[RFI] Powerful RFI
Gary at doctorgary.net
Fri Oct 10 01:50:38 EDT 2008
O'course it's always bad RFI but I'm stumped on this one (and I used
to think the dog fence down the street was the issue...
Here goes; I live at the last house on a dead end with 1 mile worth
of trees to the north, 3/4 mile of trees and ocean to the East, 2
miles of trees and ocean to the west with a small airport about three
miles away. And there is the street leading in a straight line to my
Pristine, eh? Problem is there is an electric train Amtrak uses that
passes by frequently (there are 12' high Hurricane fences on both
sides of the track so hikers from one state park crossing the tracks
to the other won't get hit by the "silent" train. In addition, there
are power lines (not the really big ones) that intersect at the
corner of my 2 acre lot. But these are lines that carry the power to
a nearby island so they are not the normal residential variety.
When it's quiet here radio wise, it's what you would expect and the
only bugger was 8 houses away there is a hidden dog fence that
splatters in the 160 meter range.
Recently though something new has happened RFI wise at this QTH and
I'm pretty stymied as to what it is & what to do about it or who even
to complain to; the sound can be heard on the links I have provided
The sound is intermittent but frequent. I asked my father to use his
icom with a scope to see what he could see and it is detectable from
the 1.6Mhz broadcast band through 18Mhz with the worst being around
7Mhz. Perfectly regular pulses.
I thought perhaps it was from something in the line so I disconnected
the antenna but the interference stopped. I set up a remote receiving
antenna alongside the salt marsh but the sound comes in just as
strong on that as it does on my Butternut Vertical, as it does the
Inverted V for 80M & 40M. It registers a solid S20 on 40M and S6 on
80M but it is always the loudest sound I can hear and the noise
blanker in the Corsair does only a fair job of removing it. The Omni
V has a poor noise blanker.
Can't imagine it will help much but here's an overhead of the house
from Google Earth http://doctorgary.net/QTH.jpg
Finally I decided to run the remote antenna (small receiving loop) to
the corsair & via battery so there is no connection of any kind to
this gear and yes, the problem was the same on battery & an antenna
300' from the house.
So tonight I got tired of hearing it and started writing down the
times it started & stopped. I only did this for a half hour but I
discovered the RFI is almost always 38 seconds long and tapers off
and stops in about three seconds. For awhile it was coming almost
every 2 minutes but around 11PM it became less frequent, being two
times over the space of a half hour. I have noticed that the
interference is less in the late evening but this was the first time
I tried putting times to the occurrances.
So those two recordings, they're the same for all practical purposes
only they were separated by two minutes.
More information about the RFI