I would like to throw out an RFI matter for the group to
ponder. I have had an arc-type
inference for almost 2 years, that has defied solution. It is repetitive at
approximately a 2 second
interval. It sounds almost electric
fence-like, but unlike the fences I’ve encountered, is very frequency
specific. It seems to avoid the amateur
bands, but plagues the 19 meter SWBC band, among others. I like SW listening
as much as ham radio, so
I would be appreciative of any well considered help.
I have had our electrical power company assist in trying to
track it twice, initially using their ultrasonic device, and the second time a
radio DF unit they have. On the second
visit, the local engineer brought in one of his peers from some distance away,
who is also a ham operator, but we still were stymied.
I have walked my area with a portable SW set and it
localizes near the power poles at my property. This is just a broad test, as
it is difficult to tell without the
benefit of a directional antenna. One
of those poles was replaced by the power company in an effort to eliminate the
noise, but that had no effect. The
telephone company checked some of their services in the area for stray voltages
and came up with nothing. The cable TV
engineer, who also happens to be a ham operator, has checked their plant in the
area and also came up nil.
In addition to my solo efforts, the power company engineers
and I walked the area with their equipment (listed above) but to no avail. I
have swept one neighbor’s home with a
portable radio, but came up nil. Working on the other neighbors.
This noise defies traditional detection methods because it
inhabits frequency segments where neither the power company, nor I, have
portable equipment with directional antennas.
The noise is still present when I disconnect all AC power to
my residence. That test revealed a TV
we have that put out interference for well over a minute after it was
unplugged, and a few other low level sources, like the refrigerator of all
things, but the arc noise kept right on doing its thing with my house
disconnected at the main.
Its greatest signal strength is between 14.550 Mhz to 16.660
Mhz. It also appears between 18.300 to
19.200 Mhz, and a couple other smaller segments. It is not present in the AM
broadcast band, nor at VLF. I know what various radars such as CODAR,
SUPERDARN, and OTHR sound like, and it is not those.
It doesn’t seem this would be an electric fence, due to the
specific frequencies it inhabits. My
experience with electric fences shows them to be very broadband RFI generators.
Synopsis: fairly regular 2 second period repetition rate;
very frequency specific; pulse similar to electric fence (but immune to the
noise blankers in my radio).
Anyone have any experience with a source that is so
frequency specific?
Thanks and 73,
Scott
NM8R
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