OrCAD PCB Designer offers export PDF format, so it's your best choice for dra to pdf conversion. This seems like to be the only reliable way to achieve PDF export, but you will need the original software for this. Without OrCAD PCB Designer it will be very hard to convert dra to pdf.
Convert OrCAD PCB drawing to Adobe Portable document format.
We found one software available in the database for this conversion.
Microsoft Windows software - convert dra to pdf on Windows
A modeling suite used to design printed circuit boards
Convert from dra file format
The table with program actions contains information about what each program is capable of doing with their files. This may be a good pointer for further searches for certain file conversions and help you find the converter you are looking for if our search result is insufficient for you. However, it is far from perfect and may sometimes show results which are not really usable because of the nature of the software handles the files. So a conversion that appears as possible, just because of matched actions, may in fact not be possible.