[Elecraft] Tracking down S9+ noise on 40M

[Rich - K1HTV]

And don't forget ELECTRIC BLANKETS! I just found the source of a loud noise
which appeared to be emanating from a neighbor's house. The noise source turned
out to be an electric blanket with independent control boxes and control units
(rotary controls). Each box was causing either a loud click every second or a
loud AC buzzzzzz when the electric blanket's control was set to call for more
heat. I took a portable Sony AM/FM/SW radio with me to the neighbor's house and
walked around the inside the house with him. At the far end of the house the
signal was moderately loud with the antenna collapsed while listening on 10
Meters. When we got to the master bedroom, the signal got noticeably louder.
Unplugging the AC from one box stopped one of the clicks/buzzes. Unplugging the
second box produced silence. In the bedroom, the noises could also be heard on
broadcast band frequencies, but were not very strongly in the AM BC band outside
the house.

The frequencies with the strongest signal from a noise source is often related
to the length of the wires attached to it. In this case, the signals seemed to
peak on higher frequencies in the 6M and 10M bands. In the case of a noisy power
line, where the wires are attached to arcing hardware are physically longer, you
can expect to have stronger signals on the lower frequencies. But even with
power lines, in addition to using an AM BC radio, it is often helpful to use a
portable radio that can tune in the 108-130 MHz AM aircraft band to find noise
sources on power line poles.

In your case, if you can hear the noise on a portable AM radio at the breaker
panel, try killing power to one breaker at a time to see which one kills the
noise. Good luck in playing noise detective!

73,
Rich - K1HTV

= = =

From: riese-k3djc at juno.com [mailto:riese-k3djc at juno.com] 
Sent: Wednesday, January 18, 2012 22:49 PM
To: kc9ehq2003 at yahoo.com
Cc: elecraft at mailman.qth.net
Subject: Re: [Elecraft] Tracking down S9+ noise on 40M

light dimmers
touch on off lamps
plasma tv sets

bob k3djc

On Wed, 18 Jan 2012 19:41:33 -0800 (PST) David Dietrich <kc9ehq2003 at yahoo.com>
writes:
> Hi All,
> 
> Could someone please explain the proper way to track down RF noise in 
> and around my house?  
.....

> 
> 73,
> 
> David, KC9EHQ