[RFI] RF quiet UPS?

Raymond LaRue Raymond.LaRue at SkyAngel.com
Wed Oct 28 13:13:21 PDT 2009

FYI:  All square or stepped wave (read cheap) UPS's generate harmonics
well up into the HF bands.  

More expensive but RF quiet, online models that produce a sine wave
output with 1 to 2% or less, distortion, are typically clean.  I have
double conversion a PowerWare 1KVA and a Triplight 1KVA sine wave models
in the ham shack.  They are active (on-line) all the time and produce no
perceptible RF noise.

At Skyangel we use Staco on-line UPS's exclusively.  We have about 25 or
30 of them from 1 to 3 KVA.  They are power factor corrected, low
distortion units.  They also work well with a generator.  

Ray, W4BYG
Vice President, Broadcast Engineering
SkyAngel US, LLC

"I predict future happiness for Americans if they can prevent the
government from wasting the labors of the people under the pretense of
taking care of them."  Thomas Jefferson


-----Original Message-----
From: rfi-bounces at contesting.com [mailto:rfi-bounces at contesting.com] On
Behalf Of Roger (K8RI)
Sent: Wednesday, October 28, 2009 3:46 PM
To: Mel Crichton
Cc: rfi at contesting.com
Subject: Re: [RFI] RF quiet UPS?

Mel Crichton wrote:
> About to buy a new UPS for the shack computer.  Need 800 VA minimum
but thinking that 1500 would be better for future.
> Any models that I should avoid (especially noisy ones)?
This isn't what you asked, but I have 6 APC units. They vary from the
little 500 VA I use for the network, to the 1500 VA for the big
computers. The 1500 APC is sometimes on sale in the $150 range (give or
take). 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.  I checked them from 1.8 through 50 MHz and found no problems. I
didn't check lower.  I did have one of the big ones from Best Buy but
the software was buggy and it kept shutting down although it didn't
create any noise problem either.


Roger (K8RI)
> Any that you really like?
> Mel KJ9C
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