Buying the Linux PC for Linrad use.

[wb9uwa@xxxxxxxxxxx]

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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