Update: I started having some problems with my R2 Extract recently. I've contacted DiFluid, but I"m out of warranty. The LCD screen also started showing some defects along the edge (I'm not the only one to have had that problem). I don't know that I still recommend these. For the money, I'd say just save up a little more and get an Atago PAL Coffee. You can find them on Ebay used from Japan for ~$300.

You said that you mixed 10g of salt with 100g of water. That's 110g total, so the TDS should be 10/110 = 9.09%, right?

At least yours reads consistently. Mine will read anywhere from 1.32 to 1.47 for the same sample, giving extraction yield from 18-21 %. I think it’s a piece of junk.