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Re: (meteorobs) radio meteor detection question
Becky asked:
>A few days ago on this post equipment for detecting
>meteors with radio was discussed. It was mentioned
>that satellites, and aircraft, could and do interfere
>with the signal. My question is this, what about having
>the equipment set up near power poles with transformers
>on them. There's one about 100 feet away from the back of
>the house. Would that create some kind of static noise?
>I'm electrically ignorant per-se and was wondering if such
>a situation would not be desirable.
Hello Becky,
This situation is certainly not desirable, but it may not be entirely
fatal, either. Each pole mounted transformer is somewhat different, radio
noise wise, and may or may not cause you trouble. There are ways to figure
this out, and even possible solutions if you are unfortunate in that your
own nearby transformer is a "jammer."
The step-down transformer which supplies my home sits atop a pole about 75
yards away from the meteor station antenna. While I currently have no RFI
(radio frequency interference) problems from this source, this was not
always the case.
When I first started experimenting with VHF television signals, I noticed a
strong buzzy-static noise which would come up when the temperature dropped
at night and the humidity reached the dewpoint. This noise could become
so strong as to swamp out everything else, and was quite annoying. If the
sun came out in the morning and warmed things up, the noise would
dissipate. If it was cloudy, the noise would hang around for a longer
period, but would usually be gone by the afternoon. Because of this, I
suspected an outside source for the noise. I then began a process of
elimination by shutting off all of my appliances and other electrical
devices one by one when the noise was present, especially those outdoor
items like the heat pump and well pump. I eliminated everything that I
owned, leaving either the power pole or a neighbor's house. The pole is
closer so I began with that.
I bought a cheap, hand-held VHF receiver from Radio Shack which came fairly
close too my frequency range, and used it as a rather crude direction
finder for my spurious noise source. It did not take long to verify that
the power pole was the culprit, as the radio went off like a geiger
counter the closer one approached to the pole. On sunny afternoons,
however, the pole would be quiet. I even drove down the highway to see
what other transformers were doing when mine was noisy. I was pleased to
find that most were pretty quiet, but every few miles or so, a noisy one
would crop up. This meant that the problem was fixable.
My next trip was to the engineer at my local power company -- equiped with
papers, diagrams, and other stuff to show what i was doing. It took some
convincing, but he then sent out an inspectorto take a look. After going
over my equipment and verifying with me that it wasn't being generated by
something around the house or yard, he finally walked up and down the road
with his own hand-held receiver, equiped with an S-meter. My pole pegged
the thing high.
Finally, they sent out a work crew to rework the pole, from the top
insulators down to its electrical ground. I have never had a problem
since. I guess the moral to the story is that such problems can be solved
IF you can convince your power company to help, after persistence.
However, there is a limit as to how well i would expect any transformer to
behave itself. No matter how quiet my local power transformer was, I would
never point a beam antenna in the same direction as the pole. This is
asking for RFI! My own transformer is kept hidden on one of the side-nulls
of the beam. I would also avoid placing the transformer in the back-side
of the beam as well (that is, the opposite direction from the one pointed).
Good Luck!
Jim
James Richardson
Graceville, Florida
richardson@digitalexp.com
Operations Manager / Radiometeor Project Coordinator
American Meteor Society (AMS)
http://www.serve.com/meteors/
References: