It's very common to see the noise level drop when turning off the main
because you have just disconnected a large portion of the antenna which
will weaken the signal. It's possible the noise source is the same just a
lot weaker because of reducing the antenna size. You have also disconnected
the physical connection between the wires in the house and the wires
outside of the house. Any noise coming in through the house and into the
radio via the wiring would be disconnected. I often have clients that call
me from a customer's house telling me the ham has 20 over noise level but
they see nothing on their RFI equipment.
I tell them to connect the receiver to the house power and it totally
changes the level of noise they receive when their battery powered
equipment.
Michael Martin
RFI Services
51 W Bay Front Rd
Lothian, MD 20711
240-508-3760
mike@rfiservices.com
www.rfiservices.com
On Mon, Jan 29, 2024, 6:52 AM Hare, Ed, W1RFI via RFI <rfi@contesting.com>
wrote:
> <In conversation with the tech a few days ago I offered to battery power
> my TS-890 and turn off the whole house breaker. When I did the noise went
> from S9+10 dB down to about S4, but it was still there! >
>
> What you are hearing at S4 is either a different noise source, or even the
> ambient noise levels present in typical residential environments.
>
> Re-energize the main breaker, but turn off every other breaker in the
> house. Then, turn them on one at a time and note any increase in noise
> level. If the noise goes up significantly, it is likely that there is a
> noisy device in your own home. Next, turn the breaker to that circuit off
> and turn on the next breaker. You want only one breaker at a time turned
> on at a time because there could be multiple devices in your home
> generating noise.
>
> That S4 noise could either be the ambient noise in your neighborhood from
> the aggregate of many devices or even coming in by skywave. At most
> locations, on the lower bands, at night, an S4 noise level would be pretty
> typical.
>
> Even if the S4 noise is coming from a local source, it is not likely that
> the utility would be able to locate it. It might be coming from some
> distance away. If the specific source can be identified, you may be able
> to get the utility or operator of the noisy device to address it.
>
> At S4, it is not likely that the FCC will take any specific action. On
> the lower bands, the median levels of human-made noise are typically S6 in
> most residential environments and the FCC generally does not act for noise
> levels below what most residential environments endure. Keep that in mind
> as you may negotiate with the operator of the device generating that S4
> noise (assuming is not just the ambient noise from no specific device).
>
> Ed Hare, W1RFI
>
> ________________________________
> From: RFI <rfi-bounces+w1rfi=arrl.org@contesting.com> on behalf of Wes
> Stewart via RFI <rfi@contesting.com>
> Sent: Sunday, January 28, 2024 10:50 PM
> To: RFI@contesting.com <rfi@contesting.com>
> Subject: [RFI] Mystery Noise (Aren't they all)
>
> I have been plagued for months with raucous noise, primarily on
> 160-meters. Our power co-op has a tech who maintains their com gear and
> fills in as their RFI guy. I gave him a plug at a meeting with the CEO and
> suggested that he needed better equipment. So he has the latest Radar
> Engineers 243, ultrasonic dish, etc. But he's struggled to find this
> particular noise and I finally got him into my shack and connected to my
> antenna, which pegged his meter and gave him a signature.
> The problem with this organization is if he finds a suspect, he has to
> request a line crew which usually shows up when he's not around. That was
> the case here; he identified a pole, they came out later and said they
> didn't find anything. This was all unbeknownst to me and a few days later
> I happily reported the noise was gone. He said, "Huh, that's funny, they
> said they didn't fix anything." Of course, it came back.
> It has a strong 120 Hz component, but overlayed on that is a lower
> frequency modulation that is frequency sensitive. In other words, if I
> tune for example to 1830 kHz I might hear the low frequency noise (Which I
> have dubbed rotating machinery) and then tune just +/- 10 kHz the low
> frequency stuff goes away and I'm left with the background stuff.
> In conversation with the tech a few days ago I offered to battery power my
> TS-890 and turn off the whole house breaker. When I did the noise went
> from S9+10 dB down to about S4, but it was still there! I re-energized
> the house but opened the breaker to the shack and the noise was the same as
> with the whole house turned off.
> I have limited test equipment these days. In addition to the shack
> transceiver I have a Sony ICF-SW7600GR, which with just a loopstick
> antenna, has proved to be nearly worthless, and a TinySA Ultra, that I
> haven't tried.
> This place has a smart meter which radiates prodigious garbage within a
> couple feet or so on the Sony RX on several bands, but falls off rather
> quickly with distance. The RFI guy has suggested that I get a meter maid
> out here to pull the meter while I run further tests.
> Any other suggestions?
>
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