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



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 its 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





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