Most definitely a power line noise and one that is exposed to rain too.
One technique that you can use to home in on the source is to use your
AM radio and start with a clear frequency as high up in the bands as you
can go and still hear the interference. As you get closer to the source
and the noise gets stronger you can either go higher in frequency and/or
select a weak station that you can hear the noise on.
Then as the interference gets stronger and becomes more noticeable you
can continue to find stronger stations and/or move higher in frequency.
It is important to stay in the AM mode in order for the interference to
Good luck in dealing with the utility but you will have a stronger
position if you can locate the problem for them.
Date: Sat, 30 Sep 2006 21:39:12 +0530
From: "Ramakrishnan Muthukrishnan" <email@example.com>
Subject: [RFI] RFI all over the band
Content-Type: text/plain; charset=UTF-8; format=flowed
I am Ramakrishnan, VU3RDD from Bangalore, India. For the past two
months, I am experiencing unprecedented amount of RFI all over the
amateur radio bands 40m, 20m till 10m at S9+10db level. I haven't
checked upwards in the frequency. Virtually nothing can be recieved.
It's also there in the broadcast bands as well.
I live in a very densely populated area full of apartments. I am also
in an apartment. To rule out any problems inside my house and also
inside our apartment, I selectively switched off/on all the individual
circuits including the lift (elevator) without any success. i.e. RFI
didn't reduce at all. After reading some available material on the
various webpages, I started roaming around our building and the area
near the circuit breaker box is kept, with a battery operated AM radio
tuned to a shortwave frequency where no station exist. I see that
noise is strong almost everywhere inside our small compound wall, but
I haven't found any specific source yet.
Today it rained a bit and to my surprise I found that the noise level
has reduced quite a lot from the S9+10 db that I was seeing. But once
the rained stopped and water drained off, RFI is back to its usual
I am completely clueless on how to find the source. I do not have a
VHF/UHF AM equipment or DF antenna yet. Many webpages suggest using
such equipment to locate the source. The power company here
(controleld by the Govt) is not very helpful either. Infact I had
already reported to them about the problem and no one turned up. This
is usual practice in this part of the world.
I would appreciate any help from experienced members of this forum. I
think the rain was a good source of clue, but don't know how to
Ramakrishnan - VU3RDD
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