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@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@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@contesting.com> on behalf of
>AA5CT via RFI <rfi@contesting.com>
>
>
>
>Sent: Saturday, September 11, 2021 9:13 AM
>To: RFI List <rfi@contesting.com>; Stephanie WX3K <wx3k@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@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
>
>_______________________________________________
>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
>
>
>
>
>_______________________________________________
>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
|