Hi Ed,
Your "critical" information is great advice.
I'm also not the least impressed with one of the local power companies
(name not given to protect the guilty) that uses the Radar Engineers Model
243 in finding the root cause of RFI as they often overlook the pole
causing RFI at the hams house and jump to a different pole that's not
related, or they go looking for RFI that really turns out to not be power
line noise and they never find the true source. This happens a lot when
they suddenly go to VHF or UHF and drive around looking aimlessly for
something that has the same signature they thought they saw at the hams
house which may or may not have been power line noise in the first place.
I'm not sure how much of this is user error, or how much of this is getting
tripped up on so many other devices that produce spikes that sync up with
the power line frequency of 60 Hz which really is not generated by arcing
power line hardware. I've never had my hands on a Model 243 and wish I
better understood its capabilities versus some of the other tools I use in
order to understand its true capabilities/usefulness.
To piggyback on your statement about the time domain, the one tool that I
don't have that I wish I had was SDR software that also provided a very
good audio scope display (with a horizontal time axis of around 20ms)
that's becoming more common on HF rigs like the (IC-7851). The IC-705
which is portable has an audio scope display, and I'm pushing to have one
of the local hams in my area that has an IC-705 to investigate its
capability when looking at arcing power line hardware (I hope to sit down
with him and his IC-705 sometime in the future to see what it can do).
CubicSDR software has an audio scope display which I've been able to use to
see the power line noise signature in the time domain, but it's very
limited with very little user adjustable control but it at least provides
insight into how useful an audio scope display can be if it had more user
adjustable parameters. I know there are ways to port the audio from my
laptop based SDR receiver over to an audio scope program that's running at
the same time on my laptop, but I'm not interested in messing around with
virtual audio cable programs to accomplish this as we need a simple and
robust tool that does not require messing around with computer settings
that then mess up other programs on ones computer (been there, done it,
hated it). A simple solution might be a TRRS plug that I wire up that I
can just plug into my computer audio jack that routes the audio output
right back into the mic input that the audio scope program is using, but
again much more complicated then just having a good SDR program that
includes a nice audio scope display.
Bottom line is that I'm really pushing for folks that have the IC-705 to
investigate the usefulness of its Audio Scope display for RFI hunting as
I'm hopeful it will provide functionality similar to what the Radar
Engineers Model 243 provides in regards to obtaining the signature of
arcing power line hardware in the time domain.
Just FYI, and thanks for all you do.
Don (wd8dsb)
On Thu, Feb 17, 2022 at 9:57 PM Hare, Ed, W1RFI <w1rfi@arrl.org> wrote:
> This is critical! If you have a noise and 6 sources around you, you may
> hear only one of them. Some propagate down the lines for a long distance,
> while others are strong locally, but drop off rapidly with distance. If you
> make the utility fix 5 noises you are not hearing, they may stop working on
> your case altogether, leaving you with the noise and a much harder time to
> get them moving.
>
> There are two ways to correlate your noise with noises in the field. The
> first and best is getting a time-domain signature with Radar Engineers or
> similar equipment. The second is less reliable, but if you can hear your
> noise from your driveway with an HF mobile receiver and you can follow it
> to a source, getting louder and louder (standing waves notwithstanding) as
> you approach a source, this is also a reasonable correlation. If you can't
> do either, you have no guarantee that you have found the right source.
>
> Ed, W1RFI
>
>
>
> ________________________________
> From: RFI <rfi-bounces+w1rfi=arrl.org@contesting.com> on behalf of AA5CT
> via RFI <rfi@contesting.com>
> Sent: Wednesday, February 16, 2022 8:32 AM
> To: Rfi List <rfi@contesting.com>; Charles Plunk <af4o@twc.com>
> Subject: Re: [RFI] carried powerline noise on 15m and 20m
>
> I want to "second" what Charles wrote! Always make sure the
> 'rabbit' you're after with VHF/UHF is the one bothering you on HF!!
>
> I have chased down 160m and 80m noise sources that were miles
> away and, of course, there were many low-level 'sources' between
> my place and the *real* source that I did not hear on 80 or 160m
> bands at my QTH/place.
>
> de Jim AA5CT
>
> - - - - - - - - - - - - - - - - - - - - - -
>
>
> On Wednesday, February 16, 2022, 2:24:55 AM GMT-6, Charles Plunk <
> af4o@twc.com> wrote:
>
> Ignacy,
>
> I sent you a more detailed message direct.
>
> Have you got a VHF yagi you could more accurately pinpoint its
> direction? If so, does the VHF noise match the HF noise? Helps a lot if
> the noise goes intermittent (has a distinctive pattern) to match. I no
> longer use 2m at all, but have left my 2m horizontal up for just this
> reason.
>
> Have you tried to see the 120hz spikes somehow?
>
> Are the private property poles drops 120/240 or higher voltages (mine
> are 7.2kv for example)?
>
> A strategy may be to try triangulating on 2m then 70cm.
>
> And most important, make sure you are triangulating the source you are
> hearing at your station. From my experience, there is lots of near field
> noise when out using a loop/2m yagi etc to easily throw you off your
> intended target. Those sources may not even be heard at your station.
> This maybe why you are getting confusing directions with the loop. I
> retransmit my noise to an ht to match the noise audibly with my tracking
> receiver. Again, helps a lot if the target source is intermittent to
> more easily match. Not easy to do, I have ran out at a moments notice
> when the target went intermittent, lol. Not any single technique has
> helped me as much as this. Ignoring all the other noise. Seems every
> pole has some noise when near it that will throw you off track.
>
> 73
>
> Chuck
> W4NBO
>
> On 2/15/22 20:43, Ignacy Misztal wrote:
> > My radio shows about S4 noise on15m when the beam is oriented towards the
> > nearest power pole. There is S3 noise on 10m and almost none on 20m and
> > below. The noise is canceled completely with NB so I assume it must be
> from
> > a single source.
> >
> > My MFJ VHF sniffer detects just a trace or nothing. A DX engineering loop
> > has weak readings, similar in strength to the nearest pole and to the
> next
> > few poles.
> >
> > The QTH is in a rural area. I walked along power lines for a mile and
> > could not find anything strong. There are some poles deep on private
> > properties.
> >
> > My first question is whether the power lines are somewhat resonant on 15m
> > and carry the signal for a long distance. My second question is about a
> > strategy to find the RFI when teh culprit is far away and directions from
> > loops change every 50 ft.
> >
> > Aside from the MFJ 3 el sniffer, I have their ultrasonic dish, a tuned
> loop
> > for HF and a DX engineering directional loop. Also a Yagi for 70cm.
> >
> > Ignacy NO9E
> > _______________________________________________
> > RFI mailing list
> > RFI@contesting.com
> > http://lists.contesting.com/mailman/listinfo/rfi
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