Pixelated Patches When Printing to PDF

[R37447530rlnc]

I'm using Illustrator CS6 and Windows 10.  When printing a large drawing to the Adobe PDF printer, seemingly random patches of the drawing wind up pixilated, shown in the small excerpt below.  However, if I divide the drawing into four artboards, I can print each of the four without any pixilation.  That makes me suspect the drawing is simply too large to print correctly.  The .ai file is 19mB (saved with compression and without PDF compatibility, or 55mB with compression and with PDF compatibility).

Any thoughts?

[Ton Frederiks]

Does that also happen when you save as PDF?

[R37447530rlnc]

No pixelation (see below)!  I'm embarassed that I hadn't thought to try that instead.  That would seem to solve the problem, except that the saved PDF file winds up about twice as big as the printed PDF file (32mB vs. 18mB).  But that's a problem I can address separately.

[Ton Frederiks]

If you save as PDF there is an option to Preserve Illustrator Editing Capabilities, this will put the entire Illustrator file into the PDF, making it larger.

If you do not want to edit the PDF in Illustrator (make a copy), turn the option off for a smaller file.