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Re: [RFI] Solar question

To: rfi@contesting.com
Subject: Re: [RFI] Solar question
From: KD7JYK DM09 <kd7jyk@earthlink.net>
Date: Mon, 6 Dec 2021 14:25:34 -0800
List-post: <mailto:rfi@contesting.com>
I initially thought that it was a solar panel inverter, but since it occurs when it is dark, I'm thinking that is not quite right. Can someone confirm my thought on this as not being a solar issue?  The only thing that I can think of is if there are battery storage of electricity and they run an inverter at night to power the house.  Thoughts on this?  Would that inverter run during the daytime too?

Just some thoughts...

"It used to be only from 9AM to approximately noon and the rest of the day was clear"

Suggests it's controlled, or someone is controlling it.

"Now the problem seems to be happening all day long -- just about 24 hours a day and it's bad"

Could be something failing, could be something someone is now leaving on.

"s7 on 20m and s3 to 5 on 40m and I suspect that it affects just about every other hf band"

A good start, just to get a basic baseline, would be check ever other band. Check "DC to daylight", if you can, for starters. Every radio, every frequency, every mode, every antenna, is a good way to get a general idea of the extent of the problem, frequency range, and rule out equipment. If you can, check at higher frequencies, as due to various reasons, the higher a frequency the noise is heard on, the closer one will be to the source. I often check up to 1 GHz, which narrows the cause down from several square miles on HF (one pole near me covered 18 square miles with RFI), to a few tens of feet at most when it comes to power lines (generally the source, and nothing else).

"I have been through the exercise of turning off the power to my house and running the transceiver on battery with no difference in the noise level."

Not a bad place to start. Before that, did you install anything? If you did nothing, changed nothing, no reason to suspect the RFI is yours.

"I initially thought that it was a solar panel inverter, but since it occurs when it is dark, I'm thinking that is not quite right. Can someone confirm my thought on this as not being a solar issue?"

There are panels, panels with invertors, and invertors. Panels are generally not noisy. Panels with invertors/"optimizers" will be noisy when operational, that is, when sufficient light is hitting them. Invertors to convert stored DC power, to household AC power, would typically be operational when household AC power is needed, so essentially 24/7/365, from the moment a system is put in. If there was a sudden change, and not across all hours, or light-only hours, it's probably not solar related.

"Thoughts on this?  Would that inverter run during the daytime too?"

Yes, there's a very good chance a solar powered home uses electricity 24/7, like a commercially powered home, so the noise would have been constant the moment the system was put online.

"My suspicions right now are that it is a solar cell going bad on a light pole or cable TV leakage."

Curious how you came to each of these. A "solar cell" (did you mean photocell) on a dusk/dawn light, may produce a buzzing, hissing, crackling sound when failing, and would be across a very wide range of frequencies, although depending on wiring configuration, could be stronger at certain frequencies. Cable TV leakage, in the past, and analog signals, had an odd buzzing sound that changed with the image being sent. It's quite unique, and sounds like nothing else. If you have an older TV, and a pocket AM radio, turn on the radio, set it to the upper end of the band, crank up the volume, set it on a TV, then turn on the TV. The cable TV leak detectors I've seen use AM, and listen at 135MHz. I don't know what RFI from new digital cable systems sounds like, we don't have anything like that around here.

"I have walked around the neighborhood with a portable radio and the only place I hear interference coming from is the light pole across the street and from the power transformer located two houses away. My thought are that this is just a symptom, but not necessarily the cause. Thoughts?"

Is it the exact same sound you hear at home on 20, and 40? Are you checking on the same frequencies, and same modes as what you hear at home?

"I've contacted the electric utility company and asked for their help"

It is a 60, or 120 Hz AC line noise/arcing that you are hearing isolted to only their equipment? They are good to call when it has been narrowed down to a good 98-100% that it's related to their equipment, but not for general RFI, as most people live in a self-induced RFI cesspool. Any other operators in the are that can help you track down what you are hearing? As for power lines, most are bad, in most places, so you can get a feel for this, and rule in/out, compared to what you are hearing, and may hear power related issues, by driving around with am AM broadcast band receiver. Turn on your radio, crank up the volume, drive up and down a few streets, I imagine you'll get noise from a LOT of poles, and hardware, most of it sounding the same, since the driving source is the same. Compare that to what you are hearing.

How about the tons of RFI generating electronic christmas garbage that goes up this time of year?

Kurt

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