Ray cross posted this topic on the RFI list and this list. Here's what I
wrote on the RFI list, tagging it onto a post from an RFI investigator
from a power company.
= = = = = =
As always, great advice. I'll expand on it only to help understanding.
RFI is like any other radio transmitter connected to an antenna -- make
RF current flow on a piece of wire and it will radiate. The more power
and the better the antenna, the greater the strength of the radiated
RF. The antennas can be anything conductive connected to the source --
power supply conductors, audio cables, video cables, etc. Wires running
down a wooden pole to "ground" power wiring are ANTENNAS, and will
radiate any RF current that they carry, including arcing on the power
system. Coax carrying video and/or internet signals are antennas, and
will radiate RF trash generated by the equipment to which they are
connected. Virtually everything connected to a power source (battery or
AC power system) is a potential noise source, every piece of
electronics, including microprocessors built into products like
refrigerators, washing machines, dryers, etc.
73, Jim K9YC
On Mon,5/9/2016 8:50 AM, Frank N. Haas KB4T wrote:
There is no definitive answer to this question. In just a few replies, you
can see that RFI can travel great distances. There are an infinite number
of combinations all of which result in a widely varying range.
There is no way to predict if the new subdivision will raise your noise
floor. It's likely but impossible to predict. The suggestion made to begin
measuring and recording your current noise floor is a good one. As the
subdivision grows you may see your noise floor come up.
Check to see if the electrical utilities planned for the new subdivision
will be overhead or underground. If underground, less noise is likely.
Frank N. Haas KB4T
Utility RFI Investigator
On Mon,5/9/2016 7:32 AM, Grant Saviers wrote:
One thing I noticed when driving around with a PC+ USB spectrum
analyzer to find a new QTH, was how much quieter neighborhoods with in
ground utilities were from those with the old "poles and pigs"
distribution systems. Another observation was that big HV
transmission systems were quieter than expected when a few hundred
yards from them. My conclusion is the buried systems shield and choke
the rf, just as happens with buried coax. IMO, much of the rf trash
we hear is generated by bad devices and then radiated from pole
systems. 60 acres NW of me were recently developed, 20 homes on 2
acre lots plus open space and underground utilities and so far so
good. A plasma TV SW from me is an S4 problem, but I haven't tracked
it down. Hopefully, the new subdivison near you will be all buried.
Several local hams here are seriously affected S9+ all bands by large
grow lights for recreational substances that are clearly not FCC
compliant re radiated and conducted emissions. The distance can be
significant - 1/4 mile or more. Most are probably illegal but of no
interest to law enforcement given trends of the new laws. The FCC
either "doesn't have the resources" or "won't investigate where
illegal activity may be happening without law enforcement present". A
perfect Catch22. In the past, when growing was clearly illegal, law
enforcement used AM radios to find the grow sites.
Grant KZ1W
Redmond, WA
On 5/9/2016 0:21 AM, Ray Benny wrote:
body {height: 100%; color:#000000; font-size:12pt;
font-family:arial, helvetica, sans-serif;}This may seem a strange
question to ask and there maybe many answers, so I will try to be
specific as to what I am looking for.
A new subdivision is being built about 1/4 mile away, east and north
east, towards EU. The homes are custom build on 1 acre parcels. What
I am trying to find out: can I expect my noise level to go up as more
homes are built?
I spend a lot of time on 160m. I have a RX 4SQ and 2 wire beverage,
and I do hear a number of small RFI noises in a number of directions
from nearby homes in my rural area. Most of the time they do not
cause any long term problems. My thought is that when new housing
comes in, new and more electronic gadgets will be inside that can
generate more RFI.
I have done some RFI tracking, mostly electric fences and
leaking/defective power line hardware, but these sources are usually
very distinctive and usually easy to fine. Finding wall wart, LED,
etc RFI is harder to find, especially on someone else's property.
Another way to ask my questions: "Does this type of RFI noise
typically radiate more than several hundred feet"?
Any thoughts or experiences are welcome.
Tnx & 73,
Ray, N6VR
Chino Valley, AZ
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