[BC] Can't Get A Direct Answer

[Lamar Owen]

On Wednesday 24 October 2007, Rik van Riel wrote:
> I have an APC Back-UPS 1000 here at home, which does
> not seem to cause much trouble.
>
> According to a discussion on freenode #hamradio, the
> Back-UPS series are offline UPSes that mostly keep the
> battery out of the loop, while the APC Smart-UPS are
> online UPSes that cause RFI problems.

My rackmounted 3000VA SmartUPS's are standy units, too, just with very 
agressive switchover.  They don't run the inverter constantly.  They do have 
a pure sine output, though.  Different eras of SmartUPS will likely act 
differently.  Symmetrix high-end UPS's are full online, as far as I know.

I have five Xantrex charger/inverters that are, well, quite strange in the way 
they operate.  This are the SineWave Plus models; to charge the batteries 
they run the inverter at a low voltage; the switching devices in the inverter 
are bidirectional, and inverting at the lower voltage actually acts as an 
in-phase charger, and keeps the inverter online constantly as well.  Very 
slick, very elegant, but not a super-smooth sinewave, either.  Not as much 
noise as the high-frequency ProSine line; the SWPlus operates at line 
frequency and has three bits of resolution in the sinewave, using techniques 
similar to magamps to produce the waveform.

> OTOH, I am seeing some RFI on eg. 10780 kHz and have
> not tracked down the cause yet.  

10.7MHz is a rather common IF for several receivers (ICOM R8500, for 
instance).  Could be images or a LO somewhere mixing in.

The more interesting question is, to me: What is a Linux kernel developer 
doing on BC? :-)

Incidentally, thanks for the DNSBL you host at surriel....
-- 
Lamar Owen
Chief Information Officer
Pisgah Astronomical Research Institute
1 PARI Drive
Rosman, NC  28772
(828)862-5554
www.pari.edu