HFU HF Underground
General Category => General Radio Discussion => Topic started by: ultravista on June 01, 2018, 1813 UTC
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https://youtu.be/Y5SGkI7NUg8 (https://youtu.be/Y5SGkI7NUg8) <--- video
I was lucky to catch the QRM start this morning @ approximately 10 AM Pacific Standard time. It was wide, starting around 3000 khz up to 10000 khz.
It starts fast then slows to a crawl. The noise has pronounced high/low bumps as you'll see in the video. Almost like a train with high/low boxcars rolling through ...
The rolling was faster before I started recording.
Once it stops, it is very still with minor drift +/- and is present until approximately 10 PM Pacific Standard time. When it stops rolling, it does not start up again. It present periodically throughout the bands from 80 -> 30 meters.
Before and after 10 AM/PM, it is not present anywhere that I can see.
What would cause rolling QRM like this?
I caught it yesterday and powered-down my house at the breaker only leaving one circuit up for the radio and switching circuits to validate whether or not it was the house. To the best of my knowledge, it is not my house but something in the environment radiating RFI.
Living in Las Vegas, NV, we have a lot of solar rooftops that could perhaps contribute to this in some way. However, it lasts until 10 PM which is far past sunset.
Radio FT-950
Astron RS-35M power supply
Active Mini-Whip antenna
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That was pretty cool, but my bet is it's local psu noise.
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The PSU powering the Yaesu is a linear Astron. Yesterday, I powered-off everything in the house but the problem persisted.
If it is a PSU, it is a neighbors.
I am able to determine that it starts @ 10 AM local time - like clockwork.
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Hmm...Nevada, 12 hour flowering cycle....cheap Chinese switcher psu...ganja?
rgg
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The PSU powering the Yaesu is a linear Astron. Yesterday, I powered-off everything in the house but the problem persisted.
If it is a PSU, it is a neighbors.
I am able to determine that it starts @ 10 AM local time - like clockwork.
A neighbor's grow light?
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I am able to determine that it starts @ 10 AM local time - like clockwork.
So something on a timer. Anything where the frequency isn't terribly well controlled and allowed to drift, which means probably lots possibilities. As others have mentioned, grow lights are possible or maybe a fish tank heater, a swimming pool pump, air conditioning, an air humidifier, HEPA filter unit, LED light power supplies, etc. Many possibilities.
It matters little but Las Vegas, NV is on Pacific Daylight Time right now, not Pacific Standard Time.
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Is it typical for the interference to roll fast, then progressively slow, until it comes to a near standstill?
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Grow lights on a 12 hour timer.
I suffered from the same interference a few years back. Same characteristics on start-up which I documented in these two videos. The first video shows the same start-up cycle:
https://www.youtube.com/watch?v=iqexZsorHsw
https://www.youtube.com/watch?v=0jPzsoou03s
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From ARRL
- Generally grow lights are set by a timer for 12 hours on and 12 hours off but this can vary
Once you have established the turn on time, listen to the noise as the lamp turns on. It’s generally noisier with less of a flat spectrum. This generally lasts about 5 minutes until the lamp is warm
Damn, that pretty much sums up my experience exactly. Noisy and unstable for a few minutes that settles in and becomes stable.
Thank you for helping me narrow down the possible sources. Now the fun begins, which house is it emanating from. What type of directional antenna can I used with a Tecsun PL880 to direction find it?
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Thank you for helping me narrow down the possible sources. Now the fun begins, which house is it emanating from. What type of directional antenna can I used with a Tecsun PL880 to direction find it?
You may be able to collapse the whip (so the radio is less sensitive) and then walk/drive around until you find where it gets stronger, to locate the source. Good luck!
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I still have a UPS that does the Frankenstein Movie BZZZZZZZZZZZZZZZZ-BZZZZZZZZZZZZ-BZZZZZZZZZZZZ sounds from 67kHz to 24MHz. I'm too damn cheap to replace it, and reduced the spurs a lot with capacitors and ferrite chokes, but still hear it on close-to-house and indoor antennas. I ended up moving some antennas +50ft away from the house and power lines. Then, Clearstream water sanitizer has a UV power supply buried in our back yard for the septic that blew away LF, MF, and HF. A 1uF - 250VAC CAP across the 120VAC terminals reduced the spur range down to just 5ft. (YEA!!!!!) Very acceptable. How did I find that? Took my Eton E-10 portable and walked around the property, until I DF'ed it. You might have to do the same. Oh yeah, one mo' thing, is if you have something with MOV's (Metal Oxide Varistors.), in it, when they go bad from multiple spikes, like lightning, they too send spurs from DC to light.
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If you can hear the rfi on an ambc portable, the ferrite loopstick antenna will provide nulls in the signal when the antenna is aligned with the signal source. If you can only hear it on hf, the whip antenna will show a null in the signal when the antenna is pointed directly at the noise source. The ability to get a azimuth to the rfi source will allow you to reduce it, hopefully, that being said, some neighbors are not very cooperative.
Also, what, if any, businesses are near you by a few miles? Some use rf to seal plastics and so on and can cause a lot of rfi, however those are usually pretty stable and in the ism bands.
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Today's video from start-up to stabilization. It takes approximately 2 minutes to start-up, the the fast rolling begins around the 2 minute mark.
https://youtu.be/4XyqMayYElc
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I'd be careful approaching the place if it's a grow light(s). While weed may be legal in Nevada, the grow may not be. If it's the latter, they're not going to be happy to see you when you knock on that door. There's no point in ending up dead before your time over RFI. Call the power company and let them handle the RFI problem.
I would think in a state like Nevada, there would be a permit process for legal and medical grows? That would be a matter of public record and something you could likely find online on the county or state permit page. If the RFI source matches up with one of the local addresses you've found, it's likely safe to approach. Otherwise send in the power company. The sight of a power truck pulling up in front of the house scares illegal indoor growers more than the cops themselves.
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I won't confront anyone, but I would like to find the source.
I walked around my neighborhood today with a Tecsun, one end of the block was stronger than the other. It clearly isn't one of my immediate neighbors. I walked 30-40 houses down the road and could stick pickup the interference.
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It almost sounds like a am transmitter that has gone nuts, like it has some modulation to it but the pll is losing lock and sweeping to find it.