Hi folks
I would like to share a pleased however unexpected expediency with power
line noise on top band. Since last year the noise level in my suburban lot
had increased and after the raining season the power line noise become
impeditive to use my vertical RX antenna, with only 22 db of external preamp
and no internal preamp on my radio the S meter was s9+5 db due north, my
dual flag antenna has a very low gain < 40 db. This level of noise was just
unbearable.
Finally after 4 month I decided to call Florida Power and Light and open a
case complaining about RFI. One thing that help me a lot was the ARRL Q&A
section, I read it and mentioned during my call the Title 47, CFR Section
15.5 from FCC, Also I read about the new signature teachniques and the new
radio from Radar Engineers. You can see a picture of it on ARRL web site.
http://www.arrl.org/tis/info/powerline-FAQ.html
Well,,, you know that part, after calling every week for 3 weeks I got a
call form Orlando, He is also a ham and works for FP&L, he visited me in the
same day and for my surprise he showed up with a large van with 5 or 6
vertical antennas on the roof, men he was armed and well equipped to fight
noise.
Here my first big surprise, Orlando asked me to plug my antenna on his
portable radio to capture the signature of the noise, I turned my RX antenna
to North and voala!, the radio capture a sequence of spikes on the screen,
The radio is very sensitive in AM and it was tuned to 1830 KHz. Orlando
said this was a typical crack isolator spark, Them he asked me to turn the
antenna south and we check the noise from that direction, that noise was s7
but the signature completely different.
Whit the information right from my antenna Orland went to find the noise
source. He got back after 3hours and showed me a photo of the device that
needed to be replaced and the location of the post. That was incredible
because one point was 1.3 miles ( 2 km ) north and the second was 1,7 ( 2.7
km ) miles south of me. I never realized that it could be that far.
Both problems were related with lighting arrestor. This device protects the
power line for strikes and it is connected to the line and to a ground wire,
the wire is grounded and runs up 24 to 30 ft. This combination is a good
vertical or inverted L with the spark on it corner. This noise was radiated
like an antenna does.
FP&L did take over a month to fix the two problems, the noise due north was
eliminated right away but the one south decreased from s7 to s2. Orlando
come back on the same day and capture the signature of the noise and it was
different from the first one, after 4 hours he called me and asks for
another visit next day because he was not sure about that noise.
Next day Orland come back and confirmed the signature, the new source was SW
at 3.2 miles away, ( 5.1 km). That sounds hard to believe but when FP&L
fixed the post the noise just went down to zero.
To find this kind of noise demand a strong discipline to identify the noise
signature and pick up the right one to fix. Orlando did find 3 sources with
100% accuracy.
For the fist time in 10 years the QRM was the same in all directions and
close to s0, on my 160m full size vertical with no internal preamp the noise
without noise blanker is s5 and with noise blanker on s2 during the day.
This new techniques really can help to fix the main power line noise
offenders. There are several post near by that I knew have strong buzz, but
no one of them radiates into my 160m RX antenna, only the 3 identified post
were causing me 99% of the problems. My QTH is a suburban lot and 20 miles
west of Ft Lauderdale and 30 miles north of Miami, 8 million people lives in
South Florida,
That was my best Christmas present.
Regards
Jose Carlos
N4IS
_______________________________________________
"160-meters is a band for men, not for sissies!" - SM5EDX
|