In my 20 years of working as a Power Line Interference Investigator with a
full complement of Radar Engineers equipment, I found the ultrasonic
detector to be only marginally useful.
One thing is CERTAIN: the ultrasonic detector is NOT the correct choice
for the initial phase of the search for the source.
I carried the ultrasonic detector all the time but experience taught me
that it wasn't useful until I found the structure which held the source
device i.e. pole or other exposed structure.
Once I knew I had found the pole from which the interference was radiating,
I scanned each device on the pole including insulators and their hardware,
cutouts (fused switch), mounting brackets & crossarm hardware, lightning
arresters, connections to transformers, bond wire & staples and the neutral
wire connections.
In my experience, the ultrasonic detector only sounded off if there was
arcing occuring on an exposed, outside device or joint.
In Florida, lightning arresters were/are the most frequent sources of power
line interference. Lightning arresters arc internally and rarely, extremely
rarely, produced a response in the ultrasonic detector.
The Radar Engineers M330 (receiver with attached yagi antenna) consistently
pointed at lightning arresters or bond wire staples or loose hardware
sources. The ultrasonic detector never reacted to devices that were arcing
internally.
When it was unclear precisely what on the pole was arcing, the crew and I
would conduct a step by step troubleshooting process which would eventually
kill the source.
If you are able to accurately locate the source structure and report it to
the utility, do all you can to get the utility to notify you when they will
dispatch a crew to effect repairs. You want to be present to confirm that
the crew's work actually eliminates the source. (A concept few utilities
appreciate.)
If you are fortunate enough to be present when the source is eliminated,
use your equipment to scan 360 degrees to determine if there are additional
sources that need crew attention. In 40% of the cases I worked, there were
multiple sources that needed to be silenced. When you work with the crew
you stand a good chance of getting the secondary and tertiary sources
silenced in that one trip.
The M330 was the one tool I used most to locate structures with sources.
Pinpointing the actual source required step by step troubleshooting about
30% of the time.
Most utilities don't send a skilled properly equipped interference
investigator out to work with the dispatched crew. It took me a year to
prove to my employer that allowing me to accompany the crew working an
interference job would clear the trouble in one trip 99% of the time. Most
utilities send a crew out alone up to 2 or 3 times without someone who can
confirm resolution before they claim they have done all they can and close
the ticket...leaving the complainant to suffer with the interference.
You would think that common sense would dictate that the complainant or a
staff investigator should be present to confirm success or failure of the
crew effort. This clearly demonstrates how poorly most utilities understand
the problem or how to successfully resolve it.
Power line Interference became a problem for utilities immediately after
power lines got close to Amateur Radio stations. It took decades before my
employer accepted my suggestion to have a properly equipped skilled
individual accompany crews to confirm the complaint was really resolved.
73,
Frank N. Haas KB4T
Retired Utility Interference Investigator
Florida
On Wed, Mar 25, 2026, 20:37 Richard Karlquist <richard@karlquist.com> wrote:
> I investigated building a homebrew detector like this some 20 years ago
> or so, and found that the ultrasonic transducers that I could find had a
> fairly narrow angle of reception. The only parabolic reflectors I could
> find were very "deep" and it turned out that those transducers would
> poorly utilize the dish. We would say they wouldn't "illuminate" much
> of the dish. It was obvious from a catalog page showing the Radar
> Engineers product, that it used a much "shallower" dish, which would
> give much better "illumination". It is not sufficient to say that the
> dish is accurately parabolic and then you just locate the focal point
> and put the transducer at the FP.
>
> I just wanted to give everyone a reality check. My suboptimal device
> did "work", but probably not as well as the Radar Engineer's one, and
> was much larger to boot. If I had to do it now, I would make a 3D
> printed shallow dish and as much as possible clone the Radar Engineer's
> dish. I would say that the dish in the photo looks much shallower than
> the one I tried to use, but it is hard to say just from the photo. The
> key figure of merit for a dish is the ratio of diameter to focal length.
> My dish was such that the focal point was in the plane of the rim of
> the dish.
>
> Another thing is that the transducers are very narrow band in terms of
> frequency, probably because they are optimized for TV remote controls,
> I guess. Since we are looking at wideband noise, I suppose it doesn't
> matter a lot, except we lose a lot of sensitivity that way.
>
> ---
> Rick Karlquist
> N6RK
>
> On 2026-03-25 13:42, Don Kirk via RFI wrote:
>
> > I finally decided it was time to add the one missing tool I had from my
> > RFI
> > detection/direction finding toolbox so I undertook the building of my
> > own
> > ultrasonic parabolic dish receiver system for detecting arcing on power
> > line hardware based on the W1TRC design that was in the April 2006
> > issue of
> > QST. Unfortunately Jim (W1TRC is an SK).
> >
> > I know this tool has been discussed many times over the years on the
> > RFI
> > reflector but thought I would share my recent build information with
> > the
> > group as it might be helpful to those currently wanting to build one,
> > and I
> > also think I kept my build very simple.
> >
> > I had a lot of assistance from Charles (N0TT) and I also picked up a
> > lot of
> > great information from Jeff (W4DD) and Frank (K7SFN).
> >
> > Here is the link to my simple website that I created today for those
> > interested in my build:
> > https://sites.google.com/view/ultrasoundarcdetector/home
> >
> > 73,
> > Don (wd8dsb)
> > _______________________________________________
> > 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
|