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In this video, I have explained a simple method of importing PDF file in AutoCAD and converting it into DWG file with the right scale.
Following are the contents of the video:
00:17 Setting Unit
02:18 Importing PDF
06:03 Fixing Imported Drawing
10:49 Scaling DWG file
Here is a video explaining method of converting raster PDF or images into native AutoCAD DWG files https://youtu.be/q4QIuR8T9Js