[RFI] Quidance on finding noise?

[Don Kirk]

Hi Ken,

I helped W9TC locate a street light that was causing interference on HF
that sounded just like power line noise.  Noise only during hours of
darkness, and it was on continuous.  The bad light pole had a bulb that
appeared to be burned out (it never illuminated).  The audio signature was
similar to what you see from power line noise (120 Hz), and I was able to
use 136 MHz AM to confirm the light pole was the source.  Don't know what
the problem was with the light pole, but the property owner had the light
repaired, and problem went away.  The light pole was located 560 feet from
W9TC antennas.

I really don't think you should be thinking about anything, other than
using good direction finding techniques to locate the source.  You need to
use direction finding techniques to identify the property where the noise
is originating, and then identify the culprit device, not the other way
around (just my stead fast opinion).

Just FYI,
Don (wd8dsb)

On Wed, Jan 8, 2020 at 6:52 AM Kenny Silverman <kenny.k2kw at gmail.com> wrote:

> Thanks for the replies so far.  Just to reiterate, the noise is only from
> sunset to sunrise and it’s constant. So it’s likely lighting related, but
> it doesn’t cycle.  Have there been examples of constant noise from street
> light or should we be thinking more about store signage?
>
> Regards , Kenny K2KW
>
> > On Jan 8, 2020, at 3:47 AM, Don Kirk <wd8dsb at gmail.com> wrote:
> >
> > 
> > Kenny,
> >
> > I should also mention that I did have to track down noise from faulty
> light pole (problem only between sunset and sunrise), and same setup I use
> for power line noise worked great to find the suspect light pole.  136 MHz
> AM in close again was necessary to pinpoint the pole that was in a
> commercial parking lot. (Distribution/trucking company parking lot).
> >
> > Don (wd8dsb)
> >
> >> On Wed, Jan 8, 2020 at 3:38 AM Don Kirk <wd8dsb at gmail.com> wrote:
> >> Hi Kenny,
> >>
> >> I normally use portable HF radio with portable tuned loop and preamp on
> 160 or 80 meters to triangulate on power line noise and then back the RF
> gain down as I get close and sometimes use my car radio on 1710 KHz to
> locate potential areas.  I also have 3 pennant RX antennas at home that
> each point about 120 degrees from each other that let me know the exact
> direction from my QTH the problem is coming from which really helps get me
> started if I’m working on issues at my QTH versus another hams QTH.
> >>
> >> Typically using portable AM receiver (portable police scanner) on 136
> MHz and 4 element hand held beam with elements lengthened for 136 MHz I
> typically hear power line noise at least 0.2 miles from the arcing power
> line pole and sometimes greater distance.  When I’m in close (when I can
> see the suspect pole) I normally have to throw in 20 to 30 db of
> attenuation to pin point the pole.
> >>
> >> The arcing power lines I have located have typically been 1.25 miles
> away or less.
> >>
> >> To pinpoint the pole I have to use 136 MHz AM with lots of attenuation
> (not HF).
> >>
> >> 73.
> >> Don wd8dsb
> >>
> >>
> >>
> >>
> >>> On Tue, Jan 7, 2020 at 11:55 PM Kenny Silverman <kenny.k2kw at gmail.com>
> wrote:
> >>> Hi and thanks in advance!
> >>>
> >>> We’ve been trying to track down some noise at a friends house but no
> luck so far and I was hoping for some tips on finding it.  The buzz comes
> on at sundown and turns off at sunrise. It’s bad on 160 but it can be heard
> Lightly on 80 and 40.  The noise is constant and does not cycle (at least
> for the 90 minutes I was listening to it tonight).  The worst direction is
> on the East beverage on 160. On 80m it seemed like the worst was to the
> NW...  it could be 2 sources but the noise appears to come on at the same
> time in all directions,  not a staggered turn on/off.   Could be a single
> source but poor F/B on the beverages. The Listening to the ARRL RFI files
> it sounds like power line noise or street lamps ( but without the
> cycling).  Over the 90 minutes tonight there were almost no variations
> (except for an occasional change in pitch).
> >>>
> >>> We've DF’d on a portable AM radio, 2m and ultrasonic device. AM
> identified some noisy poles but we’re not convinced these are the main
> offenders.   Not much luck with VHF or ultrasonic.  Our next plan is to use
> a KX3 on 160m and a decent RX loop to direction find and triangulate.
> >>>
> >>>   I suspect we’re not looking out far enough...  suggestions on how
> far away we should be looking?  And how close do we need to be to hear it
> on  VHF?
> >>>
> >>>  Besides power lines and street lamps, other thoughts on possible
> offenders? Most of the area is residential with street lamps on most
> streets.
> >>>
> >>> Regards , Kenny K2KW
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