[RFI] apc ups

Michael Tope W4EF at dellroy.com
Mon Apr 11 15:59:46 EDT 2005

What you describe Leonard is similar to what my UPS
does. Presumeably what you are seeing when the
interference changes frequency is the operating
frequency of the switchmode power supply inside the
UPS drifting around in response to temperature and
load variations. The fixed I described in my earlier email
with the toroids on the line cords should be helpful to you
as well.

73 de Mike, W4EF....................................

----- Original Message ----- 
From: "Leonard Keepers" <lkeepers99 at comcast.net>

> hello all i have a apc bacupups pro 1100. maybe apc might have a problem 
> with many of their units.the rfi i get is a squeeling type of interference 
> that moves up and down the band. i mostly operate between 3905 and 3910. 
> some days on 3905 there is no  noise,go up to 3910 it is there. it can go 
> as much as a week and no noise on 3905,then again it doesn't. just thought 
> i would send this as a fyi.
> Leonard Keepers

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