Topband: Another take on power line noise hunting

[N1BUG]

Thanks for adding to the discussion Don.

That reminds me I forgot a couple of important details so I'm 
replying on-list to add them.

I hadn't thought about using a spectrum analyzer even though I'm 
well aware of the increasing high frequency component as you get 
closer to the source. The bloom sounds like an even quicker way to 
get very close to the source than the variable frequency method 
(assuming, perhaps, there aren't too many overlapping noise 
radiations from multiple sources).

I forgot to add I have been using a UHF FM link to hear audio from 
my home receiver in the field. In early stages with multiple noise 
sources being heard at home and in the field I couldn't sort one 
from the others by ear. I could sort them pretty well at home where 
I had the scope and felt that having one in the field would have 
saved me countless hours of frustration. In later stages comparing 
by ear started to be useful, though with some of the steady noises 
it was difficult to know for sure if I had the right one. I also had 
(and still have) many sources in the field that I do not hear at 
home on any band. I'm leaving them alone. It's amazing that I have 
one not more than 500 feet several of my antennas. Loud on HF 
through 135 MHz as I pass by it, deafening on ultrasound, but not a 
whisper of it at home.

I would agree most folks may not need the ultrasonic unit but I owe 
mine a huge debt of gratitude and will never be without one - 
preferably the most capable one I can get my hands on. It saved my 
bacon this summer. The power company had been out and wrote a work 
order to address multiple problems. Three months had passed and the 
work had supposedly been completed, yet I still had noise from all 
but one of those poles. Nothing I said about my RF observations was 
convincing him to come out and check again. He was doing everything 
possible to convince me I couldn't possibly have power line noise 
any more and whatever I was hearing must be generated in a home and 
radiated from power lines. I wouldn't have been the first to go down 
in flames dealing with this company. I was losing the argument big 
time until I asked him to kindly explain why I could be hearing 
ultrasound from a particular insulator and the changing sound 
pattern matched up perfectly with audio from the home receiver over 
the UHF link. He was back out here in 2 days, and 3 work days after 
that every one of those poles had been rendered absolutely silent.

73,
Paul



On 01/05/2013 02:41 PM, Don Moman VE6JY wrote:
> Similar observations here Paul in my never ending battle to keep on top of
> the  noise situation in my rural area - mainly 14.4 kv distribution and
> some 25kv 3 phase stuff.
>
> Many sources top out above 135 mhz but well below 450  so a yagi in between
> is certainly helpful.  Like a ch 13 tv yagi or something for UHF mil
> aircraft.
>
> In the vehicle I often like to use an old (i.e. analogue and inexpensive)
> spectrum analyser like some of the portable Texscan CATV ones. Mine is the
> VSM-1 which covers up to 300 mhz so that coupled to a little whip on the
> vehicle is almost always enough to get you to the nearest pole or two as
> you drive by. The AVCOM PSA 65 I have is also OK but one wants something
> with a really wide RBW so you gather lots of the noise energy and in my
> experience the cheap and dirty Texscan gives me the best noise "bloom" as
> you drive by the pole.  Depending on ambient light it can be tough to see
> the screen and still drive safely so fortunately they also have a wide band
> video out jack that can be used to drive a amp'd speaker.
>
> To zero in a bit closer I use the ICOM R-10 and a Create 50-1300 mhz log
> with the rear elements removed to make  easier to get in the vehicle.  It's
> "OK" but the pattern is not as nice as a single band yagi.  But with this
> setup I can almost always tell the utility which pole is the culprit and
> they take it from there.
>
> I have some ultrasonic stuff and the power guy has the Radar Engineers unit
> - the hand held dish style and these are generally NOT helpful in finding
> much other than in maybe 1/3 of the cases confirming the findings that we
> are on the right pole.  I think on many of the sources the arc is weak
> enough that there's not much ultrasonic energy.  I have seen it not work
> enough that I wouldn't spend much energy or money on this route.
>
> The one ultrasonic device you want the power guys to have is the hot line
> sniffer from RE and that can (in their hands, not yours) pinpoint the exact
> hardware.
>
> The most challenging noise situation that I have experienced is the faulty
> transformer (all from brand new units) with a micro arc inside the can.
>   TONS of LF noise around 80 and 160m but nothing at VHF, nothing ultrasonic
> as everything is in the can.  And as you know, the noise at lower
> frequencies can travel a LONG way and you'll get noise peaks at corner
> structures etc, all trying to mislead you.  When you don't see any obvious
> source in the normal fashion and there's still plenty of noise then you
> have to start suspecting the transformer.  Getting the utility to drop the
> primary is about the only way to tell.  On the one case I was
> most familiar with they even listened with a mechanics stethoscope to the
> case but no arc noise.  Keep in mind that many will NOT arc when the power
> is connected back on for several minutes or hours so don't let this mislead
> you.  Obviously the utility doesn't want to change out a good transformer
> so don't let this trick you.  And the new one could be bad, altho I haven't
> had that piece of bad luck - yet! Once the first bad transformer was
> identified and replaced, proving I was right, it became a LOT easier to
> convince them in future bad transformer cases.
>
> I have not used the o'scope much at all for noise signatures. I prefer to
> rebroadcast my noise from home on a very low power tx so I can hear it
> while I'm at the suspected source.  It is easy to find all kinds of noise
> when we go looking around but one should focus on the noise that actually
> bothers you first.  In a perfect world we'd like to clean up everything but
> with costs and manpower issues being a big issue with the utilities it's
> best to stay focused on the problems that affect you and save some good
> will and budget for the next one.
>
> 73 Don
> VE6JY