Thanks for the reply, but no this is off! If I use lossy the file is indeed smaller otherwise as mentioned the DNG is approx twice the size.
There are some files that Adobe can't preserve raw data and so converts to linear instead, or something like that.. (I never understood details, but I've heard of this before, and Eric Chan of Adobe generally has an explanation, if not yet a solution).
Dunno if yours is such a case, but if you want an answer:
* Consider posting your camera model.
* Version of Lightroom and/or DNG Converter (try latest if you haven't yet).
* Which OS
* A sample raw file.
* Instructions to recreate problem.
I mean, if you just post camera model and details of raw format (e.g. is it sRAW?, mRAW?, normal-raw, ... ), that may be enough to start with - somebody may have noticed same symptoms and have learned reason etc.
Probably obvious, but simple work-around: don't convert to DNG (sorry ).
Just my humble opinion. Working with dng files (which I have only done on two occasions for a very short time) is like the provobial "Tower of Babel" story in the Bible "total confusion".
To each his own but it requires lots of research to be aware of all the loops and hoops.