On Sat, 5 Dec 2009, Brendan Minish wrote:
> On Sat, 2009-12-05 at 04:17 -0500, Roger (K8RI) wrote:
>> I'm running 6 APCs that vary from 500 watts to 1500. I can't imagine
>> running a modern computer on anything less than the big ones. So far
>> "on the ones I have", when running off the battery I've found no
>> discernible noise in the HF range.
> Well I am quite active on 160M 80M and 500Khz and I have found quite a
> bit for trash there, also between 2-3.3Mhz .
> I had a 5KVA Smartups here for a while it was horrible on 40m until
> fitted with a pretty serious line filter. In all cases my connected
> systems included quite a bit of network cabling thus providing the noise
> source with an effective antenna
> There is no need to over-spec the UPS capacity too much, modern
> computers actually use less electricity than the older ones, LCD flat
> panels also consume far less than CRT monitors
3kva unit, same issues. Noisy control system, noisy charger, very noisy
run time. Ended up adding heavy duty corecom filters to both the input
and output, as well as ferrite to the network cable to silence it.
Not too surprising though, late 90s commercial meant for class A use.
Worth the work to filter though, for 4 hrs run-time for an entire rack of
I have had good luck with the small consumer APC units, I have at least 3
1000 VA smartUPS rigs at the moment. ($99 costco specials). Other then
moderate noise during a power fail I never heard anything from them except
with a pickup look right against the case. The electronics (computers, DV
player, TV, etc) were much noisier. The ferrite and/or isobars I used to
silence the electronics connected to them more than took care of the run
time noise. (A single Apple Airport Extreme power supply put out more
noise than all three combined, and a neighbors cell phone charger 10x
RFI mailing list