A collection of information to assist those in locating powerline arc rfi involving amateur radio licensee W4NBO (formerly AF4O)
Updated as information is available
FCC License Data: https://wireless2.fcc.gov/UlsApp/UlsSearch/license.jsp?licKey=4439683
Primary Source - Resolved!
Radio Frequency Interference in the area of West End Street and Clifft Street in Bolivar, Tennessee
History Note: Even during these long appearances and disappearances source is intermittent. Such that the source may not be active when a RFI location crew is able to come by. I am in a
rural area and it takes time for them to come out.
My power company graciously offered to request a TVA rfi location crew to come out but my concern was that they would come out and the source not be active due to its highly intermittent
nature, thus the location efforts here.
First noticed in Fall of 2019 and lasted until June 2020. As strong as a devastating 25db over s9 on 80 meters.
Reappeared December 2020
Disappeared late December 2020 but can often hear brief to ongoing pulses from it.
Reappeared January 2021 and was active often although intermittent until a severe winter weather event in February
Disappeared mid February and reappeared early April 2021
When absent, noise levels are blissfully quiet.
Firstly pulled the main breaker to my house while listening to the transceiver on battery power. This made no difference in reception of the RFI.
Frequencies affected
Well below the AM broadcast band up to at least 144mhz, probably up to around 300mhz near the source. Not heard at 440mhz.
Identification of source type
120Hz spikes from a typical recording of the rfi as seen on Audacity
Audio/Video logs – Click on to hear/see
Jan 11, 2021 Audio
Jan 12, 2021 Audio/Video
Triangulation &
Final Identification
Either
there is 2 sources or I mistakenly tracked to pole on West End
Street. Was tracking for maximum noise and not noise pattern, see
below.
The source on West End is still active although
diminished to where it is not seriously affecting my station at this
time.
Direction finding with my 6 meter beam at 40' proved
to be misleading. Likely due to the close proximity of the source
pole some 50' away.
Initial HF triangulation with FT817 on AM and loop tuned to 14.1mhz
145 Mhz Triangulation Gear: 440Mhz HandiTalkie receiving retransmitted audio from HF Transceiver tuned near 10Mhz monitoring the Arc RFI
145Mhz HandiTalkie on AM and 3 element handheld yagi
Listening to both HandiTalkies to compare noise pattern to make sure I was tracking the correct noise.
This lead me to the pole at the back corner of my lot behind my house
Noise ceased before I could use my Ultrasonic dish due to a malfunction of the dish and a subsequent winter storm.
Update; Source reappeared in early April 2021 and was able to locate on this same pole with the ultrasonic dish.
After locating with the ultrasonic dish, after dark was able to see the arc's with binoculars (Red arrows in the pictures below).
The arcs are tiny but visible. They remind me of tiny welding
arcs. One appeared to move an inch or so on the wire and would come
and go. The others were constant. My digital camera faintly
picked up one of the arcs but little can be seen of the pole in the
dark.
A night vision camera maybe something to add to my
growing rfi toolbox.
Weather Log
- To correlate weather conditions so those involved with finding the
arc will have a better
chance of being present when the arc is
active. Readings taken on 80 meter SSB for consistency.
Best Practices and notes for this hunt
House. Pulled the main breaker on the house while listening to HF on battery power.
Type identification I recorded the audio of the noise and used the program Audacity to analyze and identify the 120hz spikes
indicative of a power arc.
Triangulate. I use a FT817 on AM mode and several hf loops. As I got closer to the source (a utlity pole) switched to a FT-60
on AM mode and a 2m yagi built with light weight metal tape
measure elements. Retransmitted the noise from my HF
receiver
to a HT on 440mhz FM thus being able to compare the
noise pattern with the tracking HT/Yagi. Waiting until the
noise
has a distinctive pattern is helpful.
Ultrasonic. Able to narrow area of the pole to 2-3 feet. I built the W1TRC dish in the QST article years ago.
Binoculars. Was lucky that I could see these arcs at night and no streetlight on this pole or nearby.
A good night vision hunting camera maybe a good item to add to my rfi tools. A thermal imaging camera would be nice
but are expensive at this time. There are many youtube videos on
how to remove the IR filter lens of a standard digital camera
to
allow the CCD to be sensitive to IR light. Might be a worthwhile
project
Results
Wow,
just Wow. Crews did the repairs requested some 3-4 days after
requested. The local utility was nothing short of cooperative and
willing
to work to resolve the issue best they could without
outages. Its now about 3-4 days post repair as of this writing and
the overwhelming majority
of the main source of 120hz noise is
gone.
Even during times of lull's as noted in the logs
above, I would occassionally hear a second or so of loud pop. Not
even hearing
that anymore from the main source. One word of
caution to myself though. Much of the hardware which built up the
path to arc remains so this
could reoccur over time but its
anyones guess as to how long it will take if ever since the wire is
further away from the hardware where the path
likely built
up.
RESOLUTION
UPDATE FALL 2021
Crack in the fused disconnect likely the Ultimate cause of this issue
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