[time-nuts] UPS for my time rack
Jim Sanford
wb4gcs at wb4gcs.org
Sat Oct 10 21:26:29 UTC 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!
Jim
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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