Re: [RFI] Testing a Switching Power Supply

[michael.findley@ni.com]

I would test this product in 3 configurations.
1. Full rated Load current at all voltage outputs.
2. Half rated Load current at all voltage outputs.
3. No Load free-running.
Attach a cap in series with a 50 Ohm resistor from the output lead to the
Oscilloscope. Make sure the cap is a short around RF but no below 1 ohm Xc.
Xc=1/(2*PI*Freq*Capacitance)
The resistor is to help limit the current to the o-scope.

The LISN we use is a 50 uH inductor in series with a 1uF cap to Physical
Earth. This is placed between the wall outlet and the Switching Power
supply on Neutral and Phase. A .1uF cap in series with a 50 Ohm resistor to
Physical Earth. The analyzer connects across the 50 Ohm resistor to measure
the noise from the unit.

Hope this helps.
(Embedded image moved to file: pic19264.gif)


                                                                                
                                                
                      Eric Rosenberg                                            
                                                
                      <wd3q@starpower.n        To:       rfi@contesting.com     
                                                
                      et>                      cc:                              
                                                
                      Sent by:                 Subject:  [RFI] Testing a 
Switching Power Supply                                 
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                      01/09/2004 04:26                                          
                                                
                      PM                                                        
                                                
                                                                                
                                                
                                                                                
                                                




I recently obtained a SAMLEX RM-40 4A rack-mounted swithcing power
supply.

I'd like to know what to test/how to test this supply for noise, etc.
(as in the QST reviews from 2000).  Is there a test procedure that I can
follow?

Thanks in advance,

Eric W3DQ
Washington, DC
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