The 3b1 supply just rectifies the line as I remember, not really
sure what the monitor need though. Your square wave ups should
work just fine, in fact the supply may like it better than AC.
If you try it out please post the results.
gwr
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Gregory W. Ratcliff, {osu-cis}n8emr!uncle!nz8r!gwr
ham radio,aviation,tcp-ip,unix-pcs.