RNase: RNA ratio - making dsRNA (Aug/21/2009 )

I am trying to make dsRNA using sense and antisense transcripts generated off the same plasmid. I want to anneal the transcripts and degrade any remaining ssRNA. I plan to use RNase A or RNase T1. Does anyone know the ratio of RNase to RNA that I should use?

Thanks!

try 2ul when starting with 1-2ug of DNA tmplate