby streetlights. Likely expect a faint little pinpoint
> > arc.
> >
> > Just more tools to consider. One has to keep a really open mind
> > chasing this stuff and get all your ducks in a row before calling the
> > utility.
> > It is really time consuming for me but worth it and really satisfying
> > when the utility fixes the source you found. Kind of like solving a
> > complex puzzle. And can be very frustrating at the same time for many
> > reasons.
> >
> > The knowledge base on this reflector is incredible. I am happy to be a
> > student here.
> >
> > Currently chasing 3 sources. I have identified all 3 poles and got one
> > pinpointed with the Ultrasonic. The other 2 are intermittent to the
> > point of ceasing for weeks and months at the time making the hunt long
> > term. One of these I identified today. Its 2 houses down and singing
> > like a canary. The pattern matched. Not long after I got back to the
> > shack it ceased so no Ultrasonic for now....
> >
> > 73
> >
> > Chuck
> >
> > W4NBO
> >
> >
> > On 9/29/21 10:50 AM, EDWARDS, EDDIE J via RFI wrote:
> >> Alan,
> >>
> >> Sorry for my delayed post on this subject. Some things previously
> >> mentioned on this group by the professional RFI investigators who
> >> have posted in the past but I wasn't sure if you were aware of in
> >> your post:
> >>
> >> 1. In older neighborhoods with older power lines, you should be able
> >> to find dozens and maybe over 100 RFI sources within a short distance
> >> to your station. Not all of them are creating RFI being picked up at
> >> the location of you antenna(s). And the utility is not required to
> >> fix all of them if they are not causing harmful interference to anyone.
> >>
> >> 2. Best way to verify that a source in the field is your RFI source on
> >> your radio is to get a noise signature on a scope, save it on the
> >> scope, then go into the field and find a matching noise signature in
> >> the field. One ham on the list has done this using his ears, but most
> >> of us with tinnitus need visual scope readings. LOL
> >>
> >> 3. If you let multiple sources ramp up, you will be "pealing the
> >> onion" as you remove the loud sources first only to find less strong
> >> ones below that layer. You may have found this to be the situation in
> >> your case.
> >>
> >> 4. Back in the pre-cable, pre-streaming TV days, it was the utilities
> >> responsibility to find and repair RFI sources causing interference to
> >> TV or radios. It is to their benefit to perform their work tasks in
> >> the most efficient way possible. So it is to their benefit to have
> >> trained and well equipped RFI investigators. Not all utilities will
> >> be this efficient as you have found. Utility's budgets and internal
> >> politics can interfere with these tasks. But the FCC's viewpoint is
> >> that it is the utilities responsibility to find and eliminate harmful
> >> interference from their equipment and only their equipment. The ham
> >> should only verify that it is from the utility's equipment and not
> >> his own or his neighbors'.
> >>
> >> 5. Always continue to listen at higher and higher frequencies when
> >> searching for RFI sources on powerlines. You should be able to
> >> confirm a source by finding it at 300Mhz or higher. If you cannot
> >> hear it that high, keep moving down the line until it gets stronger
> >> or fades away. And it is possible it is not from the utility
> >> equipment at all if it is not broadband noise.
> >>
> >>
> >> 73, de ed -K0iL
> > _______________________________________________
> > RFI mailing list
> > RFI@contesting.com
> >
> https://urldefense.com/v3/__http://lists.contesting.com/mailman/listinfo/rfi__;!!AvPafw!eHxyMw-Sw5J0_IwvZIA0SibFtDFiGM3OuXiLeAPGRQvdf30r270pradB5xS8nQ$
> _______________________________________________
> RFI mailing list
> RFI@contesting.com
> http://lists.contesting.com/mailman/listinfo/rfi
>
_______________________________________________
RFI mailing list
RFI@contesting.com
http://lists.contesting.com/mailman/listinfo/rfi
|