[ADXA] Noise

[w5znjoel at gmail.com]

ADXA Folks,

 

Second to antennas, noise is my favorite topic to discuss. Unfortunately for
radio amateurs, the exponential expansion of cheap consumer devices that
generate RF has significantly complicated our ability to receive weak
signals and many times impacts higher amplitude signals as well. Years ago,
the radio amateur was the source of RFI to televisions, stereos, and other
consumer devices but today the tables have turned.

 

Our initial reaction to noise is it must be power line interference but in
over 90% of the noise issues I am aware of today the source is not sparking
or arcing from power line issues. Mark, K5OO, who has provided details here
worked professionally in this area and has extensive experience and
knowledge with power line interference. Power line interference has some
unique characteristics and Mark has provided photos of what that looks like
and it won’t occur on just one band. It is easy to identify but sometimes
quite difficult to track down, especially if it is an intermittent source.

 

A noise source from a consumer device is much more complicated and difficult
to locate. As I have noted, and Jussi is now experiencing, consumer devices
can generate a significant noise source on one band in a small, discreet
bandwidth or over a larger bandwidth. The source may even “sweep” across a
frequency segment and most important it may not be in your house! I’ve noted
my 160-meter noise source to the east is originating from 1,500 feet away,
that’s over ¼ mile! One of the greatest offenders are switching power
supplies, wall warts, and internet routers and other LAN equipment can be
just as bad. Grow lights are notorious. Kim bought a lemon tree last year
and this winter it was brought in the house and a grow light was used to
provide “artificial” sunlight a few hours a day. That darn thing just
obliterated my receiver!

 

Obviously the first approach is to kill power to your house and any external
buildings and run the radio on a battery to see if the noise disappears. If
it does there is a simple procedure to follow to track down the source. If
the noise is still present then things get complicated because the source is
outside of your control. My house, shop, and station are as clean as a
hound’s tooth but I see junk originating from the neighbors’ homes. 

 

There are tons of stories of various noise sources being identified. My
buddy W0FLS in Iowa spent a year tracking down a noise source on 160 meters
to the NE toward EU, a vital direction where you don’t want to have a noise
source. The source was finally identified as a switching power supply out in
his shop that was radiating from the power cord that was acting like an
antenna. K3LR had a significant noise source appear on 15 meters one day.
Everyone has seen Tim’s massive antenna farm on video but what you don’t
know until you’ve been there is he is surrounded by houses. His noise source
was tracked down to a battery charger at a neighbor’s house across the
street.

 

As I noted, the examples are many but my point is we live in an RF
environment that is overrun with noise generators today and power line noise
is the least likely source. Over the past 15 years my noise floor on 160
meters has risen 10 dB, not from power line issues but consumer RFI
generators. That is significant when trying to copy very weak signals, even
with FT8.

 

Now, don’t just “GET IN THERE AND WORK ‘EM”, but GET IN THERE and find your
noise sources and eliminate them. Noise is Grim Reaper of radio reception!

 

73 Joel W5ZN

 

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.qth.net/pipermail/adxa/attachments/20260324/6d9e1ffe/attachment-0001.html>