wrote in message
oups.com...
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.

All the cases I have bought have a metal insert that mounts behind the
plastic front piece. If that isn't there a simple piece of aluminum screen
wire could be cut and fit on the back side of the drive bay.

Tim..

Having dabbled around in this noisy rf environment for
about 20 years..the following things will help:

1. The Antec Sonata is a good starting point as far
as cases go.
2. Get away from the noise of the convential CRT
monitor! Check on a good Flat panel from NEC or
Samsung and many others. Study up on the FCC type
shielding they adhere to...usually Canada, Japan
Korea and others. Usually they are represented by the
series of stickers of authenication as to rf rules
they adhere to. This has improved over time.

Also, some old video cards have a lot of rf type noise.
If you have an older sound card, many of them have
digital/analogue converters that sing with noise and
Rf.

Be extremely awsare of any "switching power supplies"
these are a nightmare, generally, in a radio environment.
Stay away from these supplies..confirm that it is not
a switching supply.

Also, the battery back up power supply has
the same problem in a radio environment...they
emit unbearable noise on most radios..particularly
on the 80/75 meter bands.

Put your PCI card slot metal shields in where
you've removed the PCI card. Also, most of the
good cases, including the Antec, have some RF
shields..I've never proven to myself if these
work or not..however, these in theory help
maintain a lot of RF energy from escaping from the
above mentioned components..however, it is best
to get a better built component that does not
radiate much RF.

Make sure the radio is removed from the PC area as
far as possible...also note the reduction in noise
at different angles from the PC. Mind you, an old
CRT monitor will wipe you out with noise. A small
palm held am radio put next to a pc will help
find out which component is offending you. Note
also, on difficult situations, there are all types
of shielding material. Don't overlook your AC power
and noise brought in on the lines. Some power
filtering supplies from some cable suppliers
will help.

Good luck,

Leonard...

P.S some cheap fans cause electrical noise.
Again pc positioning is critical.
Google on rf shielding material





On Sun, 15 May 2005 11:00:57 -0700, shoppa 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.

In article ,
lcw999 wrote:


Tim..

Having dabbled around in this noisy rf environment for
about 20 years..the following things will help:

1. The Antec Sonata is a good starting point as far
as cases go.
2. Get away from the noise of the convential CRT
monitor! Check on a good Flat panel from NEC or
Samsung and many others. Study up on the FCC type
shielding they adhere to...usually Canada, Japan
Korea and others. Usually they are represented by the
series of stickers of authenication as to rf rules
they adhere to. This has improved over time.

Also, some old video cards have a lot of rf type noise.
If you have an older sound card, many of them have
digital/analogue converters that sing with noise and
Rf.

Be extremely awsare of any "switching power supplies"
these are a nightmare, generally, in a radio environment.
Stay away from these supplies..confirm that it is not
a switching supply.



All PC power supplies are of the switching type.

A laptop running on it's batteries may be the quietest out-of-the-box
system.

A "KVM" (remote "keyboard/video/mouse") box will allow you to put your
PC many feet away from your radio. Use this with an LCD screen.

Some models are he http://makeashorterlink.com/?E27C22D1B

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

Don't blame me. I voted for Gore.

On 20 May 2005 21:33:49 -0400, (Al Dykes) wrote:

A "KVM" (remote "keyboard/video/mouse") box will allow you to put your
PC many feet away from your radio. Use this with an LCD screen.

What would that help, unless we are talking about at least one hundred
meters ?

The important thing is to keep the radiation away from the _antenna_.

For the direct connection of noise from the computer to the radio,
audio transformers can be used to connect the sound card to the radio
and an optoisolator for the PTT signal. This will eliminate any direct
galvanic connection between the systems, thus preventing noise
currents from flowing from the computer via the radio to the antenna
ground, causing all kinds of interference on the way.

As I said above, it is important to minimise the radiation from the
computer from reaching the antenna.

Paul OH3LWR

Be extremely awsare of any "switching power supplies"
these are a nightmare, generally, in a radio environment.
Stay away from these supplies..confirm that it is not
a switching supply.
-------
Professional receivers like the ones from Watkins -Johnson have internal
(obviously high quality) SMPS

Also, the battery back up power supply has
the same problem in a radio environment...they
emit unbearable noise on most radios..particularly
on the 80/75 meter bands.
-------------------------------------
I have an APC - Back-UPS PRO650 less than a metre away from my TenTec
transceiver and do NOT suffer from noise on any band ,because of this UPS
(which is always on -line).

Frank GM0CSZ / KN6WH

I have an APC - Back-UPS PRO650 less than a metre away from my TenTec
transceiver and do NOT suffer from noise on any band ,because of this
UPS
(which is always on -line).

************************************************** **********************
i use 2 of the APC CS 500. lot of noise. i wraped both in alu-screening.
and grounded both to third pin on the mains. cleared up that noise. and,
if you use a router, check out the d-link- DI604. i used a link-sys for
too many years. they were cheap and easy to set up. tried all the known
name routers. ended up with the d-link DI-604. no noise at all. i have
a friend who's a manager for compUSA, and she let me try a bunch. this
is
wired, i didn't try the wireless units...
good luck/ just my 2 cents...
Drifter...

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

On 15 May 2005 11:00:57 -0700, 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.

I haven't seen a case that wasn't metal. Some/most have plastic
fronts over the metal.

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.

As do the expensive ones as well. The $30 - $40 ones I've used had
metal pieces that had to be removed from the 5 1/4" bays to use them.
Unfortunately when in use the drives have plastic fronts even if they
do have a metal chassis.


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

Standard is metal, fancy is a plastic insert with metal cross pieces
and a lighted fan for effects.
Surprisingly, those come with metal covers over the drive bays behind
the plastic ones in the front panel.

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.

Find a local computer store and look at the cases they handle. Look
them over and find which ones have the metal pieces over the drive
bays. They aren't inserts, they are actually part of the front
stamping and have to be broken out. Sorta like knockouts in
electrical boxes.

However, I doubt you will find much relief even with a full metal
case.

I built up all 4 computers we use here using standard parts.

Now, I have one of those with the plastic insert on the side setting
about a foot and a half below my rigs (Icom 756 Pro, Alpha 76A,
Alinco DR610T, and Kenwood TMV7A. The computer is an MSI K7N2Delta
Platinum with a 3.2 Gig Athlon, 1 Gig 400 MHz CAS-2 DDR Ram, 400 Gig
SATA RAID, and three EIDE 7200 RPM HDs totaling 920 Gig. The monitor
(19" CRT)sets directly above the two duobanders. About three feet to
the left is this computer which is the standard all metal case with an
MSI K8N Neo Series with a 3.4 Gig 64-bit Athlon, 2 Gig 400 MHz Dual,
DDR RAM.and about 650 Gig of HD space. (I don't have the SATA RAID
installed yet.) The monitor is a 17" NEC 1760v. Each computer is on
its own UPS.

All have the dual layer, high speed DVD R/W drives and are part of a
gigabit network that has two more computers. There is a 5 port
gigabit switch, router, and cable modem less than two feet to the left
of the duobanders and just over three feet from the HF rig. (I also
run the legal limit from 160 through 10)

I have no detectable interaction between the rigs and the computer
system in the house. The one in the shop will break the squelch if
you put the HT next to the case, or hold the antenna for the best
pick up, out to about 3')

I just brought the HT (VX-7R) in and the squelch did not open even
when touching the antenna to the individual computer cases.
I should add that right now the network is running near capacity with
backups across the network and several large downloads from the cable
modem.

My wife's computer is about 15 feet to the south (in another room)
and I do not hear it with the HT in there. The one is the shop is at
the end of about 115 feet of Cat-5e and I use the HT within a foot of
the monitor. That one is only a 2 Gig Athlon, but it too has 620Gig
of HD space and a 19" CRT monitor. Those too are MSI motherboards
with my wife's being a K7N2 Delta series and 2.8 Gig Athlon. I've
forgotten the model of the one in the shop, but it's the oldest of the
four. BTW, that case is also one of those with the plastic side
windows and lighted fan.:-))

Whether it's the motherboards, the cases, grounding, or a combination,
I don't know, but interference has not been a problem...unless you
count the electric fence across the road. Why I can not pick up the
computers at all in here, but can open the squelch out to about 3'
from the computer in the shop under ideal conditions I have no idea.
I think it's more of a crap shoot. Some high end systems bother as
bad as some low end systems while some low end systems cause no
problems.

All four computers run 24 X 7.



Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com

Tim.

On 16 May 2005 01:13:01 GMT, (Martin Potter)
wrote:


) 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.



Have you considered trying an old used HP computer case, one that was used
by government? My Linux box is an HP Kayak XA (Pentium II 350 MHz) that

Most of the new boxes are very well shielded with knockouts in the
drive bays. .

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com
has a Tempest-certified case. It was used by the Canadian government for
classified work and it was part of a lot that I bought from Crown Assets
Disposal. I expect that anything similar would satisfy your needs. (My
Linux box does't need all that shielding but why bother changing it?!)

... Martin VE3OAT

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.

I know this is an old thread, but I have a related question:

Quite a few people are building their own PC cases these days--
for example, http://www.mini-itx.com (follow the links on the right side
of the page).

As far as I can see, none of these has *any* RF shielding at all. And I
have yet to hear of them causing any problems (these are not ham radio
operators). The only RF problems I've heard of recently (with consumer
electronics) are microwave ovens interfering with some kinds of cordless
phones.

I'm thinking maybe the only kind of RFI "the masses" are worried about
is TV, and they all have cable...

So I'm thinking of building a computer case for a specific use, and
I'm wondering if I should bother to worry about shielding (evidence
suggests maybe not).

My first thought was aluminum foil, but aluminum forms a non-conductive
oxide, and I don't know if it would ground reliably (not to mention the
"tinfoil hat" jokes). My second thought was copper foil from
http://www.onlinemetals.com (around $.98/sq ft, but shipping adds quite
a bit).

Any comments?

PS:
I like this one:
http://www.mini-itx.com/projects/cardboardcube/