My 3.3Ghz seems to broadcast on most frequencies--from rfi in the am radio,
fm radio, sw bands, etc... toroid chokes on the phone/modem/net card cables
helps a lot...

Warmest regards,
John
--
If "God"--expecting an angel... if evolution--expecting an alien... just
wondering if I will be able to tell the difference!

"Jeremy Boden" wrote in message
...
| In message .com,
| writes
| I'm looking for a solid desktop (either pizza-box or mini-tower)
| computer case that has an all-metal exterior for shielding RFI. This
| is for use around radios etc. I realize that SVGA monitors, mice, and
| keyboard leak too, but right now I'm looking mainly at the PC box.
|
| Most of the cheaper cases come pretty close to good shielding, but they
| have these plastic filler panels in the drive bays that offer no
| shielding and let a lot of RF leak out.
|
| Most of the fancier cases in the computer stores around here have
| humongous plastic pieces on the side. I'm looking for all-metal.
|
| Rack-mount server cases seem to be pretty good in terms of metal
| shielding all around but I need something for desktop use.
|
| Any suggestions? If all else fails I can just put some perforated
| metal over the holes in a cheap case, but I'd rather just buy a good
| case to begin with.
|
| Tim.
|
| What band does a PC broadcast on?
|
| --
| Jeremy Boden

Jeremy Boden wrote:

What band does a PC broadcast on?

It leaks on wide range, with peaks varying on different PC's. You can
certainly hear it clearly enough bringing an AM radio near your
computer.

On Sun, 15 May 2005 20:08:27 +0100, Jeremy Boden
wrote:

What band does a PC broadcast on?

My laptop screws up my HT on two frequencies in the VHF band. I have
to be at least 20 or 30 feet away before the hiss goes away. The same
hiss is still present when the laptop is unplugged so it's not the
power adapter.

Tony

wrote:

I'm looking for a solid desktop (either pizza-box or mini-tower)
computer case that has an all-metal exterior for shielding RFI. This
is for use around radios etc. I realize that SVGA monitors, mice, and
keyboard leak too, but right now I'm looking mainly at the PC box.

Most of the cheaper cases come pretty close to good shielding, but they
have these plastic filler panels in the drive bays that offer no
shielding and let a lot of RF leak out.

Most of the fancier cases in the computer stores around here have
humongous plastic pieces on the side. I'm looking for all-metal.

Rack-mount server cases seem to be pretty good in terms of metal
shielding all around but I need something for desktop use.

Any suggestions? If all else fails I can just put some perforated
metal over the holes in a cheap case, but I'd rather just buy a good
case to begin with.

Tim.

Take a look at these barebones systems:

http://www.tigerdirect.com/applications/category/category_slc.asp?MfrId=1106&CatId=31

If the link doesn't work click on "Barebones", then select "Shuttle"
from the brands menu.
--
Former professional electron wrangler.

Michael A. Terrell
Central Florida

Take a closer look at some of the higher quality cases.

All the cases I have purchased within the past few years have plastic, as
you say, over the drive bays, but there is metal behind that plastic. If
you want to use the bay you need to pop out the metal. Except for floppies,
the drives generally have metal behind their plastic faces, too.

More important is the scheme for attaching the sides. Those little drive
holes will let some RF out, but long, narrow gaps in the side let out a lot
more. Most recent cases seem to have fairly elaborate schemes to be sure
that the sides don't leak.

I can't believe many of the mass marketed cases actually make it to
manufacturers who need to be certified, but the lengths they go to ensuring
RF shielding lately would indicate to me they are getting pressure from
somewhere.

As best I can tell, the case isn't nearly the problem the wires are, but
even there, it seems like the newer stuff is pretty well behaved. My
radios are pracically surrounded by computers and no noise anymore. Used to
be a real problem but as the computer equipment has gotten newer, the
interference problems have faded. I can still hear my Ethernet on some
bands, but I have a pretty ancient hub. Once that gets replaced I suspect
the ethernet problem will disappear, too.

...

xpyttl wrote:


Don't forget to throw some toroids on your cabling. I have a whole bunch of
2" cores I keep around just this purpose. My wifes machine threw out a lot
of QRM. Cheap case and power supply (though all-metal). Wrapped the cord
twice around a core and poof! QRM gone.

--
Visit the new Unlicensed QRP website and forums: http://www.qrp.timpauly.com
The site and forums are geared toward legal, unlicensed (non-ham) radio
operation for low-power hobbyists around the world.

xpyttl wrote:

[Good hints about where to look for shielded cases,
esp. related to FCC standards]
[...]
the case isn't nearly the problem the wires are

This is very true. A typical SVGA copper cable puts out all sorts of
hash (as well as the monitor!). And lotsa junk is radiated and
conducted out by the power supply cable, even for the "best of the
best" PC clone supplies.

I've discovered and/or engineered some workarounds, consisting of going
to optical fiber instead of metal whenever possible. But my converters
are usually outside the PC case so this doesn't completely eliminate
the radiation from copper cabling.

I'm starting to think I should just sit inside the Faraday cage with my
computer, and put all the radios outside!

Tim.

In article .com,
Tim Shoppa wrote:
xpyttl wrote:

[Good hints about where to look for shielded cases,
esp. related to FCC standards]
[...]
the case isn't nearly the problem the wires are

This is very true. A typical SVGA copper cable puts out all sorts of
hash (as well as the monitor!). And lotsa junk is radiated and
conducted out by the power supply cable, even for the "best of the
best" PC clone supplies.

I've discovered and/or engineered some workarounds, consisting of going
to optical fiber instead of metal whenever possible. But my converters
are usually outside the PC case so this doesn't completely eliminate
the radiation from copper cabling.

I'm starting to think I should just sit inside the Faraday cage with my
computer, and put all the radios outside!

Tim.



They "lumps" found on many power and data cables are ferrite cores
that attenuate the RF hash that leakes out on the conductors.
Building an RF-proof case is trivial if you don't need any
peripherals. RF comes out on the wires.

Look at a copy of the Ham Radio _The ARRL Handbook for Radio
Communications_, in any decent library or bookstore. They cover RFI
solutions.

Do you have an EMI problem ?







--
a d y k e s @ p a n i x . c o m

Don't blame me. I voted for Gore.

In message .com, Tim
Shoppa writes
xpyttl wrote:

[Good hints about where to look for shielded cases,
esp. related to FCC standards]
[...]
the case isn't nearly the problem the wires are

This is very true. A typical SVGA copper cable puts out all sorts of
hash (as well as the monitor!). And lotsa junk is radiated and
conducted out by the power supply cable, even for the "best of the
best" PC clone supplies.

I've discovered and/or engineered some workarounds, consisting of going
to optical fiber instead of metal whenever possible. But my converters
are usually outside the PC case so this doesn't completely eliminate
the radiation from copper cabling.

I'm starting to think I should just sit inside the Faraday cage with my
computer, and put all the radios outside!

Tim.

Have you tried unplugging the PC from the mains?

--
Jeremy Boden

I recently purchased a Mac Mini G-4. Quietest computer I've ever owned. I DX
mostly BCB, and I can point my KIWA loop directly at the box (about 3.5 feet
of separation), and there's no noise. The flat panel monitor causes some
hash, but I simply put the Mac to sleep and the monitor shuts up. Get a Mac!

--Guy
Thurston, OR


On 5/16/05 5:42 AM, in article , "Jeremy
Boden" wrote:

In message .com, Tim
Shoppa writes
xpyttl wrote:

[Good hints about where to look for shielded cases,
esp. related to FCC standards]
[...]
the case isn't nearly the problem the wires are

This is very true. A typical SVGA copper cable puts out all sorts of
hash (as well as the monitor!). And lotsa junk is radiated and
conducted out by the power supply cable, even for the "best of the
best" PC clone supplies.

I've discovered and/or engineered some workarounds, consisting of going
to optical fiber instead of metal whenever possible. But my converters
are usually outside the PC case so this doesn't completely eliminate
the radiation from copper cabling.

I'm starting to think I should just sit inside the Faraday cage with my
computer, and put all the radios outside!

Tim.

Have you tried unplugging the PC from the mains?