I have an Excel file in which various data manipulations are made on several
worksheets and I end with all the data from multiple columns being
concatenated together in column A on a final worksheet.

I then save this worksheet as a text file in order to upload it into another
program.

However, in some rows double quotes are added. These double quotes are not
visible in Excel, but they do cause my upload to fail. I can see them, and
edit them out, through a text editor like Notepad. But where do they come
from? How can I avoid them alltogether.