I have 3 APC SmartUPS2200NET UPSs. I have detected no interference to
my HF ham station from these. One antenna is several hundred feet away;
another passes less than 10 feet away. I have listened to these with an
IC-R10, and not found much noise.
I get much more from noise radiated by ethernet cables, unless I have
choked them (which is effective).
I bought a sun-power (I think) 1KW sine wave inverter for ham radio
field day use, to run antenna rotors, etc. While not a disaster, it
will have to be in a shielded box and all cables in and out choked, to
not interfere with HF communications. Based on rough measurements, I
don't think much of a problem at 1 GHz.
Good luck!
Jim
wb4...@amsat.org
On 10/10/2015 2:32 PM, Esa Heikkinen wrote:
Chris Waldrup kirjoitti:
I have decided I'd like to get a UPS to put on the rack containing my
Thunderbolt, the laptop that runs Lady Heather, and frequency
counter. Has anyone had bad experience noise wise with the APC brand
units like are available on Amazon and at Staples? I'd like to get
one that doesn't generate lots of RFI. Thank you.
Get a line-interactive model which has inverter with classic iron
transformer. Line-interactive means that the inverter is not
continuously on when the mains voltage is OK, but the mais voltage is
routed thru multitap transformer which gives some filtering and
enables to fix under/overvoltage errors without turning on the
inverter. When there's blackout and inverter is really started the
transformer will act as a filter which reduces the HF interference
caused by sine wave inverter.
You can recognize this kind of ups from treir weight. For example 2
kVA model should weight more than 25 kg without batteries and more
than 50 kg with batteries. You could look for example old APC
SmartUPSes or APC Matrix UPS, which has separate inverter unit,
transformer unit and battery units. Old SmartUPS'es may require float
voltage modification because their charging voltage tends to increase
when aging. Without fix it will kill the batteries too soon.
Worst case to buy is double conversion on-line model without any kind
of transformer. These are cheap but the inverter is on all the time
and it's output is not filtered. I have measured the output of these
kind of UPSes with spectrum analyzer and they are really horrible
interference sources. Not recommended if there's any kind of sensitive
electronics.
Regards,
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