[RFI] Powerful RFI - Solved

[Gary Smith]

Many thanks to the on & off list replies to help me on this. I kept 
trying to hear this problem on the AM broadcast radio but when it was 
on 40M it was not showing up at all on the AM radio. 

I went on a snipe hunt & walked the neighborhood looking for anything 
that was an issue. The only thing I noticed was some kind of flicker 
on the street lights (only one street for a long way & I'm at the 
dead end of it). So I looked for it but all the lights were lit. I 
walked 1/4 mile & saw no unlit lights so I turned around and while 
walking back, saw a flicker again. 

I couldn't tell for sure but the flicker seemed to be coming from the 
last light which is close to my house. I went in, turned the tape 
recorder on & left the radio on to 7.000 and went upstairs to see the 
light & listen to tha AM radio. Sonofagun, the light was out and the 
AM radio showed nothing though the light was 70 feet away. The light 
lit and nothing on the AM radio so I marked the time,immediately went 
downstairs & listened to what was recorded & yup, that was it. 

I went out and waited for it to happen again (and recorded the 40M on 
the Ten-Tec again to co-ordinate events once again. The light went 
out and again I timed the sequence in the dark (one elephant, two 
elephant & so on) and about 38 seconds later the light switched 
itself on the light be it High pressure Sodium or Metal Halide, the 
prolonged firing sequence was the long sound and the 2-3 seconds at 
the end of that is when it sparked into life. 

I went back to the recording, checked it and yes, that was it. 
Problem solved. The thing is how the AM radio did not pick up a 
single thing but it was well over +20 when it was heard in the Ten- 
Tec on 40M. 

I am assuming that the frequency is that faulty ballast must be 
closer to 7Mhz than 1.6Mhz but perhaps if my radio was portable it 
would have made the difference if I were under the light when it went 
out. I suppose I could have moved my car under it & turned on AM but 
for it to be so powerful in the shack and not to show in the house AM 
radio was indeed a surprise, 

Calling the power company tomorrow. 

Again, thanks for those that replied! 

Gary 
KA1J 

> Hi, 
> 
> 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 house. 
> 
> 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 
> below: 
> 
> http://doctorgary.net/QRM-1.mp3 
> http://doctorgary.net/QRM-2.mp3 
> 
> 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. 
> 
> 
> Any ideas? 
> 
> Thanks! 
> Gary 
> KA1J 
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