Re: [linrad] Buying the Linux PC for Linrad use.

[David Garnier <dgarnier@xxxxxxxxx>]

Hi Jim,

If you piecing together your own system you would find motherboards
(in general) aren't all that expensive. Retail boxed Intel motherboards
are generally price competitive.  For example, a year ago the Intel
845GBV board we used in product retailed for about $95.  This board
was attrative because it was highly integrated: (onboard I/O, 10-100
ethernet, 4 USB's (2 were USB 2.0,) Intel's Extream Graphics chipset,
4 PCI slots.)  The big minus in the Intel solution is the P4 pricing and
DDR pricing...  If you don't need bleeding edge performance the
pricing of P3 CPU's and ram are real attractive.  At Dayton I was
looking at a P3 Intel retail mother board for $75 dollars (Intel board
guarantee is 3 years) and 1.X Ghz CPU is about the same price.
Gateway is using Intel motherboards in some of their products. In fact
those brand new P3 Intel boards were being solde by that same
vendor for $45 dollars...

Try this once. Go to Pricewatch.com once, search on motherboards,
then on Intel once, check the prices once.
http://www.pricewatch.com/2/2/32-1.htm

It's getting late, I will look at the PCUSA tomorrow...  There have
been a couple threads in the past 2 years on the IEEE EMC listserve
on which quiet PC's are used... HP Vectra's and some Dell's were
some favorites.  Buying used is another option.  More later.
73's and goodnite.

dave garnier



wb9uwa@xxxxxxxxxxx wrote:

> HI Dave,
>
> Can you go to the PCUSA web site and suggest a suitable Intel machine?
> I have done the needed screening and bypassing on a 486DX2 66 Mhz, PC,
> but it was not an easy task. Before screening it sprayed a broad band hiss
> all over the band. I fear the needed Intel machine may be above my budget.
> I do not need the rugged aspect of your testing, but if the Intel machine
> is so quiet, I would be inclined to replace the main PC with an Intel when
> the time comes. So far, I am marginally getting by with my Compaq 475 Mhz
> Pentium as a Win98SE PC, but I see that it will need replacement in the next
> few years. Already the PC clock can not keep time when the PC is on.
>
> 73, Jim Shaffer, WB9UWA.
>
> On 3 Jul 2003 at 13:47, David Garnier wrote:
>
> > Jim & All,
> >
> > I work for a major medical electronics company in the midwest,
> > I do EMC test & certification and I have some experiance on
> > certifing PC based products.  My last product met Group 1
> > Class A - IEC61000-1-2 Revison 2.
> >
> > We ended up selecting an Intel P4 CPU and Intel P4 mother
> > board for a couple of reasons.  1) The P4 processor has a better
> > overtemp solution (if the heatsink pops off) than comparable
> > AMD cpu's do.  Our product can be rolled around anywhere
> > in or outside a hospital. It has to be reliable and survive bumps and
> > elevator thresholds and the like. Boxed Processors come with a fan and
> > as a package are garanteed for 3 years, (think about this.) 2) Intel
> > claims their motherboards are tested to comply with FCC Home & Office
> > use Class B radiated emissions specs.  3)  FCC Home & Offices
> > specifies that radiated emissions testing to be done WITH the PC
> > cabinet's cover OFF.  I did such "cover off testing" to our 845GBV
> > Intel board & 2 Ghz P4 processor, from 30 Mhz to 6.5 Ghz their were
> > under the Group 1 Class B limit!  4) I did comparaible radiated
> > emission testing to a P4 based MSI motherboard and they did not fare
> > as well as the 845GBV. 5) Intel assembly notes (for PC assemblers)
> > states "to meet radiated emission compliance must use their supplied
> > I/O shield cutout to pass. 6) My take away (for this testing) is that
> > Intel manufactured motherboards are a excellent choice for being
> > radiated emission quiet.  7) Since my testing I have upgraded 3 of my
> > home PC's to Intel motherboards, that's what I use.
> >
> > Trying to purchase a FCC compliant PC cabinet & supply
> > for home use has not been so easy.  I purchased 3 PC boxes
> > at Dayton, clearly marked as being "FCC Class B compliant,"
> > they are not.  I would go as far as stating this practice as
> > fraudulant.  From past experiance I have found that the power
> > supply vendor cut corners by de-populating the power supply's
> > the AC line filtering componets (pi-network caps & chokes)
> > and adding wire jumpers in their place.  I discovered this
> > problem when 20 meters suddenly had a S15 noise floor. The
> > solution was to replace these wire jumpers with simular filter
> > componets from dead donor supplies.
> >
> > If all else fails add ferrite beads to every cable and copper tape
> > ever seam or orfice.  Remove items one at a time until the RFI appears
> > again. (Copper Tape is the EMC version of duck tape.)
> >
> > If you are going to purchase a PC, make sure the compliance
> > label on the box says it's "tested to comply with FCC home or
> > office use" run away from PC clones that are labled "assembled
> > from FCC tested componets."  As we say in the EMC business,
> > CE+CE does not equal CE.
> >
> > I have some application notes and RFI gasketing suggestings I
> > can send to you or others on this subject.  73's & GL.
> >
> > Dave Garnier - wb9own
> >
> > wb9uwa@xxxxxxxxxxx wrote:
> >
> > > Hi All,
> > > >... I am looking at
> > > >the most basic AMD option. Before I order this PC, is there
> > > >anything I should be careful of or perhaps specify a different
> > > >option? I am concerned that I can not test the PC for RF emissions
> > > >before I buy it. Perhaps there is a better case that I should
> > > >select?
> > >
> > > http://www.pcusa.com/
> > >
> > > Home Series: AMD Duron / Athlon / XP DDR System
> > >
> > > Home Series: AMD Duron / Athlon / XP DDR System Configurator :
> > > Standard with all ports : 1 serial, 1 printer, 2 USB Ports.
> > >   Current Price: $275
> > > AMD XP 1800+  1.53 ghz 266 fsb
> > > 266mhz fsb pc chips 810d sis730d w/video, audio, lan
> > > 256mb ddr / 266 MHZ ram
> > > Maxtor 20gb 7200 rpm
> > > 52x cd rom internal, IDE
> > > video 32mb max 3d svga share
> > > Specs are available on site.
> > >
> > > 73, Jim Shaffer, WB9UWA.
> >
> >



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