In 2001 I posted here about a line noise problem I was having. Well, I'm
still having it and I seek the group's advice as to how best to proceed.
First, a description of the problem. I truly believe it to be line noise,
as it sounds like a 60- or 120-Hz buzz, sometimes containing hissy-sounding
audio frequencies and sometimes just a hummy buzz. Depending on conditions,
it is present continuously or intermittently (kind of a sputtering sound).
It tends strongly to be present in the daytime and not at night, and on
crisp dry days, and not on rainy, humid, or even just cloudy, days. It is
most strongly audible on 15, 10 and 6 meters. Occasionally I can hear it on
20M and even on 2M. When it's going good (which is lots of the time) it's
S9 on 6M. It's never audible on, say, the AM broadcast band.
In one of my original 2001 postings I lamented how, when I contacted my
power company, they sent someone out who didn't seem to know or care much.
He said that if he couldn't hear the noise on his truck's AM radio he
couldn't find it, but if I found suspected poles he'd be happy to examine
the poles and fix any found problems.
To make a very long story a bit shorter, I build a DFing apparatus
consisting of a 3-element 2M yagi and a 2M HT with an AM detector and an S
meter. Right away I found one source: the pole right across the street from
my house was easily DF'ed as a strong source. The power company found
nothing when they checked the pole, but "tightened the hardware anyway." It
made a big improvement, which lasted a few weeks as I recall.
I kept on complaining, and eventually found that my power company really
does have an RFI troubleshooting specialist. Why I wasn't put in touch with
him the first time, I don't know. I stayed home from work one crisp morning
in January 2003 and met this friendly and cooperative person, and we went
around the neighborhood a bit together checking poles. He used three pieces
of equipment: He had an HT-like radio with a rubber duckie antenna that he
said was tuned to 50 MHz. He said he used this to check on
interference-to-TV-channel-2 type problems. He also had two _ultrasonic_
(high frequency audio) receivers; one with a clear plastic parabolic
reflector that he used from street level to identify bad poles, and one that
he used right up at the wires and insulators to search out the actual
problem spot. He said that it was easiest to find arcing by listening
ultrasonically rather than listening to radio frequencies. And indeed, we
really couldn't hear anything on his 50-MHz radio with the rubber duckie,
but we identified a couple of arcings with the ultrasonics.
It was a very educational morning for me. But, at this point I need to give
a bit more background on my problem. I've lived at this location since
1983, and until 1995 or 1996 (I can't remember exactly) there was no noise
of any kind, ever. In 1995 or 96 my line noise problems started, and they
started virtually overnight like someone turned on a switch. I didn't
complain about the problem at that time because my ham radio activity level
was very low -- I had other family and job concerns that prevented me from
doing much hamming. I had, however, developed the habit of leaving my 6M
radio on all the time on the SSB calling frequency, so I'd not miss any
openings. So it was obvious to me, even though I wasn't active, that my
quiescent 6M noise level had gone from S0 to S9 overnight. I just didn't
have any time to investigate it for several years. I did notice a big clue
right at that time, though. The power company had just rebuilt the entire
power grid in my area. All the lines, insulators, transformers, even some
of the poles and pole locations, were brand new. The line noise started
exactly when they did this.
When I told my power company line noise guy this story that morning, he
nodded knowingly. He said they had increased the distribution voltage at
that time. I don't recall what the old distribution voltage was (I think he
said either 7200 or 9600 volts), but he said the new voltage was 14400. He
said that they usually get RFI complaints when they increase the voltage,
and wasn't surprised that that was when my problems started.
What I learned that morning, in a nutshell, was that it's amazing that any
power can be distributed at 14400 without problems. Arcing, as indicated by
our ultrasonic testing, came and went for the most capricious of reasons.
For example, if a piece of debris were to strike one of those thick stranded
cables that jump power from one insulator on one side of a pole to the
other, it might get unraveled or "unstranded" slightly. I'm talking about
just a tiny fraction of an inch of strand separation, and just for a short
length, say two inches, of cable. Just these separated strands would arc
merrily, despite being fully connected just one inch away. The tiniest
hairline or speck of debris on an insulator would cause arcing. This stuff
just loves to arc.
Anyway, despite fixing the apparent problems at a couple of poles that
morning (and even having my wife listen to the 6M radio in my shack while we
wiggled stuff and hearing the noise level vary), I noticed no appreciable
reduction in line noise in my ham shack later. It was apparent (it actually
had been clear to me already) that there were _many_ different sources of
noise affecting my radio reception. As he parted, the power company RFI guy
said that if I would DF the noise with my tower-mounted beam and tell him
the direction, he would come out and try to find the source and fix it. I
did this many, many times over the ensuing months, and he came out many,
many times in response. He would usually tell me that he found this or that
problem and fixed it. Unfortunately all this activity produced at most only
a transitory reduction in noise level. Sometimes there was no difference at
all. Often I found the noise very hard to DF since there were several
sources emitting at once from different directions.
And that's where I find myself today. My line noise problem, which has been
going on since 1996, is as bad as ever. Usually there are several sources
all acting together to make 15 through 6M unusable no matter which direction
I beam in. As always, the noise is strongest on crisp, dry, winter days,
and sometimes entirely absent on humid and cloudy days. My last contact
with the power company guy was in December 2003. I bet he's tired of coming
out here only to have me report "no improvement" over and over again.
So I solicit advice. Even though the power company guy seems knowledgeable
and has noise-finding tools, he hasn't gotten any results in a year of work.
I don't exactly know what to do at this point; at least I feel that he is
"on my side" regarding his willingness to work toward a solution. I don't
want to alienate him by suggesting he get help.
Also, does anyone know if is really suitable to distribute power in a
residential area at 14,400 volts? From my experience, this stuff will never
I hope you enjoyed reading this as much as I did writing it! Thanks.
Antique Radio Web Site http://www.radiophile.com
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