RE: [digitalradio] RFI-Free PCs? TEMPESTING
The I had to look at the esthetic side. After thinking of doing all sorts of drawings on the aluminium foil (hi) I decided to glue the foils inside the cases. I works. If you want a really neat job, there are conductive spray coatings (usually containing nickel) that you can spray on the inside of your (plastic) PC case... in many cases, this'll do a nice job of STARTING to shield the enclosure. de Peter K1PGV
Re: [digitalradio] RFI-Free PCs? TEMPESTING
Not exactly. I refer you to: http://www.nsa.gov/ia/industry/tempest.cfm in which you find the phrase "...Compromising Emanations..." . This does not necessarily imply any emanations although some do attack the problem by attempting to restrict all emanations. 73 Ted WA7ZZB - Original Message - From: Omar Shabsigh To: digitalradio@yahoogroups.com Sent: Thursday, March 27, 2008 1:15 AM Subject: [digitalradio] RFI-Free PCs? TEMPESTING Hi folks; Protecting PC's from external electromagnetic radions and protecting other electronic devices near the PC from PC radiated noise is called TEMPESTING. [...SNIP...]
Re: [digitalradio] RFI-Free PCs?
All, Thanks for the replies regarding PC RFI. Dell states that most of their computer systems are FCC Class-B certified. Class-B being the more stringent standard over Class-A. The bottom line is that there are no guarantees a Class-B device will not cause interference. From what I gather, the difference between the two FCC class ratings is about 10db. Seems that whether you build your PC from scratch or buy it ready-made, it's best to check the ratings. I intend to call Dell to find out more before I purchase one of their products. Thanks again, Tony -K2MO
RE: [digitalradio] RFI-Free PCs?
If you can run your radio on battery then kill the entire house at the main. If it is still there then you are in trouble. If it stops do a binary search for the circuit. Turn on Half and if not then turn that off and turn on half of the other half, etc.. When you find the circuit you are on you r way. I think it is outside the house. Does it stop if you remove the antenna? That can also give some hints. Gil, W0MN http://webpages.charter.net/gbaron N 44.082147 W 92.513085 1050' Hierro Candente, Batir de repente _ From: digitalradio@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Rodney Sent: Saturday, March 22, 2008 10:26 AM To: digitalradio@yahoogroups.com Subject: Re: [digitalradio] RFI-Free PCs? Bill, I haven't been following this thread, but THANKS! You've answered several questions that "I" had! Now I have a question: I have an 11-meter rig in my shack (Sorry guys, but I started in CB LONG before I became a Ham and that was in 1981) that has HALF SCALE noise! I also have the same problem with my 10-meter rig! So basically, they are both useless! I've turned off all my cordless phones, computers and anything else I can think of that would cause this, but it still exists. I live in a residential area so there are houses all around me. I'm HOPING that the problem is in MY house and not in someone else's house, that way I can locate and fix the problem! Any ideas on WHAT could be generating this noise? Rod KC7CJO Bill Turner <[EMAIL PROTECTED]> wrote: ORIGINAL MESSAGE: On Fri, 21 Mar 2008 23:17:22 -0400, Tony <[EMAIL PROTECTED] <mailto:DXDX%40optonline.net> net> wrote: > >Need to replace the PC in the shack and would like to find something >that's RFI-free out of the box. REPLY FOLLOWS What kind of RFI? RFI caused by the computer and picked up by your receiver or RFI caused by your transmitter and picked up by your computer? A couple of general observations: The first kind is caused mostly by the monitor, not the computer. Going to an LCD monitor, as you are, will cure most of that kind. The second is more difficult, but try to have the computer and transmitter physically close together with the two chassis bonded together with a short ground wire. Without that bonding wire, your interconnecting wiring creates a sort of small loop antenna. The bonding wire shorts it out. And best of all, if you can, is keep your antenna as far away from your equipment as possible, and use coax feedline instead of open wire. Use a balun at the junction of antenna and feedline to prevent current from flowing on the outside of the coax. Such current flows as a result of unbalance in the antenna system and is a major cause of RF-in-the-shack syndrome, which in turn is a major cause of computer RFI. 73, Bill W6WRT _ Never miss a thing. Make Yahoo <http://us.rd.yahoo.com/evt=51438/*http://www.yahoo.com/r/hs> your homepage.
Re: [digitalradio] RFI-Free PCs?
Turn off your main circuit breakers for the house. That will quickly tell you if the problem is in your house or not. Run the CB and 10m units off of a battery for the test. Ken WA8JXM On Mar 22, 2008, at 11:25 AM, Rodney wrote: I've turned off all my cordless phones, computers and anything else I can think of that would cause this, but it still exists. I live in a residential area so there are houses all around me. I'm HOPING that the problem is in MY house and not in someone else's house, that way I can locate and fix the problem!
Re: [digitalradio] RFI-Free PCs?
Tony I can't say for sure about the Dell model you picked but I have 7 Dell's running here in the room. One running as a server without any problem. Wish I could say the same for my power company. BTW - still on 40 P1 to P3. John, W0JAB At 03:00 PM 3/24/2008, you wrote: >All, > >I found what seems to be a good deal for the next shack PC. Dell offers >a 200 Slim Tower with a 19" LCD monitor for around $400. > >As for the RFI issues, I have my fingers crossed. Anyone using a Dell in >the shack? Any RFI complaints? > >Tony -K2MO > > >
Re: [digitalradio] RFI-Free PCs?
All, I found what seems to be a good deal for the next shack PC. Dell offers a 200 Slim Tower with a 19" LCD monitor for around $400. As for the RFI issues, I have my fingers crossed. Anyone using a Dell in the shack? Any RFI complaints? Tony -K2MO
Re: [digitalradio] RFI-Free PCs?
Is your display LCD or CRT? In my experience, CRT displays are sometimes a major source.
Re: [digitalradio] RFI-Free PCs?
On Mar 21, 2008, at 11:17 PM, Tony wrote: > All, > > Need to replace the PC in the shack and would like to find something > that's RFI-free out of the box. I've had terrible luck with desktop > PC's, but the last two laptops (Toshiba) were very quiet. > > I'm leaning towards something in the small-PC catagory with an LCD > monitor. Sound card and multiple USB ports are a must. Any suggestions > would be greatly appreciated. > > Tony -K2MO I am running a g4 mac mini, very small, solid aluminum case, no rfi at all. If you absolutely need to run windows, just get one of the intel versions and install it. -- Alex / AB2RC My rechargeable batteries are revolting.
Re: [digitalradio] RFI-Free PCs?
Bill, > What kind of RFI? The RFI was caused by the computer and picked up by the receiver. The noise level would rise a few S-units on HF when the unit was turned on. I tried two different desktops using an LCD monitor and the results were the same. One was a little noisier than the other. On the other hand, the Toshiba laptop I have is virtually noise-free and so was the one before it. My kids have a new Acer laptop and that proved to be very quiet as well. It seems odd that laptops (being mostly plasitc) would generate less noise than a metel cased desktop. Guess that's partly due to lousy components and shielding on the desktops I've tried. Thanks Bill... Tony -K2MO PS: What are you using in your shack? - Original Message - From: "Bill Turner" <[EMAIL PROTECTED]> To: Sent: Saturday, March 22, 2008 6:26 AM Subject: Re: [digitalradio] RFI-Free PCs? > ORIGINAL MESSAGE: > > On Fri, 21 Mar 2008 23:17:22 -0400, Tony <[EMAIL PROTECTED]> wrote: > >> >>Need to replace the PC in the shack and would like to find something >>that's RFI-free out of the box. > > REPLY FOLLOWS > > What kind of RFI? RFI caused by the computer and picked up by your > receiver or RFI caused by your transmitter and picked up by your > computer? > > A couple of general observations: The first kind is caused mostly by > the > monitor, not the computer. Going to an LCD monitor, as you are, will > cure most of that kind. The second is more difficult, but try to have > the computer and transmitter physically close together with the two > chassis bonded together with a short ground wire. Without that bonding > wire, your interconnecting wiring creates a sort of small loop > antenna. > The bonding wire shorts it out. > > And best of all, if you can, is keep your antenna as far away from > your > equipment as possible, and use coax feedline instead of open wire. Use > a > balun at the junction of antenna and feedline to prevent current from > flowing on the outside of the coax. Such current flows as a result of > unbalance in the antenna system and is a major cause of > RF-in-the-shack > syndrome, which in turn is a major cause of computer RFI. > > 73, Bill W6WRT > > > >
Re: [digitalradio] RFI-Free PCs?
ORIGINAL MESSAGE: On Sat, 22 Mar 2008 08:25:34 -0700 (PDT), Rodney <[EMAIL PROTECTED]> wrote: >Any ideas on WHAT could be generating this noise? REPLY FOLLOWS There are many possibilities. One of the strangest I personally ran across was a battery charger for an electric golf cart at a neighbors house about 300 feet away. Wiped out 40 meters intermittently as it cycled on and off. This was a tricky one because it mostly was off. Regardless, the best thing is to track it down using your CB radio. One by one, turn off the circuit breakers in your house. Hopefully, the noise will quit when you get the right one. If you get down to the last breaker (the one the CB radio is on), power it up with a battery and turn off the last breaker. Obviously, if the noise remains, it isn't your house. Next, start snooping around the neighborhood with your battery powered CB. You don't need a real antenna, just a short piece of wire in the antenna jack. When you get really close to the noise source and the noise gets really loud, shorten it up some more. With this method, you should be able to track it down in a matter of minutes, maybe an hour. If you find it is from a neighbor's house, knock on the door and tell him what you are doing. Ask him if he has been having any interference himself and offer to help find the cause. He probably has been having some and if you present yourself correctly, he will probably be quite eager to help. Good luck. 73, Bill W6WRT
Re: [digitalradio] RFI-Free PCs?
On Sat, Mar 22, 2008 at 5:25 AM, Rodney <[EMAIL PROTECTED]> wrote: > I've turned off all my cordless phones, computers and anything else I can > think of that would cause this, but it still exists. > > I live in a residential area so there are houses all around me. I'm HOPING > that the problem is in MY house and not in someone else's house, that way I > can locate and fix the problem! > The first step is to power your radio from a battery. If doing so cuts the noise, then the noise is traveling up the power cord to the receiver. A noise filter on the AC line will help. Once the radio is battery powered, then go and cut the main power to the house. That will tell you if the problem is in your house or not. These days, most any kind of device that plugs in can be the culprit. It doesn't have to use RF (like cordless phone, etc.)
Re: [digitalradio] RFI-Free PCs?
Bill, I haven't been following this thread, but THANKS! You've answered several questions that "I" had! Now I have a question: I have an 11-meter rig in my shack (Sorry guys, but I started in CB LONG before I became a Ham and that was in 1981) that has HALF SCALE noise! I also have the same problem with my 10-meter rig! So basically, they are both useless! I've turned off all my cordless phones, computers and anything else I can think of that would cause this, but it still exists. I live in a residential area so there are houses all around me. I'm HOPING that the problem is in MY house and not in someone else's house, that way I can locate and fix the problem! Any ideas on WHAT could be generating this noise? Rod KC7CJO Bill Turner <[EMAIL PROTECTED]> wrote: ORIGINAL MESSAGE: On Fri, 21 Mar 2008 23:17:22 -0400, Tony <[EMAIL PROTECTED]> wrote: > >Need to replace the PC in the shack and would like to find something >that's RFI-free out of the box. REPLY FOLLOWS What kind of RFI? RFI caused by the computer and picked up by your receiver or RFI caused by your transmitter and picked up by your computer? A couple of general observations: The first kind is caused mostly by the monitor, not the computer. Going to an LCD monitor, as you are, will cure most of that kind. The second is more difficult, but try to have the computer and transmitter physically close together with the two chassis bonded together with a short ground wire. Without that bonding wire, your interconnecting wiring creates a sort of small loop antenna. The bonding wire shorts it out. And best of all, if you can, is keep your antenna as far away from your equipment as possible, and use coax feedline instead of open wire. Use a balun at the junction of antenna and feedline to prevent current from flowing on the outside of the coax. Such current flows as a result of unbalance in the antenna system and is a major cause of RF-in-the-shack syndrome, which in turn is a major cause of computer RFI. 73, Bill W6WRT - Never miss a thing. Make Yahoo your homepage.
Re: [digitalradio] RFI-Free PCs?
ORIGINAL MESSAGE: On Fri, 21 Mar 2008 23:17:22 -0400, Tony <[EMAIL PROTECTED]> wrote: > >Need to replace the PC in the shack and would like to find something >that's RFI-free out of the box. REPLY FOLLOWS What kind of RFI? RFI caused by the computer and picked up by your receiver or RFI caused by your transmitter and picked up by your computer? A couple of general observations: The first kind is caused mostly by the monitor, not the computer. Going to an LCD monitor, as you are, will cure most of that kind. The second is more difficult, but try to have the computer and transmitter physically close together with the two chassis bonded together with a short ground wire. Without that bonding wire, your interconnecting wiring creates a sort of small loop antenna. The bonding wire shorts it out. And best of all, if you can, is keep your antenna as far away from your equipment as possible, and use coax feedline instead of open wire. Use a balun at the junction of antenna and feedline to prevent current from flowing on the outside of the coax. Such current flows as a result of unbalance in the antenna system and is a major cause of RF-in-the-shack syndrome, which in turn is a major cause of computer RFI. 73, Bill W6WRT
