You will never know for certain what is causing the noise that you are
hearing until you find it. Speculating about what the noise could be
is a complete waste of time. Different sources of RFI sound the same.
It is impossible to know for sure until the culprit has been located.
A better use of your time would be to learn how to find it or enlist
the aid of someone near you who knows.
Locating sources of HF RFI requires a portable receiver and a
convenient form of directional antenna. There are many good choices in
portable receiver and a few decent choices in directional antennas.
The receiver needs:
1. To cover the frequency range and higher. AM/FM/SW battery operated
handheld radios are the logical choice;
2. To be sensitive in the desired frequency band(s);
3. A good signal strength indicator;
4. A jack to plug in an external directional antenna.
Eton, Grundig and Sangean make good radios for this purpose. Shop
around and find one that suits you.
Antennas suitable for HF searching and are convenient enough to carry
are generally LOOP style antennas. My personal favorite is the
National RF HFDF Vector Gun kit. The HFDF includes 3 or 4 loop
antennas that attach to a tunable amp box powered by a 9V battery held
with a pistol grip. You can see the basic setup at
http://www.nationalrf.com and look for the HFDF. You will need to
fabricate an RG-58 coaxial cable with a BNC male on one end and the
appropriate plug on the other end that will mate with your receiver.
If you don't want to spend $250 for an antenna set, you can build your
own loop for the frequency band desired. There are plans in older
versions of the ARRL Antenna Book. A local friend recently built a 160
meter portable loop antenna that we've been using to track low
frequency (2.0) MHz RFI with some success.
When the RFI is present, get outside with your DF "rig" and spin
around 360 degrees. At two points you will detect a NULL in the
receiver. Note the direction to which the broadsides of the loop are
pointing. Move at least 100 feet in a perpendicular direction and take
another bearing. Note again where the broadsides of the loop are
pointing. Where the "lines" created by these two bearings and
additional bearings all cross is where your RFI source is situated.
Achieving good accurate results with this kind of setup requires
practice. Start with known sources. You can create your own using your
HF rig and a dummy load.
Guessing about MIGHT be causing your RFI will do nothing to help you
locate the real source. Learning to find the source and taking
affirmative steps to pinpoint it is the only way you will ever truly
know what is causing the RFI you hear.
Good luck!
73,
Frank N. Haas KB4T
Utility Interference Investigator
Florida
On Sat, Jan 21, 2012 at 10:32 AM, EZ <EZRhino@fastmovers.biz> wrote:
> Hello guys!
>
> Just joined the group, found out about it from a friend.
>
> For several years now I have been plauged with an annoying noise during
> winter months. Here is a clip of what it sounds like: (Scroll all the way
> to the bottom).
> http://www.kf7p.com/KF7P/Ham_Radio/Entries/2010/1/30_RFI...its_everywhere!.html
>
<Enable Virtual Scissor>
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