[RFI] RF quiet UPS?

Jim Brown jim at audiosystemsgroup.com
Wed Oct 28 15:50:22 PDT 2009

On Wed, 28 Oct 2009 15:45:41 -0400, Roger (K8RI) wrote:

>They set right next to both stations and within about 30 feet of 
>the lower frequency antennas.  I've even run the 756 Pro off the one as 
>a test.  

How did you test them? No "standby" UPS is likely to make noise when 
it's plugged in and only monitoring the line in standby mode. The noise 
will be generated when power has failed and it's regenerating 120V from 
its battery. AND, you can't simply test it by unplugging it while it's 
in standby mode -- noise is usually radiated by both the input and 
output power lines, so simply unplugging it disconnects the noise source 
from half of its antenna. 

Another point -- conducted RFI is NOT usually conducted from a power 
line noise source to your rig. Rather, it is conducted from the noise 
source to the power line, radiated by the power line, and picked up by 
your ham antenna. 


Jim Brown K9YC

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