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Author Topic: Carriers on 40M Every 10 KHz  (Read 3091 times)
W2MV
Member

Posts: 233




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« on: May 28, 2017, 04:24:15 AM »

7.006, 7.016, 7.026[...]MHz. Any ideas what the source might be?

Tnx
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W8JX
Member

Posts: 12080




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« Reply #1 on: May 28, 2017, 01:47:07 PM »

7.006, 7.016, 7.026[...]MHz. Any ideas what the source might be?

Tnx

Foreign broadcasting in Europe. (its actually 7005, 7015, etc if you zero beat it)
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--------------------------------------
Ham since 1969....  Old School 20wpm REAL Extra Class..
G4LNA
Member

Posts: 129




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« Reply #2 on: May 29, 2017, 06:32:27 AM »

No broadcasts from Europe today in 40M, the skip is just right for EU-UK so I would certainly hear them and there's nothing.
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PA0NVD
Member

Posts: 15




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« Reply #3 on: June 03, 2017, 12:29:14 AM »

someone placed solar panels on the roof nearby? hose charging converters can be VERY noisy and the lines to the roof are nice antenna┬┤s. The same night and daytime, sunny day`s and cloudy day`s?
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K1HMS
Member

Posts: 458




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« Reply #4 on: June 03, 2017, 09:24:44 AM »

You can really see them on a panadapter. Mine were across all bands through 20m and were coming from a neighbor's network router. We are friends and he helped isolate the problem.  Yours may be from some other source.
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K0UA
Member

Posts: 1172




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« Reply #5 on: June 03, 2017, 01:01:07 PM »

Mine are about every 40khz. and they vary in frequency.. Solar panel microinverters huh?  Yep that could explain why they are constantly changing frequency it seems like up and down about 3khz .  Sometimes will sit still, but mostly on the move... Hum.. cloud sun or load conditions constantly changing would perhaps explain it.  If it ain't one thing it is several.  I have managed to git rid of most of the ethernet birdies in my own house through chokes and converting as many hosts to wireless as possible.  Just about have that totally whipped. but these things whatever they are are outside my home.
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K1HMS
Member

Posts: 458




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« Reply #6 on: June 05, 2017, 12:33:29 PM »

My LinkSys router was every 32 kHz until I put it in a cookie tin with ferrites on all of the leads to it and replaced the wall wart with a TDK wall wart
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ZENKI
Member

Posts: 1415




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« Reply #7 on: June 10, 2017, 05:03:41 AM »

This item is becoming popular in Europe for finding noise.

https://www.box73.de/product_info.php?products_id=2763

EMV-Spion nach DJ3VY und DB1NV, Komplettbausatz

The webpage is in German,, Google translate will do a decent job.

You can pinpoint the noise  very easily.
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KE2KB
Member

Posts: 555




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« Reply #8 on: August 24, 2017, 02:27:45 PM »

I'm getting spikes on 160 through 40m every 40Khz, fairly constant amplitude and frequency. 7001, 7041, 7081, etc.
The noise is there only during the day. As dusk falls, the noise disappears, and I can hear stations very clearly.
I had suspected my neighbor's solar panels, but recalled that he has had them up for several years now, and this EMI only started early this spring.

I had a similar issue last winter after buying an SDRPlay and hooking it to an un-tuned wire antenna with a 9:1 unun. That time the spikes showing up on the spectrum display were on 160m through 20m, but most pronounced on 80m and spaced 8Khz apart.
The source of that EMI turned out to be the USB cable connecting the SDRPlay to my PC. Replacing the cable solved it.

Then, in March I had to take down the wire antenna, and I did not have anything for HF until late July when I put up a 40m inverted vee.
When I connected my SDRPlay to that antenna, I was getting spikes on 40m at 40Khz intervals as I indicated earlier.
These spikes are only present during the day, so I thought solar panels. But during the early evening, when the sun was going down, the amplitude of the spikes was varying as though the signal was coming from some distance, just as normal amateur radio signals do. The timing of this was about right for the band to be changing with the diminishing sunshine; at the time when the 40m band begins to open. Even before the sun was completely down, the EMI was gone, and I was hearing stations 5x9.

I suppose the source could be solar panels, as the strength of the signal would diminish as the sun goes down, but if it is my neighbor's panels, then I would expect the amplitude to drop off much faster than this did, since his panels are only about 75ft from my 40m antenna. Also note that I was still hearing the EMI after the sun was no longer shining on his panels - although I know that the panels can still produce power even when not in direct sunlight.

I really wish I had a directional antenna on 40m. Perhaps I can rig up my SDRPlay to my Android phone and build some sort of miniature sniffer antenna to do some investigating.
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ZENKI
Member

Posts: 1415




Ignore
« Reply #9 on: August 26, 2017, 07:34:32 PM »

You can use these EMI sniffers like this one. Full sized antennas are too sensitive for pin pointing noise sources

https://www.box73.de/product_info.php?products_id=2763

This is a good general purpose product.

You can use use one of the cheap Degen  receivers with a small magnetic loop.

The best PROBE for  finding noises is whats called a H field loop probe. You can make one very easily yourself.

http://emcesd.com/tt120100.htm

These probes are so good when used with a SDR receiver that i can measure leakage  from the seams of my PC case. Its also great for find the exact WalWart  switchmode that causes hash. Every ham should have an collection of H field probes. You can buy them from EMC companies like ETS Lindgren, R&S or  Beehive in the USA.  When have a set of these probes and you start poking around you will find all the crap the spew off USB cables,  keyboards, mice and every little gadget in your house. THESE ARE MUST HAVE TOOL otherwise you just flying blind trying to find a needle in the hay stack.


I'm getting spikes on 160 through 40m every 40Khz, fairly constant amplitude and frequency. 7001, 7041, 7081, etc.
The noise is there only during the day. As dusk falls, the noise disappears, and I can hear stations very clearly.
I had suspected my neighbor's solar panels, but recalled that he has had them up for several years now, and this EMI only started early this spring.

I had a similar issue last winter after buying an SDRPlay and hooking it to an un-tuned wire antenna with a 9:1 unun. That time the spikes showing up on the spectrum display were on 160m through 20m, but most pronounced on 80m and spaced 8Khz apart.
The source of that EMI turned out to be the USB cable connecting the SDRPlay to my PC. Replacing the cable solved it.

Then, in March I had to take down the wire antenna, and I did not have anything for HF until late July when I put up a 40m inverted vee.
When I connected my SDRPlay to that antenna, I was getting spikes on 40m at 40Khz intervals as I indicated earlier.
These spikes are only present during the day, so I thought solar panels. But during the early evening, when the sun was going down, the amplitude of the spikes was varying as though the signal was coming from some distance, just as normal amateur radio signals do. The timing of this was about right for the band to be changing with the diminishing sunshine; at the time when the 40m band begins to open. Even before the sun was completely down, the EMI was gone, and I was hearing stations 5x9.

I suppose the source could be solar panels, as the strength of the signal would diminish as the sun goes down, but if it is my neighbor's panels, then I would expect the amplitude to drop off much faster than this did, since his panels are only about 75ft from my 40m antenna. Also note that I was still hearing the EMI after the sun was no longer shining on his panels - although I know that the panels can still produce power even when not in direct sunlight.

I really wish I had a directional antenna on 40m. Perhaps I can rig up my SDRPlay to my Android phone and build some sort of miniature sniffer antenna to do some investigating.
Logged
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