Sorry to have followed your answer Dave, I resorted my email and your
email looked like something newer than the RFI question...
73s and thanks,
Dave
NK7Z
https://www.nk7z.net
On 06/11/2018 05:57 PM, Dave Cole (NK7Z) wrote:
No question is silly... All questions answer something someone does not
know, and hence are useful. Thank you for asking! Please feel free to
ask any question you want an answer for again.
Inverse Square Law:
Yes, all RF follows this rule, RFI is something that RF can cause. Here
are a few examples:
a. You are on 7.050 CW.
b. I open up on 7.010 with RTTY, there is no RFI.
c. If I then move to 7.050 and transmit RTTY, and it interferes with
you, then I am causing RFI.
d. If I start a saw, and it blasts 7.050, and no one hears it, then
there is no RFI...
It's sort of like the "If a tree falls in the forest, and no one hears
it did it make a noise?", question.
This could be rewritten for RFI as follows:
"If RFI is generated and no one hears it, is it RFI?" The answer in
this case is no, it is not RFI. RF needs to interfere with something to
be RFI, otherwise it is just stray RF.
Power lines carrying RFI:
Yes, it is common for this to happen. The RFI is "conducted" via the
power lines from the source, to your antenna, sometimes across miles,
sometimes across yards...
Location:
Get the ARRL RFI book, and "AC Power Line Interference by Loftness. AC
Power can be gotten here:
https://www.amazon.com/Power-Interference-Handbook-Marv-Loftness/dp/0965376036
The ARRL book can be gotten here:
http://www.arrl.org/shop/The-ARRL-RFI-Book-3rd-Edition
Both are good reading for the RFI hunter... They cover a bevy of
situations, and can help you understand what you are up against. This
helps you better locate your RFI.
Conducted RFI, (carried by the wires), can be difficult to locate, but
for the most part it is not... Conducted RFI, carried via underground
power wiring is more difficult, but not impossible...
I hope that helps...
73s and thanks,
Dave
NK7Z
https://www.nk7z.net
On 06/11/2018 02:36 PM, Tony wrote:
All:
These might be a silly questions, but given how complex this subject
is, I thought I'd ask anyway.
1. Does the inverse square-law apply to all devices that emit RFI
where the RF energy emanating from the device falls off exponentially
with distance?
2. Is it common for power and other utility cables to carry and
radiate RFI from a device located in a neighbors home over long
distances before being attenuated?
In a case like that, I would imagine locating the source of
interference would be nearly impossible with all that RFI being
radiated by utility lines.
73, Tony -K2MO
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