Computer RFI problems-FARMERIK
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Rik
Thanks for the tip. I went snooping around the basement, and found the surge protector/outlet box for the server, and all along the wiring back to the panel had a large amount of noise when I put the PL-310 nearby, tuned to a fairly weak AM station. I coiled the surge protector power cord into a number of turns, to form a choke, for now, since the new ones won't be here until next week. That did cut the noise by perhaps 50% upstairs.
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I saw a number of other small things I could do too. For example, we have cable for Internet,telephone and TV, and the shielded cable for them has some RFI along it. I need to check the ground on that. Some of the cables which connect the different computers run close to the server and surge protector much more than they could. One other interesting thing I noticed was a huge boost in the AM signal when I got the PL-310 near the phone company ground for the old hard wired phone lines. Interesting! - FARMERIK
--- In ultralightdx@..., Richard Bradley <rbswl@...> wrote:
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Richard Bradley <rbswl@...>
--- On Wed, 1/12/11, farmerik wrote:
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Rik
Update- I did order the surge protectors with 70 db of RFI blocking from 100 Kc. up. One unit for each computer and one for my radios and another for the TV and cable box. AC line filters should work in either direction, [I think]. The filter units are available on line, for anyone who wants to install them at the power input jack on most computers, or as a device which can be wired in series with the power leads in a device or box.
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The chokes don't work much for LW and AM frequencies, and the RFI is throughout the household power wiring. I learned on line that a small water leak into an underground power feeder, [which I have from the road to my house], can also cause RFI. After I receive and install the new filtered outlet boxes, [APC P8VT3 R], I plan to post if that worked or not. - FARMERIK
--- In ultralightdx@..., "farmerik" <farmerik@...> wrote:
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ferrite61 <dxrx@...>
Yeah, computers are an RFI trash heap. If possible complete shut-down is the easiest cure (which is why I like Linux). I would go so far as to say unplug from the wall... the monitors also leak quite a bit. I have a UPS device, so its power off devices, power off UPS, and then unplug. Restart to desktop is about 90 seconds.
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I would recommend this proceedure along with disconnect of broadband wire from wall to first device (at the first device) should noise reduction be insufficient. I note that the modems emminate quite a bit of hash also. Its a good idea during thunderstorms also to protect the equipment! Paul S. in CT (we got 20" snow at the house this morning!)
--- In ultralightdx@..., "farmerik" <farmerik@...> wrote:
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Russ Edmunds <wb2bjh@...>
--- On Wed, 1/12/11, farmerik wrote:
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Russ Edmunds <wb2bjh@...>
--- On Wed, 1/12/11, R. Mark Barnett wrote:
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Russ Edmunds <wb2bjh@...>
--- On Wed, 1/12/11, farmerik wrote:
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huelbe_garcia@fastimap.com <huelbe_garcia@...>
Hi Farmerik,
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one of the most common sources of RFI (as noticed by colleagues here in Brazil) are the Compact Fluorescent Lights (CFL). Some brands generate lots of noise, other not that much. If you open one of these (be careful) its base contains a high frequency, harmony rich oscillator. Although the placeholders are marked in the circuit board, cheap brands hardly install the inductors/capacitor meant to mitigate the RFI. PY2WM DeMarco wrote an article specifically on CFL-generated noise and how to solve it. The translated article (by Google Translator) is available here: http://tinyurl.com/4hfjqzt the original article is here http://py2wm.qsl.br/RFI/More_on_RFI_lamps/Filter.html --hg
----- Original message -----
From: "farmerik" <farmerik@...> To: ultralightdx@... Date: Wed, 12 Jan 2011 19:34:38 -0000 Subject: [ultralightdx] Re: Computer RFI problems-FARMERIK It looks like the smaller mixture numbers are better for lower frequencies, so I had that wrong in my first post. My focus is the AC house wiring, all circuits seem to be loaded with RFI. If I put a portable radio next to a filament bulb, I get tons of RFI when I switch it on, and the higher the bulb wattage, the more noise. I started down this road when I had way too much noise in my Hammerlund HQ-100, even on the standby position, with no antenna connected. Not much sense working on antennas, if the house is so full of RFI. I did read that excellent article [tried to understand what I could] and went to the Fair-rite catalog. I don't see split chokes for LW and AM though. I see Delta make power filters for RFI, which may be what I need most. Thanks for the help, there is a lot to learn about this. -FARMERIK --- In ultralightdx@..., "Mike Mayer" <mwmayer@...> wrote:
------------------------------------ Yahoo! Groups Links
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Rik
It looks like the smaller mixture numbers are better for lower frequencies, so I had that wrong in my first post.
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My focus is the AC house wiring, all circuits seem to be loaded with RFI. If I put a portable radio next to a filament bulb, I get tons of RFI when I switch it on, and the higher the bulb wattage, the more noise. I started down this road when I had way too much noise in my Hammerlund HQ-100, even on the standby position, with no antenna connected. Not much sense working on antennas, if the house is so full of RFI. I did read that excellent article [tried to understand what I could] and went to the Fair-rite catalog. I don't see split chokes for LW and AM though. I see Delta make power filters for RFI, which may be what I need most. Thanks for the help, there is a lot to learn about this. -FARMERIK
--- In ultralightdx@..., "Mike Mayer" <mwmayer@...> wrote:
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Mike Mayer <mwmayer@...>
Peter,
I agree that the presentation you linked to is one of the best out there.
If you remember one thing it is that the suppression is proportional to the square of the number of turns. The typical clamp-on ferrite is one turn (the wire goes through once). If you look at some of the suggestions you will see multiple turns. Two turns is four times as good, three turns is 9 time as good, etc.
And yes, everything has either a noisy processor or a noisy switching power supply. That is why another option is to use an external antenna away from all of the noise sources in the house.
========================================================== From: ultralightdx@...
[mailto:ultralightdx@...] On
Behalf Of Peter Laws
On Wed,
Jan 12, 2011 at 08:35, farmerik <farmerik@...>
wrote:
> Anyone out there RFI proofed there house already, and have any pointers? http://audiosystemsgroup.com/RFI-Ham.pdf This is hardly a FAQ, but it is a good tutorial on RFI. It's ham-oriented, but RF is RF and a lot of it is receive oriented (as opposed to RFI from your own transmitter, though that is covered, too). I'm about a 1/3 of the way through it. :-) -- Peter Laws | N5UWY | plaws plaws net | Travel by Train!
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R. Mark Barnett
RFI is everywhere! I kept hearing a fuzzy "pulse" and traced it down to a battery powered Seiko wall clock. It seems like they stick a noisy processor in everything they make these days. Thanks for the link! Mark B.
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Peter Laws
On Wed, Jan 12, 2011 at 08:35, farmerik <farmerik@...> wrote:
Anyone out there RFI proofed there house already, and have any pointers?http://audiosystemsgroup.com/RFI-Ham.pdf This is hardly a FAQ, but it is a good tutorial on RFI. It's ham-oriented, but RF is RF and a lot of it is receive oriented (as opposed to RFI from your own transmitter, though that is covered, too). I'm about a 1/3 of the way through it. :-) -- Peter Laws | N5UWY | plaws plaws net | Travel by Train!
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Rik
My house hold computers are leaking RFI into the house wiring, and it is acting like an antenna for RFI where ever anything uses AC power.
I started looking around, and noticed at New Egg, some of the APC brand of outs/surge protectors sold for computers and home AV block 70 db of RFI. Also, split ferrite chokes can be fit over cables near computer devices. Higher ferrite mixture numbers are better for lower RF frequencies. Anyone out there RFI proofed there house already, and have any pointers? For now it looks like I should get RFI rated surge suppressors for each computer station and the server, as well as the TV and cable box. Also I should get a large number of the ferrite chokes for phone lines and all computer cables. -FARMERIK
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