[RFI] Tracking the Noise
EDWARDS, EDDIE J
EDWARDS, EDDIE J" <email@example.com
Thu, 1 Oct 1998 16:37:49 -0500
Carlos PT2HO (also PY1CAS) wrote:
> I have a problem of constant noise in my reception on all bands, it is
> an increase of the static level. The noise looks to be man made and
> when it
> rains the noise disappears.
> My question: how can I track this noise source?....As you know Brazil
> is an
> emerging country and the Power Company notified me that they won´t
> any kind of help. Any ideas?? I have a portable shortwave
> transceiver.....Does it help??
> I need to solve this problem by myself. The Eletricity Agengy and the
> Co. will not help me at all.
[K0iL] Are you saying the power company will not find the noise
for you, or they won't even correct the cause of the problem once you
find it? I hope it is only the first situation, otherwise you're SOL
(out of luck).
You'll need to learn alot about power lines and associated
hardware. I recommend the "Interference Handbook" by William R. Nelson,
WA6FQG sold by ARRL and CQ magazines. I don't know how much hardware
specific info in the book will apply to you in Brazil, but the info on
how to search will definitely be helpful. While your waiting for the
book to show up you can start searching for the noise with your portable
rcvr. It would really help to have a hand-held VHF yagi and VHF AM rcvr
to conduct your search and narrow in on the dirty pole.
First make sure it's not something in your own house. Kill the
main breaker feed and listen on the portable radio. No noise? Start
looking inside the house by opening only one breaker at a time to see if
it goes away. Once you've determined what circuit it's on, start
unplugging anything on that circuit one at a time. If the noise is not
inside the house go, start your search outside.
Start the search by listening on the portable rcvr (on AM) at
low freqs like about 1-2 MHz (AM broadcast band is good). Walk around
your block and neighborhood (maybe even drive around) while listening on
the low freqs. Note where the noise is strong then starts getting
weaker. This indicates you are going away from the noise. But watch
out for standing waves along power lines conducting the noise. It may
get better at one pole only to get worse at the next pole again. And
the phase may change too (i.e. vertical to horizontal to vertical
again). Without good equipment like a yagi, you probably won't notice a
phase difference as long as you hold the rcvr at the same angle all the
Once you've found good clean areas, start listening at higher
and higher freqs like 30-150 MHz (again AM mode, not FM) and do the same
thing in the noisy areas. You shouldn't have to go as far away to find
quiet low noise areas this time.
This is important: The higher in frequency you tune to listen
to the noise, the closer you have be to the source to hear it. Keep
this in mind as you tune and wander around.
Without a VHF yagi and VHF AM rcvr, it will be very time
consuming and perhaps impossible to narrow it down to the single noisy
pole. I recommend getting this equipment to conduct your search ASAP.
You don't want to tell the power company it's that pole over there and
then be wrong. They might not come back to correct the right pole when
you finally do find it. And be cautious about multiple noisy poles
where only one of them is causing your noise.
Good Luck Carlos!
de ed -K0iL
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