[RFI] Christmas light display - SOLVED

Fri Jan 11 01:12:37 EST 2019

The power company guys were good to their word and contacted me a couple 
of days after Christmas.  They came over and I hooked up their 
receiver/SA (radar engineers 242) to my antenna and they got a look at 
the signature but it was not clear.  They drove around the neighborhood 
looking for a source and could not confirm my report.  The plan was to 
come back and look again the next week with a bit more equipment.  They 
did mention that there was some noise off to the NW and could I be 
confusing the SE with some response off the back side of my 4-square.

On new years day, I got my 660 and decided I would double check my SE 
noise by driving the entire neighboorhood to check any additional noise 
source.  4 hours later I had reconfirmed the SE noise source on the same 
pole as before, singing loud as ever. And found a 2nd noise source off 
to the NW just as the guys had mentioned - this one being about 2 miles 
from my QTH.  The NW noise source was easier to find once I expanded my 
search area as 2 miles distant 'seemed' to be pretty far but I got to 
thinking about it and that's only twice the distance of the SE source.  
2x the distance means 1/4 the noise level (all other things being equal) 
which is about 6 dB.  And the noise I was seeing pushed the NW noise 
floor up by at least 25 dB - so what's 6 dB more if you got closer?

The power company guy came back and this time I went with the fellow.  I 
showed him how I found the noise, and how I localized it to the pole by 
going up in frequency.  This time he had a hand-held LPDA to use with 
the 242 and we did the same test using his gear.  Worked great and by 
moving around in the street and the yards, he was able to triangulate on 
the SE pole clearly at about 250 Mhz.

What had been a problem is that the guy had never seen a MOV which did 
not provide noise when he used his ultrasonic dish mic. My local buddy 
K3PA told me he's had 4 MOV fixed out by his place and all 4 of those 
noise makers were MOV - and none of them had an ultrasonic footprint.  
But in all 4 cases, once the MOV was disconnected the wide band RF 
racket disappeared.  Fortunately this time the guy was able to accept my 
argument that regardless of his past history, the noise was definitely 
from that pole and pulling a leg off the MOV to test it was easy enough 
for a crew to do.  At this point I felt real progress was being made.

Next we went over to the NW noise source.  I had identified a pole that 
had insulators and MOV but nothing else.  There was one adjacent pole 
with a lot more hardware including a bunch of caps and the guy really 
wanted to believe that was the source.  Went through the same exercise 
and it took longer because the poles were more distantly spaced.  
Fortunately there was nothing else in the area and we could walk well 
out into an a bordering farm field to listen to the two poles.  
Eventually the guy agreed the pole previously identified as the NW noise 
source was certainly making more noise than either of the neighboring 
poles including the one with the caps hanging on it.  He told me a crew 
would be out to look at these two poles some time the next week.

I was pretty surprised to get a call at 815am on Monday with the fellow 
saying a crew was at the SE pole now.  And that I should go down to the 
shack and wait his call.  That I did, and sat in the recliner in the 
shack eventually falling back to sleep.  The guy called about 830 and 
asked if it was better - no joy.  They had tightened up and checked out 
the hardware but had not disconnected the MOVs!  They were really not 
wanting to buy the failed MOV theory...  The next step was to pull the 
MOV.  The guy called back and when I looked, the SE noise was completely 
gone.  They had just pulled the MOVs on that line!  SUCCESS #1.

I praised the work of the fine power company crew and thanked them 
profusely.  And encouraged them to extend the winning streak to the NW 
pole.  They headed over and I sat back in the chair with the 4sq 
pointing NW and the rig turned up.

About 10am the noise went silent.  I called the guy and he told me they 
checked out the pole with the caps on it first, and then went over and 
pulled the MOVs on the NW pole.  I guess the lesson of the MOVs as 
culprit was not quite learned - but after the 2nd pole I think the 
fellow was a believer.

Much greatness was expressed.  And I've enjoyed the quiet conditions 
since!  Many thanks to the local that helped me out on the 
identification and to the power company who had no problem fixing the 
problems once they were convinced the proper pole was identified.

73/jeff/ac0c
alpha-charlie-zero-charlie
www.ac0c.com

On 23-Dec-18 8:15 PM, Jeff Blaine wrote:
> Turns out this was not a Christmas light display, but apparently is a 
> MOV on a pole in front of the guy's house.
>
> Diagnosis and tracking involved driving around looking at signal 
> levels on a PL660 SWL.   Then looking at higher and higher frequencies 
> to try to localize.  I still could not identify a particular pole though.
>
> Next step was to use a MFJ VHF noise detector which allowed me to 
> localize down to a 4 pole location over a 200' area.  The local power 
> company was not motivated to go out and check into it with this level 
> of diagnosis.
>
> So a buddy K3PA brought over his industrial stuff today and we got it 
> nailed down to a single pole which has a pair of MOV. Tools used in 
> that were a 440 yagi with a Yaesu FT817, then a confirmation with a 
> Radar Engineers Ultrasonic/UHF detector.  The guy had an ultrasonic 
> dish but we did not need to use it.
>
> The power company was updated with my single pole diagnosis and today 
> promised they would contact me for repair details in 48 hours.  That 
> would be great and just in time for the SP next weekend!
>
> 73/jeff/ac0c
> alpha-charlie-zero-charlie
> www.ac0c.com
>
> On 08-Dec-18 12:15 PM, Jeff Blaine wrote:
>> I'm going to go see a neighbor today who always has a great looking 
>> display about this time each year. This go around, he's expanded to 
>> even more and better looking stuff.
>>
>> The problem is when it fires up the noise floor from 160 up through 
>> 10m bumps up a few dB to a few tens of dB.  And the guy is about 1/2 
>> mile away!
>>
>>
>> Looks like the primary energy point is about 6 Mhz which was a 
>> surprise.  Very wide banded.  And amazingly strong.
>>
>> 73/jeff/ac0c
>> alpha-charlie-zero-charlie
>> www.ac0c.com
>> _______________________________________________
>> RFI mailing list
>> RFI at contesting.com
>> http://lists.contesting.com/mailman/listinfo/rfi
> _______________________________________________
> RFI mailing list
> RFI at contesting.com
> http://lists.contesting.com/mailman/listinfo/rfi