[time-nuts] UPS for my time rack

Jim Sanford wb4gcs at wb4gcs.org
Sat Oct 10 17:26:29 EDT 2015

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!
wb4gcs at 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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