Re: No UPS's - Re: [linrad] Buying the Linux PC for Linrad use.

["B. Aurand" <bob@xxxxxxxxxx>]

Dave, you seem to have good working knowledge of the different FCC 
certifications when it comes to computer, etc.   Maybe you could give the 
group a very brief run-down of the standards and how they affect us.

Someone else on the list mentioned only using dc-dc supplies as a strategy 
to avoid generating RFI.   I don't understand this idea.   Isn't a dc-dc 
supply simply a switcher?   Seems to me the operation is not much different 
from the line operated computer supply.   A poorly designed switching power 
supply generates RF noise and it doesn't matter where the primary power 
source comes from--line operated or battery.

Bob
K3VOT

At 04:15 PM 7/5/03 -0500, you wrote:
>Hello,
>
>I want to offer the group a piece of advice when considering
>putting an Pc system together or adding to - that is a UPS.
>
>During the certification (of our rolling around the hospital
>product) I ruefully discovered that the PC's built in UPS
>supply was extremely noisy - conducted emissions wise.
>Finding this surprise required additional testing and defining
>a new device operation mode:  "power off - ATX supply
>in standby."
>
>The UPS part of the PC supply actually runs all of the time,
>in effect it's a power conditioner which runs 100% of the time.
>
>Note, if you are considering an external UPS supply - they
>may also operate all of the time as "power conditioners."
>The switching power supplies in these things are very  noisy!
>
>The manufacture of these devices are claiming compliance
>(to the FCC's old definition of a Class A digital device for
>radiated emissions,)  that the "USER must accept interference
>from the operation of it."  (This is my pharaphasing of the FCC
>statement.)
>
>If you want to buy a UPS - ask for a "money back guarantee"
>given the possible of radiated emission interference.  Some
>manufacturers are stating their UPS's are Class B compliant,
>try them first - but make sure there exists a money back guarantee
>in case it "self jams you."  Good luck & 73's
>
>dave garnier - wb9own
>
>
>
>

LINRADDARNIL