An open-source solution is inkscape. It can open pdf and then save as dxf. But be prepared that there will be a lot of editing necessary. Text and dimensions will be shown as dumb lines only, also distances can always be a little bit off the real value. Pdf just is no cad compatible format.
I've also been looking for this, but couldn't find I good freeware solution.
The PDF files we get can contain vector drawings or scanned drawings (or both), so I had to find a solution that supported vectorizing bitmap drawings.
The list of programs I've tried:
- Aide pdf2dxf
- anydwg pdfdxf
- autodwg pdf2dwg
- cadsofttools abviewer
- coolutils totalpdftodxfconverter
- investintech able2extract
The only program I found that did what we wanted was PDF2DWG from AutoDWG, but it's $220,-