[RFI] CASE HISTORY - Powerline - Multiple Sources (re-post w/o errata)

[Charles Plunk]

Yes, great list.

That maybe me on #2, lol. I re-transmit the audio from the HF receiver 
on 440 while DFing on 2m or vica versa with 2 HT's. Could be done with 
one dual bander I suppose as long as you can listen to both bands at the 
same time. Seems like nearly all my 120hz noise at some point will 
develop a distinctive pattern especially as the weather changes but one 
has to be really patient for this method. Got to be ready to go when it 
does happen, usually at a non convenient time. But when it does, its 
obvious by listening to the two sources that you have a match.

It helps also to have a rotatable vhf (or possibly uhf) station beam to 
get you started in the right direction. Listening to the pattern 
(especially if its intermittent) on vhf and hf at the same time to match.

And you maybe able to actually see the arc at night especially with 
binoculars once you have found the pole. Of course it helps if its dark 
and no nearby streetlights. Likely expect a faint little pinpoint arc.

Just more tools to consider. One has to keep a really open mind chasing 
this stuff and get all your ducks in a row before calling the utility. 
It is really time consuming for me but worth it and really satisfying 
when the utility fixes the source you found. Kind of like solving a 
complex puzzle. And can be very frustrating at the same time for many 
reasons.

The knowledge base on this reflector is incredible. I am happy to be a 
student here.

Currently chasing 3 sources. I have identified all 3 poles and got one 
pinpointed with the Ultrasonic. The other 2 are intermittent to the 
point of ceasing for weeks and months at the time making the hunt long 
term. One of these I identified today. Its 2 houses down and singing 
like a canary. The pattern matched. Not long after I got back to the 
shack it ceased so no Ultrasonic for now....

73

Chuck

W4NBO


On 9/29/21 10:50 AM, EDWARDS, EDDIE J via RFI wrote:
> Alan,
>
> Sorry for my delayed post on this subject.  Some things previously mentioned on this group by the professional RFI investigators who have posted in the past but I wasn't sure if you were aware of in your post:
>
> 1. In older neighborhoods with older power lines, you should be able to find dozens and maybe over 100 RFI sources within a short distance to your station.  Not all of them are creating RFI being picked up at the location of you antenna(s).  And the utility is not required to fix all of them if they are not causing harmful interference to anyone.
>
> 2. Best way to verify that a source in the field is your RFI source on your radio is to get a noise signature on a scope, save it on the scope, then go into the field and find a matching noise signature in the field.  One ham on the list has done this using his ears, but most of us with tinnitus need visual scope readings.  LOL
>
> 3. If you let multiple sources ramp up, you will be "pealing the onion" as you remove the loud sources first only to find less strong ones below that layer.  You may have found this to be the situation in your case.
>
> 4. Back in the pre-cable, pre-streaming TV days, it was the utilities responsibility to find and repair RFI sources causing interference to TV or radios.  It is to their benefit to perform their work tasks in the most efficient way possible.  So it is to their benefit to have trained and well equipped RFI investigators.  Not all utilities will be this efficient as you have found.  Utility's budgets and internal politics can interfere with these tasks.  But the FCC's viewpoint is that it is the utilities responsibility to find and eliminate harmful interference from their equipment and only their equipment. The ham should only verify that it is from the utility's equipment and not his own or his neighbors'.
>
> 5. Always continue to listen at higher and higher frequencies when searching for RFI sources on powerlines.  You should be able to confirm a source by finding it at 300Mhz or higher.  If you cannot hear it that high, keep moving down the line until it gets stronger or fades away.  And it is possible it is not from the utility equipment at all if it is not broadband noise.
>
>
> 73, de ed -K0iL