Author Topic: computer generated RFI  (Read 2348 times)

MDK2

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computer generated RFI
« on: January 10, 2017, 1539 UTC »
Hello, looking for a little guidance.

I recently got an RSP2 for Xmas from my mom, a nice little gadget. Because of certain physical and monetary considerations, rather that use this on the household Mac, I'm set up on a PC my wife used to need for her work (a Dell Inspiron from 2011, where the computer is built into the monitor). It has its limitations, particularly when running SDRuno (a resource-heavy program) but it works alright. Except for one thing - the screen is LCD and so the RFI is ranges from crappy to good god, why am I putting up with this. (It doesn't help that it's in the same room as our modem and wireless router, both of which are good RFI polluters themselves.)

As a long term solution I know that I'll have to get something else. It will need to be another Windows running PC because my daughter is getting to the age of online gaming and this PC is woefully inadequate for the task, so we'll need something to share. I'm leaning toward a less expensive gaming laptop. My question is, aside from getting something with an LED screen (which doesn't look to be an issue), are there other RFI generating components I need to be aware of?

In the meantime, I have a question about the short term. I had googled this and found a forum posting from 2006 where someone claimed to have grounded the frame of the power supply to his shack's common ground, which took care of the issue well. I don't really want to open up the back of this thing to attach a ground (unlike a tower from then, this thing is tight on space), but another forum (from 2010) advised that laptop users could attach a ground to the screw on the serial port or video connector. So, where would be a good place for me to attach a ground wire on mine? (I'm attaching a link to this model's manual so you can see what I'm dealing with.)

Thanks again as always.

EDIT: it would help if I provide the link that I said I would. (PDF)
http://downloads.dell.com/manuals/all-products/esuprt_desktop/esuprt_inspiron_desktop/inspiron-one-2320_setup%20guide_en-us.pdf
« Last Edit: January 10, 2017, 1550 UTC by MDK2 »
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JCMaxwell

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Re: computer generated RFI
« Reply #1 on: January 10, 2017, 1642 UTC »
MDK2, how about picking up an inexpensive, used LED monitor at a computer repair place, plugging it in and telling the Dell to kill the video to the built-in screen?
Archdale, NC  USA
Elad FDM-S2, T2FD

MDK2

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Re: computer generated RFI
« Reply #2 on: January 10, 2017, 1704 UTC »
MDK2, how about picking up an inexpensive, used LED monitor at a computer repair place, plugging it in and telling the Dell to kill the video to the built-in screen?

Intriguing possibility. Thanks for the suggestion!
Denver, CO.
Grundig Satellit 750, Tecsun PL-600, SDRPlay RSP2 Pro.
W6LVP active loop and two homebrewed mag loops (10' and 15' circumference).
eQSL's appreciated, wickerjennie (at) gmail

James Brownyard

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Re: computer generated RFI
« Reply #3 on: January 10, 2017, 1945 UTC »
Have you tried grounding the RSP2 from the ground terminal on the Hi-Z port?  On my RSP1, I attached a ground to the outside of the SMA connector and it eliminated a great deal of RFI I was dealing with.

MDK2

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Re: computer generated RFI
« Reply #4 on: January 10, 2017, 2320 UTC »
Have you tried grounding the RSP2 from the ground terminal on the Hi-Z port?  On my RSP1, I attached a ground to the outside of the SMA connector and it eliminated a great deal of RFI I was dealing with.

Not yet, but I don't have anything to ground it to at the moment. That's going to change soon, when I get my shack in order and my mini whip up, but since the PC is a part of it, whatever solution I come up with now will apply there as well.

In the meantime, it makes listening to my Satellit 750 unpleasant as well. There's a ground out on that, but again, nothing to run it to yet.

So, another question: ARE ANY OTHER COMPONENTS IN A TYPICAL PC KNOWN TO BE RFI POLLUTERS? (All caps used to make it stand out for those who are scrolling through.)
Denver, CO.
Grundig Satellit 750, Tecsun PL-600, SDRPlay RSP2 Pro.
W6LVP active loop and two homebrewed mag loops (10' and 15' circumference).
eQSL's appreciated, wickerjennie (at) gmail

James Brownyard

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Re: computer generated RFI
« Reply #5 on: January 11, 2017, 0035 UTC »
The power supplies in computers can raise hell depending on their quality. When I first got an SDR, I was surprised at how much junk the various chargers and switching power supplies put out. Noise I could not hear on a regular radio, but contributed to the noise floor in a big way, if you know what I mean. An SDR is a great tool to actually see the noises and eliminate them.

Josh

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Re: computer generated RFI
« Reply #6 on: January 11, 2017, 1745 UTC »
Cheap psus are really noisy as the maker saves on ac line filtration... there is none. This allows a lot of the backwash from the switcher to flood the ac line, making all your ac lines into antennas broadcasting the backwash. Higher quality psus employ effective ac line filtration, and the good news is you can normally add your own if you wanna.
http://www.digikey.com/products/en/filters/power-line-filter-modules/838?WT.srch=1&gclid=CPj8gMbRutECFRyewAodJUQP7w

Ferrites on the input and output sides of a psu can help in many cases. I take it as a matter of course that every lead has to have ferrites. Video cable, usb, ac or dc power, if it's a conductor it's an antenna.

Also, once you get the antenna away from the home or at least the worst of the noisemakers, the noise greatly diminishes or is overcome by stronger desired signals.

:nerd:

:D

whatdidyouhear

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Re: computer generated RFI
« Reply #7 on: March 12, 2017, 1820 UTC »
This may come as a suprise to you check your modem.
Shut it off and see if the rf goes away.
I have a netgear modem, I had to move to another room
in order to stop interference.

MDK2

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Re: computer generated RFI
« Reply #8 on: March 12, 2017, 2019 UTC »
This may come as a suprise to you check your modem.
Shut it off and see if the rf goes away.
I have a netgear modem, I had to move to another room
in order to stop interference.

My modem and my router both put out a lot of RFI. I already knew about that. They're across the room, about 20 feet away, and they don't impact things too much, but I can't have my receivers and antennas that far from the computer.
Denver, CO.
Grundig Satellit 750, Tecsun PL-600, SDRPlay RSP2 Pro.
W6LVP active loop and two homebrewed mag loops (10' and 15' circumference).
eQSL's appreciated, wickerjennie (at) gmail

Pigmeat

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Re: computer generated RFI
« Reply #9 on: March 13, 2017, 1317 UTC »
I hate modems. My wife and I are always fighting over it. She'll go out, I turn it off to do a little dx'ing. The next thing I know I'm hearing noise again. She's back home surfing cat pictures. A ferrite choke or two as the man above said works wonders.

At least flat screen monitors don't kick out the hash those old ones did. Sweet Jesus, I could tell when the neighbors kids got home due to that crap monitor of their's kicking spurs from DC to daylight.

MDK2

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Re: computer generated RFI
« Reply #10 on: March 13, 2017, 1452 UTC »
I hate modems. My wife and I are always fighting over it. She'll go out, I turn it off to do a little dx'ing. The next thing I know I'm hearing noise again. She's back home surfing cat pictures. A ferrite choke or two as the man above said works wonders.

At least flat screen monitors don't kick out the hash those old ones did. Sweet Jesus, I could tell when the neighbors kids got home due to that crap monitor of their's kicking spurs from DC to daylight.

I've got ferrite chokes, but they don't seem to be the right material. The noise floor barely budged when I put them on. I'll need to get more, but ultimately I'm going to move everything into another part of the house, and I'll be as far from the modem and router as I can be. I'll also finally have my mini-whip up when that happens, and ultimately I hope to have a newer computer with an LED screen before long.
Denver, CO.
Grundig Satellit 750, Tecsun PL-600, SDRPlay RSP2 Pro.
W6LVP active loop and two homebrewed mag loops (10' and 15' circumference).
eQSL's appreciated, wickerjennie (at) gmail

skeezix

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Re: computer generated RFI
« Reply #11 on: March 17, 2017, 0216 UTC »
I've usually have nothing useful happen with RFI chokes on feedlines, until I put one on a coax to a loop antenna. Then it was pure magic and RFI went away.

As the Internet sez: YMMV

There's a whole lotta black magic in this stuff.  (for those that disagree, please supply proof & evidence of your work).


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Josh

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Re: computer generated RFI
« Reply #12 on: March 17, 2017, 1715 UTC »
Yes don't forget to festoon the coax to the antenna with ferrite. This hinders noises traveling up to the antenna from the in-home noisemakers as well as keeps noises from coming back down the outer coax shield.

Static_Mantra

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Re: computer generated RFI
« Reply #13 on: March 19, 2017, 1428 UTC »
i wonder if anybody has the same problem as I do, it happens in the morning, and at sunset. it starts off as the big blobs, then goes away after an hour or so! Maybe those street lights, but i'm far away from them. I live in apartment building, so it could be anything.

https://archive.org/download/Screenshot2_20170319/Screenshot%20%282%29.png

edit: it is only between 6-8 khz
« Last Edit: March 19, 2017, 1431 UTC by Static_Mantra »
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ChrisSmolinski

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Re: computer generated RFI
« Reply #14 on: March 19, 2017, 1433 UTC »
Those two greenish wide lines look like QRM from a switching power supply.
Chris Smolinski
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