Some decades ago I had a persistently high AC noise level, even on VHF, so I
went hunting. Eventually, I tracked it down to the local airport, and with a
440 HT set to AM mode and an 11 element beam, the strongest indication was at
the top of a pole next to the control tower. I called the airport, and the
noise went away pronto. Why THEY had not complained before is open to
speculation.
HF-only noise is tricky. Remember the 3.52 MHz carrier current modems the NCDX
guys complained about? Ed and the ARRL got the FCC to lean on AT&T and they
were all replaced. I tracked a number of them down (not really needed -- Ed
worked fast) but one of my hardest was where the strongest radiated signal came
from an advertising pylon and sign outside a local mall. It was actually at a
dwelling in a development across the street.
By the time you get to "which room is it in?" detail with strong signals you're
using a handheld receiver and loop only inches across. I was hunting these
things one Sunday and I noticed a guy run out his door into the back yard.
Thought nothing of it; barbecue might have needed urgent attention. But I saw
another. And ANOTHER. Then it hit me; I had a loop on the car, and was
sniffing dwellings. It was Super Bowl Sunday. They thought I was from the cable
company and were rushing to rip out illagal taps to their neighbors' service!
Cortland
KA5S
-----Original Message-----
>From: N0RQ-lists <n0rq-lists@sbcglobal.net>
>Sent: Oct 10, 2010 8:21 AM
>To: rfi@contesting.com
>Subject: Re: [RFI] Power Line Noise Conundrum
>
>Kim,
>
>You've already had several other excellent responses, so mine will be short.
>
>I've found it hard to get very accurate readings on HF, partly because the
>noise can be radiated, partly because most folks (like me) don't have
>4+element beams on HF.
>
>I almost always start with 6m. With 5 elements from home, it gives me a
>really good idea of the direction.
>
>Then, in mobile and/or walking, with 2m/70cm AM receiver and small handheld
>beams, the pinpointing is done.
>The 2m vertical on the car may tell you when you pass a bad pole.
>An Arrow 3-element 2m beam is pretty helpful.
>An Arrow 7-element 70cm beam is outstanding.
>
>Make sure to flip the beam back and forth -- vertical, horizontal,
>in-between -- as you point at different poles. If there are several poles
>close to each other that have a problem, it can be confusing, so multiple
>triangulation spots could be needed. Sometimes you just find the worst one,
>get it fixed, and if there is still a problem, do it again.
>
>Write down the pole #, the closest address, and contact the utility.
>
>By the way, in our day with heightened security awareness, don't be
>surprised if someone questions you about pointing an odd-looking device at
>poles. This has happened to me several times. A friendly smile and a brief
>explanation have taken care of it for me, but I wouldn't surprise me if
>someone called law enforcement. ;-)
>
>The ARRL has lots of good info, as Ed mentioned, and my web page has (I
>think) lots of good advice and references as well:
>www.powerlinenoise.com
>
>73, Dave N0RQ
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